Intertwin anastomoses in monochorionic placentas after fetoscopic laser coagulation for twin-to-twin transfusion syndrome: Is there more than meets the eye (original) (raw)
Ultrasound in Obstetrics and Gynecology, 2006
Methods Thirty-nine cases with severe TTTS were treated at 16-26 weeks of gestation. Maternal hemodynamic evaluation was performed, including heart rate (HR), arterial pressure and echocardiography with calculation of shortening fraction (SF), left atrial dimensions, stroke volume (SV), cardiac output (CO) and total vascular resistance (TVR), before and 6 h and 24 h after placental surgery. Hemoglobin (Hb), hematocrit (Ht) and protein levels were also measured. Cases were retrospectively divided into groups according to treatment: Group A had laser therapy followed by amnioreduction > 1000 mL (n = 25); Group B had laser therapy followed by amnioreduction < 1000 mL (n = 14).
Ultrasound in Obstetrics and Gynecology, 2008
Objective To assess outcome after fetoscopic laser coagulation (FLC) of placental vascular anastomoses with the 30 • fetoscope in mid-trimester severe twinto-twin transfusion syndrome (TTTS) with completely anterior placenta compared with the regular 0 • fetoscope in TTTS with other placental locations. Methods This was a prospective study of 176 consecutive monochorionic twin pregnancies undergoing FLC for severe TTTS. Of these, 51 patients required use of the 30 • fetoscope (study group) and 125 placental locations permitted use of the 0 • fetoscope (controls). Results The two groups had very similar outcomes. The median gestational age at FLC in the study group vs. control group was 21.0 (range, 17.4-24.6) weeks vs. 20.6 (range, 15.9-24.6) weeks. Both fetuses survived in 58.8% (30/51) of study patients vs. 66.4% (83/125) of controls. At least one fetus survived in 84.3% (43/51) of study patients and 88.8% (111/125) of controls (P = 0.45). Study patients delivered at a median of 34.1 (range, 25.0-38.4) weeks and controls at 34.0 (range, 25.0-40.3
Placenta, 2008
Background: The twin-to-twin transfusion syndrome (TTTS) is a severe complication of monochorionic twin pregnancies, caused by a net intertwin transfusion of blood from one fetus (the donor) towards the other fetus (the recipient) through placental anastomoses. TTTS is driven by unidirectional arterio-venous anastomoses, and mitigated by bidirectional arterio-arterial or veno-venous anastomoses which reduce the net inter-twin transfusion. In contrast to these accepted concepts, cases have been described paradoxically devoid of arterio-venous anastomoses but including arterio-arterial anastomoses. We hypothesized that TTTS may develop in such cases as a consequence of a stenosed chorionic artery in the recipient placenta that connects with the arterio-arterial anastomosis. Clinical cases: We describe two cases of monochorionic twin placentae without arterio-venous anastomoses but with only an arterio-arterial and veno-venous anastomosis. In one case severe TTTS developed. There, the arterio-arterial anastomosis connected to a stenosed chorionic artery in the recipient placenta and showed a tortuous appearance. The other case developed uneventful. It lacked a stenosed chorionic artery and the arterio-arterial anastomosis was non-tortuous. Conclusion: We present evidence that the arterio-arterial anastomosis represented a functional collateral artery whose outgrowth was driven by an increased shear-stress caused by an increased flow to a lower pressure vascular bed in the placenta of the recipient. The lower arterial pressure occurred from the moment that a chorionic artery which was connected to the anastomosis developed a significant stenosis. The resulting collateral flow through the anastomosis maintained blood supply to the lower pressure placental bed, the beneficial function of collaterals, but also resulted in an increasing net inter-twin transfusion which triggered onset of severe TTTS. (J.P.H.M. van den Wijngaard). 1 Jeroen van den Wijngaard was in part supported by the European Community Eurofetus program. 0143-4004/$ -see front matter Ó
Placenta, 2010
Twin-to-twin transfusion syndrome (TTTS) is a multifactorial disorder that develops in 9-15% of diamniotic-monochorionic twin gestations. While the pathogenesis of TTTS remains poorly understood, unbalanced deep artery-to-vein (AV) anastomoses have traditionally been implicated in the gradual shift of blood from donor to recipient. The aim of this study was to define the placental markers of twin-totwin transfusion syndrome, with special emphasis on the deep AV anastomoses. A prospective cohort of 284 consecutive diamniotic/monochorionic twin placentas was examined at Women and Infants Hospital between 2001 and 2008. Following exclusion of monoamniotic, multiple, disrupted and lasertreated placentas, 218 twin placentas (21 TTTS and 197 non-TTTS controls) formed the subject of this study. Placentas were injected with color-coded dyes. Anatomic characteristics and choriovascular anastomotic patterns of TTTS placentas were compared with non-TTTS controls. The TTTS placentas showed significantly higher frequencies of velamentous cord insertion, magistral vascular distribution patterns, uneven placental sharing, absence of AA anastomoses and presence of VV anastomoses. Deep AV anastomoses were identified in !95% of TTTS and non-TTTS placentas and were overall more abundant than previously reported. The total and net numbers of AV anastomoses were similar in both groups. However, the net cross-sectional area of AV anastomoses, which also takes into account the caliber of the vessels, was significantly smaller in TTTS placentas. There was no correlation between the direction of the AV imbalance and the twin donor/recipient status. In conclusion, TTTS has distinct placental characteristics, warranting their routine inclusion in the diamniotic-monochorionic placental pathology report. Our findings suggest imbalance of AV anastomoses is not required for the development for TTTS, although their presence, whether balanced or unbalanced, may contribute to the creation or perpetuation of the syndrome. Elucidation of the role of the various placental determinants in diamniotic-monochorionic twin gestations may lead to further refinement of therapeutic strategies.
Ultrasound in Obstetrics & Gynecology, 2007
Objective To assess outcome after fetoscopic laser coagulation (FLC) of placental vascular anastomoses with the 30 • fetoscope in mid-trimester severe twinto-twin transfusion syndrome (TTTS) with completely anterior placenta compared with the regular 0 • fetoscope in TTTS with other placental locations. Methods This was a prospective study of 176 consecutive monochorionic twin pregnancies undergoing FLC for severe TTTS. Of these, 51 patients required use of the 30 • fetoscope (study group) and 125 placental locations permitted use of the 0 • fetoscope (controls). Results The two groups had very similar outcomes. The median gestational age at FLC in the study group vs. control group was 21.0 (range, 17.4-24.6) weeks vs. 20.6 (range, 15.9-24.6) weeks. Both fetuses survived in 58.8% (30/51) of study patients vs. 66.4% (83/125) of controls. At least one fetus survived in 84.3% (43/51) of study patients and 88.8% (111/125) of controls (P = 0.45). Study patients delivered at a median of 34.1 (range, 25.0-38.4) weeks and controls at 34.0 (range, 25.0-40.3