Title: Intramural pregnancy embedded in a previous Cesarean section scar treated conservatively
Abstract: Myometrial pregnancy developing in a previous Cesarean section scar is the rarest and most dangerous of all ectopic pregnancies. As with cervical ectopic pregnancy, in the past the diagnosis was made late in the first trimester and was often only established after hysterectomy for uncontrollable, even life-threatening, hemorrhage from the eroded blood vessels within the myometrial tissue1 We describe here a case of pregnancy developing in a previous Cesarean section scar that was treated conservatively with methotrexate (MTX). A 32-year-old woman, gravida 3 para 1 and with one previous miscarriage, was referred to our department from another hospital where she had been admitted for first-trimester vaginal bleeding and where sonographic diagnosis of cervical pregnancy had been made (Figure 1). Her past surgical and medical histories were unremarkable. She had undergone Cesarean section for acute fetal distress at the age of 23 years. Her last menstrual period was 9 weeks prior to admission. Transvaginal ultrasound image showing mixed anechoic (in the inner part) and echogenic round mass (large 1), situated between the uterine corpus (2) and the cervix (3). A diagnosis of cervical pregnancy was made. After admission the patient underwent ultrasound examination that confirmed the presence of a non-viable pregnancy and revealed an empty uterus, empty cervical canal and the sac implanted in the anterior part of the isthmic portion. Therefore, the diagnosis of pregnancy developing in a previous Cesarean section scar was made. The patient was clinically stable. The initial serum β-human chorionic gonadotropin (β-hCG) level was 6380 mIU/mL, the hemoglobin level was 13.7 g/dL and the white cell count and platelets were normal. Liver function tests and creatinine levels were also normal. On pelvic examination, a small amount of blood was noted in the vagina. The external os was closed and a 5-cm mass was detected anterior to the uterine isthmus. After discussion with the patient, according to our experience with cervical pregnancy, the decision was made to treat with a single intramuscular dose of 100 mg MTX. The patient tolerated the therapy well and there were no procedure-related complications. On the days following MTX injection a drop in β-hCG level was observed, and vaginal bleeding decreased but failed to stop. Ultrasound examination revealed very little change, and color Doppler examination showed 'angiomatous' vascularization with high flow and low resistance and areas with turbulence within them (Figure 2). On the basis of these findings we decided to perform dilatation and curettage (D&C). During the surgical procedure copious hemorrhaging occurred so a Foley catheter with a 30-mL balloon was inflated in the cervical canal. The hemorrhage stopped and the patient's postoperative course was uneventful. Ten days after D&C, after progressive balloon deflation (5 mL every 24–48 h), the Foley catheter was removed and no further bleeding occurred. Twenty days after D&C, ultrasound examination revealed a reduction in the volume of the mass but significant vascularity persisted. Because of suspicion of the presence of an arteriovenous malformation, we decided to perform a uterine artery angiographic embolization. Five days after embolization, the β-hCG level was 9100 mIU/mL but vascularization still persisted and it was only 2 months later that ultrasound examination revealed a marked reduction of the abnormal vascularization; its resolution occurred 4 months later. Nine months later the woman became pregnant and delivered at 38 weeks by Cesarean section. Transvaginal ultrasound image showing the vascularization of the mass. Although many hypotheses have been proposed to explain the pathogenesis of this rare ectopic pregnancy, a reasonable proposal is that the conceptus enters into the myometrium through a microscopic dehiscent tract or defect of the Cesarean section scar2, 3. Wedge defects of the Cesarean scar may be identified by transvaginal sonography before pregnancy3. Certain conditions have been associated with intramural pregnancy, including previous Cesarean section, adenomyosis, previous D&C and history of in-vitro fertilization treatment3-6. Some authors have described imaging criteria to assess the diagnosis of this condition: empty uterus, empty cervical canal, development of the sac in the anterior part of the isthmic portion and thinning or complete absence of healthy myometrium between the bladder and the sac2, 3, 7, 8. This last criterion together with the absence of dilatation of the cervix and the location of the gestational sac in the previous Cesarean scar area (anterior wall of the uterus) allows differentiation of a pregnancy implanted in a Cesarean section scar from a cervical pregnancy3, 7. Even if intramural pregnancy must be distinguished from cervical pregnancy because of the possibility of carrying the former to term7, therapy is similar in both conditions. The advent of high-resolution transvaginal sonography and readily available β-hCG assays allowed earlier diagnosis and either surgical or medical conservative treatment9. Surgical techniques consist of D&C in combination with various other methods: intracervical balloon tamponade, local hemostatic sutures or cervical cerclage, cervicotomy, bilateral uterine artery ligation or embolization and hysterectomy10-12. We think that D&C should not be the first choice of therapy because of the risk of uterine perforation, damage to the urinary bladder and uncontrolled bleeding. Local injection of MTX is usually indicated in viable pregnancies because of its high success rate, its minimal systemic side effects13, 14 and because it allows a more rapid interruption of the pregnancy3, 15, 16. We believe that in cases of non-viable intramural pregnancy embedded in a previous Cesarean section scar, treatment with systemic MTX is simple and highly effective16, 17, even if various side effects have been described14. Selective uterine artery angiographic embolization is indicated to prevent and to stop intraoperative bleeding11, and when heavy bleeding persists after medical treatment or when there is the suspicion of arteriovenous malformation associated with the ectopic pregnancy12. P. Marchiolé*, F. Gorlero*, G. De Caro , M. Podestà*, M. Valenzano*, * Department of Obstetrics and Gynecology, San Martino Hospital, Italy, Department Radiology, University of Genova, San Martino Hospital, Italy