MCDA twins
Also written as: MCDA — Monochorionic Diamniotic
Monochorionic diamniotic twins; identical twins sharing one placenta but having separate amniotic sacs.
Full Definition
Monochorionic diamniotic (MCDA) twins are identical twins who share a single placenta but have separate amniotic sacs. This type of twinning occurs in approximately 70% of monozygotic twin pregnancies and results from embryo splitting between days 4-8 after conception. MCDA twins are at higher risk for complications compared to dichorionic twins due to placental vascular anastomoses that can lead to twin-to-twin transfusion syndrome, selective intrauterine growth restriction, and twin anemia-polycythemia sequence. Management requires specialized monitoring with regular ultrasound assessments, Doppler studies, and potentially referral to a fetal medicine specialist. The shared placental circulation makes these pregnancies particularly challenging to manage.
Usage
Usage note: Always specify chorionicity and amnionicity when documenting twin pregnancies.
In Context
- "The MCDA twin pregnancy required intensive surveillance for twin-to-twin transfusion syndrome." — Antenatal care plan
- "Chorionicity determination confirmed MCDA twins at the 11-week scan." — Ultrasound report