Parasitic pygopagus conjoined twins' incidental findings in the obstructed labor of an intrapartum dead baby that had undergone emergency C-section: rare case report in South Papua.

Background: Conjoined twins (CT), which used to be historically defined as "monstrous human" and previously so-called Siamese twins in the early eighteenth century, are one of the very rare congenital malformations with an uncertain etiology and complex yet remain inconclusively debatable regarding its pathophysiological mechanisms of fusion and fission theories. Among all types of CT, parasitic CT, especially the pygopagus sub-type, is exceedingly rarer. To the best of the authors' knowledge, no parasitic CT had been reported in Papua, and this is the first finding in South Papua.

Case Report: Herein, a 30-year-old multigravida female with 37th-week gestation, previous twice spontaneous miscarriage, and non-adequate antenatal care history is presented with a chief complaint of painful construction and greenish fluid leakage from the vagina, with an examination that showed a cephalic presentation with a "peculiar" big mass at the upper uterus and complete cervical dilation toward second-stage inpartu. Vaginal delivery was performed with a complication of obstructed labor due to uncommon dystocia with a suspected "big mass" below the fetal buttocks and intrapartum dead. Intrapartum transabdominal ultrasound demonstrates a gross anatomically like an organ inside a fluid-filled mass with unidentified parts, leading to a suspected type of congenital malformation at the baby's sacral region. Emergency C-section was done with findings of parasitic pygopagus CT, showing an attachment of a large irregular fluid-filled mass-like incomplete twin (parasite) with palpable soft tissue and bony structure inside to the buttocks of a male autosite twin, and an additional third leg which happened to be an under-developed lower extremity with a sacrum-like structure.

Conclusions: An obstetrician's routine ANC and critical radiological evaluation will increase the odds of identifying CT or other congenital malformations to provide better delivery planning or further management. Increasing maternal health knowledge in society, improving medical skills and knowledge levels for health providers, and advancing supporting facilities and specialists are future strategies for managing and preventing such cases in low-middle-income countries.