Abstract
Background: Cesarean scar ectopic pregnancy is a novel and rare disease that is increasing across the globe at a threatening rate. Thus, this study aimed to assess the effect of a single dose of methotrexate (MTX) to treat the scar ectopic pregnancy (SEP) and to compare its effects with the treatment by multiple doses of MTX.
Methods: A retrospective cohort study was conducted in Security Forces Hospital in Riyadh, Saudi Arabia from 2016 to 2020. The study included 13 pregnant women with history of cesarean section, diagnosed by official pelvic ultrasound or pelvic magnetic resonance imaging with SEP. Participants were sampled using a convenient non-probability sampling technique and data were collected via phone interviews.
Results: In the selected cohort, around 10 (76.9%) women reported a complete and uncomplicated resolution within a few months with a single dose of MTX, whereas, three women (23.1%) were successfully treated with multiple doses of MTX. However, seven (53.8%) had symptoms after taking MTX (which included vaginal bleeding, pain, fever, headache, diarrhea, low mood, and stomatitis), where the other six (46.2%) had no symptoms. For all participants, the level of beta human chorionic gonadotropin became normal after an average of 61 days from administration of MTX and six (46.2%) of them conceived with normal pregnancy.
Conclusion: MTX therapy seems to be an effective and safe approach for SEP treatment, especially in women who want to conceive successfully.

Key words: Cesarean scar pregnancy, ectopic pregnancy, methotrexate, scar ectopic