Intramural pregnancy in a previous cesarean section scar: a case report on conservative surgery

Ectopic pregnancy located in a lower segment uterine scar following previous lower segment cesarean section is rare and involves the risk of uterine rupture and uncontrollable hemorrhage 1-3). Management of this type of ectopic pregnancy is unknown because cesarean scar pregnancy can have various presentations. Successful births have been reported with expectant management (4, 5), but there are reports of spontaneous uterine rupture during pregnancy, even in the first trimester (3). We report a cesarean section scar pregnancy confirmed by transvaginal ultrasonogram and magnetic resonance imaging (MRI), and treated conservatively with surgery. A 36-year-old woman, who had a history of two low transverse cesarean sections and presented at 6 weeks' gestation with cramping and spotting, was referred to us from a clinic because of suspected cesarean scar pregnancy. Her urine human chorionic gonadotropin (hCG) level was 32 000 mIU/mL. Transvaginal ultrasound imaging demonstrated a gestational sac implanted in the anterior ithmic wall of the uterus (Fig. 1a). This sac contained an embryo with cardiac activity and crown–rump length corresponding to 6 weeks of gestation. Serial sonographic examinations with color-flow Doppler imaging were performed to determine whether the pregnancy was implanted in the uterus or was ectopic. No gestational sac in the endometrium nor in the cervical canal was observed. No normal myometrium was visualized between the bladder and the gestational sac. In addition, serial imaging did not suggest the sac was growing toward the fundus. MRI at 7 weeks' gestation also demonstrated that no normal myometrium existed between the pregnancy and the bladder (Fig. 1b). After extensive counseling, the couple chose laparotomy with the intention of definitively localizing and terminating this pregnancy. (a) Ultrasonographic imaging at 6 weeks of the gestational sac (GS) implanted at a previous cesarean section scar between the cervix and the uterine cavity. (b) Sagittal T2 magnetic resonance image at 7 weeks of the gestational sac implanted in the previous cesarean section scar. At 7 weeks' gestation, a laparotomy was performed. An almost normal-sized uterine corpus with normal bilateral adnexae and no blood in the abdominal cavity were found. Intraoperative ultrasound (7.5 MHz probe) was used to locate a thin part of the myometrium. Hysterotomy was performed by clamping the bilateral uterine artery with vascular forceps to reduce intraoperative blood loss (Fig. 2). After gentle, sharp excision of the gestational mass, the uterine defect was closed in two layers with 3–0 Vicryl. The estimated blood loss was 180 mL. The pathological report described intermediate trophoblasts, which were stained by immunohistochemistry using anti-human placental lactogen antibody, present inside the myometrium. The woman had an uneventful recovery without blood transfusion. On the ninth postoperative day, her urine hCG level was below the detectable level and she was discharged Bilateral uterine artery clamped with vascular forceps (A, B) before resection of the gestational sac (GS). Although use of transvaginal ultrasonography in the diagnosis of ectopic pregnancy is well established, differential diagnosis between spontaneous abortion in progress, cervical pregnancy and ectopic pregnancy developing in a previous cesarean section scar remains difficult. Strict imaging criteria must be used to assess the diagnosis: empty uterus, empty cervical canal, development of the sac in the anterior part of the isthmic portion, and absence of healthy myometrium between the bladder and the sac (1). In our case MRI was useful to establish early diagnosis of cesarean section scar pregnancy, allowing effective surgical treatment with uterine preservation. Because of the rarity of pregnancy in a cesarean section scar, optimal treatment is unknown. Some cases of successful births have been reported. In these cases, the gestational sac developed toward the uterine cavity. However, Herman et al. (5) and Jelsema and Zuidema (4) reported that blood transfusion and hysterectomy were required after fetal survival birth because of uncontrollable hemorrhage. Moreover, Marcus et al. (3) reported that uterine rupture occurred in early gestation after cesarean section and hysterectomy was also required. Early diagnosis and therapy (medical and/or surgical) is necessary for uterine preservation. Dilatation and curettage is linked to a high risk of severe vaginal hemorrhage and a following hysterectomy (6). The use of methotrexate (MTX), locally as well as systemically, is already known from conservative therapy of tubal ectopic pregnancies. Nawroth et al. (7) reported successful therapy for ectopic pregnancy in a cesarean section scar at 9 weeks' gestation with local and systemic administration of MTX. In this case, the serum hCG level dropped below the detection level at 43 days after MTX. In the case of a cesarean section scar pregnancy at 7–8 weeks' gestation, like that of our patient, hysterotomy by clamping the bilateral uterine artery is a fast, safe and useful treatment, especially for histological confirmation. A laparoscopic operation, if possible, is useful not for only diagnosis but also for treatment (8). In view of the increasing rate of cesarean deliveries, medical personnel should be aware of the possibility of this type of ectopic pregnancy.