What is the risk of neurological injury to the surviving twin in monochorionic twins if one twin demises?

In cases of monochorionic twin pregnancies, the twins share a placenta and may have interconnecting blood vessels, leading to unique risks, particularly when one twin dies. When one twin in a monochorionic pair dies, the surviving twin is at significant risk for neurological injury, primarily due to the phenomenon called "twin-to-twin transfusion syndrome" and the potential for vascular disruption.

The correct answer reflects that when one twin demises, the risk of neurological injury to the surviving twin can rise to approximately 18%. This elevated risk is due to several factors, including the likelihood of cerebral infarcts, hemorrhage, or other complications arising from the shared vascular supply and the dramatic changes in circulation that can occur with the death of one twin.

In clinical practice, this statistic underscores the importance of close monitoring of monochorionic twins during pregnancy, as well as careful consideration of the implications of a twin's demise on the health and development of the surviving twin.