Ultrasound Staging

Ultrasound Staging of Twin–Twin Transfusion Syndrome

TTTS staging was introduced by Quintero et al in 1999. This is based on ultrasound features: 

• stage 1 – oligo/polyhydramnios sequence only with bladder visualized in the donor twin 

• stage 2 – bladder not visualized in the donor twin 

• stage 3 – critically abnormal Dopplers (absent or reversed diastolic flow) in the donor umbilical artery, pulsitile venous or reverse flow in the ductus venosus 

• stage 4 – hydrops in either twin 

• stage 5 – demise of one or both twins. 

A retrospective study of 50 TTTS cases treated by amnioreduction in Australia27 between 1993 and 2002, classified patients into stages at presentation. Overall, 22% of the cases improved after one amnioreduction, 40% remained with the same stage, and 38% progressed. It was found that the less severe TTTS was at presentation, the higher the chance to improve. 

A prospective study of 52 cases from London28 showed that 15–60% of the cases can improve in stage, and that mortality was similar regardless of improvement. The gestational age at presentation was 24, 20, 20, 21, and 16 weeks for stages I–V, respectively. 

Data from our center with 175 cases of TTTS treated by laser is shown in (Figure 4.7). We found that gestational age between groups was not different. 

This information suggests that stages may not represent different times during the natural history of the disease, but rather different forms of presentation with possibly different prognosis. In Quintero et al’s paper30 where the stage system is analyzed as a prognostic factor for outcome, laser photocoagulation appeared to be better than amnioreduction in stages III or IV, whereas the outcome in stages I and II was similar in both groups. However, in the Eurofetus randomized trial,31 72 TTTS treated by laser were compared with 70 TTTS treated by amnioreduction. At least one survivor was obtained in 86% and 58% of the cases treated by laser and amnioreduction in TTTS stages I or II. This difference persisted in stages III and IV (66% vs 44%).