Samer Assaf

Residual Vascular Communications in Twin-twin Transfusion Syndrome Treated with Sequential Laser Surgery: Frequency and Clinical Implications

OBJECTIVES The goal of fetoscopic laser surgery for twin-twin transfusion syndrome (TTTS) is to ablate all placental vascular communications, thereby separating the fetal circulatory systems. We sought to ascertain the frequency and clinical implications of residual vascular communications (RVC) post preferential sequential selective laser photocoagulation of communicating vessels (SQLPCV). STUDY DESIGN TTTS placentas treated via preferential SQLPCV were examined. Patency of vascular communications was assessed via water and/or milk injections. Cases with intrauterine fetal demise or placental disruption were excluded. Outcomes with and without RVC were compared. RESULTS One hundred seventy-four TTTS patients were treated during the study period. Dual survival at birth was 76% (133/174). Of the 133 dual survivors, 105 (79%) submitted an intact placenta. Five of these 105 placentas had RVC (4.8%). Comparison of RVC versus non-RVC cases revealed the following: gestational age at delivery 28.7(6.5) vs. 33.4(3.3) weeks (p=0.178); recipient birth weight 1287(1061) vs. 1973(610) grams (p=0.020); donor birth weight 1429(1369) vs. 1653(715) grams (p=0.518); donor central/eccentric placental cord insertion 80% vs. 17% (p=0.006). One case required a second laser surgery to complete the laser ablation; this placenta did not have RVC after delivery. Otherwise there were no cases of persistent TTTS. One of the 5 RVC cases (20%) exhibited neonatal findings consistent with twin anemia-polycythemia sequence (TAPS), while none of the non-RVC cases had TAPS (p=0.005). CONCLUSIONS The rate of RVC was less than 5% among gestations with dual survivors post preferential SQLPCV treatment for TTTS.

Discordant Blood Chimerism in Dizygotic Monochorionic Laser-Treated Twin―Twin Transfusion Syndrome

BACKGROUND: Twin–twin transfusion syndrome occurs in 10% of monozygotic monochorionic twin gestations and results from an unbalanced exchange of blood from the donor to the recipient fetus through placental anastomoses. CASE: We present a case of twin–twin transfusion syndrome with differing fetal sex treated with in utero laser surgery. Genetic analyses showed 46,XX/46,XY hematologic chimerism in both twins at birth and at 6 months, with the recipient twin being significantly more chimeric than the donor. Placental pathologic examination confirmed monochorionicity and laser ablation of all anastomoses. CONCLUSION: Despite in utero separation of the fetal circulations remote from delivery, hematologic chimerism persisted after birth. We speculate that the greater degree of blood chimerism in the recipient compared with the donor was related to the pathophysiology of twin–twin transfusion syndrome before laser surgery.

Amniopatch as a Treatment for Rupture of Membranes following Laser Surgery for Twin-Twin Transfusion Syndrome

Objective: The risk of iatrogenic rupture of membranes (IROM) is 5–30% after operative fetoscopy. The aim of this study was to describe outcomes of patients with IROM following selective laser photocoagulation of communicating vessels (SLPCV) for twin-twin transfusion syndrome (TTTS) who were subsequently treated with amniopatch therapy. Methods: A review of patients who underwent treatment for mid-trimester TTTS between March 2006 and February 2008 with IROM within 7 days of SLPCV was performed. IROM patients without evidence of preterm labor or chorioamnionitis were offered expectant management, pregnancy termination, or amniopatch therapy. Results: Ninety-three patients were treated with SLPCV, of which three (3.2%) had IROM within 7 days. All three opted for amniopatch therapy which was performed at 18 2/7, 23 1/7, and 22 6/7 weeks’ gestation in patients 1, 2 and 3, respectively. In patients 1 and 2, amniopatch therapy sealed membranes within 7 days. A second amniopatch was required for patient 3 before IROM resolved. Gestational ages at delivery were 38 2/7, 37 5/7 and 30 2/7 weeks, respectively. Conclusion: Amniopatch is a viable treatment option for iatrogenic ROM following SLPCV.

Spontaneous twin anemia-polycythemia sequence complicated by recipient placental vascular thrombosis and hydrops fetalis.

Twin anemia–polycythemia sequence (TAPS) is an atypical form of twin–twin transfusion syndrome (TTTS) that presents as a large intertwin hemoglobin difference with one twin developing anemia and the other developing polycythemia, without oligohydramnios–polyhydramnios sequence (Lopriore et al., Placenta 2007;28:47–51). The prenatal diagnostic criteria for TAPS require that the middle cerebral artery-peak systolic velocity (MCA-PSV) measure greater than 1.5 multiples of median (MoM) in the donor twin and less than 0.8 MoM in the recipient twin (Robyr et al., Am J Obstet Gynecol 2006;194:796–803; Klaritsch et al., Ultrasound Obstet Gynecol 2009;34:149–154; Mari et al., N Engl Med 2000;342:9–14). The presumed etiology of TAPS involves the presence of small caliber arteriovenous anastomoses, which generate a slow transfusional process allowing for hemodynamic compensation (Lopriore et al., Placenta 2007;28:47–51; Lopriore et al., Placenta 2009;30:223–225; Lewi et al., Am J Obstet Gynecol 2006;194:790–795; Lopriore et al., Am J Obstet Gynecol 2008;112:753–758; Van den Wijngaard et al., Placenta 2007;28:611–615). The resulting polycythemia in the recipient twin is a risk factor for fetal and placental thrombosis (Van den Wijngaard et al., Am J Physiol 2005;288:R799–R814). We present a case of spontaneous TAPS complicated by a large placental vessel thrombosis and hydrops fetalis. Treatment via selective laser photocoagulation of communicating vessels (SLPCV) resulted in normalization of the MCA-PSV discordance.

Normalization of Amniotic Fluid Levels After Fetoscopic Laser Surgery for Twin-Twin Transfusion Syndrome

Objective. The purpose of this study was to describe amniotic fluid (AF) normalization after laser surgery for twin‐twin transfusion syndrome (TTTS). Methods. Patients with TTTS (n = 174) who had laser surgery from 2006 through 2009 underwent serial measurements of the AF maximum vertical pockets (MVPs) during postoperative weeks 1 through 10. A normal MVP was defined as greater than 2 cm and less than 8 cm. Postoperative TTTS criteria required an MVP of 2 cm or less in one sac and 8 cm or greater in the other sac. Patients with septostomy, immediate fetal death, or missing MVP values were excluded. Results. Inclusion criteria were met by 115 patients. Normalization of the MVP occurred by week 5 in donors and week 8 in recipients in approximately 95% of the cases. Recipient fetuses with Quintero stage 3 or 4 TTTS (J Perinatol 1999; 19:550–555) were more likely to have an abnormal MVP than those with stage 1 or 2 TTTS during weeks 3 and 4 (P = .0049) and 5 and 6 (P = .0239). The criteria for TTTS were met in 6 cases (6.9%) in week 1: 5 resolved spontaneously, and 1 (1.2%) had persistent TTTS and required a second laser surgery. After week 1, 6 additional patients had abnormal MVP values for both fetuses simultaneously: 1 met TTTS criteria in week 3; 2 had oligohydramnios in week 2; and 3 had polyhydramnios in weeks 2, 4, and 7; none of these patients required further interventions. Conclusions. Although the AF of individual donor and recipient fetuses may take several weeks to normalize after laser surgery for TTTS, it is rare for both fetuses to meet TTTS criteria beyond the first postoperative week.

Postoperative Middle Cerebral Artery Peak Systolic Velocity Changes Confirm Physiological Principles of the Sequential Laser Technique for Twin-Twin Transfusion Syndrome

Introduction: Treatment of the twin-twin transfusion syndrome (TTTS) via sequential selective laser photocoagulation of communicating vessels (SQLPCV) mandates ablation of donor-to-recipient arteriovenous anastomoses first. It is hypothesized that SQLPCV facilitates intraoperative transfusion to the donor, thereby minimizing donor hypovolemia and anemia. We sought to determine if postoperative changes in fetal middle cerebral artery-peak systolic velocities (MCA-PSV) support this hypothesis. Materials and Methods: Patients undergoing preferential SQLPCV for TTTS had MCA-PSV measured 1 day before surgery and on postoperative day 1 (POD-1). Fetal anemia was defined as an MCA-PSV ≧1.5 multiples of the median (MoM). Exclusions included: POD-1 demise, missing MCA-PSV data, or gestational age <18 weeks. Results: Study criteria were met by 139 patients. Mean MCA-PSV in recipients increased from 0.97 to 1.15 MoM postoperatively (p < 0.0001). Donor mean MCA-PSV remained stable at 1.00 MoM preoperatively and 0.98 MoM postoperatively (p = 0.272). Nine fetuses, 6 donors and 3 recipients, had preoperative anemia; SQLPCV was not attempted in the 3 anemic recipients. Postoperatively, the proportion of donors with anemia remained stable (increase 3.6%, p = 0.419), and the proportion of recipients with anemia increased (increase 12.2%, p = 0.009). Discussion: Our findings confirm the presumed physiological basis for the SQLPCV treatment of TTTS.

Fetal heart rate changes associated with sequential selective laser surgery for twin-twin transfusion syndrome

Objective:To investigate perioperative changes in fetal heart rate (FHR) associated with sequential vs standard selective laser photocoagulation of communicating vessels for the treatment of twin-twin transfusion syndrome (TTTS).Study Design:Women with TTTS were treated with the intent of using the sequential procedure. Those who failed this treatment were categorized as having undergone the standard procedure. Pre- and postoperative FHR of donor and recipient fetuses were analyzed.Result:Of 98 women, 35 received the standard technique. A postoperative drop in the mean donor FHR was observed in gestations receiving the standard laser, but not in those receiving the sequential technique. In multivariable models that included operative and gestational characteristics, the use of the sequential treatment was associated with improved stability of the FHR of the donor twin.Conclusion:The stability in donor FHR following sequential laser ablation when compared with the standard technique is consistent with improved donor hemodynamics.

Fetal middle cerebral artery Doppler fluctuations after laser surgery for twin–twin transfusion syndrome

Objective:The objective of this study was to compare alterations in the middle cerebral artery (MCA) pulsatility index (PI) and mean velocity (V mean) after laser surgery for twin–twin transfusion syndrome (TTTS).Study Design:MCA Doppler studies were conducted 1 day before and after laser surgery for TTTS. The pre- and postoperative mean (standard deviation) of the MCA PI and V mean z-scores of the recipient and donor fetuses were calculated and compared. Data were analyzed using paired testing and multivariable linear regression models.Results:A total of 103 patients met the study criteria. Recipients’ MCA PI increased from −1.29 (1.20) preoperatively to 0.14 (1.52) postoperatively (P<0.0001), whereas the donors’ PI did not change significantly (−0.31 (1.67) to −0.67 (1.29); P=0.12). There was no significant difference between preoperative and postoperative MCA V mean in donors (0.39 (0.83) and 0.38 (0.93), respectively; P=0.5048) or recipients (0.60 (0.74) and 0.63 (0.90), respectively; P=0.5324).Conclusions:Despite the changes in the MCA PI after laser surgery for TTTS, the MCA V mean remained constant. These findings may suggest some autoregulatory capacity in the cerebral vessels of the mid-trimester fetus.