Pygopagus
Pygopagus (Iliopagus): Two bodies joined at the pelvis, is one of the rare types of conjoined twins.
They are joined at the sacral area with sharing of terminus of spine, gastrointestinal system, genitourinary system and spinal cord to a variable extent. They represent a group of conjoints in which the separation of the embryonic axis in the caudal region was incomplete 1).
Pygopagus conjoined twins represent 6–19% of all the conjoined twins 2).
The reported incidence worldwide is estimated at 1:50,000 to 1:100,000, live births, with higher incidence of 1: 14,000 to 1: 25000, experienced in Asia and Africa 3).
Treatment
Twins with this configuration display symptoms and carry surgical risks during separation related to the extent of their connection which can include anorectal, genitourinary, vertebral, and neural structures. Neurophysiologic intraoperative monitoring (NIOM) for these cases has been discussed in the literature with variable utility.
The separation of conjoined twin is a unique challenge due to its complex anatomy and physiology. Although advancement in imaging and monitoring has improved the survival rates, separation can be successfully achieved only with meticulous planning and team work.
Case reports
Cromeens et al., present a case of pygopagus twins with fused spinal cords and imperforate anus where the use of NIOM significantly impacted surgical decision making in division of these critical structures 4).
Awasthi et al. present the case of one-and-half month-old male pygopagus conjoined twins, who were joined together dorsally in lower lumbar and sacral region and had spina bifida and shared a single thecal sac with combined weight of 6.14 kg. Spinal cord was separated at the level of the conus followed by duraplasty. They had uneventful recovery with normal 15 months follow-up 5).
Separation surgery of pygopagus asymmetrical conjoined twins sharing U-shaped spinal cord: case report and literature review 6).
A report describes the successful surgical separation of pygopagus twins who had a conjoined thecal sac and an epidermal cyst 7).
Multidetector computed tomography angiography for successful surgical separation 8).