Heteropagus twins: six cases with systematic review and embryological insights

Purpose Heteropagus twinning (HT) is a rare anomaly. Six new cases along with a systematic review are described. Methods Six cases of HT managed at two tertiary care teaching hospitals over the last 26 years are described. A PubMed search with words: Heteropagus AND/ OR parasitic twins from 2001 to 2021 hit 183 articles. 36 were added from non-PubMed sources. Finally, 120 cases including 114 from 69 articles and 6 new cases were analysed. Results Of the new cases, 2/6 had an antenatal diagnosis. Five were males. 4 autosites had omphaloceles. Split notochord and 2 parasites attached to a single autosite were encountered. 5/6 autosites survived. On systematic review, the most frequent variant seen was rachipagus ( n = 50) followed by omphalopagus ( n = 46). Limbs were reported in 75 cases. Congenital heart disease was seen in 17/120(14.2%) autosites. Omphalocele and meningomyelocele were the most common extracardiac anomalies in autosites. Weight along with the anatomy and position of heteropagus twins was a better determinant of the mode of delivery than weight alone. Mortality was reported in 12 cases. Conclusion Autosites in HT generally carry a good prognosis, however, final outcome depends mainly on associated major cardiac anomalies. Meticulous antenatal assessment and preoperative planning are of paramount importance. Level of evidence IV.