P345: Twin to twin transfusion syndrome (TTTS) in momoamniotic monochorionic pregnancies (MAMC) does exist: proposition of antenatal surveillance

Abstract

MAMC gestations have a high fetal morbidity mainly due to cord entanglements. TTTS has been suggested to be a common cause of fetal death. Rarely is this complication described early in pregnancy. We report a MAMC twin pregnancy referred at 16 weeks' gestation for polyhydramnios. The 2 cords were marginally and closely inserted. Morphology and diameters of both cords were obviously different. Doppler waveforms (UA, DV) were normal in twin 1 and presented high resistances in twin 2. TTTS was suspected. Weekly scans were performed. At 19 weeks + 4: increased AFI (320 mm) and UA reverse flow on twin 2 were noted. At 20 weeks: AFI decreased slightly with improvement of umbilical impedance to flow in foetus 2 (RI: 1, PI: 1.73). DV in both twins came to normal. The invasive procedure was postponed. Isolated absent end diastolic flow on donor's UA was kept observed all over the pregnancy associated with good biophysical profile. Hemodynamics on twin 1 was also normal. Both bladders remained visible with a constant slight difference of size. At 30 weeks a biventricular cardiac hypertrophy appeared in twin 1 associated with a tricuspid regurgitation and an estimated right ventricular pressure around 110 mm HG. A caesarean section was decided: twin 1 : 1640 g, Apgar scores 4/5/6, centile 50, haemoglobin rate 17. Twin 2, 1270 g, Apgar scores 6/7/7, centile 10, haemoglobin rate 13. Post natally twin 1 presented a cardiac failure related to a myocardial hypertrophy and deceased on day 1. Pathology finding confirmed superficial large venous as well as deep anastomosis. TTTS is possible in MAMC gestations but its incidence remains unknown. MAMC as monochorionic diamniotic pregnancies should be closely managed: early diagnosis of chorionicity, repeated fortnight scans and Doppler examinations for early detection of TTTS. Rise of polyhydramnios or discrepancy of bladder repletion are the first warning signs leading to complementary Doppler and cardiac function studies.