RESUMO
BACKGROUND: Intraoperative blood transfer between twins during laser surgery for twin-twin transfusion syndrome can vary by surgical technique and has been proposed to explain differences in donor twin survival. OBJECTIVE: This trial compared donor twin survival with 2 laser techniques: the sequential technique, in which the arteriovenous communications from the volume-depleted donor to the volume-overloaded recipient are laser-occluded before those from recipient to donor, and the selective technique, in which the occlusion of the vascular communications is performed in no particular order. STUDY DESIGN: A single-center, open-label, randomized controlled trial was conducted in which twin-twin transfusion syndrome patients were randomized to sequential vs selective laser surgery. Nested within the trial, a second trial randomized patients with superficial anastomoses (arterioarterial and venovenous) to ablation of these connections first (before ablating the arteriovenous anastomoses) vs last. The primary outcome measure was donor twin survival at birth. RESULTS: A total of 642 patients were randomized. Overall donor twin survival was similar between the 2 groups (274 of 320 [85.6%] vs 271 of 322 [84.2%]; odds ratio, 1.12 [95% confidence interval, 0.73-1.73]; P=.605). Superficial anastomoses occurred in 177 of 642 cases (27.6%). Donor survival was lower in the superficial anastomosis group vs those with only arteriovenous communications (125 of 177 [70.6%] vs 420 of 465 [90.3%]; adjusted odds ratio, 0.33 [95% confidence interval, 0.20-0.54]; P<.001). In cases with superficial anastomoses, donor survival was independent of the timing of ablation or surgical technique. The postoperative mean middle cerebral artery peak systolic velocity was lower in the sequential vs selective group (1.00±0.30 vs 1.06±0.30 multiples of the median; P=.003). Post hoc analyses showed 2 factors that were associated with poor overall donor twin survival: the presence or absence of donor twin preoperative critical abnormal Doppler parameters and the presence or absence of arterioarterial anastomoses. Depending on these factors, 4 categories of patients resulted: (1) Category 1 (347 of 642 [54%]), no donor twin critical abnormal Doppler + no arterioarterial anastomoses: donor twin survival was 91.2% in the sequential and 93.8% in the selective groups; (2) Category 2 (143 of 642 [22%]), critical abnormal Doppler present + no arterioarterial anastomoses: donor survival was 89.9% vs 75.7%; (3) Category 3 (73 of 642 [11%]), no critical abnormal Doppler + arterioarterial anastomoses present: donor survival was 94.7% vs 74.3%; and (4) Category 4 (79 of 642 [12%]), critical abnormal Doppler present + arterioarterial anastomoses present: donor survival was 47.6% vs 64.9%. CONCLUSION: Donor twin survival did not differ between the sequential vs selective laser techniques and did not differ if superficial anastomoses were ablated first vs last. The donor twin's postoperative middle cerebral artery peak systolic velocity was improved with the sequential vs the selective approach. Post hoc analyses suggest that donor twin survival may be associated with the choice of laser technique according to high-risk factors. Further study is needed to determine whether using these categories to guide the choice of surgical technique will improve outcomes.
RESUMO
BACKGROUND: Prenatal repair of open spina bifida via the percutaneous fetoscopic approach does not require maternal laparotomy, hysterotomy, or exteriorization of the uterus. This technique requires intrauterine partial CO2 insufflation. Limited data exist on the physiological effects of CO2 insufflation on human fetuses, with no data on open spina bifida repair performed using the entirely percutaneous fetoscopic surgical technique. OBJECTIVE: Our aim was to examine the effects of intrauterine partial CO2 insufflation on fetal blood gases after percutaneous fetoscopic open spina bifida repair. STUDY DESIGN: This was a prospective study of patients who underwent percutaneous fetoscopic open spina bifida repair from February 2019 to July 2020. Fetal cordocentesis of the umbilical vein was performed in cases with favorable access to the umbilical cord. The umbilical vein cord blood samples were obtained under ultrasound guidance immediately at the conclusion of the open spina bifida repair. Simultaneous maternal arterial blood gas samples were also obtained. The results are reported as median (range). RESULTS: Of the 20 patients who underwent percutaneous fetoscopic open spina bifida repair during the study period, 7 patients (35%) underwent fetal blood sampling. The gestational age at the time of surgery was 27.4 (24.0-27.9) weeks and the operative time was 183 (156-251) minutes. The CO2 exposure time was 122 (57-146) minutes with maximum pressure of 13.5 (12.0-15.0) mm Hg. Fetal umbilical vein results were as follows: pH 7.35 (7.30-7.39), partial pressure of O2 56.2 (47.1-99.9) mm Hg, partial pressure of CO2 43.8 (36.2-53.0) mm Hg, HCO3 23.9 (20.1-25.6) mmol/L, and base excess -2.2 (-4.5 to -0.4) mmol/L. Simultaneous maternal arterial blood gas results were as follows: pH 7.37 (7.28-7.42), partial pressure of O2 187.5 (124.4-405.2) mm Hg, partial pressure of CO2 36.6 (30.7-46.0) mm Hg, HCO3 21.3 (18.0-22.8) mmol/L and base excess -3.2 (-5.9 to -1.8) mmol/L. CONCLUSION: Despite prolonged CO2insufflation of the uterus, fetal umbilical vein pH and base excess values did not approach those associated with potentially pathologic fetal acidemia.
