ABSTRACT
The birth of conjoined twins remains an unusual and noteworthy event to physicians and laymen alike. They are reported to occur in approximately one in every 50 000 deliveries, with females predominating over males by a ratio of 2:1.1
While most believe that conjoined twins result when incomplete fission of the zygote’s primitive streak occurs during the second week of gestation, there is also evidence that they may result from the union of two separate embryonic disks.2 The most prominent site of connection between the twins classifies them. These areas include skull (craniopagus), thorax (thoracopagus), upper abdomen (xiphopagus), lower abdomen (omphalopagus), pelvis (ischiopagus), or sacrum (pygopagus). They may also be described as symmetrical and asymmetrical forms, depending upon the degree of development of the respective twins.
