Ovarian ectopic pregnancy (OEP) is defined as the implantation of a fertilized ovum within the ovarian tissue. It accounts for 0.5–3% of all ectopic pregnancies and remains one of the rarest non-tubal forms. The diagnostic challenge stems from its clinical and radiological similarities to ruptured corpus luteum and tubal ectopic pregnancy. Spiegelberg's criteria, which were described in 1878, remain the definitive diagnostic framework. The criteria being 1) gestational sac located in the region of ovary, 2) the ectopic pregnancy is attached to the uterus by the ovarian ligament; 3) ovarian tissue in the wall of the gestational sac is proved histologically, 4) tube on the involved side is intact. Early recognition is difficult because patients often present with an acute abdomen secondary to rupture, necessitating emergency surgery.

The incidence of non-tubal ectopic pregnancies has increased owing due to the widespread use of assisted reproductive technologies, ovulation-inducing agents, and intrauterine devices. However, primary ovarian pregnancies continue to be underreported owing to misdiagnosis or lack of histopathological confirmation. This case series presents the detailed clinical, operative, and histopathological characteristics of four confirmed cases managed in a tertiary care center, highlighting diagnostic dilemmas, fertility implications, and management outcomes.

Case Series

Case 1: A 22-year-old G3P1L1A1 patient presented with severe lower abdominal pain, spotting, and dizziness. Vitals: BP 100/60 mmHg; PR 114/min. Hb was 8.8 g/dL. Ultrasonography revealed a right adnexal sac-like lesion with significant free fluid. Emergency laparotomy revealed approximately 800 mL of hemoperitoneum and a ruptured right ovarian ectopic pregnancy. Right oophorectomy was performed. The postoperative recovery was uneventful. Histopathology confirmed chorionic villi embedded within the ovarian stroma, fulfilling Spiegelberg criteria.

Case 2: A 23-year-old patient G3P2L2 with two months amenorrhea presented with acute abdominal pain and presyncope. Vitals: BP 100/70 mmHg, PR 118/min. Ultrasonography revealed the presence of a ruptured adnexal mass. Laparotomy revealed nearly 500 ml hemoperitoneum and a ruptured right ovarian pregnancy. Right oophorectomy was performed. Histopathological examination confirmed primary ovarian ectopic pregnancy.

Case 3: A 21-year-old patient G2P1L1 presented with sharp pain in the left iliac fossa pain. β-hCG was 3357 mIU/mL. TVS revealed a left adnexal mass with pelvic free fluid. Intraoperatively, 200 mL hemoperitoneum was found with a ruptured left ovarian ectopic gestation. Left oophorectomy was performed. The postoperative β-hCG level decreased to 393 mIU/mL. Histopathological examination confirmed ovarian implantation.

Case 4: A 34-year-old woman with history of right tubectomy, and patient had ingested medical abortion pills during this pregnancy and presented with shock (BP 70/40 mmHg; PR 140/min). TVS revealed a right adnexal gestational sac-like structure with a massive hemoperitoneum. Laparotomy detected >1 L hemoperitoneum and ruptured right ovarian pregnancy. Right oophorectomy performed, patient also opted for tubal ligation on the left side tube, to prevent further pregnancies, 3 units of packed cell volume (PCV) also given to the patient, to cover for the blood loss. Histopathological examination confirmed primary ovarian ectopic pregnancy.

Figure 1: Intraoperative image of ruptured ovarian ectopic pregnancy.

Figure 2: Histopathological report of the case 4

Discussion

Ovarian ectopic pregnancy is a frequently encountered forms of ectopic pregnancy. Although representing only 0.5–3% of all ectopic gestations, accurate preoperative diagnosis remains difficult. Transvaginal ultrasonography has improved detection, but most cases still present with rupture, leading to hemoperitoneum and shock.

Recent literature highlights that early detection may allow conservative surgical approaches, including ovary sparing excision or laparoscopic management. However, in low-resource settings and in hemodynamically unstable patients—as in our series—laparotomy remains the standard of care.

Spiegelberg’s criteria distinguish between primary ovarian pregnancies and secondary implantations. Histopathological examination remains essential for confirmation. Reported risk factors include IUD use, PID, ART, and previous surgeries, though many patients have no identifiable risk factor as in our study. Prompt laparotomy and timely transfusion reduce morbidity and mortality, particularly in resource-limited settings.

Conclusion

Primary ovarian ectopic pregnancy should be treated as a differential diagnosis in reproductive-aged women with an acute abdomen and positive pregnancy test. Prompt surgical management is still a lifesaving procedure. Histopathology is crucial to confirm diagnosis.

Funding Statement: The study was supported by grant NN from the Foundation of Basic Research. This work was carried out under research program NNN of NN University. Author NN was supported by grant NN from the Ministry of NN.

Ethical Compliance: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.

Conflict of Interest declaration: The authors declare that they have no affiliations with or involvement in any organization or entity with any financial interest in the subject matter or materials discussed in this manuscript.

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