A prospective cohort study is conducted among women with cesarean scar pregnancy (CSP). Women with increasing B-human chorionic gonadotropin (B-hCG) concentrations are included.~Two study arms were planned:~women treated with a single dose of 100 mg MTX intravenously and 50 mg MTX in intra-amniotic injection (day 0), along with 30 mg potassium chloride in case of positive fetal heartbeat (FH)~women treated with a single dose of 100 mg MTX intravenously and 50 mg MTX in intra-amniotic injection (day 0), along with 30 mg potassium chloride in case of positive fetal heartbeat (FH) with additional use of letrozole 5 mg orally (from day 0) for 10 days.~Blood parameters (B-hCG, hemoglobin, total blood count, creatinine, urea, alanine/aspartate transaminase, gamma-glutamyltransferase, bilirubin) were tested on days 0,4,7, followed by B-hCG concentration measurement every 7 days until surgery. After obtaining satisfactory decrease in B-hCG and POC vascularization, women underwent hysteroscopic evacuation of POC. Blood loss parameters, frequency of conversion from hysteroscopy to laparoscopy and laparotomy were measured.~The women were given the option to choose the treatment used in the study. All enrolled women gave informed written consent to participate in the study.
It is hypothesized that the inhibition of estradiol production by letrozole may interfere with physiological effects of progesterone necessary to maintain the pregnancy. There is no reference treatment of cesarean scar pregnancy (CSP) as the limited number of cases precludes the extrapolation of results. In our center we successfully use two-step treatment with methotrexate (MTX) followed by hysteroscopic removal of products of conception (POC). The time in between is needed to achieve a decrease in the trophoblast's vital potential (B-hCG fall) and its vascularization. Additional administration of letrozole could further reduce the vital potential of the pregnancy, eliminating the need for another dose of MTX, resulting in faster healing and lower rate of complications.