Patient empowerment improves follow-up data collection after fetal surgery for spina bifida: institutional audit

OBJECTIVES

To define and grade fetal and maternal adverse events following fetal surgery for spina bifida and to report on the impact of engaging patients in collecting follow-up data.

METHODS

This prospective single-center audit included 100 consecutive patients undergoing fetal surgery for spina bifida between January 2012 and December 2021. In our setting, patients return to their referring unit for further pregnancy care and delivery. On discharge, referring hospitals were requested to return outcome data. For this audit, we prompted patients and referring hospitals to provide data in cases of missing outcomes. Outcomes were categorized as missing, returned spontaneously or returned following additional request, by the patient and/or referring center. Postoperative maternal and fetal complications until delivery were defined and graded according to Maternal and Fetal Adverse Event Terminology (MFAET) and the Clavien-Dindo classification.

RESULTS

There were no maternal deaths, but severe maternal complications occurred in seven women (anemia in pregnancy, postpartum hemorrhage, pulmonary edema, lung atelectasis, urinary tract obstruction and placental abruption). No cases of uterine rupture were reported. Perinatal death occurred in 3% of fetuses and other severe fetal complications in 15% (perioperative fetal bradycardia/cardiac dysfunction, fistula-related oligohydramnios, chorioamnionitis and preterm prelabor rupture of membranes (PPROM) before 32 weeks). PPROM occurred in 42% of patients and, overall, delivery took place at a median gestational age of 35.3 weeks (interquartile range, 34.0-36.6 weeks). Information provided following additional request, from both centers and patients but mainly from the latter, reduced missing data by 21% for gestational age at delivery, 56% for uterine-scar status at birth and 67% for shunt insertion at 12 months. Compared with the generic Clavien-Dindo classification, the MFAET system ranked complications in a more clinically relevant way.

CONCLUSIONS

The nature and rate of severe complications following fetal surgery for spina bifida were similar to those reported in other large series. Spontaneous return of outcome data by referring centers was low, yet patient empowerment improved data collection. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Core outcome set for perinatal interventions for congenital diaphragmatic hernia

OBJECTIVE

To develop a core set of prenatal and neonatal outcomes for clinical studies evaluating perinatal interventions for congenital diaphragmatic hernia, using a validated consensus-building method.

METHODS

An international steering group comprising 13 leading maternal-fetal medicine specialists, neonatologists, pediatric surgeons, patient representatives, researchers and methodologists guided the development of this core outcome set. Potential outcomes were collected through a systematic review of the literature and entered into a two-round online Delphi survey. A call was made for stakeholders with experience of congenital diaphragmatic hernia to review the list and score outcomes based on their perceived relevance. Outcomes that fulfilled the consensus criteria defined a priori were discussed subsequently in online breakout meetings. Results were reviewed in a consensus meeting, during which the core outcome set was defined. Finally, the definitions, measurement methods and aspirational outcomes were defined in online and in-person definition meetings by a selection of 45 stakeholders.

RESULTS

Overall, 221 stakeholders participated in the Delphi survey and 198 completed both rounds. Fifty outcomes met the consensus criteria and were discussed and rescored by 78 stakeholders in the breakout meetings. During the consensus meeting, 93 stakeholders agreed eventually on eight outcomes, which constituted the core outcome set. Maternal and obstetric outcomes included maternal morbidity related to the intervention and gestational age at delivery. Fetal outcomes included intrauterine demise, interval between intervention and delivery and change in lung size in utero around the time of the intervention. Neonatal outcomes included neonatal mortality, pulmonary hypertension and use of extracorporeal membrane oxygenation. Definitions and measurement methods were formulated by 45 stakeholders, who also added three aspirational outcomes: duration of invasive ventilation, duration of oxygen supplementation and use of pulmonary vasodilators at discharge.

CONCLUSIONS

We developed with relevant stakeholders a core outcome set for studies evaluating perinatal interventions in congenital diaphragmatic hernia. Its implementation should facilitate the comparison and combination of trial results, enabling future research to better guide clinical practice. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Placental gas exchange during amniotic carbon dioxide insufflation in sheep

OBJECTIVE

Insufflation of the amniotic cavity with carbon dioxide (CO₂ ) is used clinically to improve visibility during complex fetoscopic surgery. Insufflation with heated, humidified CO₂ has recently been shown to reduce fetal hypercapnia and acidosis in sheep, compared with use of cold and dry CO₂ , but the underlying mechanisms are unclear. The aim of this study was to investigate whether differences in placental CO₂ and oxygen (O₂ ) exchange during insufflation with heated and humidified vs cold and dry CO₂ could explain these findings.

METHODS

Thirteen fetal lambs at 105 days of gestation (term, 146 days) were exteriorized partially, via a midline laparotomy and hysterotomy, and instrumented with an umbilical artery catheter, an umbilical vein catheter and a common umbilical vein flow probe. Arterial and venous catheters and flow probes were also inserted into the maternal uterine circulation. Six ewes were insufflated with cold, dry CO₂ (22°C; 0-5% humidity) and seven with heated, humidified CO₂ (40°C; 95-100% humidity) at 15 mmHg for 180 min. Blood-flow recordings and paired arterial and venous blood gases were sampled from uterine and umbilical vessels. Rates of placental CO₂ and O₂ exchange were calculated.

RESULTS

After 180 min of insufflation, fetal survival was 33% (2/6) using cold, dry CO₂ and 71% (5/7) using heated, humidified CO₂ . By 120 min, fetuses insufflated with heated, humidified CO₂ had lower arterial CO₂ levels and higher arterial pH compared to those insufflated with cold, dry gas. Insufflation decreased significantly placental gas exchange in both groups, as measured by rates of both (i) fetal CO₂ clearance and O₂ uptake and (ii) maternal O₂ delivery and CO₂ uptake from the fetal compartment.

CONCLUSIONS

Lower arterial CO₂ and higher pH levels in fetuses insufflated with heated and humidified, compared to cold and dry, CO₂ could not be explained by differences in placental gas exchange. Instead, heated and humidified insufflation appeared to reduce fetal CO₂ absorption from the uterus, supporting its use in preference to cold, dry CO₂ . © 2019 International Society of Ultrasound in Obstetrics and Gynecology.

Antenatal sildenafil treatment improves neonatal pulmonary hemodynamics and gas exchange in lambs with diaphragmatic hernia

OBJECTIVES

Infants with congenital diaphragmatic hernia (CDH) are predisposed to pulmonary hypertension after birth, owing to lung hypoplasia that impairs fetal pulmonary vascular development. Antenatal sildenafil treatment attenuates abnormal pulmonary vascular and alveolar development in rabbit and rodent CDH models, but whether this translates to functional improvements after birth remains unknown. We aimed to evaluate the effect of antenatal sildenafil on neonatal pulmonary hemodynamics and lung function in lambs with diaphragmatic hernia (DH).

METHODS

DH was surgically induced at approximately 80 days' gestation in 16 lamb fetuses (term in lambs is approximately 147 days). From 105 days' gestation, ewes received either sildenafil (0.21 mg/kg/h intravenously) or saline infusion until delivery (n = 8 fetuses in each group). At approximately 138 days' gestation, all lambs were instrumented and then delivered via Cesarean section. The lambs were ventilated for 120 min with continuous recording of physiological (pulmonary and carotid artery blood flow and pressure; cerebral oxygenation) and ventilatory parameters, and regular assessment of arterial blood gas tensions. Only lambs that survived until delivery and with a confirmed diaphragmatic defect at postmortem examination were included in the analysis; these comprised six DH-sildenafil lambs and six DH-saline control lambs.

RESULTS

Lung-to-body-weight ratio (0.016 ± 0.001 vs 0.013 ± 0.001; P = 0.06) and dynamic lung compliance (0.8 ± 0.2 vs 0.7 ± 0.2 mL/cmH₂ O; P = 0.72) were similar in DH-sildenafil lambs and controls. Pulmonary vascular resistance decreased following lung aeration to a greater degree in DH-sildenafil lambs, and was 4-fold lower by 120 min after cord clamping than in controls (0.6 ± 0.1 vs 2.2 ± 0.6 mmHg/(mL/min); P = 0.002). Pulmonary arterial pressure was also lower (46 ± 2 vs 59 ± 2 mmHg; P = 0.048) and pulmonary blood flow higher (25 ± 3 vs 8 ± 2 mL/min/kg; P = 0.02) in DH-sildenafil than in DH-saline lambs at 120 min. Throughout the 120-min ventilation period, the partial pressure of arterial carbon dioxide tended to be lower in DH-sildenafil lambs than in controls (63 ± 8 vs 87 ± 8 mmHg; P = 0.057), and there was no significant difference in partial pressure of arterial oxygen between the two groups.

CONCLUSIONS

Sustained maternal antenatal sildenafil infusion reduced pulmonary arterial pressure and increased pulmonary blood flow in DH lambs for the first 120 min after birth. These findings of improved pulmonary vascular function are consistent with improved pulmonary vascular structure seen in two previous animal models. The data support the rationale for a clinical trial investigating the effect of antenatal sildenafil in reducing the risk of neonatal pulmonary hypertension in infants with CDH. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Physiological effects of partial amniotic carbon dioxide insufflation with cold, dry vs heated, humidified gas in a sheep model

OBJECTIVE

Partial amniotic carbon dioxide (CO₂ ) insufflation (PACI) is used to improve visualization and facilitate complex fetoscopic surgery. However, there are concerns about fetal hypercapnic acidosis and postoperative fetal membrane inflammation. We assessed whether using heated and humidified, rather than cold and dry, CO₂ might reduce the impact of PACI on the fetus and fetal membranes in sheep.

METHODS

Twelve fetal lambs of 105 days' gestational age (term = 145 days) were exteriorized partially, via a midline laparotomy and hysterotomy, and arterial catheters and flow probes were inserted surgically. The 10 surviving fetuses were returned to the uterus, which was then closed and insufflated with cold, dry (22 °C at 0-5% humidity, n = 5) or heated, humidified (40 °C at 100% humidity, n = 5) CO₂ at 15 mmHg for 180 min. Fetal membranes were collected immediately after insufflation for histological analysis. Physiological data and membrane leukocyte counts, suggestive of membrane inflammation, were compared between the two groups.

RESULTS

After 180 min of insufflation, fetal survival was 0% in the group which underwent PACI with cold, dry CO₂ , and 60% (n = 3) in the group which received heated, humidified gas. While all insufflated fetuses became progressively hypercapnic (PaCO₂  > 68 mmHg), this was considerably less pronounced in those in which heated, humidified gas was used: after 120 min of insufflation, compared with those receiving cold, dry gas (n = 3), fetuses undergoing heated, humidified PACI (n = 5) had lower arterial partial pressure of CO₂ (mean ± standard error of the mean, 82.7 ± 9.1 mmHg for heated, humidified CO₂ vs 170.5 ± 28.5 for cold, dry CO₂ during PACI, P < 0.01), lower lactate levels (1.4 ± 0.4 vs 8.5 ± 0.9 mmol/L, P < 0.01) and higher pH (pH, 7.10 ± 0.04 vs 6.75 ± 0.04, P < 0.01). There was also a non-significant trend for fetal carotid artery pressure to be higher following PACI with heated, humidified compared with cold, dry CO₂ (30.5 ± 1.3 vs 8.7 ± 5.5 mmHg, P = 0.22). Additionally, the median (interquartile range) number of leukocytes in the chorion was significantly lower in the group undergoing PACI with heated, humidified CO₂ compared with the group receiving cold, dry CO₂ (0.7 × 10^-5 (0.5 × 10^-5 ) vs 3.2 × 10^-5 (1.8 × 10^-5 ) cells per square micron, P = 0.02).

CONCLUSIONS

PACI with cold, dry CO₂ causes hypercapnia, acidosis, hypotension and fetal membrane inflammation in fetal sheep, raising potential concerns for its use in humans. It seems that using heated, humidified CO₂ for insufflation partially mitigates these effects and this may be a suitable alternative for reducing the risk of fetal acid-base disturbances during, and fetal membrane inflammation following, complex fetoscopic surgery. © 2018 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Lung size and liver herniation predict need for extracorporeal membrane oxygenation but not pulmonary hypertension in isolated congenital diaphragmatic hernia: systematic review and meta-analysis

OBJECTIVES

To identify antenatal predictors of persistent pulmonary hypertension (PPH) and the need for extracorporeal membrane oxygenation (ECMO) in fetuses with congenital diaphragmatic hernia (CDH).

METHODS

We performed a systematic literature review on antenatal diagnostic tests in fetuses with isolated CDH. The primary outcomes assessed were PPH within 28 days of age and the need for ECMO. Quality of studies was assessed with the QUADAS-2 tool. Meta-analysis was performed when at least three studies reported on the same test. Sensitivity analysis was performed according to prenatal management of CDH (tracheal occlusion vs expectant management).

RESULTS

Thirty-eight studies met the inclusion criteria. Fifteen reported on the incidence of PPH only, 19 on the need for ECMO only and four reported on both outcomes. The general quality of the studies was moderate; most studies were retrospective (61%) and single-center series (92%). One study included only fetuses undergoing tracheal occlusion, 22 included only fetuses managed expectantly in utero and 15 included both populations. We could not identify antenatal predictors of PPH. The need for ECMO was predicted by parameters indicative of lung size: lung-to-head ratio (LHR) (relative risk (RR) for LHR < 1, 1.65 (95% CI, 1.27-2.14)) and observed/expected LHR (standardized mean difference (SMD), -0.70 (95% CI, -0.98 to -0.42)) measured by ultrasound and observed/expected total lung volume (SMD, -1.00 (95% CI, -1.52 to -0.48)) measured by magnetic resonance imaging. Liver herniation was also associated with an increased risk of need for ECMO (RR, 3.04 (95% CI, 2.23-4.14)). These results were confirmed by a sensitivity analysis of studies that included only expectantly managed cases. Data on vascular assessment for the prediction of PPH could not be pooled as most of the parameters were evaluated in a single series or in different series by the same principal investigator.

CONCLUSIONS

In fetuses with CDH, lung size and liver herniation predict the need for ECMO, however a predictor for PPH is still lacking. Further studies aimed at diagnosing impaired vascular development in utero should therefore be undertaken. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Fertility, pregnancy and gynecological outcomes after fetoscopic surgery for congenital diaphragmatic hernia

STUDY QUESTION

What is the impact of fetoscopic surgery for isolated Congenital Diaphragmatic Hernia (CDH) on future reproductive and gynecological outcomes?

SUMMARY ANSWER

We did not observe an increase of obstetric or gynecological problems after fetoscopic surgery nor was there an increased risk for subsequent infertility.

WHAT IS KNOWN ALREADY

The reproductive and gynecological outcomes of patients undergoing open maternal-fetal surgery are known. The most relevant counseling items are the elevated risk for uterine dehiscence and rupture (up to 14%).

STUDY DESIGN, SIZE, DURATION

Bi-centric study over a 10-year period including 371 women carrying a fetus with isolated CDH either managed expectantly (n = 167) or operated in utero (n = 204).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Consenting patients filled out a survey with 23 questions (2 open and 21 multiple choice). Questionnaires were custom designed to obtain information on subsequent reproductive or gynecological problems as well as psychological impact.

MAIN RESULTS AND THE ROLE OF CHANCE

The response rate was 40% (147/371). More women in the FETO group attempted a subsequent pregnancy: 70% (62/89) when compared with 47% (27/58) in controls (P = 0.009). This coincided with a longer follow-up in the FETO group (76 versus 59 months; P < 0.001) and a lower survival rate in the index pregnancy (53 versus 72%; P = 0.028). There was no difference in the number of nulliparous or parous women, neither in the conception rate. In total, there were 129 subsequent pregnancies. Nobody reported secondary fertility problems. Four women in the FETO group and one in the control reported a congenital anomaly in a subsequent pregnancy. Twenty-one pregnancies were reported with at least one complication (FETO: 23% (14/60), controls 27% (7/26)). During delivery or in the post-partum period 11 patients reported at least 1 complication (FETO 17% (10/59), controls 4% (1/24)). New onset gynecological problems occurred in 14 participants (10%). None of these events were more likely in one or the other group. Psychological and emotional impacts were frequent in both the FETO (41%) and the control groups (46%) (P = 0.691).

LIMITATIONS, REASONS FOR CAUTION

The response rate was 40% (147/371), less than desired. The use of unvalidated self-reported outcomes may skew exact determination of the nature and severity of medical complications. The number of observations for uncommon events was low. The mean follow-up period to detect gynecological complications may be too short.

WIDER IMPLICATIONS OF THE FINDINGS

This is the first evidence that fetoscopic surgery for CDH does not compromise future reproductive potential or obstetrical outcome when compared with expectant management. A pregnancy complicated by a serious congenital birth defect, such as CDH, frequently has a measurable psychological impact.

STUDY FUNDING/COMPETING INTEREST

The authors have no conflicts to declare. J.D. receives a fundamental clinical research grant of the Fonds Wetenschappelijk Onderzoek - Vlaanderen (FWO; 18.01207). A.C.E. is supported by the Erasmus+Program of the European Union (Framework agreement number 2013-0040; contract 1011990). This was presented at the 61st meeting of the Society of Gynaecologic Investigation, in Florence, March 2014 (F-111).

Cardiac assessment in fetuses with right-sided congenital diaphragmatic hernia: case-control study

OBJECTIVE

To evaluate cardiac anatomy and function in fetuses with right-sided congenital diaphragmatic hernia (RCDH), and to compare these values with those of normal controls.

METHODS

Fetal echocardiography was performed in 17 consecutive cases with isolated RCDH and 17 gestational age-matched controls. Two-dimensional measurements included ventricular and outflow tract diameters. Doppler ultrasound was used to measure the flow pattern in the ductus venosus and over the pulmonary and aortic valves, right and left ventricular myocardial performance index and the E/A wave ratio over the atrioventricular valves. Stroke volume, cardiac output and shortening fraction were calculated.

RESULTS

Median gestational age at evaluation was 27.4 (interquartile range, 24.4-28.9) weeks. RCDH cases had a significantly smaller right ventricle and pulmonary valve diameter. Furthermore, stroke volume and cardiac output from the right ventricle were lower than in controls. Myocardial contractility, however, appeared normal.

CONCLUSIONS

Despite significantly reduced right ventricular dimensions and cardiac output, cardiac contractility was normal in a cohort of fetuses with RCDH.

Collagen plug sealing of iatrogenic fetal membrane defects after fetoscopic surgery for congenital diaphragmatic hernia

OBJECTIVES

To investigate the efficacy of collagen plugs at reducing the risk of preterm premature rupture of membranes (PPROM) after fetoscopic surgery for congenital diaphragmatic hernia (CDH).

METHODS

This was a single-center cohort study on all consecutive cases undergoing fetoscopic endoluminal tracheal occlusion (FETO) for severe or moderate CDH, between April 2002 and May 2011 (n = 141). Cases either received a collagen plug for sealing the fetal membrane defect after FETO or did not, depending on the operating surgeon. The principal outcome measure was the time from fetal surgery to PPROM, further referred to as 'latency'. A multivariable Cox regression model was used to investigate the association between collagen plug and latency while adjusting for risk factors for PPROM.

RESULTS

Of the 141 cases, 54 (38%) received a collagen plug and 87 (62%) did not. Sixty cases experienced PPROM, 26 among cases with and 34 among cases without a plug (48 vs 39%). The hazard ratio of plug use was 1.29 (95% CI, 0.76-2.19), which does not exclude a potentially increased risk for PPROM when a collagen plug is used. For cases with a plug, 24% had PPROM before balloon removal and 24% had PPROM after elective balloon removal. For cases without a plug, these rates were 30 and 9%, respectively. Perinatal outcomes were similar in both groups.

CONCLUSIONS

No evidence was found that collagen plugs reduce the risk of PPROM after FETO for CDH.

Identification of dosage-sensitive genes in fetuses referred with severe isolated congenital diaphragmatic hernia

OBJECTIVE

Congenital diaphragmatic hernia (CDH) is a fetal abnormality affecting diaphragm and lung development with a high mortality rate despite advances in fetal and neonatal therapy. CDH may occur either as an isolated defect or in syndromic form for which the prognosis is worse. Although conventional karyotyping and, more recently, chromosomal microarrays support a substantial role for genetic factors, causal genes responsible for isolated CDH remain elusive. We propose that chromosomal microarray analysis will identify copy number variations (CNVs) associated with isolated CDH.

METHODS

We perform a prospective genome-wide screen for CNVs using chromosomal microarrays on 75 fetuses referred with apparently isolated CDH, six of which were later reclassified as non-isolated CDH.

RESULTS

The results pinpoint haploinsufficiency of NR2F2 as a cause of CDH and cardiovascular malformations. In addition, the 15q25.2 and 16p11.2 recurrent microdeletions are associated with isolated CDH. By using gene prioritisation and network analysis, we provide strong evidence for several novel dosage-sensitive candidate genes associated with CDH.

CONCLUSIONS

Chromosomal microarray analysis detects submicroscopic CNVs associated with isolated CDH or CDH with cardiovascular malformations.

In vitro sealing of iatrogenic fetal membrane defects by a collagen plug imbued with fibrinogen and plasma

OBJECTIVES

We aimed to demonstrate local thrombin generation by fetal membranes, as well as its ability to generate fibrin from fibrinogen concentrate. Furthermore, we aimed to investigate the efficacy of collagen plugs, soaked with plasma and fibrinogen, to seal iatrogenic fetal membrane defects.

METHODS

Thrombin generation by homogenized fetal membranes was measured by calibrated automated thrombography. To identify the coagulation caused by an iatrogenic membrane defect, we analyzed fibrin formation by optical densitometry, upon various concentrations of fibrinogen. The ability of a collagen plug soaked with fibrinogen and plasma was tested in an ex vivo model for its ability to seal an iatrogenic fetal membrane defect.

RESULTS

Fetal membrane homogenates potently induced thrombin generation in amniotic fluid and diluted plasma. Upon the addition of fibrinogen concentrate, potent fibrin formation was triggered. Measured by densiometry, fibrin formation was optimal at 1250 µg/mL fibrinogen in combination with 4% plasma. A collagen plug soaked with fibrinogen and plasma sealed an iatrogenic membrane defect about 35% better than collagen plugs without these additives (P = 0.037).

CONCLUSIONS

These in vitro experiments suggest that the addition of fibrinogen and plasma may enhance the sealing efficacy of collagen plugs in closing iatrogenic fetal membrane defects.

Severe diaphragmatic hernia treated by fetal endoscopic tracheal occlusion

OBJECTIVES

To examine operative and perinatal aspects of fetal endoscopic tracheal occlusion (FETO) in congenital diaphragmatic hernia (CDH).

METHODS

This was a multicenter study of singleton pregnancies with CDH treated by FETO. The entry criteria for FETO were severe CDH on the basis of sonographic evidence of intrathoracic herniation of the liver and low lung area to head circumference ratio (LHR) defined as the observed to the expected normal mean for gestation (o/e LHR) equivalent to an LHR of 1 or less.

RESULTS

FETO was carried out in 210 cases, including 175 cases with left-sided, 34 right-sided and one with bilateral CDH. In 188 cases the CDH was isolated and in 22 there was an associated defect. FETO was performed at a median gestational age of 27.1 (range, 23.0-33.3) weeks. The first eight cases were done under general anesthesia, but subsequently either regional or local anesthesia was used. The median duration of FETO was 10 (range, 3-93) min. Successful placement of the balloon at the first procedure was achieved in 203 (96.7%) cases. Spontaneous preterm prelabor rupture of membranes (PPROM) occurred in 99 (47.1%) cases at 3-83 (median, 30) days after FETO and within 3 weeks of the procedure in 35 (16.7%) cases. Removal of the balloon was prenatal either by fetoscopy or ultrasound-guided puncture, intrapartum by ex-utero intrapartum treatment, or postnatal either by tracheoscopy or percutaneous puncture. Delivery was at 25.7-41.0 (median, 35.3) weeks and before 34 weeks in 65 (30.9%) cases. In 204 (97.1%) cases the babies were live born and 98 (48.0%) were discharged from the hospital alive. There were 10 deaths directly related to difficulties with removal of the balloon. Significant prediction of survival was provided by the o/e LHR and gestational age at delivery. On the basis of the relationship between survival and o/e LHR in expectantly managed fetuses with CDH, as reported in the antenatal CDH registry, we estimated that in fetuses with left CDH treated with FETO the survival rate increased from 24.1% to 49.1%, and in right CDH survival increased from 0% to 35.3% (P < 0.001).

CONCLUSIONS

FETO in severe CDH is associated with a high incidence of PPROM and preterm delivery but a substantial improvement in survival.

Prenatal prediction of neonatal morbidity in survivors with congenital diaphragmatic hernia: a multicenter study

OBJECTIVES

To investigate the value of the observed to expected fetal lung area to head circumference ratio (o/e LHR) and liver position in the prediction of neonatal morbidity in survivors with congenital diaphragmatic hernia (CDH).

METHODS

Neonatal morbidity was recorded in 100 consecutive cases with isolated CDH diagnosed in fetal medicine units, which were expectantly managed in the prenatal period, were delivered after 30 weeks and survived until discharge from hospital. Regression analysis was used to identify the significant predictors of morbidity, including prenatal and immediate neonatal findings.

RESULTS

The o/e LHR provided significant prediction of the need for prosthetic patch repair, duration of assisted ventilation, need for supplemental oxygen at 28 days, and incidence of feeding problems. An additional independent prenatal predictor of the need for patch repair was the presence of fetal liver in the chest.

CONCLUSIONS

In isolated CDH the prenatally assessed size of the contralateral lung is a significant predictor of the need for prosthetic patch repair, the functional consequences of impaired lung development and occurrence of feeding problems.

Biochemical composition of fluids for amnioinfusion during fetoscopy

OBJECTIVE

To evaluate which of the commercially available solutions is best suited for amnioinfusion during fetoscopy, based on resemblance with the biochemical properties of amniotic fluid.

MATERIALS AND METHODS

Amniotic fluid samples from 10 pregnancies were studied. Specimens were obtained from 5 pathologic pregnancies (of which 3 were complicated by polyhydramnios) and 5 uncomplicated pregnancies. The concentrations of sodium, potassium, chloride, bicarbonate, calcium, glucose, osmolality, pH, total protein content and albumin were determined in each sample. A literature search (PubMed, Embase) was performed to identify commercially available fluids used for amnioinfusion in clinical practice. The composition of these infusion solutions was compared to the amniotic fluid samples mentioned above.

RESULTS

We identified two different electrolyte solutions used in clinical practice for amnioinfusion. We identified four additional commercially available solutions that could potentially be used for amnioinfusion. Most of these infusion solutions differ considerably from midtrimester amniotic fluid samples both in electrolyte composition and pH, with the most striking difference in the latter.

CONCLUSION

Lactated Ringer's solution approximates amniotic fluid the closest for both electrolyte composition and pH. This infusion solution seems to be the most suitable choice for amnioinfusion during fetoscopy.

Comparison of fetal lung area to head circumference ratio with lung volume in the prediction of postnatal outcome in diaphragmatic hernia

OBJECTIVES

To compare prediction of postnatal survival in isolated diaphragmatic hernia by prenatal two-dimensional (2D) versus three-dimensional (3D) sonographic assessment of the contralateral lung.

METHODS

The lung area to head circumference ratio (LHR) of the contralateral lung was measured and expressed as a percentage of the normal mean for gestation (O/E) in 47 fetuses with isolated diaphragmatic hernia at 26 (range, 21-36) weeks of gestation. The lung area was measured by tracing the limits of the lungs (LHR trace) and by multiplying the longest diameter by its perpendicular (LHR diameters). The contralateral lung volume was measured by the Virtual Organ Computer-Aided anaLysis method and the O/E was calculated. Regression analysis was used to determine the significance of the LHRs and volume in the prediction of postnatal survival.

RESULTS

The survival rate was 59.6% (28 of 47). There were significant associations between O/E LHR trace and O/E LHR diameters, and between each O/E LHR and O/E volume, but multiple regression analysis demonstrated that significant prediction of survival was provided only by O/E LHR trace and intrathoracic herniation of the liver.

CONCLUSIONS

In diaphragmatic hernia prenatal prediction of postnatal outcome is better by 2D measurement of LHR trace than it is by 3D measurement of lung volume.

Relationship between lung area at ultrasound examination and lung volume assessment with magnetic resonance imaging in isolated congenital diaphragmatic hernia

OBJECTIVES

To prospectively examine the relationship between contralateral lung area measured by two-dimensional (2D) ultrasound examination and contralateral and total fetal lung volume (FLV) estimated by magnetic resonance imaging (MRI) in the assessment of fetuses with congenital diaphragmatic hernia (CDH).

METHODS

Sixty-six fetuses with isolated CDH were entered in this prospective study. Contralateral fetal lung area was measured by 2D ultrasonography using the longest axis method. Ipsilateral, contralateral and total FLV were measured using multiplanar axial T2-weighted MRI. Regression analysis was used to determine the significance of associations between contralateral lung area and contralateral and total FLV, and the predicted total FLV was subsequently calculated using the regression equation. Univariate regression analysis was used to investigate the effect on the proportionate difference between the predicted and the observed total FLV of gestational age, proportionate volume of ipsilateral vs. total FLV, side of CDH, intrathoracic herniation of the liver and intratracheal presence of a balloon.

RESULTS

The 66 fetuses underwent a total of 191 paired 2D ultrasound and MRI examinations at a median gestational age of 30 (range, 18-38) weeks. It was possible to visualize and measure the contralateral lung area by 2D ultrasound, as well as both the ipsilateral and contralateral lung volumes by MRI, in all instances. There was a significant association between contralateral lung area and contralateral lung volume (r = 0.86; P < 0.001) and with total FLV (r = 0.84; P < 0.001). Univariate regression analysis showed that the proportionate difference between the predicted and the observed total FLV was significantly associated with the proportionate volume of ipsilateral vs. total FLV but not with gestational age, side of CDH, intrathoracic herniation of the liver or intratracheal presence of the balloon.

CONCLUSIONS

In CDH, contralateral lung area measurement by 2D ultrasound correlates well with the total FLV estimated by MRI, irrespective of gestational age, liver herniation or side of herniation. Inconsistencies between the two measurements are attributable to the contribution of the ipsilateral lung to the total lung volume.

Fetal membrane healing after spontaneous and iatrogenic membrane rupture: a review of current evidence

In view of the important protective role of the fetal membranes, wound sealing, tissue regeneration, or wound healing could be life saving in cases of preterm premature rupture of the membranes. Although many investigators are studying the causes of preterm premature rupture of membranes, the emphasis has not been on the wound healing capacity of the fetal membranes. In this review, the relevant literature on the pathophysiologic condition that leads to preterm premature rupture of membranes will be summarized to emphasize a continuum of events between rupture and repair. We will present the current knowledge on fetal membrane wound healing and discuss the clinical implications of these findings. We will critically discuss recent experimental interventions in women to seal or heal the fetal membranes after preterm premature rupture of membranes.

Matrix metalloproteinases-2 and -9 and their endogenous tissue inhibitors in tissue remodeling after sealing of the fetal membranes in a sheep model of fetoscopic surgery

OBJECTIVES

We studied collagen plugging of the fetoscopic access site in an in vivo fetal lamb model for fetoscopic surgery and possible role for matrix metalloproteinase (MMP)-2 and -9 and tissue inhibitors (TIMPs).

METHODS

Eight ewes had fetoscopic balloon occlusion of the trachea as an experimental treatment for congenital diaphragmatic hernia between days 88 and 99 of gestation (term 145 days) with sampling of amniotic, allantoic, and tracheal fluid. Nonoperated cotwins were used as controls. The fetoscopy port was closed using a collagen plug. Ten days (range 9-12) later, fluids were sampled and plug sites collected for histologic analysis. Activity of MMP-2 (72 kDa, gelatinase A) and MMP-9 (92 kDa, gelatinase B) was determined in the fluids by zymography and secretion of TIMPs (27-30 kDa; TIMP-1, glycosylated TIMP-3 and TIMP-4, 24 kDa; unglycosylated TIMP-3, 21 kDa; TIMP-2) by reverse zymography and quantified by densitometric analysis.

RESULTS

No pregnancy was complicated by amniorhexis or preterm labor. At cesarean, normal volumes of amniotic and allantoic fluid were present in all cases. Histology of the plug sites revealed good integration of the collagen plug without complete restoration of membrane integrity. MMP-2, MMP-9, and TIMPs were detected in all fluids. In the operated animals, significantly (P <.05) higher activity of MMP-9 was found in amniotic fluid, with lower concentrations of TIMPs in allantoic fluid (P <.01). Tracheal occlusion was associated with a significant (P <.02) increase in both MMP-2 and -9 in tracheal fluid.

CONCLUSION

Collagen plugging of the fetoscopic access port sites in sheep resulted in functionally effective sealing of the fetal membranes. Changes in MMP-2, MMP-9, and TIMPs suggest an active remodeling of both the fetal lung and the fetal membranes.

Ultrasound determination of chorionicity in twin pregnancy: accuracy and operator experience

To evaluate the accuracy of ultrasound in early detection of chorionicity and amnionicity in twin pregnancies and evaluate the role of operator-experience, a prospective follow up of 87 consecutive twin pregnancies was performed. Chorionicity and amnionicity were determined by 17 different observers, divided in 2 groups on the basis of their experience, using a composite of US markers at the first US examination confirming a viable intrauterine twin pregnancy. Accuracy of prediction was determined for both groups by comparison with postnatal pathology. From the 87 pregnancies examined at 10.1 (minimum 5.5 weeks, maximum 26.0) weeks of gestation, pathology was available in 82 cases and a correct prediction of chorionicity was made in all but two cases, both being diagnosed as monochorionic while dichorionic by observers belonging the more experienced group. No monochorionic pregnancy was missed and amnionicity was correctly diagnosed in all cases, including two monoamniotic twins. We conclude that use of a composite of ultrasound markers for early detection of chorionicity and amnionicity is reliable in a clinical setting where physicians with a variable degree of experience perform ultrasound examination.

Effects of amniodistention with carbon dioxide on fetal acid-base status during fetoscopic surgery in a sheep model

BACKGROUND

Because the data from previous experiments on the fetal effects of carbon dioxide (CO2) amniodistention in endoscopic fetal surgery are conflicting, we set out to evaluate the fetal acid-base status during CO2 amniodistention, with or without maternal hyperventilation, using a sheep model for endoscopic surgery.

METHODS

We assigned 26 pregnant ewes undergoing amniodistention with CO2 (4-5 mmHg intraamniotic pressure) to one of the following three groups: group I had fetal surgery + no maternal hyperventilation (n = 10); group II had fetal surgery + maternal hyperventilation (n = 10); group III had no fetal surgery + maternal hyperventilation (n = 6). Hyperventilation kept CO2 at 29-31 mmHg; in its absence, pCO2 ranged from 38 to 41. Fetal surgery consisted of fetoscopic tracheal clipping. Maternal blood pressure (mean, 98/69 mmHg) and heart rate (mean, 72 bpm) were kept at values comparable to human pregnancy. Fetal and maternal blood gas measurements were taken every 15 min during 1 h of amniodistention.

RESULTS

The ranges for baseline mean fetal pCO2 (mmHg) and pH were 51-55 and 7.24-7.25, respectively, in all study groups. After 1 h of amniodistention, mean +/- SEM values of fetal pCO2 and pH were 88 +/- 3 and 7.06 +/- 0.03 in group I, 69 +/- 4 and 7.13 +/- 0.02 in group II, and 71 +/- 5 and 7.14 +/- 0.04 in group III, respectively. Therefore, maternal hyperventilation attenuated but could not prevent significant fetal hypercarbia and acidosis. Fetal surgical manipulation had no effect on these observations.

CONCLUSION

CO2 amniodistention should not be considered for clinical practice until ways of preventing its effects on the fetal acid-base status can be demonstrated.

An organ-culture for in vitro evaluation of fetal membrane healing capacity

OBJECTIVES

We aimed to set up an organ culture of human amniochorion to evaluate fetal membrane repair capacity following surgical trauma.

METHODS

Fetal membranes were collected from four patients, during elective caesarean section at term. Explants were traumatised at the centre and cultured on collagen support material for a total of 12 days. Viability was assessed by light microscopy and proliferation by detection of 5-Bromo-2' deoxy-Uridine (BrdU) incorporation and immunohistochemistry. Wound healing capacity was assessed trough photographic documentation every 2 days.

RESULTS

Cultures showed good survival for 12 days. Increased cellularity, survival and proliferations were observed at the borders of the cultures in contrast to the central trauma site. During the 12 days observation period, no significant closure of the membrane defect could be demonstrated.

CONCLUSION

This organ culture system represents a new model for the study of human fetal membrane repair. Despite good survival and localised proliferation, no obvious closure of a surgically created defect was observed in the described culture conditions.

Tracheal side effects of endoscopic balloon tracheal occlusion in the fetal lamb model

OBJECTIVE

To evaluate effects of in-utero endoluminal balloon tracheal occlusion (TO) as suggested for the treatment of Congenital Diaphragmatic Hernia (CDH) on the higher airways of a fetal lamb model.

STUDY DESIGN

Fetuses from time-dated pregnant ewes underwent at 94 days (term=145 days) in-utero tracheal occlusion. In study animals an endoluminal, detachable balloon was placed by tracheoscopy. For that purpose a 1.2mm fibre-optic, semi-rigid endoscope and a medically graded latex balloon were used. In group I (n=9) lambs were delivered after 2 weeks. In group II (n=8) the tracheal occlusion was released after 2 weeks, to allow in-utero recovery until term. In positive control animals (group III; n=5) the trachea was clipped at 98 days and fetuses were harvested near term by cesarean section. A total of 17 contralateral littermates in multiple pregnancies served as negative controls. After macroscopic inspection of the trachea, sections were evaluated by light microscopy. Alterations were scored with an empirical interval score for each of the different anatomical elements in the fetal trachea (epithelium, submucosa, cartilage, pars membranacea).

RESULTS

For the animal experiments in group I, all balloons were found in place and according to the pulmonary response they were obstructive. Tracheas were macroscopically dilated by the plug mainly due to elongation of the pars membranacea. The total histologic score was correlated to the increase in circumference (mean increase: 3.0mm). In nearly all cases, the tracheal epithelium at the level of the plug had lost its typical folding pattern. In 44% of cases, local epithelial defects were observed and in 33% of cases there was squamous metaplasia. A chronic inflammatory response was present in over half of the cases, sometimes with giant cell reaction. In group II (the in-utero recovery group) the total score was significantly lower than in group I, with much less prominent unfolding and absence of epithelial defects. Squamous metaplastia was still present in half of the cases; whereas inflammatory responses were less frequent. In group III the trachea expanded normally after removal of the clip. The epithelium had compacted folds, and cilia were well preserved. In two animals however, intraluminal synechia were observed. Below the level of occlusion animals of groups I and II all showed areas of unfolding, but without metaplasia or epithelial defects.

CONCLUSION

Tracheal obstruction by means of endoluminal plugging has been suggested as an alternative in-utero treatment for congenital diagphragmatic hernia. The balloon causes mild epithelial changes, such as unfolding, limited epithelial defects (<25% of the exposure surface) and local inflammatory changes. These changes disappear nearly completely following in-utero unplugging during the rest of gestation. Unfolding of the epithelium is also seen in the trachea under the plug.

Matrix metalloproteinases -2 and -9 and their endogenous tissue inhibitors in fetal membrane repair following fetoscopy in a rabbit model

The cellular mechanisms underlying fetal membrane repair are poorly understood. Matrix metalloproteinases (MMP) and the endogenous tissue inhibitors of metalloproteinases (TIMP) play a key role in the control of turnover of extracellular matrix in fetal membranes at normal parturition and preterm prelabour rupture of the fetal membranes (PPROM). The time course of secretion of MMP-2 (72 kDa, gelatinase A) and MMP-9 (92 kDa, gelatinase B) and TIMP into extra-embryonic coelomic, allantoic and amniotic fluids in a rabbit model was examined. Furthermore, to evaluate their role in fetal membrane repair, the changes induced by fetoscopy at mid-gestation (23 days; gestation length is 32 days) were investigated. Zymography showed predominantly secretion of latent MMP-2 at 18, 23 and 30 days of gestation in all gestational compartments. Reverse zymography detected a broad range of TIMP activity with molecular weights of 27-30 kDa (TIMP-1, glycosylated TIMP-3 and TIMP-4), 24 kDa (unglycosylated TIMP-3) and 21 kDa (TIMP-2). Following fetoscopy, both MMP-2 and TIMP increased significantly in amniotic fluid and extra-embryonic coelomic fluid, but not in allantoic fluid, as demonstrated by densitometric analyses. These findings indicate a modulating role for MMP and TIMP in the repair processes following a surgically induced fetal membrane defect.

Is the angle of needle insertion influencing the created defect in human fetal membranes? Evaluation of the agreement between specialists' opinions and ex vivo observations

OBJECTIVE

We sought to evaluate the agreement between the opinions of specialists in fetal medicine with ex vivo observations on the potential influence of the angle of needle insertion on the fluid leak through the created defect in human fetal membranes.

STUDY DESIGN

Membranes from placentas of women who were delivered by elective cesarean were harvested, cut in pieces, and secured to the bottom of plastic tubes filled with Hartmann solution. They were punctured with 18-, 20-, or 22-gauge needles, with an angle of insertion of 90 degrees (group 1) or 45 degrees (group 2), and the flow rate (in milliliters per minute) through the created defect at a constant pressure of 150 mm H(2)O was measured. Fifty physicians performing amniocentesis at fetal medicine reference centers were interviewed about their impression and clinical attitude with respect to the angle of needle insertion at the time of amniocentesis.

RESULTS

In the ex vivo study, puncture with a 45 degrees angle was associated with a significantly lower flow of fluid through the membrane defect for all needle sizes tested. Regarding survey answers, 82% of physicians try to perform amniocentesis with a given angle (ie, 90 degrees in the vast majority of cases). Among the reasons for doing so, minimizing membrane damage was mentioned in more than half of cases.

CONCLUSION

These results provide evidence that the angle of needle insertion influences the type of defect and therefore the flow rate through human membranes. Membrane damage is a concern of a proportion of specialists while performing amniocentesis, but ex vivo observations do not agree with clinical assumptions on the potential influence of the angle of insertion.

Controlled balloon dilatation for laparoscopic extraperitoneal bladder neck suspension in patients with previous abdominal surgery

PURPOSE

The balloon dilator is used in a variety of minimally invasive preperitoneal and retroperitoneal operations. In this study, we compared the ability to create an extraperitoneal cavity using a balloon spacer in patients with and without previous abdominal surgery undergoing laparoscopic bladder neck suspension.

PATIENTS AND METHODS

This prospective study included 38 patients in total, 15 of whom had had previous abdominal wall surgery and 23 who had not. A balloon spacer technique was used to develop the extraperitoneal space.

RESULTS

In 80% of the patients with previous surgery, the introduction of the balloon spacer was recorded as simple; in 20%, it was considered difficult. In 78% of the patients without previous surgery, the introduction of the balloon spacer was recorded as simple, in 17% it was difficult, and in 4% it failed. In 80% of the patients with previous surgery, the extraperitoneal view was good or acceptable, in 20% it was poor, and in 13% it failed. In 92% of the patients without previous surgery, the extraperitoneal view was good or acceptable, in 4% it was poor, and in 4% dilatation failed. Morbidity was equally divided between the groups.

CONCLUSIONS

Previous abdominal surgery is not a contraindication to laparoscopic extraperitoneal surgery using a balloon spacer. The approach carries low morbidity, similar to that in patients without previous abdominal surgery.

Bipolar coagulation of the umbilical cord in complicated monochorionic twin pregnancy

OBJECTIVES

In monochorionic twin pregnancy in which one twin is a nonviable fetus, selective feticide may be considered. We aimed to occlude the umbilical cord with a bipolar forceps for doing so.

STUDY DESIGN

This was a multicenter experience in 10 consecutive patients either with twin-to-twin transfusion syndrome and one fetus affected by a condition not compatible with normal extrauterine life or with acardiac twinning.

RESULTS

There were no intraoperative problems, and the mean procedure time was 17.5 minutes. The flow was stopped in all 10 cases. Two cases were complicated by rupture of the fetal membranes within 2 days, and the pregnancies were terminated. The other 8 pregnancies resulted in the live birth of a healthy baby. The mean interval between procedure and birth was 15.1 weeks (range, 7-20 weeks). In one patient emergency cesarean delivery for abruptio placentae was done at 26 weeks, 7 weeks after the procedure. The other 7 patients were delivered beyond the 36th week of gestation. All 8 children are alive and well, with a mean follow-up of at least 1 year.

CONCLUSION

Bipolar coagulation is a safe, effective, and simple procedure for cord coagulation that is feasible through a single port and can be performed solely under ultrasonographic guidance.

Cord occlusion techniques for selective termination in monochorionic twins

We wished to determine the optimal method for cord obliteration to perform selective reduction in complicated monochorionic (MC) twin pregnancies under different clinical conditions. For this purpose, we reviewed our experience and the available published literature and unpublished reports. Indications were a cardiac twin pregnancy, twins discordant for fetal anomaly, and severe feto-fetal transfusion syndrome where one twin had a very poor prognosis. Data were available for the following techniques: cord embolization, fetoscopic cord ligation, laser coagulation, monopolar coagulation and bipolar cautery. Unfortunately the data are heterogeneous, incomplete and reports are only sporadic. Cord embolization using coils or sclerosants has a high failure rate and can no longer be recommended. In 23 published cases of fetoscopic cord ligation a failure rate of 10% was reported. After successful ligation an overall fetal survival rate of 71% but a risk of preterm prelabor rupture of the membranes (PPROM) of 30% was documented. Four cases of monopolar coagulation have been published--all in a cardiac twin pregnancies. In three cases the abdominal aorta was coagulated prior to 20 weeks and complete cessation of flow was demonstrated. In 10 cases of bipolar cord coagulation, all procedures were technically successful. Nine of 10 were performed under ultrasound guidance through a single port. In 2 cases, frank PPROM occurred, leading to induction of labor. The other eight fetuses were born at 35 weeks or more. Nd:YAG coagulation of the cord was much more sporadically described; the success of the procedure seems to be clearly dependant on gestational age. In all our attempts prior to 20 weeks, we failed in only one out of 6 cases. In summary, there is little data to perform meaningful comparisons of available techniques for umbilical cord occlusion. Based on practical and technical considerations we use the following clinical algorithm: prior to 21 weeks, we attempt to coagulate the cord with Nd:YAG laser. If this is unsuccessful, or for gestations beyond 21 weeks, bipolar cord coagulation is currently our other method of choice. Sonoendoscopic cord ligation is reserved as backup procedure if neither of these methods are successful.

Successful sealing of fetoscopic access sites with collagen plugs in the rabbit model

OBJECTIVE

The aim of this study was to evaluate the efficacies of various plugging techniques in sealing the membrane defect created by fetoscopy in the rabbit at midgestation.

STUDY DESIGN

Fetoscopy was performed in pregnant rabbits at 23 days' gestation (term, 32 days' gestation). In group 1 fetal sacs were left unclosed (positive control group, n = 24). In group 2 injection with commercially available extracellular matrix (Matrigel; BD Labware, Bedford, Mass) was performed and a myometrial suture was inserted (n = 23). In group 3 the entry site was plugged with collagen (Colgen; Inter-Phar, Paris, France) combined with a myometrial suture (n = 22). At 30 days' gestation the membrane integrity, amniotic fluid presence, and fetal lung/body weight ratios were assessed. The plugging site was examined histologically.

RESULTS

The use of suture and collagen plugs (group 3) resulted in functional restoration of membrane integrity with preservation of amniotic fluid and normal fetal lung/body weight ratio at term in 82% of cases, compared with 42% in the positive control group (group 1; P <.05). Histologic examination revealed entrapment of membranes between the plug and the myometrium but no anatomic repair of the membranes. The use of suture and extracellular matrix (group 2) did not achieve better results than those seen in group 1 (positive control group).

CONCLUSION

Collagen plugs achieved functional sealing of fetoscopic access sites in a rabbit model and prevented oligohydramnios and pulmonary hypoplasia.

Gelatin sponge plug to seal fetoscopy port sites: technique in ovine and primate models

Amniotic fluid leakage and rupture of membranes are common complications of fetoscopy. We describe a plug technique for leakproof removal of endoscopic cannulas. Thirty gelatin sponge plugs were introduced in 5 pregnant ewes and 5 pregnant rhesus monkeys. In the primate model no evidence of amniorrhexis was noted on postoperative ultrasonography. Myometrium and membranes at the port sites were intact at term. A gelatin sponge plug technique may facilitate leakproof port removal after fetoscopy.

Closure techniques for fetoscopic access sites in the rabbit at mid-gestation

Operative fetoscopy may be limited by its relatively high associated risk of preterm prelabour rupture of membranes. The objective of this study was to study closure techniques of the access site for fetoscopy in the mid-gestational rabbit. A total of 32 does (288 amniotic sacs) at 22 days gestational age (GA; term = 32 days) underwent 14 gauge needle fetoscopy, by puncture through surgically exposed amnion. Entry site was randomly allocated to four closure technique groups: myometrial suture (n = 14), fibrin sealant (n = 15), autologous maternal blood plug (n = 13), collagen plug (n = 14); 16 sacs were left unclosed (positive controls), and the unmanipulated 216 sacs were negative controls. Membrane integrity, presence of amniotic fluid and fetal lung to body weight ratio (FLBWR) were evaluated at 31 days GA. Following fetoscopy without an attempt to close the membranes, amniotic integrity was restored in 41% of cases (amniotic integrity in controls 94%; P = 0.00001). When the access site was surgically closed, the amnion resealed in 20-44% of cases, but none of the tested techniques was significantly better than the others or than positive controls. Permanent amniotic disruption was associated with a significantly lower FLBWR in all groups. In conclusion, the rate of fetoscopy-induced permanent membrane defects in this model did not improve by using any of the closure techniques tested here.

Natural protective mechanisms against endoscopic white-light injury in the fetal lamb eye

OBJECTIVE

To evaluate light transmission, possible light trauma, and techniques for protection of the fetal eyes during intrauterine videoendoscopic surgery in a sheep model.

METHODS

In vitro studies were done at various gestational ages, including spectrometry of light output by a halogen light source and telescope and light transmission by spectrophotometry in the range of 180-3000 nm through amniotic fluid (AF) and fetal eyelids. In vivo electron-microscopic, morphologic analysis of the retinas of 65-, 95-, 108-, and 112-day-old fetal lambs with (n = 8) and without (n = 8) 30 minutes' light exposure to the open eye was also done.

RESULTS

The light spectrum at the tip of the telescope was 400-750 nm, with a maximum irradiance of 3x10(-3) W/cm2 at 580 nm. In the ultraviolet spectrum (less than 300 nm), irradiance was less than 0.5x10(-3) W/cm2. Light transmission through ovine AF ranged from 30% at 300 nm to 89% at 700 nm at 84 days' gestation, decreasing to less than 0.01% (300 nm) and 70% (700 nm) at 112 days. Fetal eyelids did not transmit more than 1% of light (any wavelength). After direct in vivo light exposure, no retinal damage was found. Photoreceptors were present from 108 days onward, but chromophores were scant or absent at all ages studied.

CONCLUSION

The light spectrum of a standard endoscope is limited to 400-750 nm; ultraviolet light is filtered out. The AF transmits harmful blue light poorly. Fetal eyelids seem to protect the eye by extremely low transmission and light dispersion. Even with the eye open, no morphologic retinal damage was found. The strong light sources used with fetal endoscopy did not appear to pose a threat to the fetal retina.

IGF-I, IGF-II, IGF binding protein 1, and C-peptide in second trimester amniotic fluid are dependent on gestational age but do not predict weight at birth

Previous data suggested that small for gestational age newborns have increased levels of IGF binding protein 1 (IGFBPI) in amniotic fluid (AF) at 15-16 wk of pregnancy. In this study, we developed an RIA for IGFBP1 and measured IGFBP1 concentrations in 209 AF samples with normal fetal karyotype between 14 and 20 wk; we measured IGF-I, IGF-II, and C-peptide in the same samples. Concentrations of these growth-modulating factors were all positively correlated with gestational age at sampling (p < 0.0001). After correcting for gestational age, AF IGFBP1 remained strongly correlated with IGF-I and IGF-II (both p < 0.0001); their concentrations were many times higher in AF than in cord serum during the third trimester. None of the growth-modulating factors in AF correlated with birth weight, after correction for gestational age; birth weight percentile distribution was comparable in two groups of newborns who had AF values of IGF-I, IGF-II, IGFBP1, or C-peptide that were either less than or equal to the 50th percentile or more than the 50th percentile at sampling. However, placenta weight and the placenta weight to birth weight percentage were negatively correlated with AF IGF-I, IGF-II, and IGFBP1; placenta weight to birth weight percentage was lower in pregnancies with IGFBP1 values more than the 50th percentile compared with those less than or equal to the 50th percentile at sampling. In conclusion, AF concentrations of IGFBP 1 increase gradually between 14 and 20 wk gestational age and correlate with IGF-I and IGF-II levels; high IGFBP1 levels do not predict small for gestational age newborns, but are associated with lower placenta weight.

The midgestational rabbit as a model for the creation of membrane defects after needle fetoscopy

OBJECTIVES

The aim of the study was to determine whether the pregnant rabbit at mid gestation could be used as a suitable in vivo model for the study of membrane defects after invasive procedures.

STUDY DESIGN

Pregnant rabbits at gestational ages of 22 and 18 days (term is 32 days' gestation) underwent needle insertion with different instrument diameters (1.1 mm, 1.35 mm, 2.0 mm, and 2.7 mm). Two different insertion techniques were evaluated, blind amniotic puncture and puncture through surgically exposed amnion. Membrane integrity, presence of amniotic fluid, and fetal lung/body weight ratio were evaluated at 31 days' gestation.

RESULTS

Among rabbits operated on at 22 days' gestation the amniotic integrity restoration at 31 days' gestation ranged from 46% to 76% in the different diameter and access technique groups, as compared with 98% in untreated sacs (P <.05 for all groups). Fetuses from sacs with persisting membrane defects had oligohydramnios and significantly lower fetal lung/body weight ratios. Survival rates among fetuses operated on at 18 days' gestation were so poor that appropriate statistical analysis was not possible in this group.

CONCLUSIONS

The rabbit at mid gestation can be used as a model to reproduce permanent membrane defects after fetoscopy, reproducing oligohydramnios and pulmonary hypoplasia. This may provide a suitable in vivo model for the study of iatrogenic membrane defects.

Obstetrical endoscopy

Fetoscopy has been reintroduced in fetal diagnosis and therapy, as a result of instrumental innovations. It has been suggested that fetoscopy be used to guide endoscopic operations on the fetus, but this application is still in the experimental phase. Its use for surgical interventions on the placenta, umbilical cord, and to a lesser extent the fetal membranes, could be called 'obstetrical' endoscopy. Nd:YAG laser coagulation of chorionic plate vessels for feto-fetal transfusion syndrome is the most common operation carried out today. Survival rates of 60% or more have recently been reported on both sides of the Atlantic Ocean. Neurological morbidity does not exceed 6%, which compares favorably with serial amnioreductions and may become the most important incentive for performing the operation. A randomized trial comparing both therapies as a next step is being proposed. Fetoscopy has also been used for cord ligation, but because of the complexity of the operation and the high risk for preterm prelabor rupture of the membranes, other alternatives have been investigated. Most experience has been gathered with bipolar cord occlusion, a procedure which can be performed under ultrasound guidance. The instrumental considerations and potential complications of fetoscopy are discussed.

Time-related cotyledonary effects of laser coagulation of superficial chorionic vessels in an ovine model

Endoscopic Nd:YAG laser coagulation of superficial chorionic plate vessels has been suggested as a 'causal' therapy for severe twin-to-twin transfusion syndrome (TTS), as it is believed to arrest flow over vascular anastomoses. The therapy remains debated, partly because it is questioned whether coagulation of superficial chorionic vessels can arrest blood flow over deeply located anastomoses. The latter are believed to be responsible for the majority of cases of severe TTs. In this study, the coagulation performance, and the immediate and delayed tissue effects of laser coagulation were evaluated in an in vivo ovine model. Eight pregnant ewes of about 100 days' gestational age (term= 145 days) were studied. In utero coagulation was done through a 1.2 mm fetoscope loaded with a 600 microm laser fibre, connected to an Nd:YAG laser in continuous mode. Superficial cotyledonary vessels were coagulated under visual control at a distance of 1 cm with a mean power of 60 watts. 31 lasered cotyledons were harvested, either immediately (n= 15), 14 days (n = 8) or 42 days (n = 8) after the surgery and evaluated by inspection and histology. Control cotyledons were either neighbouring cotyledons from the same amniotic sac (internal control) or cotyledons from another gestational-age-matched sac (external control). Immediate effects consisted of localized coagulation necrosis at the zone of laser impact with no significant histological effect at more than 2 mm distance, except tissue congestion. Long-term effects consisted of fibrosis without any vascular recanalization or tissue regeneration extending from the impact site over the whole cotyledon. All treated cotyledons underwent complete infarction over time. This study provides experimental evidence supporting that laser coagulation of superficial chorionic vessels entering a cotyledon achieves complete functional elimination of the involved cotyledon.

Fetoscopy in the pregnant rabbit at midgestation

OBJECTIVE

To develop a small animal model for fetoscopy.

METHODS

In 12 time-dated pregnant rabbits at 22 days' gestational age (term 32 days) one amniotic sac in each uterine horn (n = 24) was used for a fetoscopic procedure. After laparotomy, a 2- to 3-mm microsurgical myometrial incision was made to expose the chorionic and amniotic membrane. Under microscopic control, a 2-mm needle was inserted into the amniotic sac. Through this a 1.2-mm endoscope was passed to carry out fetoscopy during maximally 10 min, using 5-10 ml saline amnioinfusion. Mean outcome measurements were ability to visualize the placenta, umbilical cord and the different fetal elements during fetoscopy, as well as fetal survival and weight at second-look operation at 30 days. The untreated amniotic sacs served as negative controls.

RESULTS

In all cases, fetoscopy could be carried out successfully, and all fetuses survived till delivery without significant influence on fetal birth weight.

CONCLUSION

The midgestational rabbit can be used to perform fetoscopy.

Experience with fetoscopic cord ligation

OBJECTIVE

In the case of a monochorionic multiple pregnancy with one non-viable fetus who compromises its co-twin, fetoscopic cord ligation may be performed. We describe our fetoscopic cord ligation technique and discuss the efficacy of cord ligation for salvaging the co-twin, based on available data.

STUDY DESIGN

Descriptive case series of four cases and review of the cases published up to 1996.

RESULTS

We performed four successful ligations. Of the 23 reported cases, which include the present series, two ligations failed. Four fetuses died in utero, and 17 were born alive at a mean of 8 weeks following the procedure. Two babies died in the perinatal period, a third after 60 days. Preterm uterine contractions do not seem to be a clinical problem. Preterm prelabour rupture of the membranes (PPROM) complicates about 40% of cases, the majority occurring prior to 32 weeks.

CONCLUSION

Fetoscopic cord ligation is a feasible procedure with a 71% survival rate and a high risk for PPROM.

Tracheoscopic endoluminal plugging using an inflatable device in the fetal lamb model

OBJECTIVE

Intra-uterine tracheal occlusion has been proposed to reverse pulmonary hypoplasia, an important prognostic factor in congenital diaphragmatic hernia. We aimed to evaluate the feasibility and pulmonary effects of tracheoscopic tracheal obstruction with a detachable balloon.

STUDY DESIGN

Fourteen mid-trimester fetuses out of 24 in 13 ewes underwent tracheoscopic balloon obstruction. Ten non-operated fetuses served as controls. Plugging was performed under fiber-tracheoscopy using a detachable balloon. Outcome measures consisted of: total operating time, tracheoscopy time, fetal survival, efficiency of plugging, and pulmonary effects. The Mann-Whitney test and linear regression were used for statistical analysis.

RESULTS

Mean operating time and tracheoscopy time were 65+/-12 and 6.6+/-3.9 min, respectively. One intra-operative death occurred in each group. The post-operative mortality was 2/13 for cases and 2/9 for controls. In all 14 fetuses, the trachea was successfully obstructed. In the 11 treated animals born alive, the lung-to-body-weight ratio was 0.060+/-0.01, while in controls it was 0.031+/-0.01 (P = 0.0001). In a subset of six fetuses obstructed for 14-18 days, mean-terminal-bronchial density was 0.95+/-0.59, compared to 2.06+/-0.80 for controls (P = 0.046).

CONCLUSIONS

Using fetal tracheoscopy, the trachea can successfully be obstructed with an inflatable balloon. Pulmonary hyperplasia is achieved when the obstruction lasts 2 weeks.

[Minimally invasive techniques make fetal surgery possible. Disabling abnormalities can be corrected]

Increases in our knowledge of the fetus and improved skill in early prenatal diagnosis inevitably result in attempts to treat some of the abnormalities detected. Although most fetal malformations diagnosed prenatally in continuing pregnancies are best managed by medical and surgical intervention after planned delivery, some structural defects may require in utero-treatment to forestall subsequent sequelae. The article consists in a review of the current status of ultrasound-guided invasive fetal therapy, including multifetal pregnancy reduction, manipulation of amniotic fluid, drainage and shunting procedures, fetal transfusion therapy, operative fetoscopy, and in utero stem cell transplantation. Future prospects and developments in this rapidly expanding field are also outlined.

Single-port tracheoscopic surgery in the fetal lamb

BACKGROUND/PURPOSE

Endoscopic fetal surgery could help avoid many of the problems associated with open fetal surgery, but the use of multiple ports may be too traumatic to the membranes. The authors describe a single-port technique of tracheoscopic surgery in the fetus.

METHODS

Time-dated pregnant ewes (95 to 105 days; term, 145 days) underwent midline laparotomy under general halothane anesthesia. A 5-mm-diameter balloon-tipped cannula was introduced in the uterus by Seldinger technique. A 1.2-mm semirigid mini-endoscope, fitted inside a 9F, 20 degrees curved sheath, was introduced under continuous, low-pressure irrigation, inside the fetus' mouth, and advanced into the trachea.

RESULTS

Endotracheal procedures, including temporary (n = 11) and permanent balloon tracheal occlusion (n = 30) and placement of a barbed guide wire for endotracheal occlusion device insertion (n = 12), were performed by introducing a 1-mm diameter instrument alongside the telescope. These were successfully performed in 52 of the 53 fetuses. The rigidity of the telescope allowed controlled access to the pharynx; its curve allowed full tracheobronchial endoscopy with the fetus in utero.

CONCLUSIONS

The present technique marries the control and optical quality of a rigid endoscope with the physiological curve only a flexible instrument could offer until now. The types of procedures performed with this technique illustrate its potential as a research tool; the size (1.2-mm diameter), shape, and optical qualities of the telescope should make clinical applications possible.

Fetal membrane closure techniques after hysteroamniotomy in the midgestational rabbit model

OBJECTIVE

We studied closure techniques for amniotic access in midgestational rabbits.

STUDY DESIGN

Twenty-eight rabbits with a total of 313 amniotic sacs were used for this study. In each animal a 1 cm hysteroamniotomy was made in two amniotic sacs at 22 days' gestation (term = 32). For 12 amniotic sacs (group 1) only the myometrium was closed by microsurgical suturing. In group 2 (n = 12), sutures included myometrium and membranes. In group 3 (n = 8), a collagen plug was placed, and in group 4 (n = 12) fibrin glue was used. Twelve sacs were left unclosed (positive controls) and the unmanipulated 257 sacs were negative controls. Eight days later (gestational age 30 days) amniotic sacs were evaluated for the presence of amniotic fluid, membrane integrity, and fetal weight and survival. Statistics were done with two-tailed Fisher's exact test and one-way analysis of variance.

RESULTS

Membrane integrity (p = 0.0036) and amniotic fluid (p = 0.047) were best restored after myometrial closure. Fetal weight and survival rate were not affected by different closure techniques.

CONCLUSION

In this model primary closure of the myometrium only yielded best results.

Alternative technique for Nd: YAG laser coagulation in twin-to-twin transfusion syndrome with anterior placenta

Nd: YAG laser coagulation is used to treat severe twin-to-twin transfusion syndrome (TTS). Success of the technique depends on visualization of the placenta, the fetal membranes and the targeted vessels, as well as obtaining an optimal inclination angle for laser coagulation. In the rare case of an extensive anterior placenta, it may be difficult to achieve these conditions using the percutaneous approach. Here, we propose an alternative to the percutaneous procedure. Modifications involve an open access and the use of a flexible cannula and bent scope. An extraplacental area, usually at the fundus, is identified by B-mode and color Doppler imaging. A mini-laparotomy is made under general anesthesia. The viscera are retracted and the cannula is inserted under direct view and ultrasound control by the Seldinger technique. The curved fiberscope is passed through the flexible cannula, allowing adequate inspection of the placenta, and target vessels can be coagulated at an angle close to 90 degrees. After the procedure, the uterus is closed primarily to prevent postoperative leakage of amniotic fluid or hemorrhage. This technique has been successfully used in six patients with TTS and a completely anterior placenta, with a gestational age between 18.5 and 22.0 weeks. In all patients, the amniotic cavity was accessed without hemorrhage. The outcomes are similar to those published previously for laser coagulation. The mean interval from intervention until delivery was 10.5 weeks. All 12 fetuses were live born but four died from complications of extreme prematurity. No maternal complications occurred.

The plug-unplug sequence: an important step to achieve type II pneumocyte maturation in the fetal lamb model

PURPOSE

The purpose of this study was to test the hypothesis that tracheal obstruction (plugging) in the fetal lamb model leads to a decrease in the absolute number of type II pneumocytes and that reversing the obstruction before birth (unplugging), allows the type II cells to recover while maintaining the beneficial effect on lung growth.

METHODS

Nine time-dated pregnant ewes (term, 145 days), carrying 17 fetuses, were used in this surgical trial. The fetuses were divided into three experimental groups: group A underwent plugging at 93 days gestation, followed by unplugging at 110 days; group B animals had tracheal ligation at 93 days and group C consisted of unoperated controls. All fetuses were delivered by cesarean section at 136 days' gestation. The fetal trachea was obstructed with the tracheoscopically placed detachable balloon described by our group. Unplugging was performed by needle puncture of the balloon under tracheoscopic vision. Outcome measurements consisted of lung-to-body-weight ratio (LWBR), lung morphometry (mean terminal bronchial density [MTBD] and linear intercept [Lm]), and assessment of the number of type II pneumocytes. The latter was determined by in situ hybridization to the mRNA of surfactant protein-C, which is exclusively produced by type II cells. Statistics were calculated using a two-tailed unpaired t test and P less than .05 is considered significant.

RESULTS

Seventeen animals are included in the results. All of them had lung samples analyzed for lung morphometry, whereas for type II cells analysis, three animals were studied in each group. Morphometric analyses were consistent with pulmonary hyperplasia for group B, whereas group A lungs showed more histological maturity than group C albeit not as marked as group B. In group A, there was a similar number of type II cells to that observed in group C (53.2 +/- 3.9 v 55.9 +/- 4.0, P = .66). However, for group B animals, the number of type II pneumocytes was markedly decreased compared with controls (4.7 +/- 0.1 v 55.9 +/- 4, P = .0003).

CONCLUSIONS

The authors conclude that tracheal ligation until birth, although inducing pulmonary hyperplasia, significantly decreases the number of type II pneumocytes in the alveoli. After a temporary 15-day occlusion initiated at 95 days' gestation, there is complete normalization of the density of type II cells. These results bear importance on the duration of PLUG to treat the pulmonary hypoplasia seen in congenital diaphragmatic hernia. Temporary tracheal obstruction now needs to be tested in a hypoplastic lung model.

Intrauterine tracheal obstruction, a new treatment for congenital diaphragmatic hernia, decreases amniotic fluid sodium and chloride concentrations in the fetal lamb

OBJECTIVE

To evaluate the effect of fetal tracheal occlusion on sodium and chloride concentrations in amniotic and tracheal fluid.

SUMMARY BACKGROUND DATA

Intrauterine tracheal occlusion has been proposed to reverse pulmonary hypoplasia, an important prognostic factor in congenital diaphragmatic hernia. In early human trials, technical failure of the obstructive device has been reported.

METHODS

Eight fetal lambs (gestational age = 95 days) were subjected to fetal tracheoscopy, and amniotic and tracheal fluid samples were taken. In multiple pregnancies (n = 6), amniotic fluid was also sampled from the contralateral amniotic sac and used as a control. Subsequently, endotracheal obstruction, using a detachable balloon, was performed. After 14 days, all fetuses were delivered, and sodium and chloride concentrations in amniotic and tracheal fluid were measured again. Statistical analysis was done using a two-tailed Student's t test, paired or unpaired as appropriate.

RESULTS

In controls, between 95 and 109 days gestational age, no significant changes occurred in sodium or chloride concentrations in amniotic or tracheal fluid. After 2 weeks of tracheal obstruction, however, chloride and sodium concentrations in amniotic fluid decreased (chloride = 76.7 mEq/L vs. 107.6 mEq/L, p = 0.0003; sodium = 109.6 mEq/L vs. 125.9 +/- 5.2 mEq/L, p = 0.019). A concomitant increase in chloride and sodium concentration was observed in tracheal fluid (chloride = 145.4 mEq/L vs. 130.0 mEq/L, p = 0.047; sodium = 153.1 mEq/L vs. 142.9 mEq/L, p = 0.051). When comparing groups at 109 days, chloride and sodium concentrations in amniotic fluid were markedly lower in the treated group versus controls (p = 0.0004 and p = 0.05 for chloride and sodium, respectively).

CONCLUSION

Complete tracheal occlusion in ovine fetuses results in a significant decrease of amniotic fluid sodium and chloride concentrations.

Operative fetoscopy: new perspective in fetal therapy?

In a limited number of conditions in utero surgery may be life-saving, such as some cases of congenital diaphragmatic hernia, cystic adenomatoid malformation of the lung, sacrococcygeal teratoma and lower urinary tract obstruction. Postoperative premature labour and its extreme invasiveness have been major drawbacks for open fetal surgery. More recently the merger of fetoscopy and advanced video-endoscopic surgery has been the basis of the concept of endoscopic fetal surgery. In order to evaluate the opportunities of 'fetendo' surgery, animal models have been developed to test the safety of the endoscopic approach, and the feasibility of surgical manipulations on the fetus. In the non-human primate, a lesser invasiveness of endoscopy over open surgical approach was demonstrated, by a significant decrease in uterine activity in comparison with hysterotomy. The main application of fetoscopy today is the surgical treatment of complicated or abnormal monochorionic twin gestations. Fetoscopic laser coagulation of chorionic plate vessels is suggested as a causal therapy for severe feto-fetal transfusion syndrome. Survival rates are around 55 per cent with an incidence of five per cent of neurological morbidity. Fetoscopic cord ligation is associated with a 66 per cent survival rate, but unfortunately also with a risk of 30 per cent for PPROM prior to 32 weeks. Although still in its early experimental phase, endoscopy seems to offer new hope for surgical fetal therapy. Though conceptually very tempting, the development of endoscopic fetal surgery should follow the formal guidelines, as earlier formulated for open surgery by the International Fetal Medicine and Surgery Society. The prospective registration of worldwide experience is advocated and a randomized trial of laser therapy versus amniodrainage is announced.

Tracheoscopic endotracheal occlusion in the ovine model: technique and pulmonary effects

BACKGROUND/PURPOSE

The purpose of this study was to assess the tracheoscopic placement of a detachable balloon to obstruct the trachea in the fetal lamb model and to study the pulmonary effects 2 weeks later.

METHODS

Thirteen pregnant ewes carrying 27 fetuses were used in this trial. Thirteen fetuses underwent endotracheal plugging at a mean gestational age of 95 (90 to 100) days (term, 145). Fourteen nonoperated fetuses served as controls. The intended duration of obstruction was 15 days. Study parameters consisted of operating time, fetal survival, performance of the balloon, and pulmonary changes.

RESULTS

Hysterotomy time was 41 +/- 25 minutes and tracheoscopy time was 7.2 +/- 3.4 minutes. There were no intraoperative deaths in this series. Postoperative fatalities occurred in 2 of 13 plugged fetuses and 1 of 14 controls. At completion of the experiment, the balloon was recovered intact in the trachea of 12 of 13 (92.3%) fetuses. The lung weight/body weight ratio was 76 +/- 16 mg/kg for plugged animals, while in controls it was 34 +/- 8 mg/kg (P = .0001). The lung volume/body weight ratio was 101 +/- 17 mL/kg in plugged fetuses, compared with 47 +/- 4 mL/kg for controls (P = .0002). Mean-terminal-bronchial-density was 0.937 +/- 0.303 for plugged animals, compared with 1.911 +/- 0.441 for controls (P = .0002). Mean linear intercept was 60.9 +/- 5.2 microm in treated fetuses, and 46.3 +/- 5.8 microm for controls (P = .0004).

CONCLUSIONS

Fetal endotracheal occlusion, using a tracheoscopically placed detachable balloon, is reliable, and results in pulmonary hyperplasia after 2 weeks of obstruction. This technique may be beneficial in treating the pulmonary hypoplasia seen in congenital diaphragmatic hernia. Further studies using this balloon device are now required to corroborate these findings.