Chorioamniotic Membrane Separation Research Articles

Quincke versus Diamond-Tip Needles for Entry in Placental Laser Surgery for Twin-to-Twin Transfusion Syndrome.

Chorioamniotic membrane separation (CAS), preterm prelabor rupture of membranes (PPROM), and preterm delivery (PTD) remain as major complications of fetoscopic laser photocoagulation (FLP) for twin-to-twin transfusion syndrome (TTTS). We sought to examine whether use of Quincke-tip needles for initial entry during FLP reduces the risk of these complications. This is a secondary analysis of prospectively collected data from patients that had FLP for TTTS at a single tertiary care center (2011-2021). We excluded patients for whom direct trocar entry was used. Patients for whom a Quincke-tip needle was used were compared to those for whom a diamond-tip needle was used during Seldinger entry. Demographics, ultrasound findings and operative characteristics were compared between groups. Postoperative outcomes and complications (including CAS, PPROM, and PTD) were also compared. Multivariate logistic regression models were fit to assess independent risk factors for complications. 386 patients met inclusion criteria; Quincke-tip needles were used in 81 (21.0%) cases, while diamond-tip needles were used in 305 (79.0%). Rates of CAS (11.1 vs. 9.5%, p = 0.67) and PPROM (44.4 vs. 41.0%, p = 0.57) were similar between groups. Patients in the Quincke-tip group delivered 1.5 weeks earlier than those in the diamond-tip group (30.5 vs. 32.0 weeks, p = 0.01). However, these patients were more likely to be delivered for maternal (35.9 vs. 19.0%) and fetal (23.1 vs. 15.3%) indications (p < 0.01). In multivariate analysis, needle type was not identified as an independent risk factor for PPROM. However, Quincke-tip needle use was associated with PTD less than 32 weeks (aOR 1.74, 95% CI: 1.02-2.97, p = 0.043). Membrane complications following FLP were not associated with the needle type used for entry. Earlier delivery in the Quincke-tip group was likely attributable to higher rates of delivery for maternal and fetal indications, and not membrane complications. The needle chosen for entry is likely best determined by operator preference.

Neonatal survival after serial amnioinfusions for fetal bilateral renal agenesis: report from the raft trial

Bilateral renal agenesis (BRA) in the fetus leads to anhydramnios and lethal pulmonary hypoplasia. We report obstetric outcomes and neonatal survival/complications for pregnancies undergoing serial amnioinfusions (AIs) in the completed BRA arm of the Renal Anhydramnios Fetal Therapy (RAFT) trial (NCT03101891). RAFT is a nonrandomized prospective clinical trial conducted at 9 North American Fetal Therapy Network sites to assess the safety and efficacy of serial AIs to treat BRA. The primary outcome was postnatal survival ≥ 14 d and dialysis access placement. Inclusion required ultrasound (US) confirmed isolated BRA, normal genetic testing, and first therapeutic AI prior to 26 w gestational age (GA). AIs were done with US guidance to maintain adequate amniotic fluid volume during pregnancy. All delivered at a RAFT center. Enrollment was suspended in July 2022 after Data Safety Monitoring Board review of neonatal morbidity and survival data. Twenty maternal-fetal pairs underwent serial AIs (Figure). There were 18 (90%) livebirths, median GA 32 w [IQR 31.8, 34]. Obstetric complications included preterm prelabor rupture of membranes (60%), chorioamniotic membrane separation (30%) and bleeding (20%). 78% (95% CI, 0.57-0.99) (n=14) of neonates survived to ≥ 14 d and had placement of dialysis access (Table). Factors associated with survival to the primary endpoint included more AIs, GA at birth ≥ 32 w, and higher birthweight (BW). 5/14 infants who met the primary outcome survived to discharge on peritoneal dialysis (PD) at a median age of 25 w [IQR 12, 32]; 2 of the 5 died after discharge. 3 of the 5 infants discharged home and one who remains in the NICU sustained strokes. Serial AIs initiated before 26 w in pregnancies with BRA mitigated lethal pulmonary hypoplasia. Survival to discharge on PD and beyond was considerably lower than survival to ≥ 14 d and strongly associated with GA and BW, highlighting the additional morbidity and mortality independent of lung function for infants lacking kidneys. Recruitment for the non-BRA fetal renal failure arm of the trial continues.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Pregnancy outcomes following early fetoscopic laser photocoagulation for twin-to-twin transfusion syndrome at 16 weeks’ gestation

Ample evidence supports fetoscopic laser photocoagulation of placental anastomoses as a first-line treatment for twin-to-twin transfusion syndrome, but little is known about the outcomes following procedures conducted in the early second trimester. This study aimed to evaluate perinatal outcomes following early fetoscopic laser placental photocoagulation performed for twin-to-twin transfusion syndrome at 16 weeks' gestation. This retrospective review included monochorionic twin pregnancies complicated by twin-to-twin transfusion syndrome necessitating fetoscopic laser photocoagulation at a single tertiary center from 2012 to 2021. The 2 cohorts were defined as cases undergoing laser surgery at 16+0/7 to 16+6/7 weeks' gestation (early laser group) and those undergoing laser surgery ≥17 weeks' gestation (standard laser group), respectively. Primary outcomes included rates of immediate chorioamniotic membrane separation, preterm premature rupture of membranes, and clinical chorioamnionitis. Secondary outcomes included twin survival rates at birth and 30 days of life. Outcomes were compared between cohorts with a P value of <.05 denoting statistical significance. A total of 343 cases were included (35 early laser participants and 308 standard laser participants). The early laser group typically had higher Quintero staging at the time of the procedure. Following intervention, the early laser group had significantly higher rates of chorioamniotic separation than the standard laser group (34.3% vs 1.3% of cases; P<.001) and higher rates of preterm prelabor rupture of membranes (45.7% vs 25.0%; P=.009) and chorioamnionitis (11.4% vs 1.3%; P=.005). Even after adjustment for higher Quintero staging in the early laser group, twin survival was not significantly different between study groups. Early laser surgery for twin-to-twin transfusion syndrome performed at 16 weeks' gestation is associated with significantly higher rates of chorioamniotic separation, preterm rupture of membranes, and chorioamnionitis. However, twin survival does not seem to be negatively impacted following early laser surgery.

Delayed Complete Chorioamniotic Membrane Separation in the Third Trimester Following a Motor Vehicle Collision

Complete separation of the amnion and chorion is a rare pregnancy complication. The proposed causes for chorioamniotic separation are failure of fusion,spontaneous separation, and iatrogenically from invasive prenatal pro-cedures. We present the first reported case of delayed complete chorioamniotic separation following a motor vehicle collision. Close fol-low-up with serial fetal ultrasounds resulted in a favorable outcome

A collagen plug with shape memory to seal iatrogenic fetal membrane defects after fetoscopic surgery.

Iatrogenic preterm premature rupture of fetal membranes (iPPROM) after fetal surgery remains a strong trigger for premature birth. As fetal membrane defects do not heal spontaneously and amniotic fluid leakage and chorioamniotic membrane separation may occur, we developed a biocompatible, fetoscopically-applicable collagen plug with shape memory to prevent leakage. This plug expands directly upon employment and seals fetal membranes, hence preventing amniotic fluid leakage and potentially iPPROM.Lyophilized type I collagen plugs were given shape memory and crimped to fit through a fetoscopic cannula (Ø 3 mm). Expansion of the plug was examined in phosphate buffered saline (PBS). Its sealing capacity was studied ex vivo using human fetal membranes, and in situ in a porcine bladder model.The crimped plug with shape memory expanded and tripled in diameter within 1 min when placed into PBS, whereas a crimped plug without shape memory did not. In both human fetal membranes and porcine bladder, the plug expanded in the defect, secured itself and sealed the defect without membrane rupture.In conclusion, collagen plugs with shape memory are promising as medical device for rapid sealing of fetoscopic defects in fetal membranes at the endoscopic entry point.

Maternal obstetrical risk factors for severe chorioamniotic membrane separation after laparotomy-assisted fetoscopic spina bifida repair

Chorioamniotic membrane separation (CAS) after laparotomy-assisted fetoscopic spina bifida repair is one of the main known risk factors for developing PPROM and preterm birth. Gaining insight into the factors that increase the risk for CAS could be of great clinical relevance. We hypothesized that having an obstetrical history of uterine overdistension could increase the likelihood of developing severe CAS after surgery

Pregnancy outcomes following early fetoscopic laser photocoagulation for twin-to-twin transfusion syndrome at 16 weeks’ gestation

To evaluate perinatal outcomes following fetoscopic laser placental photocoagulation (FLPC) performed for twin-to-twin transfusion syndrome (TTTS) at 16 weeks’ gestation (16.0 – 16.9 weeks), as compared to FLPC performed at 17 weeks’ gestation and beyond. This retrospective review included monochorionic twins complicated by TTTS necessitating FLPC at a single tertiary center from 2012 to 2021, with cohorts defined as cases undergoing FLPC at 16.0 to 16.9 weeks (early laser group) and cases with FLPC at 17 weeks or greater (standard laser group). Primary outcomes included rates of immediate chorioamniotic membrane separation (CAS), preterm premature rupture of membranes (PPROM), and chorioamnionitis. Primary outcomes were compared between cohorts, with a p-value of < 0.05 denoting statistical significance. Secondary outcomes included dual twin survival rates at birth and 30 days of life, adjusting for maternal age and Quintero stage at the time of FLPC. A total of 343 cases were included (35 early laser, 308 standard laser), with demographics summarized in Table 1. As seen in Table 2, the early laser group had significantly higher rates of CAS when compared to the standard laser group [34.3% vs 13.3% of cases (p < 0.001)]. The early laser group also demonstrated higher rates of PPROM [45.7% versus 25.0% (p=0.009)] and chorioamnionitis [11.4% vs 1.3% (p=0.005)]. Cessation of amniotic fluid leakage following PPROM occurred more frequently in the early laser group [37.5% vs 3.9% (p=0.001)]. Dual twin survival differed between the early and standard groups, although not significantly so. Early FLPC for TTTS performed at 16 weeks is associated with significantly higher rates of CAS, PPROM, and chorioamnionitis. However, amniotic fluid leakage tends to stop after PPROM following early FLPC, which we speculate may help to ameliorate some adverse fetal effects. Even after adjustment for higher Quintero staging in the early laser group, twin survival does not seem to be affected.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Risk Factors Associated with Preterm Prelabor Rupture of Membranes after Cord Occlusion in Monochorionic Diamniotic Twins

Introduction: Preterm prelabor rupture of membranes (PPROM) is a common complication after fetal surgeries. The aim of this study was to assess risk factors for and outcomes after PPROM following cord occlusion (CO) in monochorionic diamniotic (MCDA) pregnancies. Methods: This was a retrospective cohort study of 188 consecutive MCDA pregnancies treated by bipolar or laser CO, either primarily because of discordant malformation (dMF) or severe selective fetal growth restriction (sFGR), or secondarily when complete bichorionization was not possible in case of twin-to-twin transfusion syndrome (TTTS) or sFGR. Intentional septostomy was performed when needed. The procedure-related PPROM was defined as rupture of membranes <32 weeks’ gestation (PROM <32 weeks). Selected pre-, intra-, and early postoperative variables were analyzed by univariate and binomial logistic regression to determine they are correlated to PROM <32 weeks after CO. Results: Between 2006 and 2017, 188 cases underwent CO. Diagnosis was TTTS in 28.2% (n = 53), severe sFGR in 49.5% (n = 93), and dMF in 22.3% (n = 42). PROM <32 weeks occurred in 21.3% (n = 40), resulting in worse perinatal outcomes, as preterm birth <32 weeks occurred in 80.7% (vs. 8.3%, p = 0.000), procedure-to-delivery interval was 47.5 days (vs. 125, p = 0.000), gestational age (GA) at birth 30.0 weeks (vs. 37.7 weeks, p = 0.000), and survival 65.0% (vs. 91.1%, p = 0.000). In univariate analysis, indication, anterior placenta, cervical length, GA at surgery, operation time, amniodistention and drainage fluid volumes, chorioamniotic membrane separation, and septostomy were selected as relevant factors to be included in the regression model. In a multivariate analysis, TTTS was the only factor associated to PROM <32 weeks (OR 3.5 CI 95% 1.5–7.9). Conclusions: PROM <32 weeks after CO increases the risk of preterm delivery. In this cohort, the membrane rupture was more likely when CO was done in the context of TTTS.

81 A three-layer fetoscopic spina bifida closure has fewer neonatal complications than open in-utero closure

Spina bifida is one of the most common congenital anomalies of the central nervous system. This study compares neonatal outcomes between in-utero closure of spina bifida using a three-layer fetoscopic approach and the conventional open hysterotomy approach. This retrospective cohort study included all consecutive patients who underwent in-utero spina bifida closure using either open hysterotomy (n=43) or a three-layer fetoscopic approach (n=41) at a single institution, between 2012 and 2020. The three-layer fetoscopic closure comprised a bovine collagen patch, a myofascial layer and a skin layer. The frequency of a composite of adverse neonatal outcomes including low 5-minute Apgar scores (≤3), respiratory distress syndrome, retinopathy of prematurity, necrotizing enterocolitis and neonatal death were compared between the study groups. Regression analyses were performed to determine the association of a three-layer fetoscopic spina bifida closure and the composite of adverse neonatal outcomes adjusted for maternal BMI, gestational age (GA) at surgery, chorioamniotic membrane separation, delivery mode, preterm prelabor rupture of membranes and GA at delivery at <37 weeks. The three-layer fetoscopic spina bifida closure was associated with a lower rate of the composite of adverse neonatal outcomes than the open hysterotomy spina bifida closure (14.6% vs. 37.2%; p=0.025). The median gestational age at delivery and birthweight in the three-layer fetoscopic approach group were significantly higher than in the open hysterotomy approach group; whereas maternal BMI was significantly higher in the latter group (see Table 1). Regression analysis demonstrated that the three-layer fetoscopic spina bifida closure is associated with a lower risk for the composite of adverse neonatal outcomes adjusted for confounding variables (adjusted odds ratio: 0.15; 95% CI: 0.04-0.57; p=0.006). In-utero spina bifida closure using a three-layer fetoscopic approach is associated with fewer adverse neonatal outcomes than the conventional open hysterotomy spina bifida closure.

Fetal surgery for spina bifida in Zurich: results from 150 cases.

Over the past 10years, over 150 fetal spina bifida surgeries were performed at the Zurich Center for Fetal Diagnosis and Therapy. This study looks at surrogates for success and failure of this approach. We focused on key outcome parameters including hydrocephalus shunt rate at one year, bladder control at 4, independent ambulation at 3years, and maternal, fetal, and neonatal complications. From the first 150 patients undergoing fetal surgery for spina bifida, 148 (98.7%) were included in the study. Maternal-fetal surgery was uneventful in 143/148 (97%) cases. Intraoperative problems included resuscitation in 4/148 fetuses (2.7%). 1/148 fetuses (0.7%) died on postoperative day 4. Maternal complications included chorioamniotic membrane separation in 22/148 (15%), lung embolism in 3/148 (2.1%), chorioamnionitis in 2/148 (1.4%), AV-block III and uterine rupture in 1/148 each (0.7%). 1/148 (0.7%) newborn death was recorded. Hindbrain herniation was identified preoperatively in 132/148 (90%) fetuses and resolved completely in 119/132 (90%). At one year, 39/106 (37%) children had required a CSF diversion. At 4years, 4/34 patients (12%) had normal bladder control. At 3years, 48/57 (84%) walked independently. A majority of patients benefitted from prenatal intervention, in that the shunt rate was lower and the rates of continent and walking patients were higher than reported with postnatal care.

Prevalence, risk factors, and outcome of postprocedural amniotic band disruption sequence after fetoscopic laser surgery in twin-twin transfusion syndrome: a large single-center case series

Postprocedural amniotic band disruption sequence is a condition that is associated with intrauterine interventions, and it is characterized by a constriction of the limbs or umbilical cord by fibrous strands, leading to edema, amputation, and/or fetal demise. To evaluate the prevalence of, risk factors for, and the outcome of postprocedural amniotic band disruption sequence after fetoscopic laser surgery in twin-twin transfusion syndrome cases. All consecutive cases of twin-twin transfusion syndrome treated with fetoscopic laser coagulation of the vascular anastomoses at our center between January 2002 and March 2019 were included in the study. The occurrence of postprocedural amniotic band disruption sequence in these cases was recorded, and the potential risk factors were analyzed. Postprocedural amniotic band disruption sequence was detected, at birth, in 2.2% (15/672) of twin-twin transfusion syndrome cases treated with fetoscopic laser surgery, in both the recipients (10/15, 67%) and the donors (5/15, 33%). Postprocedural amniotic band disruption sequence primarily affected the lower extremities (11/15, 73%) and, less frequently, the upper extremities (2/15, 13%), both the upper and lower extremities (1/15, 7%), or the umbilical cord (1/15, 7%). Postprocedural amniotic band disruption sequence led to the amputation of toes in 5 of 15 cases (33%) and resulted in fetal demise because of constriction of the umbilical cord in 1 case (7%). The independent risk factors identified for postprocedural amniotic band disruption sequence were lower gestational age at laser surgery (odds ratio per week, 1.43; 95% confidence interval, 1.12-1.79; P=.003) and the presence of postprocedural chorioamniotic membrane separation on antenatal ultrasound examination (odds ratio, 41.66; 95% confidence interval, 5.44-319.25; P<.001). The prevalence of postprocedural amniotic band disruption sequence is low, but, when present, it may lead to severe consequences, with amputation of extremities or fetal demise occurring in more than one-third of the cases. Lower gestational age at the time of laser therapy and chorioamniotic membrane separation are independent risk factors for the postprocedural amniotic band disruption sequence.

Maternal and obstetric complications in fetal surgery for prenatal myelomeningocele repair: a systematic review.

Comparing prenatal and postnatal surgical repair techniques for myelomeningocele (MMC), in utero fetal surgery has increasingly gained acceptance and is considered by many specialized centers the first choice of treatment. Despite its benefits, as demonstrated in the Management of Myelomeningocele Study (MOMS), including reduced need for CSF shunting in neonates and improved motor outcomes at 30 months, there is still an ongoing debate on fetal and maternal risks associated with the procedure. Prenatal open hysterotomy, fetoscopic MMC repair techniques, and subsequent delivery by cesarean section are associated with maternal complications. The aim of this systematic review is to assess the available literature on maternal and obstetric complication rates and perinatal maternal outcomes related to fetal MMC repair. The authors identified references for inclusion in this review by searching PubMed and MEDLINE, with restrictions to English language, case series, case reports, clinical trials, controlled clinical trials, meta-analyses, randomized controlled trials, reviews, and systematic reviews. The rate of maternal and obstetric complications was analyzed based on studies focusing on this issue and presenting clear results on the matter. Of 1264 articles screened, 36 were included in this systemic review, whereof 11 were eligible for data analysis and comparison. The average overall rate of maternal and obstetric complications corresponds to 78.6%. The majority of the described events are obstetric complications, varying from chorioamniotic membrane separation in 65.6% of cases, oligohydramnios in 13.0% of cases, placental abruption in 5.0% of cases, spontaneous or preterm premature membrane rupture in 42.0% of cases, and early preterm delivery in 11.3% of cases due to uterine dehiscence, occurring in 0.9% of cases. The most common medical complications are development of pulmonary edema occurring in 2.8%, gestational diabetes in 3.7%, gestational hypertension/preeclampsia in 3.7%, and need for blood transfusions in 3.2% of cases. Limitations of the review arise from the lack of data in the current literature, with maternal and obstetric complications being underreported. Although the efforts of further advancement of intrauterine prenatal MMC repair aim to increase neonatal outcomes, maternal health hazard will continue to be an issue of crucial importance and further studies are required.

EP25.07: Prenatal myelomeningocele repair complicated with chorioamniotic membrane separation: predictors of adverse perinatal outcomes

EP25.07: Prenatal myelomeningocele repair complicated with chorioamniotic membrane separation: predictors of adverse perinatal outcomes

OP17.07: Prenatal myelomeningocele repair: risk factors for developing chorioamniotic membrane separation

OP17.07: Prenatal myelomeningocele repair: risk factors for developing chorioamniotic membrane separation

EP15.26: Complete chorioamniotic membrane separation associated with bilateral club foot

EP15.26: Complete chorioamniotic membrane separation associated with bilateral club foot

EP25.06: Perinatal outcomes after detection of postoperative chorioamniotic membrane separation following prenatal myelomeningocele repair

EP25.06: Perinatal outcomes after detection of postoperative chorioamniotic membrane separation following prenatal myelomeningocele repair

Risk Factors for Preterm Birth following Open Fetal Myelomeningocele Repair: Results from a Prospective Cohort

Background: Fetal myelomeningocele (fMMC) repair is a therapeutic option in selected cases. This study aimed to identify risk factors for preterm birth (PTB) following open fMMC repair. Methods: Sixty-seven women underwent fMMC repair and delivered a baby between 2010 and 2018 at our center. Demographic, surgical, and pregnancy complications, including potential risk factors for PTB such as preterm premature rupture of membranes (PPROM), chorioamniotic membrane separation (CMS), and placental abruption were evaluated. Results: Maternal body mass index, maternal age, parity, previous uterine surgery, gestational age at fetal surgery, total surgery duration, surgical subcutaneous hematoma, oligohydramnios, and amniotic fluid leakage were not identified as risk factors for PTB. CMS (p = 0.028, 92 vs. 52%) and PPROM (p = 0.001, 95 vs. 52%) were highly associated with PTB. Placental abruption was found more often in women after fMMC repair than in a general obstetrical population (12 vs. 1%) and ended in premature birth in all cases (p = 0.024, 100 vs. 60%). However, the majority of women delivered at a gestational age >35 weeks. Conclusions: In our study cohort, risk factors for PTB were PPROM, CMS, and placental abruption, whereas surgery duration did not influence outcome. We conclude that the surgery technique should aim to minimize CMS and amniotic fluid leakage.

The Use of Indomethacin with Complete Amniotic Fluid Replacement and Classic Hysterotomy for the Reduction of Perinatal Complications of Intrauterine Myelomeningocele Repair

Objective: This study presented outcomes of classical hysterotomy with modified antiprostaglandin therapy for intrauterine repair of foetal myelomeningocele (fMMC) performed in a single perinatal centre. Study Design: Forty-nine pregnant women diagnosed with fMMC underwent classic hysterotomy with anti-prostaglandin management, complete amniotic fluid replacement and high dose indomethacin application. Results: The average gestational age (GA) at delivery was 34.4 ± 3.4 weeks, with no births before 30 weeks GA. There were 2 foetal deaths. Complete reversal of hindbrain herniation (HH), assessed in magnetic resonance imaging at 30–31 weeks GA was found in 72% of foetuses (mostly with HH grade I prior to fMMC repair). Our protocol resulted in rare use of magnesium sulphate (6%), low incidence of chorioamniotic membrane separation – chorioamniotic membrane separation (6%), preterm premature rupture of membranes – preterm premature rupture of membranes (pPROM; 15%) and preterm labour – preterm labour (PTL; 17%). The postoperative wound continuity of the uterus was usually stable (in 72% of patients), with low frequency of scar thinning (23%). Conclusion: Our protocol results in rare use of tocolytics, and the low occurrences of CMS, pPROM and PTL in relation to other study cohorts: Management of Myelomeningocele Study, Children’s Hospital of Philadelphia, and Vanderbilt University Medical Centre.

North American Fetal Therapy Network: timing of and indications for delivery following laser ablation for twin-twin transfusion syndrome

Despite improvements in fetal survival for pregnancies affected by twin-twin transfusion syndrome since the introduction of laser photocoagulation, prematurity remains a major source of neonatal morbidity and mortality. To investigate the indications and factors influencing the timing of delivery following laser treatment, we collected delivery information regarding twin-twin transfusion syndrome cases in a large multicenter cohort. Eleven North American Fetal Therapy Network (NAFTNet) centers conducted a retrospective review of twin-twin transfusion syndrome patients who underwent laser photocoagulation. Clinical, demographic and ultrasound variables including twin-twin transfusion syndrome stage, and gestational age at treatment and delivery were recorded. Primary and secondary maternal and fetal indications for delivery were identified. Univariate analysis was used to select candidate variables with significant correlation with latency and GA at delivery. Multivariable Cox regression with competing risk analysis was utilized to determine the independent associations. A total of 847 pregnancies were analyzed. After laser, the average latency to delivery was 10.11 ± 4.8 weeks and the mean gestational age at delivery was 30.7 ± 4.5 weeks. Primary maternal indications for delivery comprised 79% of cases. The leading indications included spontaneous labor (46.8%), premature rupture of membranes (17.1%), and placental abruption (8.4%). Primary fetal indications accounted for 21% of cases and the most frequent indications included donor non-reassuring status (20.5%), abnormal donor Dopplers (15.1%), and donor growth restriction (14.5%). The most common secondary indications for delivery were premature rupture of membranes, spontaneous labor and donor growth restriction. Multivariate modeling found gestational age at diagnosis, stage, history of prior amnioreduction, cerclage, interwin membrane disruption, procedure complications and chorioamniotic membrane separation as predictors for both gestational age at delivery and latency. Premature delivery after laser therapy for twin-twin transfusion syndrome is primarily due to spontaneous labor, preterm premature rupture of membranes and non-reassuring status of the donor fetus. Placental abruption was found to be a frequent complication resulting in early delivery. Future research should be directed toward the goal of prolonging gestation after laser photocoagulation to further reduce morbidity and mortality associated with twin-twin transfusion syndrome.

Use of plastic wound retractor at hysterotomy site in prenatal repair of myelomeningocele: a new technique

Objective: To describe the use of a self-retaining thermoplastic polyurethane wound retractor for the management of hysterotomy during prenatal repair of myelomeningocele.Methods: The preliminary experience with 16 consecutive cases of open surgery for prenatal repair of myelomeningocele using a new technique is presented. Under general anesthesia, the gravid uterus was partially exteriorized through a low transverse abdominal incision and a high 3–4-cm midline vertical mini-hysterotomy was performed. After chorioamniotic membranes were opened with scissors, the internal ring of the retractor was placed into the amniotic cavity to compress the chorioamniotic membranes against the internal uterine wall and permit full retraction of the hysterotomy. Once the neurosurgical intervention was completed, the retractor was removed manually and uterine and abdominal incisions were closed using conventional techniques. Intra- and post-operative complications, as well as short-term pregnancy outcomes, were evaluated.Results: Intrauterine surgery was performed at a mean gestational age of 25.3 weeks and all except two of the interventions were completed within 3.0 h. When compared with the technique described in the Management of Myelomeningocele study (MOMS) trial, the use of the retractor was associated with a lower, although statistically nonsignificant, rate of chorioamniotic membrane separation (20/78 (26%) versus 2/16 (13%), respectively), preterm rupture of membranes (36/78 (46%) versus 4/16 (25%), respectively), and persistent oligohydramnios (16/78 (21%) versus 1/16 (6%), respectively) as well as higher gestational age at delivery (34.1 weeks ± 3.1 versus 36.0 weeks ± 1.93, respectively) and birthweight (2383 g ± 688 versus 2790 g ± 529, respectively). There were no intra- or post-operative complications associated with the use of the device. Only one (6%) of the hysterotomy scars was noted to be thin at the time of the cesarean delivery and no cases of dehiscence occurred.Conclusions: The use of a plastic wound retractor at the hysterotomy site provides a less traumatic approach than the conventional technique for the management of the uterine incision during open intrauterine surgery. Our experience with this technique was associated with short-term pregnancy outcomes that are similar and perhaps even superior to the technique reported in the MOMS trial. Because the device is inexpensive, easy to use, and widely available, its use during open intrauterine surgery should be considered. However, further clinical experience is required to reach a definitive conclusion regarding whether this technique should be incorporated into the protocol of prenatal repair of myelomeningocele.