Stage I Twin–Twin Transfusion Syndrome: Outcomes of Expectant Management and Prognostic Features

Objective  This article describes the natural history of stage I twin–twin transfusion syndrome (TTTS) including risk of progression to higher stage TTTS and pregnancy outcomes, and to identify risk factors for progression. Study Design  Retrospective cohort study of monochorionic diamniotic (MCDA) twin pregnancies from 2006 to 2016 with expectantly managed Quintero stage I TTTS. Results  A total of 30 MCDA twin pregnancies with expectantly managed stage I TTTS were identified. Of these, eight (26.7%) progressed to higher stage TTTS. Median gestational age (GA) at diagnosis for those that progressed was 18.9 ± 2.9 weeks versus 21.4 ± 3.4 weeks in those that remained stable ( p  = 0.06). Presence of an arterioarterial (A-A) anastomosis was assessed for 20/30 patients, and eight A-A were identified. Of those, 7/8 (87.5%) remained stable. In the complete cohort, a tiny or transiently visible bladder was noted in seven donor twins. Of these, 4/7 (57.1%) progressed. Excluding one termination, 47/58 (81.0%) fetuses survived. Conclusion  With expectant management of stage I TTTS, nearly three-fourths of pregnancies remain stable and most have survival of ≥ 1 twin. A-A anastomoses were not associated with progression to higher stage TTTS, whereas earlier GA at diagnosis or a small or intermittently visible donor bladder may herald greater risk of progression.