Outcomes of twin-twin transfusion syndrome managed by a specialised twin clinic

To determine the perinatal outcomes of monochorionic (MC) pregnancies complicated by the twin-twin transfusion syndrome (TTTS) that were managed in a specialised twin clinic at the KK Women's and Children's Hospital.

This was a 21-month retrospective study carried out from January 2002 to September 2003. MC pregnancies were followed up every two to three weeks with regular ultrasonographical and Doppler studies from the time monochorionicity was diagnosed. Standard criteria used for the diagnosis of TTTS are the presence of oligohydramnios/polyhydramnios sequence on ultrasonography. The severity of TTTS was staged according to Quintero's system.

There were 77 sets of MC pregnancies in our database. 11 sets were diagnosed with TTTS, hence the incidence was 14.3 percent. The median gestation at diagnosis of TTTS was 17.4 (16.4 to 26) weeks. At first presentation, five were stage I, two were stage II, three were stage III and one was stage IV. Three pregnancies were terminated in the second trimester and one was lost to follow-up. Of the other seven, two were treated expectantly or delivered, four with amnioreduction/ septostomy and one with cord occlusion. The median gestation at delivery is 30.8 (26.7 to 36.9) weeks. Four (57 percent) were delivered before 32 weeks and these same four pairs required neonatal intensive care. The overall perinatal survival was 78 percent (11/14) and the median diagnosis to delivery interval was 10.7 (3.1 to 17.5) weeks.

TTTS occurs in a significant proportion of MC pregnancies. The perinatal survival outcome of this group of patients managed in this clinic is comparable to that of other good centres.