ABSTRACT
TWIN-TWIN TRANSFUSION SYNDROME About 10-15% of monochorionic (MC) twin pregnancies are complicated by severe twin-twin transfusion syndrome (TTTS) as a consequence of a chronic circulatory imbalance in the vascular anastomoses that occur in virtually all MC placentae. TTTS typically presents in the mid-second trimester. The diagnosis is based on the donor presenting with oligo-anhydramnios and the recipient having polyhydramnios. The donor appears to be stuck, with restricted growth and an absent/small bladder. The recipient appears to be of average/increased weight with a big bladder. Doppler changes may accompany these findings and usually signify worsening TTTS. The donor twin may have absent/reversed end-diastolic flow in the umbilical artery. The recipient and, less commonly, the donor may show absent or reversed flow during atrial contraction in the ductus venosus.
