The Full Form of DCDA is Dichorionic diamniotic.

A dichorionic diamniotic (DCDA) twin pregnancy is a type of twin pregnancy where each twin has its own chorionic and amniotic sacs. This type occurs most commonly with dizygotic twins, but may also occur with monozygotic twin pregnancies. This type of pregnancy may have characteristic findings on ultrasound.

Epidemiology

DCDA pregnancies account for the majority (~76%) of all twin pregnancies. They account for all dizygotic pregnancies and ~20% of monozygotic pregnancies.

Pathology

With a dizygotic pregnancy, two ova are independently fertilised by two sperm leading to two zygotes. 

With a monozygotic twin pregnancy, DCDA pregnancy results from the separation of the zygotes at ~1-4 days post fertilisation (morula) stage.