Monochorionic diamniotic twins: complications and management optionsLewi, Liesbetha,b; Schoubroeck, Dominique Vana; Gratacós, Eduardc; Witters, Ingrida; Timmerman, Dirka; Deprest, Jana,bCurrent Opinion in Obstetrics and Gynecology: April 2003 - Volume 15 - Issue 2 - p 177-194 Prenatal diagnosis Abstract Author Information Purpose of review Monochorionic compared with dichorionic twins have disproportionately high fetal loss rates, perinatal mortality and morbidity. This is because of the unpredictable vascular anastomoses and the often asymmetrical distribution of the single placenta between both twins. Recent findings The pathophysiology of twin-to-twin transfusion syndrome is usually explained on an angioarchitectural basis, although certain hemodynamic and hormonal factors also may be involved. The results of the large randomized trials on amnioreduction, fetoscopic laser coagulation and septostomy are still awaited. An update is given on hardware and instruments required for fetoscopic laser. Subsequently, the problem of the monochorionic twin set with severe early discordant growth is addressed. Several etiological mechanisms have been proposed, but little is known of its natural history. Also, umbilical artery Doppler waveforms may not have the same predictive value as in singletons. Prophylactic laser coagulation of the vascular anastomoses to protect against the adverse effects of single intrauterine demise, has so far not been shown to confer any benefit in outcome. Finally, pathophysiology and management of discordant structural and chromosomal anomalies in monochorionic twins are discussed. Laser and monopolar coagulation, which can be introduced through a needle, may be used for selective feticide in early pregnancy or low hemodynamic conditions. Bipolar coagulation seems more effective at later gestational ages and normal hemodynamic conditions. Summary Our insight into the complications associated with monochorionic twins has increased in recent years. It is hoped that this will lead to better surveillance and ultimately an improved outcome for these high-risk pregnancies. aDepartment of Obstetrics and Gynecology, University Hospital ‘Gasthuisberg’, bCentre for Surgical Technologies, Faculty of Medicine, Katholieke Universiteit Leuven, Leuven, Belgium and cDepartment of Obstetrics and Gynecology, Vall d'Hebron Hospital, Barcelona, Spain Correspondence to Dr Jan Deprest, Department of Obstetrics and Gynecology, UZ Leuven, B-3000 Leuven, Belgium Tel: +32 16 34 42 15; fax: +32 16 34 42 05; e-mail: email@example.com © 2003 Lippincott Williams & Wilkins, Inc.