More frequent exams improve diagnosis of twin-to-twin transfusion syndrome

Scheduling ultrasound examinations no longer than 14 days apart may lead to earlier detection of twin-to-twin transfusion syndrome (TTTS), more timely intervention, and better outcomes in twins who share the same placenta, researchers report.

A review of data on 108 monochorionic twin pregnancies evaluated by ultrasound for TTTS at the University of Pittsburgh Medical Center between 2001 and 2008 showed that an interval longer than 14 days between ultrasound examinations was strongly associated with diagnosis of TTTS at a later stage. Only 2 cases of late-stage TTTS were diagnosed at an interval of 14 or fewer days.

“Since outcomes are related to stage at diagnosis, it is important that we diagnose TTTS in a timely fashion,” writes senior author Stephen P. Emery, MD. The researchers note that untreated TTTS can lead to morbidity and mortality rates of 80% to 100%.

Of the 108 monochorionic twin pregnancies in the study, 42 had TTTS: 24 (57%) early-stage and 18 (43%) late-stage. Eighteen cases were diagnosed at the first ultrasonogram; 24 had had an ultrasonogram at a mean of 19 days previously. Median gestational age at diagnosis was 19 weeks and 6 days. Comparison of findings at fewer than 14 and more than 14 days found a significant association between the longer interval and late-stage diagnosis, with an odds ratio of 9.45. The association held when the findings were controlled for gestational age at diagnosis.

The researchers emphasize that specific identification of monochorionic pregnancy is crucial. “We encourage obstetric care providers to be more cognizant of the need to treat monochorionic gestations differently than dichorionic gestations, and to recognize that ultrasound diagnosis of simply ‘twins’ is insufficient,” they write.

The study was published in the January issue of Obstetrics and Gynecology (2011;117[1]:131-135).