Cesarean scar ectopic pregnancy: Management updates and challenges in a post-Roe era

Background

The prevalence of cesarean scar ectopic pregnancies (CSEPs) is estimated to be between 1:1800 to 1:2226 of all pregnancies. Although rare, the incidence has been steadily rising due to the increasing rates of cesarean deliveries, both in the US and globally.^1-3 The increasing number of CSEP diagnoses is secondary to developments in technology, more widespread availability of first-trimester ultrasound imaging, awareness of diagnosis, and, most notably, the higher number of cesarean deliveries being performed worldwide, with an estimated total of 18.5 million a year.¹ This is thought to parallel the increase in placenta accreta spectrum (PAS) diagnoses that have increased 3- to 5-fold from 1966 to 2018.⁴

A CSEP is a life-threatening abnormal pregnancy. Early evaluation and treatment are essential due to the risk for hemorrhage, uterine rupture, need for hysterectomy, morbid surgical complications, and fetal or maternal death.¹ These complications stem from the pathogenesis of a cesarean scar ectopic pregnancy, which is on a continuum with morbidly adherent placenta, also known as PAS. A CSEP occurs when the blastocyst implants at the site of dehiscence from a previous cesarean scar or hysterotomy site. The need for a high-nutrient environment causes the blastocyst to invade deeper into the surrounding tissues in search of a more nutrient-rich environment.^1,5,6 This can lead to PAS, further dehiscence, and hemorrhage as the pregnancy enlarges.⁶

A 2014 case series evaluated 10 cases with diagnosed CSEP under 10 weeks, all of which underwent hysterectomy; histology confirmed PAS on all specimens.⁶ To emphasize the congruent pathophysiology, a study in which blinded pathologists evaluated 58 histopathology slides with either CSEP or PAS and found they were indistinguishable from one another.⁷

CSEP has been differentiated into 2 types: endogenic and exogenic. Endogenic is otherwise described as type I CSEP or “on the scar,” in which there is a myometrial layer between the placenta and anterior uterine surface with the pregnancy growing toward the uterine cavity, as depicted in Figure 1.⁸ Exogenic, also known as type II or “in the niche of the scar” is thought to grow outward toward the uterine serosa (Figure 1).^1,8

Presentation and diagnosis

Retrospective reviews have found that up to 90% of patients with CSEP present with symptoms, including bleeding, pain, or cramping. In another study, 10% to 25% of patients with CSEP were asymptomatic at the time of diagnosis, underscoring that early diagnosis with ultrasound is essential.^5,9

The ideal timing for ultrasound assessment is between 5 and 10 weeks of estimated gestational age (GA) based on the last menstrual period. The physician should have an increased suspicion for CSEP when there are findings of an anterior, low-lying gestational sac in a patient with a prior hysterotomy. In addition to CSEP, differential diagnosis for this finding includes early pregnancy loss in progress, low implantation of a normal intrauterine pregnancy, and cervical ectopic pregnancy. One retrospective study found that out of 751 diagnosed cases of CSEP, 13.6% were originally misdiagnosed as one of the above.⁶

Ultrasound criteria for the diagnosis of CSEP have been proposed by the Society of Maternal-Fetal Medicine (adapted from Timor-Tritsch, et al.); it is important to note that not all these criteria are met, especially with a very early CSEP.¹

Ultrasound criteria for the diagnosis of CSEP are as follows:

1. Empty uterine cavity and endocervix
2. Placenta, gestational sac, or both embedded in scar
3. Triangular (at <8 weeks GA) or rounded (>8 weeks GA) gestational sac that fills the scar niche
4. Thin (1-3 mm) or absent myometrial layer between the gestational sac and bladder
5. Prominent or rich vascular pattern at or in the region of the scar
6. Embryonic or fetal pole and/or yolk sac within the gestational sac, independent of cardiac activity

Radiology techniques to further determine the diagnosis can be helpful and potentially beneficial in predicting the risks of PAS. The crossover sign (COS) was developed by Cali et al; this technique divides the uterus into quadrants by drawing a straight line from the top of endometrial stripe/fundus to the internal os, as seen in Figure 3.¹⁰ Using the COS (Figure 2), the pregnancy can be classified as completely anterior in the myometrium (COS-1), crossing the line embedded at the scar (COS-2+) or completely on the scar, not in the niche (COS-2-). Using this system, COS-1 had a significantly higher risk of placenta percreta when managed expectantly (OR 6.67; 95% CI; 1.3-33.3).¹⁰

The use of transvaginal ultrasound with abdominal ultrasound is the first-line imaging modality for diagnosing CSEP. Other modalities that have been described are 3-D ultrasound and pelvic MRI. MRI should be reserved for cases in which the diagnosis is unclear due to poor ultrasound imaging. This may occur in patients with fibroids, uterine anomalies, or large body habitus. MRI may be beneficial in differentiating between low implantation of an intrauterine pregnancy vs CSEP; however, ultrasound remains the imaging method of choice.¹

Management

Expectant management of CSEP is not recommended due to high rates of severe maternal morbidity due to hemorrhage, uterine rupture, and PAS (grade 1B evidence according to the Society of Maternal-Fetal Medicine). Expectant management is also advised against by the American College of Obstetricians & Gynecologists and the Society of Family Planning, and pregnancy termination is recommended after a CSEP diagnosis.¹ One consideration for expectant management in the setting of CSEP is for cases with diagnosed early pregnancy loss. These patients may be followed with serial imaging and serum β-human chorionic gonadotropin (β-HCG) measurements, but it can take weeks or months to achieve a resolution.1 Complications of expectant management in these settings include hemorrhage and the formation of arteriovenous malformation at the site of implantation.¹

Management options vary greatly, and data are limited to retrospective chart review case series with small sample sizes and a variety of proposed treatment modalities. Regarding surgical management, the Society of Maternal-Fetal Medicine recommends that “operative resection (with transvaginal or laparoscopic approaches when possible) or ultrasound-guided uterine aspiration be considered for the surgical management of CSEP, and that sharp curettage alone be avoided (GRADE 2C).”¹

Surgical management

A 2014 large systematic review recommended 5 approaches for treating CSEP when examining efficacy and complication rates: transvaginal resection (transverse incision in the lower uterine segment after creation of a bladder flap and suction curettage through the incision), laparoscopic resection, uterine artery embolization (UAE) in combination with dilatation and curettage (D&C) and hysteroscopy, UAE in combination with D&C, and hysteroscopy alone. These options were recommended based on the availability of adjunctive therapies such as UAE, patient presentation/symptoms, and skill/experience level of the surgeon.¹²

Laparoscopic resection was completed in 69 patients in this systematic review, which reported an efficacy of 97.1% with no complications.¹² A recent 2024 case report described a successful laparoscopic resection of a continuing 14-week CSEP without complication.13 These methods may allow some theoretical benefit in removing and repairing the defect while preserving fertility; however, there has yet to be evidence showing that they decrease rates of recurrent CSEP or enhance future fertility. Theoretically, there is a concern that extensive repair of the lower uterine segment and site of a CSEP may create further inflammation and scarring and provide a wider surface area for a subsequent pregnancy to implant. Additionally, a skilled laparoscopic surgeon or minimally invasive gynecologic surgeon would be necessary to ensure that this approach has a low complication rate and is feasible without introducing additional morbidity, and this is not available in all areas. For a patient who does not desire future fertility, the preferred method of management for a second trimester-CSEP is gravid hysterectomy, which has less morbidity than a term cesarean hysterectomy, although no head-to-head studies of complication rates or patient outcomes exist in the literature to date.¹

Hysteroscopy as the primary treatment has an estimated efficacy of 83% and a complication rate of 3.2%.¹² When comparing patients who underwent uterine aspiration with patients who underwent UAE with subsequent hysteroscopic removal, there was no significantdifference between serum β-HCG 2 days following surgery (P > .05) or complications. Patients with hysteroscopy had a shorter length of stay, which was thought to be at the discretion of the clinician and not secondary to complications or pain.¹⁴

More recent evidence supports the use of primary suction aspiration under ultrasound guidance as primary treatment for early CSEP (less than 50 days gestational size) with or without adjunctive therapies. A case series of 24 patients showed successful treatment of 14 confirmed CSEP cases regardless of type without complication. Ten patients in the study were between 50 and 66 days of gestation, 5 of whom were treated without complication, 1 case was complicated by tamponade with an intrauterine Foley balloon for 6 hours, and one was complicated by a perforation complicated by an exploratory laparotomy.¹⁵ Prior studies with questionable complications from D&C did not specify the type of D&C (suction vs sharp curettage) or whether intraoperative ultrasound guidance was used. These results suggest that pretreatment with UAE is not necessary prior to suction aspiration of early CSEPs.

High-frequency ultrasound is another modality that has been undergoing more research with promising results, with or without hysteroscopic suction curettage, though limited access to this technology remains.¹

Medical management

The most studied medical regimen for CSEP is intragestational sac injection of methotrexate with or without other modalities (grade 2C).¹ Systemic methotrexate has resulted in a lower efficacy and higher complication rate when used on its own and is not recommended. A systematic review of 17 articles, including 96 cases with a single local methotrexate injection, found a 73.9% success rate. This increased to 88.5% with an additional dose of local or adjunct intramuscular methotrexate. Surgical treatment was needed in 11.5% of cases, and a higher failure rate was notable for β-HCG greater than 100,000 IU/L.¹⁶ Other local treatment modalities include intrasac potassium chloride injection, which can be beneficial in rare heterotopic pregnancies due to the risk for methotrexate affecting the intrauterine sac.^1,11

Adjunctive treatment

Adjunctive treatment includes intrasac methotrexate, UAE, or prophylactic intrauterine Foley balloon in combination with hysteroscopy or suction aspiration.

Management recommendations

Surgical treatment with suction aspiration can lead to much quicker resolution of CSEP compared with medical management, which one study of local methotrexate (MTX) found that follow-up on average took 88 days.¹⁶ Patients should be selected carefully based on gestational sac size and vascularity on ultrasound, as these may be predictors for complications and may be better served with pre-procedure MTX, UAE, or surgical management with vaginal or laparoscopic resection.

The ultimate decision must be individualized for the patient, their fertility desires, and the risks associated with their CSEP.

Management of CSEP in a post-Roe era

Use of appropriate language and terminology is critical for patients with CSEP. Defining and using the term cesarean scar ectopic pregnancy or CSEP instead of cesarean scar pregnancy or CSP is essential as this communicates the abnormality of the pregnancy, severity of the diagnosis, and risk to the health of the patient. Most states, including those with abortion bans, have exceptions in the setting of threats to the life of the patient, which all major medical societies confirm and agree that CSEP does. Further knowledge about the diagnosis, recommendations against expectant management from major obstetrics and gynecology (ob-gyn) societies, and the significant morbidity and mortality associated with CSEP should allow generalists and other ob-gyn clinicians to recommend termination via an appropriate modality and to make an appropriate referral based on patient risks and gestational age.

Unfortunately, this has not been the case. In 2022, Mayron Hollis was declined management of her CSEP in a restrictive state, ultimately resulting in a uterine rupture with the need for a cesarean hysterectomy. She experienced a life-threatening hemorrhage and required a procedure with significant morbidity, not to mention loss of future fertility. Had this patient received the care as was appropriate and was not side-stepped by multiple providers in fear of the law, she could have been spared this outcome, saved her ability to conceive in the future, and avoided a life-risking procedure and hemorrhage.¹⁷

CSEP is complicated. Unlike a tubal ectopic pregnancy, it can potentially progress to term and result in a live fetus, but rarely without the expense of the person carrying the pregnancy. Prior to the Dobbs v. Jackson Women’s Health Organization case in 2022, a case series examined the outcomes of 69 cases of CSEP that were managed expectantly.18 Uterine rupture in the first or second trimester of pregnancy occurred in 9.9% of all patients and in 13.9% of patients with CSEP and no fetal or embryonic cardiac activity. Of the patients whose pregnancies continued to the third trimester (40 patients), almost 40% experienced severe bleeding, 74.8% had a diagnosis of invasive placentation at the time of delivery, and nearly 70% had placenta percreta.¹⁸ A systemic review of cases published in 2023 showed similar findings.

Of the cases where embryonic/fetal cardiac activity was present at diagnosis, uterine rupture occurred in 9% of cases, and these patients all required a hysterectomy. Of those who progressed to the third trimester, 79% developed PAS, 55% required hysterectomy, and 40% had severe bleeding.¹⁹

Summary of recommendations

Given the high morbidity associated with CSEP and the increasing incidence of CSEP and PAS, patients with prior cesarean delivery should have imaging (either by a specialist familiar with the diagnosis of CSEP or a formal radiology ultrasound) as early as possible in pregnancy, when treatment is safest with the lowest risk of complications.

1. Patients with prior cesarean delivery should have an early ultrasound evaluation between 5 and 10 weeks of gestation by the last menstrual period.
2. Any patient with an anterior, low-lying gestational sac should be further evaluated by ob-gyn specialists comfortable with diagnosing CSEP.
3. Termination/evacuation of the CSEP is recommended promptly after the time of diagnosis.
4. Suction aspiration under ultrasound guidance is recommended as a minimally invasive management technique for patients at less than 8 weeks of gestation with excellent success and a low rate of complications.
5. Intrasac injection of methotrexate can be used in patients with larger CSEPs (>8 weeks of gestational size) with subsequent systemic methotrexate dosing or staged procedural evacuation based on a decline in β-HCG levels.
6. The use of the proper terminology to define these pregnancies as ectopic is crucial in settings where early pregnancy care and abortion are restricted and potentially criminalized.

References

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3. Roche C, McDonnell R, Tucker P, et al. Caesarean scar ectopic pregnancy: evolution from medical to surgical management. Aust N Z J Obstet Gynaecol. 2020;60:852-857. doi:10.1111/ajo.13241

4. Jauniaux E, Bunce C, Grønbeck L, Langhoff-Roos J. Prevalence and main outcomes of placenta accreta spectrum: a systematic review and meta-analysis. Am J Obstet Gynecol. 2019;221(3):208-218. doi:10.1016/j.ajog.2019.01.233

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13. Elbanna W, Azmy O. Conservative laparoscopic approach for the management of a 14-week viable ectopic cesarean scar ectopic pregnancy. Case Rep Obstet Gynecol. 2024;2024:6682029. doi:10.1155/2024/6682029

14. Cao L, Qian Z, Huang L. Comparison of D&C and hysteroscopy after UAE in the treatment of cesarean scar pregnancy: a case-control study. Medicine (Baltimore). 2022;101(3):e28607. doi:10.1097/MD.0000000000028607

15. Wu BT, Feld Z, Creinin MD. Management of cesarean scar ectopic pregnancies at an academic referral center: a case series. Contraception. 2023;123:110021. doi:10.1016/j.contraception.2023.110021

16. Cheung VYT. Local methotrexate injection as the first-line treatment for cesarean scar pregnancy: review of the literature. J Minim Invasive Gynecol. 2015;22(5):753-758. doi:10.1016/j.jmig.2015.04.008

17. Doctors warned her pregnancy could kill her. then Tennessee outlawed abortion. ProPublica. March 14, 2023. Accessed April 20, 2026. https://www.propublica.org/article/tennessee-abortion-ban-doctors-ectopic-pregnancy

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19. Vieira de Mello P, Bruns RF, Fontoura Klas C, Raso Hammes L. Expectant management of viable cesarean scar pregnancies: a systematic review. Arch Gynecol Obstet. 2023;308(3):701-707. doi:10.1007/s00404-022-06835-3