Cesarean Scar Ectopic Pregnancy: A Do-Not-Miss Diagnosis

The rate of cesarean section (CS) for delivery has increased internationally, reaching 50% in some countries. Abnormal implantation of a new pregnancy at the site of the prior hysterotomy is an important complication because of the risks of hemorrhage, uterine rupture, and progression to placenta accreta spectrum (PAS), a condition with high morbidity with potential for catastrophic obstetric hemorrhage, maternal and fetal mortality, and loss of fertility. Cesarean scar ectopic pregnancy (CSEP) is the recommended term to describe these pregnancies, which are recognized on the basis of the sac implantation site, growth pattern, and associated abnormal perfusion. The true incidence of CSEP is unknown because the condition is likely underdiagnosed and underreported. The 2022 Society for Maternal-Fetal Medicine consult series notes that severe maternal morbidity and mortality are linked to difficulty in making the diagnosis of CSEP. The authors review the signs of CSEP at imaging, some pitfalls that may lead to delayed or missed diagnosis, and the consequences thereof. CSEPs must be differentiated from low implantation of a normal pregnancy, cervical ectopic pregnancy, and evolving pregnancy loss. Early recognition allows prompt and safe treatment that is usually surgical. Early treatment results in decreased health care costs, a shorter hospital stay, preservation of fertility, and prevention of iatrogenic preterm delivery, which is typical in cases that progress to PAS. Hysterectomy has serious negative psychologic consequences for patients of childbearing age; early diagnosis and prompt treatment of CSEP can prevent this often-ignored complication.