Evaluating the Effectiveness of Treatment Strategies for Managing Cesarean Scar Ectopic Pregnancies

By Alexandra Morell, MD

Adjunct Instructor, Department of Obstetrics and Gynecology, University of Rochester Medical Center, Rochester, NY

SYNOPSIS: A review of 460 international cases of cesarean scar pregnancies demonstrated that surgical treatments were extremely effective options, with successful completion in 91.5% (95% confidence interval [CI], 87.8 to 95.2) of suction evacuations and 91.8% (95% CI, 83.8 to 99.9) of surgical excisions compared with a lower success rate for medical options, including local gestational sac injection or systemic methotrexate.

SOURCE: Agten AK, Jurkovic D, Timor-Tritsch I, et al. First-trimester cesarean scar pregnancy: A comparative analysis of treatment options from the international registry. Am J Obstet Gynecol 2024;230:669.e1-669.e19.

Ectopic pregnancies are estimated to account for 2% of pregnancies in the United States.¹ The majority of ectopic pregnancies implant in the fallopian tube. Only 1% to 3% of all ectopic pregnancies are cesarean scar pregnancies (CSPs). CSPs are defined as pregnancies that implant into the myometrial defect at the site of a previous cesarean hysterotomy.² This type of ectopic pregnancy is associated with significant hemorrhage secondary to the loss of myometrium and lack of normal vasculature at the implantation site, which results in the pregnancy deriving its blood supply from high-pressure arterial vessels. In addition, the normal contractility of the uterus is impaired at this site. Transvaginal ultrasound with color Doppler flow is the most useful modality for diagnosing a CSP. Identifying these pregnancies prior to nine weeks is associated with less maternal morbidity. Multiple treatment strategies exist for CSP and include surgical and medical options.

This study used the international registry of first-trimester CSPs to evaluate the effectiveness and safety of different treatment modalities. A total of 460 patients were included from 19 countries between August 2018 and February 2023. Inclusion criteria included any patient with a CSP before 12 weeks, 6 days of gestation with or without cardiac activity that received active treatment. Exclusion criteria included patients who were managed expectantly.

The Cesarean Scar Pregnancy Registry includes demographic information, medical history, pregnancy history, ultrasound findings with images, management plans, and outcome after treatment, including adverse events and complications. The authors considered a treatment successful if treatment led to complete resolution of the CSP without additional interventions. For statistical analysis, the Mann-Whitney U test was used for ordinal or metric data, and chi-squared or Fisher exact tests were used for categorical data.

Of the cases analyzed, 58.7% (270 patients) were treated surgically with suction evacuation, surgical resection, or primary hysterectomy. Of the surgical patients, 12 patients underwent primary hysterectomy and were analyzed separately, resulting in 258 patients in the surgical treatment group. Suction evacuation (n = 221) was the most used surgical method and was effective in 91.5% (95% confidence interval [CI], 87.8 to 95.2) of cases. It was equally effective regardless of cardiac activity (P = 0.75). Nineteen patients (8.5%; 95% CI, 5.9 to 11.2) experienced a complication, most commonly hemorrhage.

Surgical excision (including hysteroscopic resection, laparoscopic resection, and laparotomy) was performed in 37 patients and was effective in 91.8% (95% CI, 83.8 to 99.9) of cases. Surgical excision had a slightly higher complication rate at 13.5% (95% CI, 0 to 29.1). Regarding primary hysterectomy, six patients were asymptomatic prior to surgery and six patients presented with symptoms. Clinically significant hemorrhage was recorded in 41.6% of hysterectomy cases and in 33% of those with bladder injury.

An additional 26.7% (123 patients) were treated medically, either with local gestational sac injection of potassium chloride or methotrexate and/or systemic methotrexate. Intrasac injection (n = 59) was successful for 74.5% (95% CI, 64.1 to 85.1) of cases and was associated with a complication rate of 9.5% (95% CI, 1.6 to 15.4). Systemic methotrexate (n = 64) was successful for 59.4% (95% CI, 48.4 to 70.4) of cases and had the highest complication rate at 23.9% (95% CI, 8.5 to 25.9).

In addition, the balloon catheter technique was used in 10% (46 patients), with a success rate of 91.3% (95% CI, 83.5 to 99.1) and a complication rate of 8.7% (95% CI, 2.4 to 14.9). Less than 5% (21 patients) received an alternative method of treatment, including mifepristone, misoprostol, or uterine artery embolization.

COMMENTARY

The Society for Maternal-Fetal Medicine (SMFM), with endorsements from the American College of Obstetricians and Gynecologists (ACOG) and the American Society of Reproductive Medicine (ASRM), released a consult series regarding CSPs in September 2022. Although the series endorses that no one specific treatment option is optimal, there are a few key points regarding treatment.

Regarding surgical treatment, the series recommends surgical resection or uterine aspiration as first-line treatment in comparison to sharp curettage. This recommendation coincides nicely with the findings in this study, since both surgical excision and uterine aspiration had greater than 90% success rates with relatively low complication rates. The concern regarding sharp curettage alone is a high rate of hemorrhage and uterine perforation because of poor uterine contractility and damage to deeply invading blood vessels. Of note, the recommendations do mention that gravid hysterectomy is an option for treatment, particularly for patients who present at later gestations or who have completed childbearing.

The SMFM’s recommendations pertaining to medical management are to consider intragestational sac injection with or without other treatment modalities. They recommend against systemic methotrexate alone. These recommendations also correspond well with these findings, given the higher success rate for local gestational sac injection compared to systemic methotrexate and the much higher complication rate for systemic methotrexate compared to all other treatment modalities. The SMFM comments that a few reviews have published data on the balloon catheter technique demonstrating high success rates with low complication rates but notes that additional studies evaluating this technique for the treatment of CSP are warranted.

When patients are first diagnosed with a CSP, it is first important to counsel patients regarding the concern about continuing a pregnancy that has implanted in a prior cesarean scar hysterotomy site and discussing why expectant management is not advised. In this discussion, patients should be made aware that there are multiple treatment modalities. Although surgical treatments have very high success rates, some patients may want to avoid surgery and opt for medical treatment. Intragestational sac injection should be recommended for these patients as opposed to systemic methotrexate.

Although this study did not look at outcomes for patients who were expectantly managed, the SMFM recommends that patients who do not proceed with active treatment undergo repeat cesarean delivery between 34 weeks and 36 weeks, 6 days of gestation. These patients need to deliver at a tertiary care center that has expertise in managing placenta accreta spectrum disorder. The team should be prepared for potential cesarean hysterectomy and the need for the massive transfusion protocol at the time of delivery.

Ultimately, when deciding which treatment option is best, a shared decision-making approach, with emphasis on the success rates of each treatment and complications associated with each one, is most important.

REFERENCES

1. American College of Obstetricians and Gynecologists’ Committee on Practice Bulletins—Gynecology. ACOG Practice Bulletin No. 193: Tubal ectopic pregnancy. Obstet Gynecol 2018;131:e91-e103.
2. Nijjar S, Jauniaux E, Jurkovic D. Definition and diagnosis of cesarean scar ectopic pregnancies. Best Pract Res Clin Obstet Gynaecol 2023;89:102360.
3. Society for Maternal-Fetal Medicine (SMFM); Miller R, Gyamfi-Bannerman C; Publications Committee. Society for Maternal-Fetal Medicine Consult Series #63: Cesarean scar ectopic pregnancy. Am J Obstet Gynecol 2022;227:B9-B20.