ABSTRACT
OBJECTIVE: This study aimed to compare the angio-architecture of monochorionic placentas of spontaneous twin anaemia-polycythemia sequence (TAPS) with placenta of twin-to-twin transfusion syndrome (TTTS) with residual anastomoses after laser coagulation and placentas of uncomplicated monochorionic twin pregnancies. METHODS: This case-control study compares the angio-architecture of monochorionic placentas of spontaneous TAPS (n = 12) with that of monochorionic placentas of TTTS treated by laser coagulation with residual anastomoses (TTTS + RA; n = 20) and placentas of monochorionic pregnancies without complications (n = 24), matched for gestational age. Placental sharing and angio-architecture were assessed by injection of colored dye. RESULTS: The median diameter of the arterio-venous (AV) anastomoses in TAPS placentas was 2.26, 0.215 with TTTS + RA and 4.17 mm in normal monochorionic pregnancies (p < .03). The mean diameter of the arterio-arterial (AA) anastomoses in monochorionic placentas with spontaneous TAPS was 0.2 mm versus 0.15 mm in TTTS + RA and 2.0 mm in normal pregnancies, respectively (p < 0.03, p < 0.007). The number of AA anastomoses was lower with TAPS (0.3 versus 0.50 and 1, respectively, p < 0.015, p < 0.0001). Besides, unequal sharing was more frequent in TAPS as compared with monochorionic normal pregnancies (75% versus 29%, p = 0.03). CONCLUSION: Age matched placentas of spontaneous TAPS are characterized by very small AV anastomoses and very few AA anastomoses of smaller diameter than placentas of monochorionic twins with TTTS or without obvious complications.
