A 32-year-old woman, gravida 3, para 3 (Cesarean section 3), was admitted to our hospital due to slight vaginal bleeding at 12 weeks' gestation. Transvaginal ultrasonography revealed a gestational sac and a non-viable embryo at the anterior wall of the uterine isthmus. The myometrium between the gestational sac and urinary bladder was thin. Ectopic pregnancy in a previous Cesarean section scar was diagnosed, with fetal death estimated to have occurred in gestational week 9. The decision was made to preserve the uterus and therefore conservative treatment with local injection of methotrexate (MTX) into the gestational sac was undertaken. On day 21 after MTX administration, tests for urinary human chorionic gonadotropin (hCG) yielded negative results. By day 50, basal body temperature (BBT) recovered its biphasic pattern. Ultrasonography 3 months after MTX administration showed a largely normal non-gravid uterus and cervix.
The patient visited our hospital 6 months after MTX administration complaining of amenorrhea. Transvaginal ultrasonography indicated a gestational sac and viable embryo in the anterior part of the uterine isthmus, the same location as the previous ectopic pregnancy. Repeat ectopic pregnancy in the previous Cesarean section scar was diagnosed at gestational week 9. Conservative treatment with MTX using the same method was again selected. On day 23, tests for urinary hCG yielded negative results. BBT recovered its biphasic pattern by 4 weeks after MTX administration, and ultrasonography revealed a largely normal non-gravid uterus and cervix.
As Cesarean scar pregnancy is rare and optimal therapeutic protocols have not been established, various interventions have been reported. Some authors have reported successful treatment of Cesarean scar pregnancy using MTX1, 2. In the present case, local treatment with MTX proved successful on two occasions. However, in this patient there were repeat ectopic pregnancies at the site of the old scar after local therapy with MTX. Although nine cases of successful pregnancy after conservative treatment of Cesarean scar pregnancy have been reported1, this was the first in which repeat Cesarean scar pregnancy occurred after conservative therapy. This case reveals the limitations of local MTX therapy in Cesarean scar pregnancy. Fylstra et al.3 have recommended surgical resection, which offers the opportunity for simultaneous termination of the pregnancy and repair of the defect. Vial et al.4 have also suggested that surgical resection of the old scar and new closure should be offered even if recurrence is unlikely. Successful surgical resection of the old scar and new closure without severe side effects have been reported4, 5.
In summary, Cesarean scar pregnancy can be effectively treated using local injection of MTX, particularly in patients who desire conservative treatment. However, in cases involving patients with Cesarean scar pregnancy who wish to become pregnant in the future, surgical repair of the scar as either the initial treatment or a secondary procedure after local conservative treatment using MTX might be a preferable option.