Fetal MRI in the pre-operative diagnosis and assessment of secondary abdominal pregnancy: a rare sequela of a previous caesarean section.

Secondary abdominal pregnancy is a rare type of ectopic pregnancy. Following fertilization, the blastocyst escapes from the uterine cavity and implants in the peritoneal cavity. The early antenatal diagnosis and identification of the site and extent of placental implantation in an abdominal pregnancy are important to prepare for the eventual surgery. We present the case of a 24-year-old patient presenting with loss of fetal movement at 26 weeks of gestation for whom an abdominal pregnancy was suspected on ultrasonography and later confirmed on magnetic resonance imaging (MRI). She had one caesarean section in the past. The MRI findings suggested a scar dehiscence. She was eventually managed surgically, and the unviable fetus was removed. Abdominal pregnancies must be treated as emergencies. They usually present with complications such as fetal death and intra-abdominal hemorrhaging and can be easily missed on routine antenatal ultrasonography. The exact anatomical relationships of the fetus, the placenta, and vital maternal intra-abdominal structures can be accurately delineated with MRI, which greatly aids the management of patients with abdominal pregnancy. A proposed imaging protocol and technical suggestions for improving the diagnostic capability of ultrasonography and MRI in abdominal pregnancies have been provided to aid in the appropriate evaluation of suspect cases.