What defines monochorionic monoamniotic twins?

Monochorionic monoamniotic twins are defined by the presence of a single chorion and a single amnion. This situation arises when one fertilized egg splits into two embryos, leading to both twins sharing the same placental structure (the chorion) and the same amniotic sac (the amnion). This configuration is important, as it has implications for the management of the pregnancy.

Monochorionic monoamniotic twins face unique risks, including cord entanglement and other complications due to their shared environment. Identifying them correctly is crucial for prenatal monitoring and delivery planning to ensure the health and safety of both twins.

The other configurations like multiple chorions or amnions imply different types of twin pregnancies, such as dichorionic or monoamniotic twins, which carry different risks and characteristics. Therefore, recognizing that both embryos share one chorion and one amnion is essential in the context of twin gestations.