analysis of ultrasonographic misdiagnosis of cephalothoracopagus janiceps conjoined twins: a case report

Background and objective: conjoined twins (cts) are rare complications of monozygotic twinning. cephalothoracopagus is the rarest subtype of cts and occurs once in every 58 sets of conjoined twins or once in every three million births. here we present such a case and analyze the possible reasons for ultrasonographic misdiagnosis and recommend solutions to avoid it.case report: in this article, we have reported a case of cephalothoracopagus janiceps twining. the ultrasonographic diagnosis was missed at 7 and 12 weeks scans. increased thickness of nuchal translucency and absent nasal bone was observed alongside with suspected gastroschisis. the patient was referred for further evaluation at 13-14 weeks of pregnancy. unexpectedly, two alive fetuses were reported fused in the head, thorax, and abdomen. because of the poor prognosis, counseling was provided for parents and elective medical pregnancy termination was carried out. we have analyzed the possible reasons for ultrasonographic misdiagnosis.conclusion: without applying a standardized scanning of the entire uterus both in a longitudinal and transverse approach in early pregnancy, cephalothoracopagus twining may be misdiagnosed with a singleton pregnancy. a high level of concerns may raise for conjoined cephalothoracopagus twinning in case of finding a single fetal pole with an irregular body outline and a disproportionally large head in the presence of two separate fetal hearts in early pregnancy. two fused heads with two brains and two sets of lower and upper extremities do confirm the diagnosis.