Revisiting MOMS criteria for prenatal repair of spina bifida: upper gestational-age limit should be raised and assessment of prenatal motor function rather than anatomical level improves prediction of postnatal function

OBJECTIVES

To determine if the lower-extremity neurological motor function level in fetuses with open spina bifida deteriorates within the 4-week interval between a first prenatal motor assessment at around 22 weeks of gestation and a second evaluation, prior to 'late' prenatal surgery, defined as surgery at 26-28 weeks and, in certain situations, up to 30 weeks, and to assess the association between prenatal presurgical motor-function level, anatomical level of the lesion and postnatal motor-function level.

METHODS

This was a two-center cohort study of 94 singleton fetuses with open spina bifida which underwent percutaneous repair using the skin-over-biocellulose for antenatal fetoscopic repair (SAFER) technique between December 2016 and January 2022. All women underwent two prenatal systematic ultrasound evaluations, approximately 4 weeks apart, with the second one being performed less than 1 week before surgery, and one postnatal evaluation via physical examination within 2 months of birth. Motor-function classification was from spinal level T12 to S1, according to key muscle function. Each leg was analyzed separately; in case of discrepancy between the two legs, the worst motor-function level was considered for analysis. Motor-function-level evaluations were compared with each other and with the anatomical level as observed on ultrasound. Independent predictors of a postnatal reduction in motor-function level were assessed using a logistic regression model.

RESULTS

Prenatal motor-function level was assessed at a median gestational age of 22.5 (interquartile range (IQR), 20.7-24.3) and 26.7 (IQR, 25.4-27.3) weeks, with a median interval of 4.0 (IQR, 2.4-6.0) weeks. The median gestational age at surgery was 27.0 (IQR, 25.9-27.6) weeks and the postnatal examination was at median age of 0.8 (IQR, 0.3-5.4) months. There was no significant difference in motor-function level between the two prenatal evaluations (P = 0.861). We therefore decided to use the second prenatal evaluation for comparison with postnatal motor function and anatomical level. Overall, prenatal and postnatal motor function evaluations were significantly different from the anatomical level (preoperative assessment, P = 0.0015; postnatal assessment, P = 0.0333). Comparing prenatal with postnatal motor-function level, we found that 87.2% of babies had similar or improved motor function compared with that prior to prenatal surgery. On logistic regression analysis, lower anatomical level of defect and greater difference between anatomical level and prenatal motor-function level were identified as independent predictors of postnatal motor function (odds ratio, 0.237 (95% CI, 0.095-0.588) (P = 0.002) and 3.44 (95% CI, 1.738-6.813) (P < 0.001), respectively).

CONCLUSIONS

During a 4-week interval between first ultrasound evaluation and late fetal surgical repair of open spina bifida, motor function does not change significantly, suggesting that late repair, ≥ 26 weeks, does not impact negatively on motor-function outcome. Compared with the anatomical level of the lesion, preoperative neurological motor-function assessment via ultrasound is more predictive of postnatal motor function, and should be included in preoperative counseling. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Outcome of laser photocoagulation in monochorionic diamniotic twin pregnancy complicated by Type-II selective fetal growth restriction

OBJECTIVES

To evaluate the outcome of monochorionic diamniotic (MCDA) twins complicated by Type-II selective fetal growth restriction (sFGR) who underwent fetoscopic laser photocoagulation and to validate a previously proposed subclassification system for Type-II sFGR in a large multicenter cohort.

METHODS

This retrospective multicenter cohort study included all MCDA twins complicated by Type-II sFGR who underwent laser photocoagulation of placental anastomoses at four large tertiary fetal-care centers between 2006 and 2020. Cases were subclassified according to a recently proposed system based on Doppler evaluation of the ductus venosus (DV) and middle cerebral artery (MCA) into Type-IIA (normal DV flow and MCA peak systolic velocity (PSV) of the growth-restricted fetus) or Type-IIB (absent or reversed flow in the DV during atrial contraction and/or MCA-PSV ≥ 1.5 multiples of the median of the growth-restricted fetus). Demographic characteristics and pregnancy outcomes were compared between the groups. Data are presented as mean ± SD or n (%) as appropriate. P-values < 0.05 were considered statistically significant.

RESULTS

A total of 98 patients with MCDA twins met our inclusion criteria, with 56 subclassified as Type IIA and 42 as Type IIB. Demographic characteristics were similar between the groups; however, Type-IIB cases had a significantly earlier gestational age at diagnosis and at laser surgery, as well as larger intertwin estimated fetal weight discordance, which may be a reflection of disease severity. Postnatal survival of the growth-restricted fetus to 30 days of age was significantly lower in Type-IIB compared to Type-IIA cases (23.8% vs 46.4%; P = 0.034).

CONCLUSIONS

In MCDA twins complicated by Type-II sFGR and treated with laser photocoagulation of placental anastomoses, preoperative Doppler assessment of the DV and MCA helped identify a subset of patients at increased risk of demise of the growth-restricted fetus following intervention. This study provides valuable information for guiding surgical management and patient counseling. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Correction of fetal umbilical vein flow imbalance following laser surgery for twin-twin transfusion syndrome

OBJECTIVES

Twin-twin transfusion syndrome (TTTS) is characterized by unequal hemodynamics between the twins. We aimed to assess preoperatively the difference in umbilical vein flow (UVF) between the recipient and donor monochorionic diamniotic twins and evaluate the change in UVF following laser surgery in both twins.

METHODS

This was a retrospective cohort study of differences in UVF that occurred following laser surgical treatment of TTTS. Sonographic assessment of the umbilical vein before and 24 h after fetoscopic laser surgery for TTTS was performed. Umbilical vein diameter and time-averaged maximum velocity were measured, and UVF per kg (UVF/kg) was converted into a Z-score by a calculator created using gestational age as an independent variable. Z-score values were converted into centiles, which were evaluated statistically. Median differences in UVF/kg centile values were adjusted for TTTS stage and presence of arterioarterial anastomoses.

RESULTS

The study population consisted of 363 TTTS patients. The adjusted preoperative median difference in UVF/kg centile between the recipient vs donor twin was 17.9% (-17.1% to 57.6%), P < 0.0001. The adjusted median difference in UVF/kg centile between the postoperative vs preoperative period among recipients was 2.2% (-10.8% to 13.8%), P < 0.0001, while the adjusted median difference among donors was 27.3% (8.2%-34.6%), P < 0.0001.

CONCLUSION

The preoperative difference in UVF between the recipient and donor twins confirms the pathophysiology of TTTS. Postoperatively, the substantial increase in UVF of the donor twin and the relatively small increase in UVF of the recipient twin confirm that ablation of the vascular communications resulted in rapid improvement in perfusion of the donor twin. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Percutaneous fetoscopic spina bifida repair: effect on ambulation and need for postnatal cerebrospinal fluid diversion and bladder catheterization

OBJECTIVE

A trial comparing prenatal with postnatal open spina bifida (OSB) repair established that prenatal surgery was associated with better postnatal outcome. However, in the trial, fetal surgery was carried out through hysterotomy. Minimally invasive approaches are being developed to mitigate the risks of open maternal-fetal surgery. The objective of this study was to investigate the impact of a novel neurosurgical technique for percutaneous fetoscopic repair of fetal OSB, the skin-over-biocellulose for antenatal fetoscopic repair (SAFER) technique, on long-term postnatal outcome.

METHODS

This study examined descriptive data for all patients undergoing fetoscopic OSB repair who had available 12- and 30-month follow-up data for assessment of need for cerebrospinal fluid (CSF) diversion and need for bladder catheterization and ambulation, respectively, from eight centers that perform prenatal OSB repair via percutaneous fetoscopy using a biocellulose patch between the neural placode and skin/myofascial flap, without suture of the dura mater (SAFER technique). Univariate and multivariate logistic regression analyses were used to examine the effect of different factors on need for CSF diversion at 12 months and ambulation and need for bladder catheterization at 30 months. Potential cofactors included gestational age at fetal surgery and delivery, preoperative ultrasound findings of anatomical level of the lesion, cerebral lateral ventricular diameter, lesion type and presence of bilateral talipes, as well as postnatal findings of CSF leakage at birth, motor level, presence of bilateral talipes and reversal of hindbrain herniation.

RESULTS

A total of 170 consecutive patients with fetal OSB were treated prenatally using the SAFER technique. Among these, 103 babies had follow-up at 12 months of age and 59 had follow-up at 30 months of age. At 12 months of age, 53.4% (55/103) of babies did not require ventriculoperitoneal shunt or third ventriculostomy. At 30 months of age, 54.2% (32/59) of children were ambulating independently and 61.0% (36/59) did not require chronic intermittent catheterization of the bladder. Multivariate logistic regression analysis demonstrated that significant prediction of need for CSF diversion was provided by lateral ventricular size and type of lesion (myeloschisis). Significant predictors of ambulatory status were prenatal bilateral talipes and anatomical and functional motor levels of the lesion. There were no significant predictors of need for bladder catheterization.

CONCLUSION

Children who underwent prenatal OSB repair via the percutaneous fetoscopic SAFER technique achieved long-term neurological outcomes similar to those reported in the literature after hysterotomy-assisted OSB repair. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Percutaneous fetoscopic closure of large open spina bifida using a bilaminar skin substitute

OBJECTIVE

We have described previously our percutaneous fetoscopic technique for the treatment of open spina bifida (OSB). However, approximately 20-30% of OSB defects are too large to allow primary skin closure. Here we describe a modification of our standard technique using a bilaminar skin substitute to allow closure of large spinal defects. The aim of this study was to report our clinical experience with the use of a bilaminar skin substitute and a percutaneous fetoscopic technique for the prenatal closure of large OSB defects.

METHODS

Surgery was performed between 24.0 and 28.9 gestational weeks with the woman under general anesthesia, using an entirely percutaneous fetoscopic approach with partial carbon dioxide insufflation of the uterine cavity, as described previously. If there was enough skin to be sutured in the midline, only a biocellulose patch was placed over the placode (single-patch group). In cases in which skin approximation was not possible, a bilaminar skin substitute (two layers: one silicone and one dermal matrix) was placed over the biocellulose patch and sutured to the skin edges (two-patch group). The surgical site was assessed at birth, and long-term follow-up was carried out.

RESULTS

Percutaneous fetoscopic OSB repair was attempted in 47 consecutive fetuses, but surgery could not be completed in two. Preterm prelabor rupture of membranes (PPROM) occurred in 36 of the 45 (80%) cases which formed the study group, and the mean gestational age at delivery was 32.8 ± 2.5 weeks. A bilaminar skin substitute was required in 13/45 (29%) cases; in the remaining 32 cases, direct skin-to-skin suture was feasible. There were 12 cases of myeloschisis, of which 10 were in the two-patch group. In all cases, the skin substitute was located at the surgical site at birth. In five of the 13 (38.5%) cases in the two-patch group, additional postnatal repair was needed. In the remaining cases, the silicone layer detached spontaneously from the dermal matrix (on average, 25 days after birth), and the lesion healed by secondary intention. The mean operating time was 193 (range, 83-450) min; it was significantly longer in cases requiring the bilaminar skin substitute (additional 42 min on average), although the two-patch group had similar PPROM rate and gestational age at delivery compared with the single-patch group. Complete reversal of hindbrain herniation occurred in 68% of the 28 single-patch cases and 33% of the 12 two-patch cases with this information available (P < 0.05). In four cases there was no reversal; half of these occurred in myeloschisis cases.

CONCLUSIONS

Large OSB defects may be treated successfully in utero using a bilaminar skin substitute over a biocellulose patch through an entirely percutaneous approach. Although the operating time is longer, surgical outcome is similar to that in cases closed primarily. Cases with myeloschisis seem to have a worse prognosis than do those with myelomeningocele. PPROM and preterm birth continue to be a challenge. Further experience is needed to assess the risks and benefits of this technique for the management of large OSB defects. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Salvage of Necrotic-Appearing Limb after In Utero Endoscopic Lysis of Constriction Bands

We report a case of amniotic band syndrome complicated by constriction bands and marked distal swelling of both lower extremities. Color Doppler interrogation of the right lower extremity revealed complete lack of blood flow below the level of the constriction. Upon fetoscopic survey, the right lower extremity beyond the constriction band appeared dusky red and discolored with desquamation, consistent with a necrotic appearance. The constriction bands were cut in utero using endoshears, thereby allowing restoration of blood flow on postoperative day 1. The patient was counseled extensively regarding the possibility of limb dysfunction or amputation. However, the baby was born with functional lower extremities, and at 21 months of age, the child was cruising and jumping on his own. This case demonstrates that there is unique plasticity in fetal limb recovery after a severe ischemic injury that is not otherwise seen in postnatal life. Reperfusion of the necrotic-appearing limb resulted in restoration of appearance and function without apparent deleterious effects on the fetus. We believe the favorable outcome in this case was likely due to timeliness of the in utero lysis of amniotic bands and the plasticity of fetal healing.

Amniotic fluid levels of phospholipase A2 in fetal rats with retinoic acid induced myelomeningocele: the potential "second hit" in neurologic damage

OBJECTIVES

There is growing evidence of ongoing, in utero neurological damage in fetuses with myelomeningocele (MMC). Phospholipase A2 (PLA2) has known neurotoxic properties and is predominantly present in its secretory isoform (sPLA2) in meconium, the passage of which is increased in MMC fetuses. The objective of this study was to determine if amniotic fluid (AF) levels of PLA2 are elevated in a rat model of MMC.

METHODS

Timed pregnant Sprague-Dawley rats were gavage fed 60 mg/kg/bodyweight retinoic acid (RA) in olive oil at embryonic day 10 (E10). Amniocentesis was performed at multiple gestational time points on MMC fetuses, RA-exposed fetuses without MMC and control fetuses. AF PLA2 levels were analyzed by a fluorescent enzyme activity assay. PLA2 isoforms were determined by measuring activity in the presence of specific inhibitors.

RESULTS

There was no difference in AF PLA2 activity between groups on E15. PLA2 activity was significantly increased in MMC fetuses on E17, E19 and E21 (p < 0.001). Secretory PLA2 primarily accounted for the overall greater activity.

CONCLUSIONS

PLA2 levels are elevated in the AF of fetal rats with MMC and may contribute to ongoing neural injury. This pathway may be a useful drug target to limit ongoing damage and better preserve neurologic function.

Identification of essential steps in laser procedure for twin-twin transfusion syndrome using the Delphi methodology: SILICONE study

OBJECTIVE

To determine, by expert consensus, the essential substeps of fetoscopic laser surgery (FLS) for twin-twin transfusion syndrome (TTTS) that could be used to create an authority-based curriculum for training in this procedure among fetal medicine specialists.

METHODS

A Delphi survey was conducted among an international panel of experts (n = 98) in FLS. Experts rated the substeps of FLS on a five-point Likert-type scale to indicate whether they considered them to be essential, and were able to comment on each substep, using a dedicated online platform accessed by the invited tertiary care facilities that specialize in fetal therapy. Responses were returned to the panel until consensus was reached (Cronbach's α ≥ 0.80). All substeps that were rated  ≥ 4 by 80% of the experts were included in the evaluation instrument.

RESULTS

After the first iteration of the Delphi procedure, a response rate of 74% (73/98) was reached, and in the second and third iterations response rates of 90% (66/73) and 81% (59/73) were reached, respectively. Among a total of 81 substeps rated in the first round, 21 substeps had to be re-rated in the second round. Finally, from the initial list of substeps, 55 were agreed by experts to be essential. In the third round, the 18 categorized substeps were ranked in order of importance, with 'coagulation of all anastomoses that cross the equator' and 'determination of fetoscope insertion site' as the most important.

CONCLUSIONS

A total of 55 substeps of FLS for TTTS were defined by a panel of experts to be essential in the procedure. This list is the first authority-based evidence to be used in the development of a final training model for future fetal surgeons.

Fetal middle cerebral artery Doppler fluctuations after laser surgery for twin-twin transfusion syndrome

OBJECTIVE

The objective of this study was to compare alterations in the middle cerebral artery (MCA) pulsatility index (PI) and mean velocity (V (mean)) after laser surgery for twin-twin transfusion syndrome (TTTS).

STUDY DESIGN

MCA Doppler studies were conducted 1 day before and after laser surgery for TTTS. The pre- and postoperative mean (standard deviation) of the MCA PI and V (mean) z-scores of the recipient and donor fetuses were calculated and compared. Data were analyzed using paired testing and multivariable linear regression models.

RESULTS

A total of 103 patients met the study criteria. Recipients' MCA PI increased from -1.29 (1.20) preoperatively to 0.14 (1.52) postoperatively (P < 0.0001), whereas the donors' PI did not change significantly (-0.31 (1.67) to -0.67 (1.29); P = 0.12). There was no significant difference between preoperative and postoperative MCA V (mean) in donors (0.39 (0.83) and 0.38 (0.93), respectively; P = 0.5048) or recipients (0.60 (0.74) and 0.63 (0.90), respectively; P = 0.5324).

CONCLUSIONS

Despite the changes in the MCA PI after laser surgery for TTTS, the MCA V (mean) remained constant. These findings may suggest some autoregulatory capacity in the cerebral vessels of the mid-trimester fetus.

Neonatal outcomes of twins according to birth order, presentation and mode of delivery: a systematic review and meta-analysis

BACKGROUND

The optimal mode of delivery for twins is undetermined.

OBJECTIVE

To review literature regarding the neonatal outcomes following twin delivery.

DATA SOURCES

Searches were conducted in PubMed, Medline, Embase, Cochrane library and reference lists.

SELECTION CRITERIA

Studies selection criteria were: both twins alive at labour, outcomes stratified for birth order, presentation, planned and actual delivery mode. Eighteen articles were included in the meta-analysis (39, 571 twin sets).

DATA COLLECTION AND ANALYSIS

The Meta-analysis of Observational Studies in Epidemiology guidelines were followed. Interstudy heterogeneity (I(2) ) was tested. A fixed model was generated whenever I(2)<25%. Pooled odds ratios (OR) with 95% CI were computed. Intergroup comparison was significant if 95% CI did not encompass 1. The first and second twins were indicated as Twin A (TA) and Twin B (TB), respectively.

MAIN RESULTS

Neonatal morbidity was lower in TA than TB (3.0 versus 4.6%; OR 0.53; 95% CI 0.39-0.70). TA experienced neonatal death less often than TB (0.3 versus 0.6%; OR 0.55; 95% CI 0.38-0.81). No differences were noted between vertex and non-vertex and attempted vaginal delivery versus planned caesarean section in either TA or TB. In TA, neonatal morbidity was lower after vaginal delivery (1.1%) than caesarean section (2.2%; OR 0.47; 95% CI 0.27-0.82). Neonatal death was not associated with actual delivery mode. In TB, morbidity following combined delivery (19.8%) was higher than after vaginal delivery (9.5%; OR 0.55; 95% CI 0.41-0.74) or caesarean section (9.8%; OR 0.47; 95% CI 0.43-0.53). When outcomes were stratified for both presentation and delivery mode, mortality rate was lower after vaginal delivery than caesarean section for both vertex and nonvertex TB. AUTHOR'S CONCLUSION: An attempt at vaginal delivery should be considered in twin pregnancies with vertex/vertex presentation.

Residual vascular communications in twin-twin transfusion syndrome treated with sequential laser surgery: frequency and clinical implications

OBJECTIVES

The goal of fetoscopic laser surgery for twin-twin transfusion syndrome (TTTS) is to ablate all placental vascular communications, thereby separating the fetal circulatory systems. We sought to ascertain the frequency and clinical implications of residual vascular communications (RVC) post preferential sequential selective laser photocoagulation of communicating vessels (SQLPCV).

STUDY DESIGN

TTTS placentas treated via preferential SQLPCV were examined. Patency of vascular communications was assessed via water and/or milk injections. Cases with intrauterine fetal demise or placental disruption were excluded. Outcomes with and without RVC were compared.

RESULTS

One hundred seventy-four TTTS patients were treated during the study period. Dual survival at birth was 76% (133/174). Of the 133 dual survivors, 105 (79%) submitted an intact placenta. Five of these 105 placentas had RVC (4.8%). Comparison of RVC versus non-RVC cases revealed the following: gestational age at delivery 28.7(6.5) vs. 33.4(3.3) weeks (p=0.178); recipient birth weight 1287(1061) vs. 1973(610) grams (p=0.020); donor birth weight 1429(1369) vs. 1653(715) grams (p=0.518); donor central/eccentric placental cord insertion 80% vs. 17% (p=0.006). One case required a second laser surgery to complete the laser ablation; this placenta did not have RVC after delivery. Otherwise there were no cases of persistent TTTS. One of the 5 RVC cases (20%) exhibited neonatal findings consistent with twin anemia-polycythemia sequence (TAPS), while none of the non-RVC cases had TAPS (p=0.005).

CONCLUSIONS

The rate of RVC was less than 5% among gestations with dual survivors post preferential SQLPCV treatment for TTTS.

Fetal heart rate changes associated with sequential selective laser surgery for twin-twin transfusion syndrome

OBJECTIVE

To investigate perioperative changes in fetal heart rate (FHR) associated with sequential vs standard selective laser photocoagulation of communicating vessels for the treatment of twin-twin transfusion syndrome (TTTS).

STUDY DESIGN

Women with TTTS were treated with the intent of using the sequential procedure. Those who failed this treatment were categorized as having undergone the standard procedure. Pre- and postoperative FHR of donor and recipient fetuses were analyzed.

RESULT

Of 98 women, 35 received the standard technique. A postoperative drop in the mean donor FHR was observed in gestations receiving the standard laser, but not in those receiving the sequential technique. In multivariable models that included operative and gestational characteristics, the use of the sequential treatment was associated with improved stability of the FHR of the donor twin.

CONCLUSION

The stability in donor FHR following sequential laser ablation when compared with the standard technique is consistent with improved donor hemodynamics.

Percent absent end-diastolic velocity in the umbilical artery waveform as a predictor of intrauterine fetal demise of the donor twin after selective laser photocoagulation of communicating vessels in twin-twin transfusion syndrome

OBJECTIVE

Absent end-diastolic velocity (AEDV) in the umbilical artery of the donor twin is a known risk factor for intrauterine fetal demise (IUFD) of this fetus after selective laser photocoagulation of communicating vessels (SLPCV) for twin-twin transfusion syndrome (TTTS). The aim of this study was to assess the proportion of time, expressed as a percentage, of the cardiac cycle spent in AEDV (%AEDV) as a predictor of IUFD of the donor.

METHODS

All patients referred for possible SLPCV underwent complete preoperative staging evaluation including Doppler assessment of the umbilical artery. %AEDV was calculated retrospectively as 100 x (time of the cycle spent in AEDV divided by duration of total cardiac cycle). Patients without AEDV were considered to have a %AEDV of 0. Follow-up Doppler studies were performed 16-24 h after SLPCV. IUFD of the donor was recorded if the donor twin died any time prior to delivery.

RESULTS

Of 401 patients undergoing SLPCV, 127 had AEDV. Preoperative AEDV of the donor twin was associated with an increased risk of IUFD of the donor (40.9% vs. 14.2%, P < 0.0001). %AEDV was measured in 72/127 (56.7%) donors with AEDV for whom digital images were available. Within these 72 patients, the mean %AEDV was significantly higher in patients with IUFD of the donor (36.5% vs. 29.6%, P = 0.01). IUFD of the donor was similar in patients with AEDV, regardless of whether %AEDV was measured (36% vs. 47%, P = 0.2). A %AEDV > 30 was associated with a 4.3-fold increase in the risk of IUFD of the donor (95% CI, 1.4-12.7), a sensitivity of 77% and a negative predictive value of 81.3%. Logistic regression showed that %AEDV, but not number of anastomoses, placental location, presence of artery-to-artery anastomoses or the presence or absence of EDV was associated significantly with IUFD of the donor.

CONCLUSION

%AEDV is a novel Doppler parameter in the assessment of patients with TTTS. %AEDV, rather than AEDV alone, is a significant risk factor for IUFD of the donor twin and %AEDV > 30 is associated with an increased risk of IUFD of the donor in TTTS patients treated with SLPCV. Assessment of %AEDV should be considered part of the preoperative evaluation of TTTS patients.

Ultrasound assessment of venous blood flow before and after laser therapy: approach to understanding the pathophysiology of twin-twin transfusion syndrome

OBJECTIVE

To estimate direction and volume of blood exchange between the donor twin and recipient twin by ultrasound assessment of blood flow in the umbilical vein before and after selective laser photocoagulation of communicating vessels (SLPCV) for twin-twin transfusion syndrome (TTTS).

METHODS

Forty-one TTTS patients underwent Doppler examination of the umbilical vein before and 24 h after SLPCV. The diameter and mean time-averaged velocity of the umbilical vein were estimated. Total umbilical venous flow (TUVF) was calculated as follows: TUVF (mL/min) = mean time-averaged velocity (cm/s) x mean cross-sectional area (cm2) x 60 (s).

RESULTS

TUVF was significantly higher in the recipient (111.2 mL/min) than in the donor twin (44.8 mL/min) before SLPCV (P < 0.0001). However, TUVF was no different between the recipient and the donor twin after SLPCV (93.1 vs. 70.7 mL/min, recipient and donor twin, respectively, P = 0.11). The donor twin's TUVF increased after surgery (P < 0.0001), while the recipient twin's TUVF decreased (P = 0.041). The median postoperative increase in the donor twin's TUVF of 25.9 mL/min had a corresponding decrease of TUVF in the recipient twin of 18.1 mL/min (P = 0.27).

CONCLUSIONS

Our data suggest that untreated TTTS is characterized by excessive umbilical venous blood flow in the recipient twin relative to the donor twin. Laser surgery results in concordant changes in umbilical venous flow in opposite directions between the donor and recipient twins, eliminating the initial imbalance. Our results lend support to the fundamental hypothesis of unbalanced blood flow exchange (net flow from donor to recipient) between monochorionic twins as the cause for TTTS and that laser surgery eliminates the pathophysiological cause.

Umbilical cord occlusion of the donor versus recipient fetus in twin-twin transfusion syndrome

OBJECTIVES

To compare the technical characteristics and perinatal outcomes of selected twin-twin transfusion syndrome (TTTS) cases treated with primary umbilical cord occlusion (UCO) of the donor vs. recipient twin.

METHODS

TTTS patients who underwent primary UCO via ultrasound endoscopic-guided umbilical cord ligation (UCL) or endoscopic umbilical cord photocoagulation (UCP) were eligible for the study. Primary UCO was offered only if a discordant lethal anomaly was present or by patient choice in TTTS Stages III/IV on the cord of the fetus with abnormal Doppler studies or hydrops.

RESULTS

Primary UCO was performed in 25 TTTS cases between July 1997 and June 2002. UCO was performed in six (24%) donor twins and 19 (76%) recipient twins. UCL was performed in 23 cases and UCP in two cases. Overall, 22 (88%) patients had liveborn infants. There were no differences in cotwin survival (100% vs. 84.2%), median gestational age at delivery (34.8 vs. 33.8 weeks) and preterm premature rupture of membranes rate (16.6% vs. 15.7%) whether the donor or recipient twin, respectively, was the subject of UCO. However, two-trocar access (50% vs. 5.3%; P = 0.03) and amnioinfusion (83.3% vs. 0%; P < 0.001) were required more often in the UCO of the donor than of the recipient twin, respectively. Operating time (75 vs. 40 min) was significantly longer in UCO of the donor twin (P = 0.04). UCP was more likely to be used in occlusion of the donor's cord (33%) than of the recipient's cord (0%; P = 0.05).

CONCLUSION

Primary UCO of the donor twin is technically more demanding than that of the recipient twin, but perinatal outcomes of the cotwins are comparable.

The cocoon sign: a potential sonographic pitfall in the diagnosis of twin - twin transfusion syndrome

OBJECTIVES

To investigate the frequency and clinical importance of the cocoon sign in twin-twin transfusion syndrome (TTTS).

METHODS

Charts and ultrasound images of all pregnancies with TTTS that underwent selective laser photocoagulation of communicating vessels at our institution over a 1-year period were retrospectively reviewed for a cocoon sign. TTTS had been diagnosed and prospectively staged if monochorionicity was suspected and the maximum vertical pocket (MVP) of amniotic fluid in one gestational sac was >/=8 cm, while the MVP in the other gestational sac was </=2 cm. The cocoon sign was diagnosed when there was an ultrasound finding of a donor twin with severe oligohydramnios enveloped by dividing membranes and connected to the uterine wall by a laminar stalk of these membranes.

RESULTS

The cocoon sign was noted in 9/58 (15.5%) cases. There were no differences in gestational age and stage of TTTS upon presentation, gestational age at delivery or number of neonatal survivors between the groups of TTTS cases with and those without a cocoon sign. One patient in the cocoon group had been misdiagnosed because the donor twin's MVP was measured from the donor's tethered membranes to the posterior wall of the uterus within the recipient's sac.

CONCLUSIONS

The cocoon sign is present in at least 15% of patients with TTTS. Its recognition is important to avoid misdiagnosis of TTTS. The practical implications and potential complications of this sonographic sign are discussed.

Hemophagocytic syndrome in pregnancy

BACKGROUND

Hemophagocytic syndrome is characterized by nonmalignant histiocytes that undergo uncontrolled phagocytosis of normal hematopoietic cells. Clinical severity ranges from complete recovery to rapid deterioration and death.

CASE

Thrombocytopenia was discovered upon routine initial prenatal evaluation of a 24-year-old, gravida 2, para 1, at 29 weeks' gestation with a history of necrotizing lymphadenitis. Cytopenia and elevated transaminases developed, followed by hyperpyrexia. The patient delivered and her postpartum course was complicated by coagulopathy, multiorgan failure, and death. Bone marrow biopsy confirmed hemophagocytic syndrome.

CONCLUSION

Early diagnosis of hemophagocytic syndrome during pregnancy might be helped by recognizing symptoms and signs, including a history of necrotizing lymphadenitis, and obtaining a bone marrow biopsy.