Placental vascular anastomoses visualized during fetoscopic laser surgery in severe mid-trimester twin-twin transfusion syndrome.

The aim of this study was to describe the type and number of placental vascular anastomoses identified during fetoscopic laser coagulation in severe mid-trimester twin-twin transfusion syndrome (TTS). In 126 patients with severe TTS, undergoing fetoscopic laser coagulation between 16 and 25 weeks of gestation, the different types of placental anastomoses [arterio-venous (AV), arterio-arterial (AA) and veno-venous (VV)] were counted. In cases of AV anastomoses their direction was identified and four groups were defined: in group 1 there were only anastomoses shunting from donor to recipient. Group 2 consisted of placentae with more anastomoses shunting from donor to recipient than in the opposite direction, group 3 showed an equal number in both directions and in group 4 there were more anastomoses shunting from recipient to donor than in the opposite direction. In 9 cases (7 per cent) the anastomoses could not be clearly identified due to impaired visualization, leaving 117 cases for analysis. The median number of anastomoses found was 5 with a range from 1-14. In all cases AV anastomoses from donor to recipient were present, 36 cases (31 per cent) had also AA anastomoses and 14 cases (12 per cent) showed VV anastomoses. Regarding the direction of AV anastomoses, the results were as follows: there were 35 cases (30 per cent) in group 1, 52 cases (44 per cent) in group 2, 14 cases (12 per cent) in group 3 and 16 cases (14 per cent) in group 4. In 54 (46 per cent) placentae there was at least one thin anastomosis whose type was unclassifiable. There were no placentae showing AV anastomoses only from the recipient to the donor fetus. This study demonstrates that AV anastomoses are the prerequisite for the development of TTS in monochorionic placentae. The majority (74 per cent) of cases showed a higher number of AV anastomoses from donor to recipient than in the opposite direction. In approximately one third of placentae there are also AA anastomoses and the overall number of anastomoses seen and coagulated during fetoscopy is higher than reported in postnatal studies.

Endoscopic laser coagulation of placental anastomoses in 200 pregnancies with severe mid-trimester twin-to-twin transfusion syndrome.

OBJECTIVE: To investigate perinatal outcome after endoscopic laser coagulation of the placental vascular anastomoses in severe mid trimester twin-to-twin transfusion syndrome (TTTS). STUDY DESIGN: In a prospective study between January 1995 and September 1999, we performed laser therapy in 200 consecutive pregnancies with TTTS between 16 and 25 weeks of gestation. We compared outcome of the first group of 73 pregnancies whose outcome has been reported previously in a study comparing laser surgery and serial amniodrainages [Am J Obstet Gynecol 1999;180:717-24], with the following group of 127 patients. RESULTS: The overall survival rate increased from 61% (89/146) in group 1 to 68% (172/254) in group 2. The percentage of pregnancies with survival of both fetuses was 42% (31/73) in group 1 and increased to 54% (69/127) in group 2 (P=0.142). The survival rate for at least one fetus was 81% (103/127) in group 2. The median gestational age at delivery of liveborn babies was 33.7 weeks in group 1 and 34.4 weeks in group 2 with a median interval of 13 weeks between the intervention and delivery. CONCLUSION: This study of a large population of pregnancies with severe second trimester twin-to-twin transfusion syndrome confirms the improvements of outcome after laser therapy as compared to serial amniodrainages reported previously. Furthermore, it shows a trend towards an increase in survival rates with growing experience in this technique, most likely attributable to a more selective identification and efficient coagulation of the placental vascular anastomoses.

Perinatal outcome in monochorionic twin pregnancies complicated by amniotic fluid discordance without severe twin-twin transfusion syndrome.

OBJECTIVES: To assess the natural history and perinatal outcome in monochorionic diamniotic twin pregnancies with discordant amniotic fluid volume without signs of severe twin-twin transfusion syndrome (TTTS). METHODS: This was an observational study of 84 consecutive monochorionic twin pregnancies which did not meet the criteria for severe TTTS and endoscopic laser coagulation of placental anastomoses at initial presentation. The population was subdivided into two groups. Group 1 consisted of 64 pregnancies (median gestational age, 20.1 (range, 15.6-24.7) weeks) with amniotic fluid discordance and no signs of congestive heart failure in the twin with the larger amniotic fluid volume (Twin 1) and positive end-diastolic flow in the umbilical artery of the twin with the smaller amniotic fluid volume (Twin 2). Group 2 (median gestational age, 19.1 (range, 16.0-24.4) weeks) consisted of 20 pregnancies with amniotic fluid discordance and intrauterine growth restriction (IUGR) (abdominal circumference < 5th percentile) in combination with absent or reversed end-diastolic (ARED) flow in the umbilical artery of Twin 2. After exclusion of one patient from Group 1, who opted for termination of pregnancy, nine patients in Group 1 and one in Group 2 developed severe TTTS, and laser coagulation was offered. The remaining 54 pregnancies of Group 1 were compared with the remaining 19 pregnancies of Group 2. RESULTS: Fetuses in Group 1 showed significantly higher survival rates (overall survival, 100/108 (92.6%) vs. 23/38 (60%), P < 0.0001; survival of both fetuses, 49/54 (90.7%) vs. 9/19 (47.4%), P = 0.0002) and median gestational age at delivery (33.6, (range, 27.6-37.8) weeks vs. 32.0 (range, 26.9-36.3) weeks, P = 0.0457). Overall, there was a significantly higher incidence of complications, defined as necessity for intrauterine intervention, fetal or neonatal death or delivery prior to 32 weeks, in Group 2 (Group 1: 30/63 (47.6%); Group 2: 16/20 (80%), P = 0.0188). CONCLUSIONS: Our data suggest that amniotic fluid discordance in monochorionic diamniotic twin pregnancies in combination with IUGR and umbilical artery ARED flow in one fetus represents an extremely high-risk constellation for adverse pregnancy outcome.

Abnormal ductus venosus blood flow: a clue to umbilical cord complication.

We report a case of umbilical cord complication causing, fetal hypoxemia and acidemia. At 30 weeks of gestation, the patient was referred because of slightly increased amniotic fluid volume and a non-reactive cardiotocogram. Biometry was appropriate for gestational age. Umbilical artery and fetal aortic Doppler findings were normal, whereas diastolic blood flow velocities in the middle cerebral artery were increased and the ductus venosus showed severely abnormal flow velocity waveforms with reversal of flow during atrial contraction. Since other reasons for fetal hypoxemia could be excluded, careful examination of the umbilical cord was performed. Traction of the hypercoiled umbilical cord due to its course around the fetal neck and shoulders was suspected. Cesarean section confirmed the sonographic findings and fetal blood gases revealed fetal acidemia. This case indicates that investigation of fetal venous blood flow may also help to identify fetal jeopardy due to reasons other than increased placental vascular resistance.

Doppler ultrasound measurements in the central circulation of anesthetized fetal sheep during obstruction of umbilical-placental blood flow.

OBJECTIVE: To establish by Doppler ultrasound the effects of acute blockage of umbilical cord vessels on the fetal central circulation. DESIGN: Experimental study in anesthetized pregnant sheep. METHODS: In 11 anesthetized pregnant sheep (0.66 of gestation), Doppler velocity profiles and/or venous flow rates were recorded in the ductus venosus, the fetal aorta, the umbilical arteries and the umbilical vein. This involved three phases. In Phase 1, the abdominal wall was closed (n = 9); Phase 2 was during fetoscopy after laparotomy (n = 8); Phase 3 was after coagulation of one of the umbilical arteries (n = 10). As an additional intervention in six fetuses, the umbilical cord was clamped for 5-15 s while blood flow velocity changes in the ductus venosus were observed. RESULTS: There were no significant differences between Doppler recordings in Phases 1 and 2. During Phase 3, the pulsatility index of the aorta and of the coagulated umbilical artery increased significantly. The umbilical vein blood flow rate was significantly reduced from a median of 408 (range, 243-575) mL/min/kg in Phase 1 to a median of 173 (range, 107-426) mL/min/kg in Phase 3, but the blood flow rate in the ductus venosus (median, 94; range, 56-148 mL/min/kg vs. median, 92; range, 33-237 mL/min/kg) remained unchanged. The ductus venosus/umbilical vein ratio increased from a median of 0.22 (range, 0.13-0.41) to 0.56 (range, 0.17-0.97) (P < 0.05). Compression of the cord (5-15 s) immediately reduced the time averaged maximum velocity in the ductus venosus from a mean of 51 (standard deviation, 11) cm/s to 20 (standard deviation, 6) cm/s (P < 0.001) without significant changes of the velocity profile. However, the pulsatility index increased from a mean of 0.55 (standard deviation, 0.19) to 1.89 (standard deviation, 0.73) (P < 0.001). CONCLUSION: Central venous flows in anesthetized fetal sheep are unaffected by laparotomy and hysterotomy. Obliteration of one umbilical artery increases the ductus venosus/umbilical vein volume flow (mL/min/kg) ratio. Compression of the umbilical cord shifts down blood flow velocity profiles in the ductus venosus, and the pulsatility index thus increases.

Ductus venosus studies in fetuses at high risk for chromosomal or heart abnormalities: relationship with nuchal translucency measurement and fetal outcome.

OBJECTIVE: To investigate, in a high-risk group of fetuses, the role of ductus venosus Doppler velocimetry as a prognostic factor, in addition to nuchal translucency measurement, for predicting chromosomal anomalies and, where the karyotype was normal, for predicting fetal outcome. METHODS: Nuchal translucency was measured and ductus venosus pulsatility index and late diastolic flow (a-wave) were recorded in 186 fetuses at a median gestational age of 12.6 weeks (range, 10-17). Fetal karyotype, the presence of structural anomalies, pregnancy outcome, neonatal examination at birth and postnatal follow up were the outcome values. RESULTS: Nuchal translucency measurement was increased in 112 fetuses. The outcome of pregnancy was normal in 130 fetuses. Fifty-six fetuses had an adverse outcome (46 chromosomal anomalies, three intrauterine deaths, six structural anomalies and one developmental disorder). The sensitivity of an abnormal ductus venosus pulsatility index or of absent or reversed flow during the a-wave was 65% for chromosomal anomalies and 68% for an adverse outcome. The specificity was 79%. There was a significant correlation between nuchal translucency and ductus venosus pulsatility index. In chromosomally normal fetuses with an enlarged nuchal translucency an abnormal ductus venosus flow was associated with a nearly nine-fold increase in adverse outcome (odds ratio 11.7). CONCLUSION: Ductus venosus Doppler velocimetry can be used in addition to nuchal translucency measurement as a predictor of chromosomal anomalies. However, as the ductus venosus blood flow pattern is correlated with nuchal translucency measurement it cannot be used as an independent variable to reduce the indication for fetal karyotyping. Ductus venosus Doppler velocimetry may have a role in the counseling of parents in the case of an enlarged nuchal translucency and normal karyotype by identifying those fetuses in need of an intensive follow up due to an increased risk of adverse outcome.

Prognostic factors in severe twin-twin transfusion syndrome treated by endoscopic laser surgery.

OBJECTIVE: The aim of this study was to investigate clinical and sonographic parameters, in particular Doppler blood flow measurements, in severe second-trimester twin-twin transfusion syndrome before and after endoscopic laser coagulation of the placental vascular anastomoses, to correlate these data with fetal outcome and to determine whether fetal blood flow measurements could help to estimate the probability of fetal survival. METHODS: In 121 cases of severe twin-twin transfusion syndrome examined between 17 and 26 weeks of gestation, the following investigations were performed: fetal biometry, placental location, deepest pool of amniotic fluid, echocardiography and Doppler sonography of the umbilical arteries and the ductus venosus of both twins before and after fetoscopic laser ablation of the placental anastomoses. RESULTS: The overall survival rate was 64% (156/242). Both fetuses survived in 48% (58/121) and one fetus survived in 33% (40/121), resulting in 81% (98/121) of pregnancies with at least one survivor. Gestational age at the time of the procedure and placental location had no significant influence on fetal survival. The amniotic fluid volume drained after laser coagulation correlated significantly (p = 0.038) with the risk of miscarriage or extremely premature delivery within 4 weeks of the procedure. Intertwin discrepancy in abdominal circumference showed a significant negative correlation (p = 0.004) with the probability for survival of donor fetuses. Before the procedure, 19% (23/121) of donor twins and 5% (6/121) of recipient twins showed absent or reversed end-diastolic flow in the umbilical artery (p = 0.001). This finding had no significant influence on the survival rate of donors. An increase of waveform indices in the umbilical artery 1 day after the procedure compared to immediately after the procedure correlated significantly with a lower probability for survival of donors (p = 0.042) and recipients (p = 0.018). Before the procedure, 37% (45/121) of recipient twins and 9% (10/113) of donor twins showed absent or reversed flow during atrial contraction in the ductus venosus (p < 0.0001). This finding had a significant negative influence on the survival rate of recipient fetuses (p = 0.02). Furthermore, an increase of waveform indices in the ductus venosus 1 day after the procedure compared to immediately after the procedure correlated significantly with a lower probability of survival in recipients (p = 0.005). CONCLUSIONS: Fetoscopic laser coagulation of the placental vascular anastomoses in severe mid-trimester twin-twin transfusion is a potentially corrective and effective, minimally invasive procedure. Doppler investigation of the umbilical and fetal circulations provides important information on the fetal condition, prognosis and therapeutic effects of the intervention. Signs of congestive heart failure in the recipient may reduce the probability of survival, whereas increased placental resistance in the donor before the procedure is not necessarily associated with a reduction in the probability of survival after laser coagulation.

Bipolar coagulation with small diameter forceps in animal models for in-utero cord obliteration.

The objective of this study was to evaluate the feasibility, efficacy and safety of bipolar coagulation using endoscopic forceps of diameters of 2.7 mm and less in animal models mimicking in-utero conditions. Forceps of 2.2, 2.3, 2.5 and 2.7 mm were tested in rabbits (n = 36). Vessel pairs were dissected and coagulated in a fluid environment under endoscopic vision at 15 and 25 W. The main outcome measure was the perforation rate. In fetal lambs (n = 25), umbilical cords were coagulated under sono-endoscopic control with power settings from 10 to 35 W. Main outcome measures were the duration of coagulation, perforation rate, change in the temperature of the amniotic fluid and efficacy of vessel occlusion rate. At 20-25 W, all cords were coagulated successfully without any perforation using 2.3, 2.5 or 2.7 mm forceps. Coagulation with the 2. 2 mm forceps was associated with a high perforation rate, although the design rather than the diameter of the forceps may have influenced this outcome. Bipolar coagulation with forceps between 2. 3 and 2.7 mm and appropriate power settings achieves efficacious and safe coagulation in animal models for umbilical cord occlusion.