Monoamniotic twins: an update on antenatal diagnosis and treatment

Monoamniotic twins are very uncommon and are characterized by a high perinatal mortality rate. Cord entanglement, prematurity, congenital anomalies and twin to twin transfusion are reportedly the main causes of death, which usually occurs before 24 weeks' gestation. The aim of this study was to review the newly developed methods for diagnosis and treatment and suggest a reasonable approach to the management of these rare cases.

We reviewed the English-language literature in the past 15 years through Medline search and subsequent examination of individual publications.

In the past two decades, newer technologies such as advanced ultrasonography and color flow Doppler studies have enabled early diagnosis of this condition and its complications. Furthermore, new treatment modalities such as fetoscopy with laser coagulation of vascular anastomoses and treatment with non-steroidal anti-inflammatory drugs such as sulindac, to reduce amniotic fluid volume, may have contributed to a better outcome. Also, occlusion of one umbilical cord (fetal reduction) at an early stage has been suggested to prevent late complications.

Cumulative experience suggests that the majority of cases can be diagnosed reliably at an early gestational age. Treatment with medical amnioreduction, surgical amnioreduction or fetal reduction in selected cases may be offered before 24 weeks' gestation. Later, intensive antepartum fetal surveillance should probably be offered until 32 weeks, at which point elective preterm delivery may be considered to prevent possible fetal death.