Monoamniotic twins

Monoamniotic Twins

Ultrasound image showing Monoamniotic Twins.

Monoamniotic Twins, commonly referred to as MoMo or Mono Mono twins, are a rare and unique type of monozygotic (identical) twins who share the same amniotic sac within their mother's uterus. Being always monochorionic, they share a single placenta but have two distinct umbilical cords. This condition arises when the embryo splits later than usual, specifically around 9 to 13 days post-fertilization.

Development

Monoamniotic twins develop from a single fertilized egg that divides later than the typical timeframe for monozygotic twins. This delayed division results in the twins sharing both the chorionic and amniotic membranes. While monoamniotic twins are a common type of monozygotic twins, the occurrence of monoamniotic multiples beyond twins, such as triplets, is exceedingly rare but possible.

Characteristics

• Shared amniotic sac and placenta
• Two separate umbilical cords
• Identical genetic makeup

Risks and Complications

Monoamniotic twins face higher risks during pregnancy compared to other twin types due to:

• Cord entanglement and compression
• Twin-to-twin transfusion syndrome (TTTS)
• Increased risk of preterm birth
• Higher mortality rate

Management During Pregnancy

Due to the high-risk nature of monoamniotic pregnancies, careful monitoring is essential. Management strategies include:

• Frequent ultrasound examinations to monitor cord entanglement and twin growth
• Hospitalization during the third trimester for close monitoring
• Considering delivery timing to minimize risks, often via cesarean section

Delivery

The delivery of monoamniotic twins is carefully planned to ensure the safety of both the mother and the babies. Cesarean delivery is commonly recommended to reduce the risks associated with cord entanglement and other complications.

See Also

• Monozygotic twins
• Twin-to-twin transfusion syndrome
• Cesarean section
• Premature birth

External Links

• March of Dimes - Twin-to-Twin Transfusion Syndrome
• American Pregnancy Association - Monoamniotic Twins