Thoraco-omphalopagus conjoined twins
The thorax and the abdomen are fused anteriorly. With separate heads and spine. Two bladders are visualized. The two twins were sharing a common heart and liver. Heart was abnormal on echocardiography.
Conjoined twins are the severest form of monoamniotic-monochorionic twin pregnancy which occur due to embryonic division after 13 days post conception. In this type there is some form of twin fusion.
Thoraco-omphalopagus is the commonest type.
Craniopagus, ischiopagus, pyopagus are the rarer types.
Usually this is a straightforward diagnosis at the routine antenatal sonography. But in difficult cases like severe oligohydramnios the confident diagnosis of conjoined twins may be in doubt.
Obstetric MRI may be useful in such cases in showing anatomic fusion. (Not in this case. Liquor amount is good. MRI was done only for academic interest prior to termination of pregnancy)
MRI may have a greater role in future where termination of pregnancy in conjoined twins is not considered and surgical separation is contemplated.
The outcome in cases like these is uniformly poor. Worldwide many attempts have been made at conjoined twins surgeries. Not many have been successful. In future we may see some breakthrough. Antenatal MRI may be useful to some extent in defining anatomy.
Dr Paresh Desai, Goa