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Shorter ultrasound interval boosts twin-to-twin detection

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – An interval of no more than 14 days between ultrasonograms in monochorionic twins appears to increase detection of twin-to-twin transfusion syndrome (TTTS), researchers report in the January issue of Obstetrics and Gynecology.

“The diagnosis of monochorionic twins versus dichorionic twins,” Dr. Stephen P. Emery told Reuters Health by email, “is actionable information in that it can be used to modify sonographic surveillance in order to improve pregnancy outcomes.”

Dr. Emery of the University of Pittsburgh Medical Center and colleagues note that the syndrome complicates up to 15% of monochorionic-diamniotic twin pregnancies. Nevertheless, lack of knowledge has resulted in inconsistent recommendations for initiation and interval of ultrasound screening.

To investigate, the team reviewed data on 108 monochorionic twin pregnancies which had had ultrasound evaluation between 2001 and 2008. In all, 24 met criteria for early stage twin-to-twin transfusion syndrome. A further 18 had late stage transfusion.

The median gestational age at diagnosis was 19 weeks and 6 days. Eighteen (42%) were diagnosed at the first ultrasonogram. Twenty-four had had a previous ultrasonogram a mean of 19 days earlier.

Comparison of findings with a interval of less than 14 days and more than 14 days showed that the longer interval was significantly associated with detection at a later stage.

Only two cases (11.8%) of late twin