monoamniotic
Pronunciation: mon-oh-am-nee-OT-ik
Twin pregnancy condition where both fetuses share a single amniotic sac, creating high risk for cord entanglement and complications.
Full Definition
Monoamniotic twins represent the rarest and highest-risk type of monozygotic twin pregnancy, occurring in approximately 1% of monozygotic gestations. These twins share both a single chorion and a single amniotic sac, resulting from embryonic splitting after day 8 post-conception. The shared amniotic space creates significant risks including cord entanglement (occurring in 50-70% of cases), twin-to-twin transfusion syndrome, and sudden fetal death. Management requires intensive fetal surveillance with frequent non-stress testing or continuous monitoring, hospitalization typically beginning at 24-26 weeks, and planned delivery by 32-34 weeks gestation. The perinatal mortality rate historically approached 50% but has improved with modern management protocols.
Usage
Usage note: Highest-risk twin type; distinguish clearly from other twin chorionicity classifications.
In Context
- "The monoamniotic twin pregnancy required hospitalization at 26 weeks for continuous fetal monitoring due to cord entanglement risk." — Maternal fetal medicine management plan
- "Ultrasound confirmed monoamniotic twinning with evidence of cord entanglement but maintained normal Doppler studies." — High-risk pregnancy surveillance report