B. Nasr

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

OBJECTIVE This study was undertaken to correlate selectivity of surgery and perinatal outcome in twin-to-twin transfusion syndrome treated by endoscopic laser coagulation, using a quantitative definition of selectivity. STUDY DESIGN 287 consecutive cases of severe twin-to-twin transfusion syndrome were reviewed. A selectivity index was built as the ratio of selective over nonselective coagulations per procedure. Outcome measures were survival at 28 days and failure of surgery as defined by recurrence of twin-to-twin transfusion syndrome or fetofetal hemorrhage. RESULTS Two populations were identified: a high selectivity group (63.8%) and a low selectivity group (36.2%). Survival of at least one twin and survival of both twins were higher in the high-selectivity group (p = .007 and p = .04 respectively). Failure of surgery rates were similar in both groups. CONCLUSION A quantitative definition of selectivity appears justified by the large variations found in the practice of a single center and by significant differences in outcome. Survival is significantly improved in highly selective procedures.

Pseudoamniotic band syndrome: a rare complication of monochorionic twins with fetofetal transfusion syndrome treated by laser coagulation

OBJECTIVE The purpose of this study was to assess the incidence and risk factors of limb constriction defects that are related to pseudoamniotic band syndrome (PABS) after selective fetoscopic laser surgery (FLS) in fetofetal transfusion syndrome (FFTS). STUDY DESIGN All consecutive cases of FFTS that were treated by selective FLS between 1999 and 2006 were examined prospectively for PABS at the time of delivery. Incidence and characteristics of PABS were reported. Univariate analysis was conducted to look for potential risk factors of developing PABS. RESULTS The 438 consecutive FFTS cases were treated at 15-26 weeks of gestation; PABS developed in 8 cases (1.8 %). The affected twin was always the former recipient. The diagnosis was made prenatally in 2 of 8 cases (25%). All cases survived the perinatal period. PABS affected fetal leg, arm, and foot in 3, 4, and 1 cases, respectively. In 5 (62.5%) and 7 (87.5%) cases, PABS occurred after premature rupture of membranes and intrauterine death of the donor, respectively. In 4 cases (50%), there was both premature rupture of membranes (PROM) and intrauterine fetal death; in 3 cases (37.5%), there was intrauterine fetal death alone, and in 1 case (12.5%), there was PROM alone. In the remaining 430 cases, PROM occurred in 62 cases (14.4%) and 66 cases (15.3%) within and after 3 weeks after surgery, respectively. PROM was significantly more frequent within the group that was complicated with PABS than within the rest of the cohort (P = .05). No maternal, fetal, or perioperative risk factor could be identified. CONCLUSION Awareness and targeted serial ultrasound evaluation in this high-risk group may improve prenatal diagnosis, counseling, and management of PABS after FLS.

Intertwin discordance in umbilical venous volume flow: a reflection of blood volume imbalance in twin-to-twin transfusion syndrome

To compare umbilical venous volume flow (UVVF) between donor and recipient twins in twin‐to‐twin transfusion syndrome (TTTS) using an index that is independent of gestational age and to correlate changes in this index with outcome following endoscopic laser surgery.

OC22.04: The importance of gestational age at laser surgery in TTTS

If deliveries by planned Cesarean section and deliveries following induced labor are excluded, 872 twin pairs remain, where 28.6% were MMP, 44.6% were MFP and 26.8% were FFP. Mean GA at delivery was 246.8 days (SD 20.4) for MMP, 245.5 days (SD 21.8) for MFP and 246.2 days (SD 21.2) for FFP (p>0.05). The distribution of preterm and very preterm births was similar in the three groups. Conclusions: Mean GA at birth does not seem to be correlated to fetal gender in twin pregnancies.

OP25.10: Intra- and interobserver variability and reproducibility of biparietal diameter and crown rump length for ultrasound dating at 11–14 weeks of gestation

Objectives: To follow up pregnancies with low PAPP-A (less than 0.3 multiples of the mean) in first-trimester screening once chromosome anomalies are excluded. Methods: Outcomes by data linkage of pregnancies of all Fetal Medicine Foundation approved centers for the entire state screened by both ultrasound nuchal translucency and free βhCG and PAPPA correlated with birth data required for all births in Western Australia. Results: Over 10 000 women were screened, with outcome data for 98.4%. The first percentile for PAPP-A in this population was 0.27. Women with low PAPP-A were more likely to have preterm birth, low birth weight and pregnancy loss. There was not a higher incidence of non-chromosomal birth defects. As a screen for nonchromosomal and non-birth-defect adverse outcomes, low PAPP-A had only a 5% sensitivity. Conclusions: Low PAPP-A may highlight pregnancies at increased risk of adverse outcome but it not sufficiently sensitive for population screening.

OP10.08: Evaluation of cardiac function in TTTS. Comparison of Diastolic filling time in the ductus venosus with Myocardial performance index and shortening fraction

Objectives: To evaluate early changes in foetal cardiac function in twin to twin transfusion syndrome (TTTS) using myocardial performance index pre and post laser therapy. Methods: Both donors and recipients of 51 monochorionic twin pregnancies complicated by TTTS were studied prospectively before and after laser therapy. The myocardial performance index (MPI) of both ventricles was calculated before (±24 hours) and after laser therapy (±24 hours) for the evaluation of early changes in the cardiac function. Results: As expected before laser, the donors had a significantly lower MPI-RV and MPI-LV (myocardial performance index in the right ventricle and in the left ventricle) (0.41 vs 0.67; P < 0.000000) and (0.36 vs 0.54; P < 0.0001) respectively. After laser therapy MPI increased in both the recipient and the donor in both ventricles: MPI-RV (0.67 vs 0.49; P < 0.02) (0.41 vs 0.19; P < 0.001), MPILV (0.54 vs 0.16; P < 0.02) (0.36 vs 0.29; P < 0.002). Diastolic time in the mitral valve of the recipient increased significantly. Conclusions: MPI appears is a sensitive index to evaluate early changes in the global cardiac function.

OP22.11: Twin-anemia-polycythemia-sequence (TAPS) management options and results

gestation who underwent fetoscopic laser surgery at four centers in Japan. We assessed perinatal survival, survival at 6 months of age, and neurological complications. A conditional logistic regression was performed using preoperative ultrasonographic variables to estimate adjusted odds ratios (OR) for fetal or neonatal death. Results: Survival of at least one twin at 28 days and 6 months of age were 91.2% and 90.1%, respectively. Survival at 6 months of age without major neurological complications was 72.4%. There were no differences in at least one survivor at 28 days of gestation between Quintero stage 1 or 2 (90.9%) and 3 or 4 (91.2%). However, two survivors at 28 days of gestation were significantly lower in Quintero stage 3 or 4 (59.1%) than 1 or 2 (81.8%). The significant independent variables of the preoperative ultrasound findings for fetal or neonatal death of the donor were reversed (OR: 9.29, 95% confidence interval (CI): 2.86–30.14) or absent (OR: 3.87, CI: 1.81–8.29) end-diastolic velocity in the umbilical artery, and reversed blood flow in the ductus venosus (OR: 2.45, CI: 0.41–14.64) of the donor. Those for neonatal death of the recipient were reversed blood flow in the ductus venosus (OR: 2.25, CI: 0.95–5.34) and hydrops of the recipient (OR: 2.14, CI: 0.76–6.05). Conclusions: Survival of at least one twin after fetoscopic laser surgery reached 90%, regardless of the stage. Two survivors were decreased in Quintero stage 3 or 4. Reversed or absent end-diastolic velocity in the umbilical artery of the donor, reversed blood flow in the ductus venosus of the donor or recipient, and hydrops of the recipient were associated with one fetal and one neonatal death.

OP34.03: Assessment of cardiac assessment of the pump twin in pregnancies with an acardiac fetus

Objective: To evaluate the mode of delivery of monochorionic twins (MC) in a tertiary center with a strict policy of late preterm delivery. Methods: Retrospective evaluation of all MC twin pregnancies delivered at Sheba medical center between 08/2005 and 08/2008. Complicated MC pregnancies were defined as patients with TTTS or sIUGR. Uncomplicated MC pregnancies were delivered between 35 to 37 weeks of gestation. The control group consisted of 1234 twin dichorionic (DC) pregnancies delivered between 2005–2007. Results: The study group included 140 pregnancies. 81 (58%) were uncomplicated and 59 (42%) were complicated. Gestational age at delivery of all MC twins was similar to controls. Complicated MC pregnancies were delivered significantly earlier than uncomplicated MC pregnancies. The rate of CS of MC twins was slightly higher compared with DC pregnancies, mainly due to the group of complicated MC pregnancies. Patients with uncomplicated MC pregnancies were more likely to attempt vaginal delivery compared to complicated pregnancies (OR = 2.23, p = 0.03) but the rate of successful vaginal delivery was similar in both groups. Complicated MC twins had a significantly higher rate of CS due to non reassuring fetal condition (7/81 vs. 15/59, p = 0.007). Newborns delivered to the complicated pregnancies had significantly lower mean 1and 5-minutes Apgar scores compared with the uncomplicated group (7.3 vs. 8.7, 8.7 vs. 9.8, both p < 0.01). Conclusions: With the above policy, gestational age at delivery of uncomplicated MC pregnancies was not lower than, nor CS section rate higher than for DC pregnancies.

OP18.10: Is CHOP Score predictive of the outcome of twin-to-twin transfusion syndrome?

Background: Cardiovascular abnormalities are common in the recipient twin in TTTS. In the donor, except for altered umbilical arterial flow, no gross cardiovascular changes are typically seen. Selective laser photocoagulation therapy (SLPT) improves outcome and can reverse many of the cardiovascular abnormalities noted in the recipient, however its impact on the donor twin heart has not been extensively studied. Objective: To investigate the effects of SLPT for TTTS on the cardiovascular status of the donor twin. Methods: Pre and post-operative fetal echos from 54 patients who underwent SLPT for TTTS Stage 2 or higher from June 2007 to February 2009 were reviewed. Cardiothoracic ratio (CTR), Doppler tricuspid and mitral E and A peak inflow velocities, umbilical artery (UA) and middle cerebral artery (MCA) pulsatility indices (PI), and myocardial performance indices (MPI) of the donor twin, were compared before and after SLPT. Presence or absence of pericardial effusion (PE) and tricuspid or mitral regurgitation were also noted. Results: CTR increased significantly as did mitral and tricuspid valve velocities, suggesting an increase in volume load. UA PI increased, but MCA PI remained unchanged. In select donors RV MPI increased substantially, however there was no difference for the group as a whole. Postoperatively, over 20% of donors developed a significant PE; nearly 50% developed tricuspid or mitral regurgitation. Conclusions: Important cardiovascular abnormalities develop in the donor twin following SLPT. The origin of these findings are unclear, but may be related to the insult of acute, rapid volume load in a previously volume depleted fetus. Serial fetal echo follow up of both donor and recipient for cardiovascular abnormalities after SLPT is warranted.

OP10.09: Assessment of the Diastolic function in TTTS before and after Laser therapy based on ductus venosus waveform analysis

Objectives: To evaluate early changes in foetal cardiac function in twin to twin transfusion syndrome (TTTS) using myocardial performance index pre and post laser therapy. Methods: Both donors and recipients of 51 monochorionic twin pregnancies complicated by TTTS were studied prospectively before and after laser therapy. The myocardial performance index (MPI) of both ventricles was calculated before (±24 hours) and after laser therapy (±24 hours) for the evaluation of early changes in the cardiac function. Results: As expected before laser, the donors had a significantly lower MPI-RV and MPI-LV (myocardial performance index in the right ventricle and in the left ventricle) (0.41 vs 0.67; P < 0.000000) and (0.36 vs 0.54; P < 0.0001) respectively. After laser therapy MPI increased in both the recipient and the donor in both ventricles: MPI-RV (0.67 vs 0.49; P < 0.02) (0.41 vs 0.19; P < 0.001), MPILV (0.54 vs 0.16; P < 0.02) (0.36 vs 0.29; P < 0.002). Diastolic time in the mitral valve of the recipient increased significantly. Conclusions: MPI appears is a sensitive index to evaluate early changes in the global cardiac function.