A definition of selectivity in laser coagulation of chorionic plate anastomoses in twin-to-twin transfusion syndrome and its relationship to perinatal outcome

Impact of cannula diameter on pregnancy outcomes after minimally invasive fetal laser surgery in the treatment of twin-to-twin transfusion syndrome: A systematic review and meta-analysis

INTRODUCTION

Preterm prelabor rupture of membranes (PPROM) remains a major complication of fetal laser surgery in the treatment of twin-to-twin transfusion syndrome (TTTS). The aim of the study was to determine the impact of cannula size on pregnancy outcomes, with a particular focus on PPROM.

MATERIAL AND METHODS

The protocol was developed and registered in the PROSPERO database under registration number CRD42022333630. The PubMed, Web of Science, and EMBASE databases were searched electronically on May 18, 2022, and updated on March 2, 2023, utilizing a combination of the relevant MeSH terms, keywords, and word variants for "TTTS" and "laser". Randomized controlled trials, prospective and retrospective cohorts, case-control studies, and case reports/series with more than five participants were considered eligible for inclusion. Studies reporting the cannula diameter and PPROM rate after laser surgery in the treatment of monochorionic pregnancies affected by TTTS between 16- and 26 weeks' gestation were included. Data was extracted independently, and when appropriate, a random-effects meta-analysis was undertaken to calculate pooled estimates and their confidence intervals. Heterogeneity in the effect estimates of the individual studies was calculated using the I2 statistic. The primary outcome was PPROM rate. Secondary outcomes were survival rate, preterm birth, and incomplete surgery. The quality of the included studies was assessed using a modified quality in prognosis study tool.

RESULTS

We included a total of 22 studies, consisting of 3426 patients. Only one study was scored as low quality, seven as moderate quality, and the remaining 14 as high quality. The mean PPROM rate after laser surgery treating TTTS was 22.9%, ranging from 11.6% for 9 French (Fr) to 54.0% for 12 Fr. Subsequent meta-regression for the clinically relevant PPROM rate before 34 weeks of gestation, showed increased PPROM rates for increased cannula size (p-value 0.01).

CONCLUSIONS

This systematic review confirmed PPROM as a frequent complication of fetal laser surgery, with a mean PPROM rate of 22.9%. A larger cannula diameter relates to a significant higher PPROM risk for PPROM before 34 weeks gestation. Hence, the ideal balance between optimal visualization requiring larger port diameters and shorter operation time and more complete procedures that benefit from larger diameters is crucial to reduce iatrogenic PPROM rates.

Selective vs complete fetoscopic coagulation of vascular equator: a matched comparative study

BACKGROUND

Complete coagulation of the vascular equator (as in the Solomon technique) has been suggested to reduce postoperative complications such as twin anemia polycythemia syndrome and the recurrence of twin-twin transfusion syndrome following fetoscopic laser coagulation of chorionic vessels for twin-twin transfusion syndrome.

OBJECTIVE

We aimed to evaluate the benefit of this technique on perinatal outcomes compared with selective ablation of anastomoses.

STUDY DESIGN

We conducted a monocentric retrospective study comparing selective laser coagulation of anastomoses to the Solomon technique from January 2006 to August 2020. To adjust for potential confounders, the cases operated by selective surgery were matched to the cases operated with the Solomon technique according to the gestational age at laser therapy, placental localization, and Quintero stage using propensity score matching.

RESULTS

With a total of 994 cases, 399 matched pairs were included in the analysis. Compared with selective ablation, the Solomon technique was associated with significantly improved survival: the overall twin survival at delivery and discharge was 72% vs 79% (P=.003) and 69% vs 75% (P=.006), respectively; the double twin survival rate at discharge was 55% vs 65% (P=.02), respectively, and the rate of intrauterine death dropped from 18% to 12% (P=.003), respectively. The Solomon technique significantly reduced the rate of twin anemia polycythemia syndrome (10% vs 4%; P=.02), leading to fewer secondary rescue procedures (13% vs 7.3%; P=.01). However, the Solomon technique was associated with an increased risk of preterm rupture of membranes, especially at early gestational ages (3.8% vs 11%; P<.001 for preterm rupture of membranes <24 weeks). Among the survivors at delivery, both the groups had similar gestational ages at birth. Both neonatal mortality and severe neurologic morbidity were similar in both the groups. However, an increased risk of bronchopulmonary dysplasia was found in the Solomon group (4.5% vs 12%; P<.001).

CONCLUSION

Although the risk of preterm premature rupture of membranes has increased, the introduction of the Solomon technique has significantly improved perinatal outcomes in pregnancies affected with twin-twin transfusion syndrome.

Perinatal outcomes and factors affecting the survival rate of fetuses with twin-to-twin transfusion syndrome treated with fetoscopic laser coagulation: a single-center seven-year experience

OBJECTIVES

This single-center study aimed to assess the perinatal outcomes and its associated factors in fetuses with twin-to-twin transfusion syndrome (TTTS) treated by fetoscopic laser coagulation (FLC).

METHODS

In this retrospective study, we included fetuses prenatally diagnosed with TTTS at Asan Medical Center, Seoul, Korea, between October 2011 and December 2018. All patients with TTTS stage II or higher and those with stage I TTTS coupled with symptomatic polyhydramnios or cardiac dysfunction were eligible for FLC.

RESULTS

A total of 172 cases of monochorionic diamniotic twins and one case of dichorionic triamniotic triplets were prenatally diagnosed with TTTS and treated with FLC. The median gestational ages (GAs) at diagnosis and FLC were 20.3 and 20.5 weeks, respectively. The median GA of survivors at delivery was 32.5 weeks. The overall at least one twin- and double-survival rates within 28 days after birth were 82.1% and 55.5%, respectively. The GAs at diagnosis and FLC, Quintero stage, inter-twin weight discordance, associated selective intrauterine growth restriction (sIUGR), procedure time, volume of amnioreduction, preterm prelabor rupture of membranes (PPROM) within one week after FLC, intraoperative intrauterine bleeding, and chorioamnionitis were significant predictive factors of perinatal death. Associated sIUGR, absent end-diastolic flow of umbilical artery, and abnormal cord insertion were significantly associated with donor demise in utero, whereas lower GA at diagnosis and FLC, smaller twins at FLC, pulsatile umbilical vein, and presence of mitral regurgitation were significantly associated with recipient demise in utero. Since the application of the Solomon technique, the survival rate has improved from 75.4% to 88.8%. The FLC before 17 weeks was associated with PPROM within one week after FLC and lower survival rate, whereas that after 24 weeks was associated with twin anemia-polycythemia sequence and higher survival rate. We reached a survival rate of 82% for at least one survival with only 12 procedures.

CONCLUSIONS

FLC is an effective treatment for TTTS. The learning curve reached the acceptable target faster than in previous studies. Several prenatal parameters are identified as predictive factors of fetal survival in TTTS treated with FLC.

Outcome reporting across randomized trials and observational studies evaluating treatments for twin-twin transfusion syndrome: systematic review

OBJECTIVE

Twin-twin transfusion syndrome (TTTS) is associated with significant mortality and morbidity. Potential treatments for the condition require robust evaluation. The aim of this study was to evaluate outcome reporting across observational studies and randomized controlled trials assessing treatments for TTTS.

METHODS

Cochrane Central Register of Controlled Trials, EMBASE and MEDLINE were searched from inception to August 2016. Observational studies and randomized controlled trials reporting outcome following treatment for TTTS in monochorionic-diamniotic twin pregnancy and monochorionic-triamniotic or dichorionic-triamniotic triplet pregnancy were included. Outcome reporting was systematically extracted and categorized.

RESULTS

Six randomized trials and 94 observational studies were included, reporting data from 20 071 maternal participants and 3199 children. Six different treatments were evaluated. Included studies reported 62 different outcomes, including six fetal, seven offspring mortality, 25 neonatal, six early childhood and 18 maternal/operative outcomes. Outcomes were reported inconsistently across trials. For example, when considering offspring mortality, 31 (31%) studies reported live birth, 31 (31%) reported intrauterine death, 49 (49%) reported neonatal mortality and 17 (17%) reported perinatal mortality. Four (4%) studies reported respiratory distress syndrome. Only 19 (19%) studies were designed for long-term follow-up and 11 (11%) of these reported cerebral palsy.

CONCLUSIONS

Studies evaluating treatments for TTTS have often neglected to report clinically important outcomes, especially neonatal morbidity outcomes, and most are not designed for long-term follow-up. The development of a core outcome set could help standardize outcome collection and reporting in TTTS studies. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Twin-twin transfusion syndrome - What we have learned from clinical trials

Monochorionic twin pregnancies are at increased risk for adverse outcome compared to dichorionic twin pregnancies and singletons. Monochorionic-specific complications include twin-twin transfusion syndrome (TTTS), twin anemia-polycythemia sequence, single intrauterine fetal demise and its consequences on the co-twin, and selective intrauterine growth restriction. Whereas the natural history of monochorionic-specific complications carries a high risk of fetal death or severe neurologic disability, a framework now exists, based on well-designed clinical trials, for optimal treatment of these entities. Fetoscopic selective laser coagulation of anastomotic vessels on the chorionic plate has been clearly demonstrated to improve survival and neurologic outcomes for Quintero stage ≥2 TTTS. However, many challenges remain unsolved, the most important of which is preterm premature rupture of membranes. Further improvement in the outcomes of monochorionic pregnancies will require improvements in the rate of premature delivery, and improved diagnosis and treatment strategies for early and late onset TTTS.

Laser Treatment of Twin–to–Twin Transfusion Syndrome

Objective: Laser ablation of all placental vascular anastomoses is the optimal treatment for twin–twin transfusion syndrome (TTTS). However, two important controversies are apparent in the literature: (a) a gap between concept and performance, and (b) controversy regarding whether all the anastomoses can be identified endoscopically and whether blind lasering of healthy placenta is justified. The purpose of this article is: (a) to address the potential source of the gap between concept and performance by analyzing the fundamental steps needed to successfully accomplish the surgery, and (b) to discuss the resulting competency benchmarks reported with the different surgical techniques. Materials and Methods: Laser surgery for TTTS can be broken down into two fundamental steps: (1) endoscopic identification of the placental vascular anastomoses, (2) laser ablation of the anastomoses. The two steps are not synonymous: (a) regarding the endoscopic identification of the anastomoses, the non-selective technique is based upon lasering all vessels crossing the dividing membrane, whether anastomotic or not. The selective technique identifies and lasers only placental vascular anastomoses. The Solomon technique is based on the theory that not all anastomoses are endoscopically visible and thus involves lasering healthy areas of the placenta between lasered anastomoses, (b) regarding the actual laser ablation of the anastomoses, successful completion of the surgery (i.e., lasering all the anastomoses) can be measured by the rate of persistent or reverse TTTS (PRTTTS) and how often a selective technique can be achieved. Articles representing the different techniques are discussed. Results: The non-selective technique is associated with the lowest double survival rate (35%), compared with 60–75% of the Solomon or the Quintero selective techniques. The Solomon technique is associated with a 20% rate of residual patent placental vascular anastomoses, compared to 3.5–5% for the selective technique (p < .05). Both the Solomon and the selective technique are associated with a 1% risk of PRTTTS. Adequate placental assessment is highest with the selective technique (99%) compared with the Solomon (80%) or the ‘standard’ (60%) techniques (p < .05). A surgical performance index is proposed. Conclusion: The Quintero selective technique was associated with the highest rate of successful ablation and lowest rate of PRTTTS. The Solomon technique represents a historical backward movement in the identification of placental vascular anastomoses and is associated with higher rate of residual patent vascular communications. The reported outcomes of the Quintero selective technique do not lend support to the existence of invisible anastomoses or justify lasering healthy placental tissue.

Twenty-Five Years of Fetoscopic Laser Coagulation in Twin-Twin Transfusion Syndrome: A Systematic Review

Objective: The aim of this study was to assess the perinatal outcome of pregnancies with twin-twin transfusion syndrome (TTTS) treated with laser therapy over the past 25 years, and in relation to different techniques used in this time period. Methods: A systematic review of studies reporting on perinatal outcome according to the Meta-Analysis of Observational Studies in Epidemiology (MOOSE) guidelines was conducted. The MEDLINE, Embase and Cochrane Library databases were systematically searched. Comparisons were made in respect to time period and laser technique and Quintero stages. Results: In total, 34 studies reporting on 3,868 monochorionic twin pregnancies were included. The mean survival of both twins increased from 35 to 65% (p = 0.012) and for at least one twin from 70 to 88% (p = 0.009) over the past 25 years. Mean gestational age at birth remained stable over the years at 32 weeks gestation. Also, we showed a significantly improved perinatal survival with the evolution of the laser technique from non-selective to selective, selective sequential and the Solomon technique (p = 0.010). Discussion: Since the introduction of laser therapy for TTTS more than two decades ago, perinatal survival improved significantly. Improved outcome is probably associated with several factors, including evolution of the laser technique, learning curve effect, better referral and improved early neonatal care.

Maternal and fetal safety of fluid-restrictive general anesthesia for endoscopic fetal surgery in monochorionic twin gestations

STUDY OBJECTIVE

To review our experience with general anesthesia in endoscopic fetal surgery for twin-to-twin transfusion syndrome (TTTS), and to compare fetomaternal outcome before and after protocol implementation.

DESIGN

Retrospective impact study.

SETTING

University-affiliated medical center.

MEASUREMENTS

Data from 85 consecutive patients who underwent endoscopic laser ablation of placenta vessels for severe TTTS were studied. Outcomes were compared in patients before (2000-2007) and after (2008-2012) a change to strict intraoperative intravenous (IV) fluid and liberal vasopressor management. Perioperative parameters (IV fluid administration, vasopressor use, maternal hemoglobin [Hb] concentration); maternal complication rate (respiratory, hemorrhagic); pregnancy outcome; and fetal and neonatal survival were recorded.

MAIN RESULTS

Patients in the early group (2000-2007; n = 55) received 1634 ± 949 mL of crystalloid fluid intraoperatively, compared with 485 ± 238 mL (P < 0.001; Student's t test) given to the late group (2008-2012; n = 30). Maternal pulmonary edema and any respiratory distress were seen in 5.5% and 12.7% of patients in the early group, respectively, and in none of the late group patients (P < 0.05; Chi-square analysis).

CONCLUSIONS

A significant risk of maternal respiratory complications exists after general anesthesia for endoscopic fetal surgery. Judicious fluid management significantly decreases this risk.

Maternal plasma and amniotic fluid cytokines in monochorionic, diamniotic twin pregnancies complicated by twin-to-twin transfusion syndrome

INTRODUCTION

Cytokine imbalance has been implicated in placental-related pathologies, i.e. recurrent miscarriage and pre-eclampsia. Such conditions are more prevalent in multiple pregnancies. Twin-to-twin transfusion syndrome (TTTS) is associated with asymmetric placental blood flow and intra-cardiac pressures. We hypothesised that cytokine expression may be aberrant in this condition and that fetoscopic laser ablation (FLA) may cause local cytokine release.

MATERIAL AND METHODS

A prospective cohort of monochorionic, diamniotic twins with TTTS (n = 23) was studied. Circulating T helper cell type 1 (TH1)/TH2 maternal cytokines and cytokine-related and angiogenic factors were measured in plasma and amniotic fluid before and after FLA by human FASTQuant or ELISA. Basal comparisons were made with uncomplicated monochorionic and dichorionic (DC) twins.

RESULTS

Median maternal plasma platelet-derived growth factor-BB was highest in uncomplicated DC twins (p = 0.049), whereas tissue inhibitor of metalloproteinases (TIMP)-1 was highest in TTTS twins (p = 0.003). In TTTS amniotic fluid, interleukin (IL)-6, IL-1β, tumour necrosis factor-α, IL-10, IL-4, IL-8, interferon-γ, TIMP-1 and intercellular adhesion molecule-1 were significantly higher than maternal plasma concentrations. There were no significant differences in plasma or amniotic fluid cytokines after FLA, with the exception of amniotic fluid keratinocyte growth factor, which was significantly reduced.

DISCUSSION

TTTS is associated with minimal changes in cytokine levels when compared to uncomplicated twins, although the majority of cytokine levels were higher in amniotic fluid than maternal blood. It does not appear that FLA evokes a significant change in cytokines.

What-and why-the pathologist should know about twin-to-twin transfusion syndrome

Approximately 20% of all twin pregnancies are monochorionic. Between 9% and 15% of all monochorionic twin gestations are complicated by severe chronic twin-to-twin transfusion syndrome (TTTS), characterized by a gradual shift of blood volume from the donor twin to the recipient twin through placental vascular connections [1 - 3] . The prognosis of severe, untreated chronic TTTS diagnosed in midtrimester fetuses is extremely poor, with mortality rates exceeding 70% [4] . Since publication of the results of the Eurofoetus trial in 2004, laser photocoagulation of the intertwin anastomoses has become accepted as the optimal first-line therapy for severe TTTS diagnosed before 26 weeks of gestation. While laser treatment of vascular communications was initially limited to selected fetal treatment centers, its increasingly widespread use has resulted in the exposure of more pathologists, even in less specialized institutions, to laser-treated placentas. Furthermore, the surge in laser coagulation has revived the general medical, scientific, and public interest in the placental and choriovascular findings in monochorionic twin placentas. The pathologist's understanding of the pathophysiology of TTTS and of TTTS-associated placental pathology, including the findings related to laser ablation of the anastomoses, can be of great benefit to the involved obstetric/neonatal/surgical team and, ultimately, to the patients. In this review, we summarize the current knowledge of the placental contributions to TTTS and other complications of monochorionic twinning and describe the strengths and limitations of placental examination in these settings. It is our expectation that overviews such as this may serve as a template to generate consensus guidelines for standardized and evidence-based pathologic evaluation of monochorionic twin placentas.

Active management of selective intrauterine growth restriction with abnormal Doppler in monochorionic diamniotic twin pregnancies diagnosed in the second trimester of pregnancy

OBJECTIVE

This study aims to compare outcomes of active management of monochorionic diamniotic twin pregnancies complicated with severe intrauterine growth restriction (IUGR) of one twin before 24 weeks with continuous or intermittent absent or reversed end-diastolic flow (AREDF) in the umbilical artery, with or without twin-to-twin transfusion syndrome (TTTS).

METHOD

This study is a retrospective comparison of 45 consecutive cases of severe selective IUGR (s-IUGR) defined as an estimated fetal weight at or below the fifth centile with a >25% weight discordance and AREDF in the umbilical artery before 24 weeks and 166 consecutive cases of TTTS stage III, with AREDF in the donor (TTTS3D) and also with s-IUGR. These were treated by either selective laser photocoagulation of chorionic vessels (SLPCV) or cord coagulation (CC).

RESULTS

The 166 cases of TTTS3D were treated by SLPCV, whereas 23 and 22 cases of s-IUGR were treated by SLPCV and CC, respectively. Overall survival was 52.17% or 45.45% in s-IUGR treated by SLPCV or CC, respectively, and 48.49% in TTTS3D. The survival of appropriately grown for gestational age (AGA) twins following CC (90.9%) was higher than that following SLPCV in s-IUGR (74%) or in recipient twins of TTTS3D (55.42%) (p = 0.001). Survival of the IUGR twin was 30% and 41.56% with SLPCV in s-IUGR and TTTS3D, respectively.

CONCLUSIONS

Active management of severe IUGR with AREDF in the umbilical artery seems beneficial. Survival rates with SLPCV were similar in s-IUGR and TTTS3D. However, there was a trend for higher survival rates in the AGA twin for CC. The choice of the technique should be driven by objective counseling on survival of both IUGR and AGA twins and therefore by the utility-based ethical values expressed by the pregnant woman.

Recurrent twin-twin transfusion syndrome after selective fetoscopic laser photocoagulation: a systematic review of the literature

OBJECTIVES

Selective fetoscopic laser photocoagulation (SFLP) is now the treatment of choice for twin-twin transfusion syndrome (TTTS). The incidence of recurrent TTTS following SFLP has been inconsistently reported across different studies. We performed a systematic review of TTTS recurrence following SFLP.

METHODS

PubMed and MEDLINE online databases were searched for articles published between 2000 and August 2011, using combinations of the terms 'twin-twin transfusion', 'TTTS', 'laser', 'recur' and 'outcome'. Citations identified in the primary search were screened for eligibility. Studies reporting outcomes from selective SFLP for TTTS in twin pregnancies, which addressed specifically the issue of TTTS recurrence, were included. The primary outcome was rate of TTTS recurrence. Secondary outcomes were therapeutic preference and fetal outcomes in cases of recurrent TTTS.

RESULTS

The primary search identified 22 eligible studies that are included in this review (n = 2447 twin pregnancies). Two studies included a minority of non-selective procedures. The published incidence of recurrent TTTS ranged from 0 to 16%. Clinical management was reported in 65.7% (71/108) cases, with repeat SFLP the most commonly performed secondary intervention. Only three studies provided comprehensive outcome data for cases of recurrent TTTS. The overall rate of neurologically-intact survival was 44% (23/52). The data were inadequate to determine the effects of secondary therapeutic approach, placental location or gestational age on perinatal outcome in cases of recurrent TTTS.

CONCLUSIONS

The published rate of TTTS recurrence following SFLP in monochorionic twin pregnancies ranges from 0 to 16%. Although limited follow-up data suggest that recurrence is associated with significant perinatal mortality and morbidity, further study is needed. Currently, there are insufficient data available to guide recommendations for clinical management of TTTS recurrence. Future studies on SFLP for TTTS must include details on recurrence rates and provide outcome data specific to the recurrent subset.

Timing of delivery following selective laser photocoagulation for twin-to-twin transfusion syndrome

OBJECTIVE

We sought to compare intrauterine risks with postnatal outcome in monochorionic pregnancies operated by fetoscopic laser surgery for twin-to-twin transfusion syndrome.

STUDY DESIGN

A cohort of 602 consecutive cases was analyzed. Unexpected prenatal adverse events were identified when a fatal or potentially fatal event occurred that could have been avoided by timely delivery.

RESULTS

The prospective risk of an unexpected adverse event dropped from 16.8% (95% confidence interval [CI], 13.6-20.5%) to 0% (95% CI, 0-11%) between 26-36 weeks. At 32 weeks, the residual risk was 1 in 17 (95% CI, 1/28-1/11). The perinatal rate of death or severe brain lesions dropped from 35% (25-47%) in infants delivered at 26-28 weeks down to 3% (1-6%) at 34-36 weeks.

CONCLUSION

Our results did not identify an optimal cut-off for elective preterm delivery in laser-operated twin-to-twin transfusion syndrome. Perinatal morbidity appears low from ≥32 weeks and the decision for elective delivery should be based upon medical history, parental demand, and expert assessment.

Neonatal outcome using ultrathin fetoscope for laser coagulation in twin-to-twin-transfusion syndrome

OBJECTIVE

To improve neonatal outcome using ultrathin fetoscope for laser treatment of twin-to-twin transfusion syndrome.

METHODS

Retrospective cohort study of a series of 80 cases of twin-to-twin-transfusion syndrome prior to 26-weeks' gestation subjected to laser coagulation by means of a 1.0/1.2 mm fiber fetoscope with a sheath sectional area 2.65 mm(2)/3.34 mm(2) (n=27) and a 2.0 mm classic lens fetoscope with a sheath sectional area: 6.63 mm(2)/11.27 mm(2) (n=53).

RESULTS

The survival rates of at least one twin in the compared groups were 94.4% (classic optic) and 100% (ultrathin optic), for both twins: 75.5% and 83.3%, respectively. By decreasing sheath diameter a pregnancy was prolonged by an average of 21.3 days (P=0.0045), with a resulting increase in the recipient's weight of 389 g (P=0.0049) and an increase in the donor's Apgar score. However, the intervention with ultrathin optic took 11 min longer (P=0.031).

CONCLUSION

The reduction of the iatrogenic damage of the amniotic membrane using ultrathin fetoscope with a small sheath, significantly improves the neonatal outcome after laser treatment of twin-to-twin-transfusion syndrome. The operator should only commence working with the 1 mm fetoscope after the learning curve has been accomplished.

Laser therapy for twin-to-twin transfusion syndrome (TTTS)

Monochorionic twins are subjected to specific complications which originate in either imbalance or abnormality of the single placenta serving two twins including twin-to-twin transfusion syndrome. The diagnosis is well established in overt clinical forms with the association of polyuric polyhydramnios and oliguric oligohydramnios. The best treatment of cases presenting before 26 weeks of gestion is fetoscopic laser ablation of the intertwin anastomoses on the chorionic plate. Although subjected to subtle variations, the core technique follows robust guidelines which could help understanding and acquiring the required skills and experience to perform this procedure. However appropriate and tailored hands-on training and appropriate perinatal set-up are critical not only for surgical management but also for the follow-up and management of related complications.

Use of the Learning Curve-Cumulative Summation test for quantitative and individualized assessment of competency of a surgical procedure in obstetrics and gynecology: fetoscopic laser ablation as a model

OBJECTIVE

We sought to determine the learning curve (LC) for fetoscopic laser photocoagulation (FLP) as a model for the evaluation of training in surgical procedures.

STUDY DESIGN

A retrospective review of consecutive case series of FLP from 2 centers with 3 operators (operator I [O-I], observer trained; operator II [O-II], hands-on trained; and operator III [O-III], clinical fellow) was performed and the LC-cumulative summation (CUSUM) test was plotted.

RESULTS

The acceptable and unacceptable success rates for at least 1 fetus survival after FLP were set at 82% and 70%, respectively, from a systematic review. A total of 171 consecutive cases were performed by the 3 operators (O-I, 91; O-II, 49; and O-III, 31). From LC-CUSUM test O-I needed 60 procedures, O-II needed 20 procedures, and O-III needed 20 procedures to reach an acceptable performance rate for at least 1 survivor.

CONCLUSION

The LC-CUSUM test can be used to accurately assess the LC in a surgical procedure in obstetrics and gynecology. Hands-on trained operators exhibit a shorter LC.

Fetoscopic laser coagulation for severe twin-to-twin transfusion syndrome: factors influencing perinatal outcome, learning curve of the procedure and lessons for new centres

OBJECTIVE

  To evaluate the effects of operator experience on perinatal outcome in a single centre.

DESIGN

  Prospective consecutive cohort study.

SETTING

  Regional tertiary referral Fetal Medicine Centre in the UK.

POPULATION

  Pregnant women with monochorionic twin pregnancies complicated by severe twin-to-twin transfusion syndrome (TTTS) (at ≤26 completed weeks of gestatiuon) treated by fetoscopic laser coagulation (FLC) between October 2004 and November 2009.

METHODS

  Pregnancy characteristics and outcomes were collected. Logistic regression analysis was employed to determine the effect of a priori defined variables on outcome.

MAIN OUTCOME MEASURE

  Perinatal survival (survival to 28 days or beyond) for one or more twins.

RESULTS

  There were 164 consecutive sets of monochorionic twins. The median gestational age (GA) at FLC was 20.4 weeks (interquartile range 18-22.1 weeks), the median interval from FLC to delivery was 88.5 days (interquartile range 53-101 days) and the median GA at delivery was 33.2 weeks (interquartile range 29.7-34.9 weeks). The overall survival was 62%; perinatal survival of one or more twins was 85%. These outcomes improved after about 61 procedures were performed, and after about 3.4 years of experience. Univariate logistic regression analysis indicated that Quintero stage-IV disease decreased (OR 0.26; 95% CI 0.10-0.69) and prolongation of GA at delivery increased the survival of the twins (OR 1.34; 95% CI 1.12-1.60) (P < 0.01). Increasing experience of the procedure by operator led to a significant increase in perinatal survival (P < 0.01; OR 4.59; 95% CI 1.84-11.44). Multivariate logistic regression analysis indicated that only GA at delivery increased survival overall (OR 1.34; 95% CI 1.12-1.60; P = 0.01).

CONCLUSIONS

  These data indicate that both relatively large numbers treated and experience with FLC minimises any adverse outcome in monochorionic pregnancies with severe TTTS.

Specific complications of monochorionic twin pregnancies: twin-twin transfusion syndrome and twin reversed arterial perfusion sequence

Monochorionic twins are subjected to specific complications which originate in either imbalance or abnormality of the single placenta serving two twins. This unequal placental sharing can cause complications including twin-twin transfusion syndrome (TTTS), twin anemia-polycythemia sequence (TAPS), selective intrauterine growth restriction or twin reversed arterial perfusion sequence (TRAP). Monochorionicity also makes the management of these specific complications as well as that of a severe malformation in one twin hazardous since the spontaneous death of one twin exposes the co-twin to a risk of exsanguination into the dead twin and its placenta. The latter is responsible for the death of the co-twin in up to 20% of the cases and in ischemic sequelae in about the same proportions in the survivors. Although the symptoms of all these complications are very different, the keystone of their management comes down to either surgical destruction of the inter-twin anastomoses on the chorionic plate when aiming at dual survival or selective and permanent occlusion of the cord of a severely affected twin aiming at protecting the normal co-twin. This can be best achieved by fetoscopic selective laser coagulation and bipolar forceps cord coagulation respectively.

The making of fetal surgery

Fetal diagnosis prompts the question for fetal therapy in highly selected cases. Some conditions are suitable for in utero surgical intervention. This paper reviews historically important steps in the development of fetal surgery. The first invasive fetal intervention in 1963 was an intra-uterine blood transfusion. It took another 20 years to understand the pathophysiology of other candidate fetal conditions and to develop safe anaesthetic and surgical techniques before the team at the University of California at San Francisco performed its first urinary diversion through hysterotomy. This procedure would be abandoned as renal and pulmonary function could be just as effectively salvaged by ultrasound-guided insertion of a bladder shunt. Fetoscopy is another method for direct access to the feto-placental unit. It was historically used for fetal visualisation to guide biopsies or for vascular access but was also abandoned following the introduction of high-resolution ultrasound. Miniaturisation revived fetoscopy in the 1990 s, since when it has been successfully used to operate on the placenta and umbilical cord. Today, it is also used in fetuses with congenital diaphragmatic hernia (CDH), in whom lung growth is triggered by percutaneous tracheal occlusion. It can also be used to diagnose and treat urinary obstruction. Many fetal interventions remain investigational but for a number of conditions randomised trials have established the role of in utero surgery, making fetal surgery a clinical reality in a number of fetal therapy programmes. The safety of fetal surgery is such that even non-lethal conditions, such as myelomeningocoele repair, are at this moment considered a potential indication. This, as well as fetal intervention for CDH, is currently being investigated in randomised trials.

Evaluation of the CHOP cardiovascular score as a prognostic predictor of outcome in twin-twin transfusion syndrome after laser coagulation of placental vessels in a prospective cohort

OBJECTIVE

To investigate the prognostic value of cardiac function assessment by the previously reported CHOP (Children's Hospital of Philadelphia) cardiovascular score in twin-twin transfusion syndrome (TTTS).

METHODS

All consecutive monochorionic pregnancies presenting with TTTS over a 24-month period were evaluated by preoperative echocardiography before percutaneous laser coagulation of chorionic vessels. Each of the 12 items of the CHOP score was evaluated prospectively and the cardiovascular score was categorized into stages using previously published cut-offs. The outcome considered for this study was neonatal survival of neither, one or both twins.

RESULTS

In total, 215 pregnancies were enrolled. Due to technical issues, CHOP evaluation was incomplete in 16% of cases and follow-up was unavailable in 12%. Overall, there was a significant relationship between the CHOP score and the Quintero staging system, although this relationship was significantly reduced when parameters used in the Quintero system were removed from the CHOP score. Based upon neonatal survival, the CHOP score did not show any prognostic value regarding overall pregnancy outcome or individual recipient survival.

CONCLUSION

Cardiac function assessment using the CHOP score is not of clinical use as a prognostic marker in TTTS. This suggests that cardiac function may not be of interest for preoperative staging when laser coagulation is the first-line treatment, other than to confirm the diagnosis of TTTS requiring surgery.

Appraisal of the selectivity index in a cohort of patients treated with laser surgery for twin-twin transfusion syndrome

OBJECTIVE

The selectivity index (SI) has been proposed as a measure of technical success in laser surgery for twin-twin transfusion syndrome. Surgeries with an index >-0.25 have been considered highly selective. The purpose of this study was to evaluate the applicability of this index in our patient population.

STUDY DESIGN

The SI was assessed in 314 consecutive laser surgeries and correlated with perinatal survival.

RESULTS

A total of 310 patients (98.7%) underwent a completely selective procedure. The SI was 0.8 in the selective laser photocoagulation of communicating vessels group vs 0.3 in the nonselective laser photocoagulation of communicating vessels group (P = .001). In the selective group perinatal survival of at least 1 twin (92.6% vs 50%) and survival of the donor (75.4% vs 0%) was significantly better (P = .05).

CONCLUSION

The SI as originally proposed is misleading and of limited use as it does not differentiate selective from nonselective procedures. We propose instead using a ratio of selective/nonselective procedures, and selectively coagulated/total number of coagulated vessels to appraise center-specific and patient-specific surgical performance of laser surgery for twin-twin transfusion syndrome.

Fetal surgery is a clinical reality

An increasing number of fetal anomalies are being diagnosed prior to birth, some of them amenable to fetal surgical intervention. We discuss the current clinical status and recent advances in endoscopic and open surgical interventions. In Europe, fetoscopic interventions are widely embraced, whereas the uptake of open fetal surgery is much less. The indications for each access modality are different, hence they cannot substitute each other. Although the stage of technical experimentation is over, most interventions remain investigational. Today there is level I evidence that fetoscopic laser surgery for twin-to-twin transfusion syndrome is the preferred therapy, but this operation actually takes place on the placenta. In terms of surgery on the fetus, an increasingly frequent indication is severe congenital diaphragmatic hernia as well as myelomeningocele. Overall maternal safety is high, but rupture of the membranes and preterm delivery remain a problem. The increasing application of fetal surgery and its mediagenicity has triggered the interest to embark on fetal surgical therapy, although the complexity as well as the overall rare indications are a limitation to sufficient experience on an individual basis. We plead for increased exchange between high volume units and collaborative studies; there may also be a case for self-regulation. Inclusion of patients into trials whenever possible should be encouraged rather than building up casuistic experience.

Profiling fetal cardiac function in twin-twin transfusion syndrome

OBJECTIVES

Cardiomyopathy in the recipient twin is a marker of severity in twin-twin transfusion syndrome (TTTS), making it a potentially valuable tool for staging the disease. This study aimed to provide a quantitative description of cardiac function in the recipient twin.

METHODS

Consecutive monochorionic pregnancies complicated with TTTS and treated by percutaneous laser coagulation underwent fetal echocardiography before surgery. An unsupervised classification analysis was conducted to identify groups of twins with similar cardiac profiles. The predictive value of the recipient twin's preoperative cardiac function based on these profiles was assessed, using perinatal death of at least one twin as the main outcome. The cardiac function profiles that we identified were compared with the current Quintero staging.

RESULTS

A total of 107 pregnancies were included, with six of these lost to follow-up; 63/107 complete cases were available for multivariate description of the recipient's cardiac function. Three different preoperative cardiac profiles were identified with increasing right and left myocardial performance index, decreasing right and left shortening fraction, and increasing ductus venosus pulsatility index. Although the three groups represented progressive stages of the syndrome-related cardiomyopathy, no correlation was found with pregnancy outcome. Of Quintero Stage 1 cases, 55% showed significant alterations of cardiac function in the recipient twin.

CONCLUSIONS

Progressive cardiomyopathy can be assessed quantitatively in the recipient twin and does not influence pregnancy outcome when fetoscopic laser coagulation is the first-line treatment. Compared with the current staging, cardiac profiling allows discrimination of cases with significant myocardial dysfunction.

Maternal serum markers of placental damage in uncomplicated dichorionic and monochorionic pregnancies in comparison with monochorionic pregnancies complicated by severe twin-to-twin transfusion syndrome and the response to fetoscopic laser ablation

OBJECTIVE

Twin-to-twin transfusion syndrome (TTTS) is a morbid perinatal condition associated with abnormal placentation and is treated by fetoscopic laser ablation (FLA). We assessed basal maternal serum alphafetoprotein (MSAFP) and free beta-human chorionic gonadotrophin (f-betaHCG) in uncomplicated dichorionic (DC) and monochorionic (MC) twin pregnancies and a cohort of MC twin pregnancies complicated by severe TTTS. Changes in MSAFP and f-betaHCG post-FLA were measured as markers of placental coagulation.

STUDY DESIGN

In a prospective case-cohort study, MC twins complicated by TTTS (n=23) were studied. A cohort of uncomplicated DC (n=12) and MC (n=6) twin pregnancies, which were appropriately grown for gestation with normal liquor volumes were also studied. Using solid phase, two site fluoroimmunometric assays, both MSAFP and f-betaHCG from uncomplicated and complicated cohorts were measured. Samples were taken, prior to FLA then at intervals after the procedures (6h, 24h and 1 week).

RESULTS

The median multiples of median (MoM) were not significantly different in uncomplicated DC twin pregnancies for MSAFP 1.85 (95% CI 1.62-2.34) or fbetaHCG 1.66 (95% CI 1.21-2.04) compared to uncomplicated MC twin pregnancies (MSAFP 1.40 (95% CI 1.16-2.58) and fbetaHCG 1.70 (95% CI 0.32-3.35)). However, the median MSAFP MoM in MC twin pregnancies complicated by severe TTTS was increased (MSAFP 3.10 (95% CI 2.67-4.43); p<0.05) with a more significant increase being noted in median fbetaHCG (MoM 5.75 (95% CI 5.22-9.12); p<0.0001) compared to uncomplicated twin pregnancies. Post-FLA, the median MSAFP increased significantly at 6h by 445% (636.65 U/ml (95% CI 616-1216.9 U/ml)) and remained elevated at 1 week (553.4 U/ml (95% CI 203.7-3020.8 U/ml; p=0.001)). No significant difference in median fbetaHCG was noted post-FLA (p=0.36). This rise in MSAFP appears unrelated to the number of placental anastomoses coagulated or the total energy used. Also, in the small cohort in which amniodrainage alone was performed no rise in MSAFP was noted.

CONCLUSIONS

MSAFP and fbetaHCG are increased in TTTS indicating an association with abnormal placentation. Post-FLA, a significant rise in MSAFP was noted for up to a week post-coagulation. This was not noted after amniodrainage.