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Introduction
Caesarean scar ectopic pregnancy (CSEP) is an uncommon form of ectopic gestation in which implantation occurs within the fibrous tissue of a previous caesarean section scar. The reported incidence ranges from 1 in 1800 to 1 in 2500 pregnancies, with prevalence increasing in parallel with rising caesarean delivery rates worldwide(1,2). Despite its rarity, CSEP carries a disproportionately high risk of severe maternal morbidity, including massive hemorrhage, uterine rupture and the potential need for emergency hysterectomy if not promptly diagnosed and appropriately managed(3). The condition therefore represents a significant diagnostic and therapeutic challenge in early pregnancy care. CSEP is broadly classified into two types based on the direction of trophoblastic growth. Endogenous (type 1) CSEP grows towards the uterine cavity, and may initially mimic a low intrauterine pregnancy. Although such pregnancies may progress further into gestation, they are associated with a high risk of placenta accreta spectrum disorders, severe hemorrhage and uterine rupture later in pregnancy. In contrast, exogenous (type 2) CSEP grows outward toward the serosal surface of the uterus and adjacent bladder, often presenting earlier and posing a greater risk of early uterine rupture and life-threatening bleeding(4). Accurate classification is therefore crucial in determining prognosis and in guiding management strategies. Transvaginal ultrasonography remains the cornerstone of diagnosis, providing high diagnostic accuracy when established criteria are applied. Key sonographic features include an empty uterine cavity and cervical canal, localization of the gestational sac at the level of the caesarean scar, a thin or absent myometrial layer between the sac and the bladder, and absence of the sliding organ sign(5). The assessment of residual myometrial thickness is particularly important, as it influences both the risk of complications and the choice of therapeutic approach. The management options range from expectant and medical therapy to minimally invasive or surgical interventions, depending on gestational age, hemodynamic stability, serum b-human chorionic gonadotropin levels, myometrial thickness and the woman’s desire for future fertility(6).
Case report
A 28-year-old woman, gravida 2 para 1, presented to the early pregnancy unit with complaints of spotting per vaginum with a history of amenorrhea of six weeks and two days. Her last menstrual period was dated 25 December 2025. She had undergone a lower-segment caesarean section five years earlier for her previous pregnancy, which resulted in a live birth. There was no history of infertility treatment, uterine curettage, myomectomy or other uterine surgical procedures. The patient had no significant medical or surgical comorbidities. At presentation, she was not having abdominal pain or syncopal episodes. General physical examination revealed stable vital signs, and the abdominal examination was unremarkable. Pelvic examination showed a normal-sized uterus with no cervical motion tenderness or adnexal masses. There were no clinical features suggestive of hemodynamic instability.
Investigations
Transvaginal ultrasonography revealed a gestational sac implanted in the anterior lower uterine segment at the site of the previous caesarean section scar (Figures 1 and 2). The uterine cavity and cervical canal were empty, with no evidence of intrauterine or cervical pregnancy. The gestational sac measured 2.89×1.36 cm, and a yolk sac was clearly visualized, confirming an early viable gestation. The residual myometrial thickness between the gestational sac and the urinary bladder was approximately 0.6 cm, indicating a high-risk caesarean scar implantation. The growth pattern was consistent with an endogenous caesarean scar ectopic pregnancy, extending toward the uterine cavity. Color Doppler imaging was not performed; however, the anatomical relationship between the gestational sac, caesarean scar niche and myometrium was sufficient to establish the diagnosis. Baseline laboratory investigations, including complete blood count and renal and liver function tests, were within normal limits. Serum b-human chorionic gonadotropin (b-hCG) level at admission was higher than 15,000 IU/L.
Differential diagnosis
The differential diagnoses considered included cervical ectopic pregnancy, low-lying intrauterine pregnancy and incomplete abortion. These were excluded based on the presence of an empty uterine cavity and cervical canal, the localization of the gestational sac within the anterior lower uterine segment at the caesarean scar site, and the absence of a sliding organ sign on transvaginal ultrasonography(5,7).
Treatment
Following detailed counseling regarding the available management options – including medical therapy, minimally invasive surgical approaches and their potential risks and benefits –, a fertility-preserving strategy was selected. Given the endogenous growth pattern, early gestational age, hemodynamic stability, thin residual myometrium and the availability of continuous real-time ultrasound guidance, ultrasound-guided dilatation and evacuation (D&E) was planned. The procedure was performed under appropriate anesthesia with continuous transabdominal ultrasound guidance. The gradual cervical dilatation was followed by the careful evacuation of gestational tissue. The procedure was completed without intraoperative complications. Hysteroscopy was not performed, and there was no excessive bleeding or need for additional hemostatic measures.
Outcome and follow-up
Post-procedure transvaginal ultrasonography demonstrated the complete resolution of the gestational sac with an empty endometrial cavity (Figure 3). The residual myometrial thickness at the caesarean scar site was noted to have increased to approximately 0.8 cm, suggesting the restoration of uterine wall integrity. A follow-up serum b-hCG sample obtained 24 hours postoperatively remained elevated (17,000 IU/L), consistent with the expected delayed biochemical decline following surgical evacuation. The patient remained clinically stable, with no postoperative complications, being discharged with advice for serial b-hCG monitoring and scheduled follow-up ultrasonography to ensure complete resolution. She was managed by single-dose methotrexate regime on follow-up and serial beta-hCG monitoring.
Discussion
Caesarean scar ectopic pregnancy (CSEP) represents a rare but increasingly recognized form of ectopic gestation, driven largely by rising global caesarean section rates and improved awareness and diagnostic capabilities. Although uncommon, CSEP is associated with a disproportionately high risk of severe maternal morbidity, including catastrophic hemorrhage, uterine rupture, placenta accreta spectrum disorders and loss of fertility if not diagnosed and managed appropriately. Early and accurate diagnosis, followed by timely intervention, is therefore essential to optimize maternal outcomes and preserve reproductive potential(5). Transvaginal ultrasonography is the cornerstone of CSEP diagnosis, and remains the most accessible and reliable imaging modality in early pregnancy. Application of established diagnostic criteria – including an empty uterine cavity and cervical canal, localization of the gestational sac at the level of the caesarean scar, thin or absent myometrium between the sac and bladder, and absence of the sliding organ sign – allows the accurate differentiation of CSEP from cervical pregnancy, low intrauterine implantation, or miscarriage in progress(5). In the presented case, the diagnosis was established solely on grayscale transvaginal imaging, without color Doppler assessment. Although Doppler interrogation may assist in evaluating trophoblastic vascularity and bleeding risk, it is not mandatory for diagnosis when anatomical relationships are clearly demonstrated, as in this case. Caesarean scar ectopic pregnancy is broadly classified into endogenous (type 1) and exogenous (type 2) variants based on the direction of trophoblastic growth(4). Endogenous CSEP, characterized by implantation within the caesarean scar niche with growth toward the uterine cavity, may initially appear less aggressive. However, continuation of such pregnancies is associated with a high risk of placenta accreta spectrum disorders, severe hemorrhage and uterine rupture later in gestation(4). Exogenous CSEP, in contrast, grows outward toward the serosa and bladder, and carries a greater risk of early rupture and acute bleeding. The accurate classification is therefore clinically relevant, as it informs both prognosis and therapeutic decision-making. The management of CSEP remains controversial, with no universally accepted standard of care(6). Over 30 treatment modalities have been described, including expectant management, systemic or local methotrexate administration, uterine artery embolization, hysteroscopic or laparoscopic resection and ultrasound-guided suction evacuation(6). Individualization of treatment is paramount and should consider gestational age, hemodynamic stability, serum b-human chorionic gonadotropin (b-hCG) levels, myometrial thickness, direction of sac growth, institutional expertise and the patient’s desire for future fertility(8). Ultrasound-guided dilatation and evacuation (D&E) has emerged as an effective minimally invasive option for selected cases of early CSEP, particularly those with endogenous growth and adequate myometrial thickness(9). Timor-Tritsch and Monteagudo (2012) demonstrated high success rates and low complication rates with ultrasound-guided suction curettage when performed in appropriately selected patients(10). Real-time ultrasound guidance allows the precise localization of the gestational sac, reduces the risk of uterine perforation and ensures complete evacuation, thereby minimizing hemorrhagic complications. In the presented case, ultrasound-guided dilation and evacuation was chosen based on several favorable factors: early gestational age, endogenous growth pattern, hemodynamic stability, absence of symptoms and availability of continuous real-time imaging. Although the residual myometrial thickness was thin (0.6 cm), careful procedural planning and ultrasound guidance enabled the successful evacuation without complications. Notably, hysteroscopy was not employed. While hysteroscopy may provide direct visualization and allow targeted resection with coagulation, it is also associated with risks of hemorrhage due to impaired myometrial contractility at the scar site. In this case, the omission of hysteroscopy did not compromise outcomes, as confirmed by post-procedure imaging demonstrating the complete resolution of the gestational sac and the restoration of myometrial thickness. Serum b-hCG monitoring plays a crucial role in post-treatment surveillance. Persistently elevated b-hCG levels in the immediate postoperative period should not be interpreted as treatment failure, as the hormone’s biological half-life results in a delayed biochemical decline following surgical evacuation(11). Serial measurements over subsequent days to weeks are essential to confirm the complete resolution. In this patient, the elevated b-hCG level at 24 hours postoperatively was consistent with expected physiological kinetics rather than persistent trophoblastic disease. An important consideration following CSEP is the risk of recurrence and adverse outcomes in subsequent pregnancies. Although the recurrence rates are relatively low, reported between 3% and 5%, future pregnancies carry an increased risk of repeat scar implantation, placenta accreta spectrum disorders and uterine rupture. Accordingly, patients should be counseled regarding the importance of early transvaginal ultrasonography in future pregnancies to confirm implantation site and enable prompt intervention if required. This case adds to the growing body of evidence supporting ultrasound-guided dilatation and evacuation as a safe and effective fertility-preserving option in carefully selected cases of endogenous CSEP. Moreover, it underscores the importance of early diagnosis, meticulous ultrasound assessment and individualized management planning. Importantly, it also demonstrates that hysteroscopy is not mandatory in all cases and that favorable outcomes can be achieved with ultrasound-guided evacuation alone when performed in an appropriate clinical setting.
Patient’s perspective
The patient expressed satisfaction with the early diagnosis and management approach, particularly appreciating the emphasis on fertility preservation. She reported reassurance from detailed counseling regarding the condition, the available treatment options and potential future implications. She acknowledged the importance of early transvaginal ultrasonography in subsequent pregnancies and expressed confidence in future follow-up care.
Learning point
Caesarean scar ectopic pregnancy is a rare but potentially life-threatening form of ectopic gestation that requires a high index of clinical suspicion in women with previous caesarean delivery.
Transvaginal ultrasonography is essential for early diagnosis, accurate classification and treatment planning.
Ultrasound-guided dilatation and evacuation can be a safe and effective fertility-preserving treatment option in carefully selected cases of early endogenous caesarean scar ectopic pregnancy.
Persistently elevated b-hCG levels in the immediate postoperative period may be physiological and should be interpreted with caution.
Long-term follow-up with serial b-hCG monitoring and early imaging in future pregnancies is mandatory to ensure optimal outcomes.
Autor corespondent: Smit Bharat Solanki E-mail: drsmitbharat@gmail.com
CONFLICT OF INTEREST: none declared.
FINANCIAL SUPPORT: none declared.
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