Incidental detection of retained oil‐based hysterosalpingography contrast medium on postoperative postpartum radiography: A case report

Hysterosalpingography is widely performed in assisted reproductive technology. We present a rare case of contrast medium retention which was incidentally found and mimicked a retained surgical instrument. A medical history of treatment for infertility can facilitate the differential diagnosis of abnormal findings on post‐caesarean section radiography. A contrast medium used in HSG can remain in the pelvis for a long time, and a medical history of assisted reproductive technology and/or HSG can aid the differential diagnosis of abnormal findings on postoperative radiography.