monochorionic diamniotic
Also written as: MCDA — monochorionic diamniotic
A type of twin pregnancy where twins share one placenta but have separate amniotic sacs.
Full Definition
Monochorionic diamniotic (MCDA) twins result from the division of a single embryo between days 4-8 after conception. These twins share a single chorion and placenta but develop in separate amniotic sacs divided by a thin membrane. This configuration occurs in approximately 75% of monozygotic twin pregnancies. MCDA twins carry higher risks than dichorionic twins due to potential vascular communications within the shared placenta, which can lead to complications such as twin-to-twin transfusion syndrome, selective intrauterine growth restriction, or twin anemia-polycythemia sequence. Close surveillance with serial ultrasounds is essential.
Usage
Usage note: Abbreviate as MCDA after first use. Ensure correct spelling of 'monochorionic' (not 'monochronic').
In Context
- "The ultrasound confirmed monochorionic diamniotic twinning with a thin dividing membrane and single placental mass." — Ultrasound report
- "Patients with monochorionic diamniotic twins require surveillance every 2 weeks starting at 16 weeks for early detection of TTTS." — Clinical protocol