Successful selective reduction of a heterotopic cesarean scar pregnancy in the second trimester: a case report and review of the literature

Cesarean scar pregnancy (CSP) is one of the rarest forms of ectopic pregnancy, located in the scar of a previous cesarean section. The incidence of CSP has been estimated to be between 1:2216 and 1:1688 [1‐4]. CSP results in life-threatening complications such as uterine rupture and catastrophic hemorrhage, which may, in turn, be associated with maternal and fetal morbidity and mortality [5]. Therefore, immediate intervention (sometimes including hysterectomy), must be performed [6].

Heterotopic pregnancy (HP) is defined as the simultaneous presence of intrauterine pregnancy and ectopic pregnancy, which is very rare but a potentially life-threatening condition. HP can be spontaneous or the subsequence of assisted reproductive technology (ART), with the frequency of spontaneous heterotopic pregnancy reported as between 1 in 50,000 to 1 in 10,000 [7, 8] and the incidence in ART is 0.2–1% [9].

Heterotopic cesarean scar pregnancy (HCSP) is cesarean scar pregnancy combined with an intrauterine pregnancy that predisposes a woman to life-threatening complications such as uterine rupture and massive bleeding. The incidence of HCSP during spontaneous cycles is extremely low. However, with the increasing incidence of cesarean section and extensive use of assisted reproductive technologies, the prevalence of heterotopic cesarean scar pregnancy (CSP) is expected to rise. Preservation of an intrauterine pregnancy in HCSP is a great challenge, and only isolated case reports of such pregnancies have been published in the literature, with the first case of HCSP published by Salomon et al. in 2003 [10]. Despite the lack of a standard treatment protocol, expectant management and medical and surgical treatment modalities have recently been suggested. In fact, urgent hysterectomy may be required in patients with uncontrolled hemorrhage and uterine rupture.

We used a list of keywords, including “Ectopic pregnancy,” “Cesarean section scar,” and “Heterotopic cesarean scar pregnancy,” to perform an extensive search of the literature; and we found fewer than 25 cases of HCSP having been reported. In the present article, we report 1 case of twin HCSP in a patient after IVF-embryo transfer (ET). We performed transabdominal intrathoracic injection of KCl into a CSP fetus at 16 + 4 weeks of gestation and the intrauterine pregnancy was successfully preserved. In addition, we performed a Medline search and reviewed the English-language literature for similar cases; and these are summarized herein. Written informed consent was obtained from the couple before the procedure and manuscript publication. The treatment procedure followed ethical principles, all data were collected from chart reviews, and approval was obtained from the Institutional Review Board.

A 33-year-old Tibetan woman, gravida 2, para 1, was admitted because of the abnormal location of one of the two gestational sacs of a twin pregnancy; she had previously undergone transverse lower segment cesarean section 7 years earlier. The patient underwent IVF-ET and 3 embryos were transferred to the uterus; a positive pregnancy test was noted 14 days after embryo transfer. Four weeks after embryo transfer, transabdominal ultrasonography revealed 1 intrauterine gestational sac. However, the patient did not adhere to the physician’s suggestion of a follow-up 1 week later.

Sixty days after embryo transfer, transvaginal ultrasonography revealed a dichorionic twin pregnancy with normal cardiac activity and 1 gestational sac situated in the uterine fundus; the other was located lower, immediately over the cesarean section scar, with a thin myometrium of 4 mm in thickness (Fig. 1). The patient manifested no abdominal pain and/or vaginal bleeding. A diagnosis of heterotopic cesarean scar pregnancy was then made, but the couple refused medical intervention.

A follow-up was pursued 7 days later, with both fetuses showing normal fetal cardiac activity and crown–rump length measurements (55 and 48 mm, respectively) that were in accordance with a fetus at 12 + 1 weeks of gestation; 1 fetus was in the upper fundus, whereas the second was still located at the level of the internal os. The ectopic placenta covered the internal cervical os and the cesarean section scar, which was in close proximity to the maternal bladder and which showed the presence of peritrophoblastic vascularity upon Doppler examination.

When the patient was transferred to our department, because of the potential of uterine rupture and catastrophic hemorrhage, we extensively counselled the couple regarding the condition, its risks, and the management options for heterotopic pregnancy. We suggested to the couple the use of selective reduction of the heterotopic cesarean scar pregnancy as soon as possible. The couple, however, refused and preferred expectant management; close monitoring was then performed without patient bleeding and lower abdominal pain. At 16 + 3 weeks of gestation, transabdominal ultrasonography revealed a thin myometrial layer of the cesarean section scar (3.8 mm thick) and complete placenta previa (Fig. 2). Massive bleeding and/or uterine rupture during an ongoing pregnancy with expectant management was discussed again with the couple, and the patient opted for selective termination of the abnormally located fetus; this was then accomplished at 16 + 4 weeks of gestation by ultrasound-guided intrathoracic injection of 1 mL of 10% KCl using a 20-G needle inserted transabdominally under local anaesthesia with lidocaine. Upon follow-up, ultrasonography was repeated every two weeks. Although fetal biometric parameters of the ongoing pregnancy were normal, the ectopic placenta still showed total placenta previa and placenta accrete. At 37 weeks’ gestation, a written informed consent was obtained from the couple undergoing MRI to evaluate the placenta. MR image showed heterotopic complete placenta previa and placenta accreta, marked focal thinning of myometrium at the region of cesarean scar. The internal cervical os was covered completely by placenta and dead fetus (Fig. 3).

At 37 + 6 weeks of gestation the baby was delivered by elective cesarean section. Before the operation, we extensively counseled the couple about the possibility of CS hysterectomy due to total placenta previa and placenta accreta. We noted intraoperatively that profuse vascularization covered the lower uterine segment, that the bladder adhered to the anterior lower segment, and that the mass of HCSP was palpated at the lower uterine segment and bulged toward the vesicoperitoneal reflection. A healthy male baby weighing 2890 gm was delivered through a transverse incision 1 cm above this mass, with Apgar scores of 10 and 10 at 1 and 5 min, respectively. When the dead fetus and placental mass of the HCSP were removed, profuse bleeding due to placenta accreta ensued, and bleeding was controlled by partial excision of the anterior lower uterine segment along with myometrial sutures and uterine packing with gauze. Three-and-one-half units of packed red blood cells were then transfused. The postoperative period was uneventful and the patient and the baby were discharged 6 days after the operation. The pathologic results of the excised anterior lower uterine segment revealed placenta accreta, showing chorionic villi in direct contact with myometrial smooth muscle fibers.

Cesarean scar pregnancy may have a silent clinical course or present with specific clinical symptoms such as abnormal vaginal bleeding and/or abdominal pain or acute abdominal pain due to uterine rupture. Heterotopic cesarean scar pregnancy (HCSP) is unusual as it is a CSP in combination with an intrauterine pregnancy. Due to its rarity, there is no standard treatment protocol for HCSP.

Early diagnosis of CSP in the first trimester may allow the preservation of viability for the intrauterine fetus and avoid maternal morbidity in HCSP. High-resolution vaginal ultrasonography is the preferred diagnostic method for HCSP, and the mean gestational age at CSP diagnosis is reported to be 7.5±2.5 weeks [11]. Ouyang et al. [4] showed that the gestational age ranged from 5 weeks and 3 days to 7 weeks and 4 days in CSP and from 5 weeks and 6 days to 7 weeks and 4 days in HCSP using transvaginal color Doppler sonography.

Treatment options for cesarean scar pregnancy include open surgery, operative hysteroscopy and curettage, systemic or local methotrexate (MTX), transvaginal embryo aspiration, and potassium chloride injection [10‐12]. The great challenge in the management of HCSP is to preserve the concurrent intrauterine pregnancy, which makes the therapeutic management more difficult and may not be the same as management of CSP.

Only a few cases of HCSP have been reported, and there is currently no standard treatment protocol for HCSP. Therefore, in the present study, we conducted a search and review of the literature pertaining to HCSP. To the best of our knowledge, a total of 23 cases of HCSP have been reported in the English literature [2, 4, 10, 12‐26], and the results are summarized in Additional file 1: Table S1. The reported treatments included conservative management, fetal reduction by potassium chloride, laparoscopic excision, aspiration of embryonic or ectopic gestational sac, hysteroscopy with directed evacuation, injection of a mixture of MTX and KCl, or laparotomic excision.

Heterotopic cesarean scar pregnancy is an extremely rare form of heterotopic pregnancy. The desire to preserve the intrauterine pregnancy in cases of HCSP is a great challenge, and no universal management guidelines have been established. The current lack of data with respect to best practices should encourage publication of more individual case reports and the establishment of further multicenter studies in the future. Importantly, patients must be appropriately counseled regarding the different treatment options available.

Based on previously reported cases and our case, injection of potassium chloride may be a safe, minimally invasive and reliable way to terminate the heterotopic gestational sac and preserve the intrauterine pregnancy. As retained gestational tissue may contribute to uterine rupture and massive uterine bleeding during an ongoing pregnancy and cesarean section, intensive management should be performed.