Classification of discordant fetal growth may contribute to risk stratification in monochorionic twin pregnancies

Objectives To determine whether classification of discordant growth between fetal twins allows risk stratification in monochorionic twin pregnancies. Methods In 12 twin-to-twin transfusion syndrome (TTTS) pregnancies and 12 c ases that were suspected of developing the syndrome, fetal growth was deter mined by serial standard sonography. Fetal growth was expressed as the diff erence-average-ratio (DAR), defined as the difference in estimated fetal we ight between both twins divided by their average weight. In each case, we d etermined the maximum value of DAR and the rate of change of DAR using a le ast squares linear fit of the estimated fetal weights. Results For the TTTS cases the maximum value of DAR was 0.44 +/- 0.21 versu s 0.52 +/- 0.13 for the suspected TTTS cases (P = 0.25). The rate of change of DAR was 0.052 +/- 0.034 per week for the TTTS versus 0.0055 +/- 0.0092 for the suspected TTTS cases (P = 0.0004). After laser therapy: DAR decreas ed in four successful cases, with a rate of change of -0.0146 +/- 0.0093 pe r week, but increased further in one unsuccessful case, due to patent anast omoses. In the seven TTTS cases treated with amnioreduction, DAR did not de crease; in one of two suspected TTTS cases the DAR decreased slightly? In t he nine amnioreduction cases, the average rate of change of DAR was 0.067 /- 0.083 per week. This was significantly different from the four successfu l laser cases (P = 0.01). Conclusions The rate of change of DAR, hut nor DAR itself, has prognostic v alue for the development of suspected TTTS pregnancies, for the onset and s everity of TTTS and for the efficacy of therapy This parameter is derived f rom routine sonography examination and may contribute to risk stratificatio n in monochorionic twin pregnancies.