Incidental diagnosis of an accessory ovary during cesarean section: a case report and literature review

A 31-year-old woman, gravida 3 para 2 (living 2), underwent an elective cesarean section in her last pregnancy at 38 weeks’ gestation due to a history of obstetric anal sphincter injury (OASIS) in her second delivery. She delivered a healthy female baby weighing 3000 g, with Apgar scores of 8 and 10 at 1 and 5 minutes, respectively. She had her first antenatal clinic appointment at 17 weeks’ gestation and completed a total of seven appointments. She was normotensive and normoglycemic, with a pregnancy BMI of 28.6 and an Hb of 13.3 g/dL before delivery. Her antenatal care (ANC) was unremarkable. Three ultrasound examinations performed during ANC showed a normal pregnancy with no abnormalities detected in the adnexa. The patient had an uneventful first pregnancy, during which she delivered a 2000-g male at 38 weeks in 2020. However, she sustained OASIS during the vaginal delivery of her second pregnancy at 41 weeks, with an outcome of 3500 g male infant who died in the early neonatal period. The history of OASIS in her previous delivery was an indication for elective cesarean section in the index pregnancy. A standard cesarean section was performed under spinal anesthesia, and a lower-segment uterine incision was closed with good hemostasis. Upon examination of the uterus and adnexa, two adjacent ovaries with visible follicles were identified on the posterior aspect of the right adnexa. Both were oval, 4 × 3 cm, with a regular surface and a pale pink color. Each had an ovarian ligament and an infundibulopelvic ligament. No other anomalies were noted (Figs 1 – 3 ). The diagnosis of an accessory ovary was made. No biopsy was taken, as there was no suspicion of malignancy; the ovaries were left in situ, and the abdomen was closed. The patient had no history of pelvic, ovarian, or abdominal surgery, supporting a congenital rather than an acquired origin of the accessory ovary. She was discharged on postoperative Day 2 and counseled on the possibility of associated congenital abnormalities and the availability of investigations to rule them out. The postoperative period was uneventful, and no further investigations were performed. Figure 1. Accessory ovary (arrow), showing the presence of a unique right fallopian tube and an ovarian ligament. Figure 2. Accessory ovary with visible follicles in the right adnexa of the uterus (arrow). An incidental finding during cesarean section. Figure 3. Two adjacent ovaries (including an accessory ovary) on the right (arrow) and a single normal ovary in the left adnexa of the uterus. Accessory ovary (arrow), showing the presence of a unique right fallopian tube and an ovarian ligament. Accessory ovary with visible follicles in the right adnexa of the uterus (arrow). An incidental finding during cesarean section. Two adjacent ovaries (including an accessory ovary) on the right (arrow) and a single normal ovary in the left adnexa of the uterus.

An accessory ovary is defined as the presence of more than two ovaries, with the third ovary located near a eutopic ovary and directly connected to the normal ovary. This is a very rare gynecological congenital anomaly [ 1 ] . The reported incidence of accessory ovaries is extremely low, estimated at approximately 1 in 29 000 to 1 in 700 000 gynecological admissions, making diagnosis and management challenging because of their rarity [ 2 ] . HIGHLIGHTS An accessory ovary is a rare congenital anomaly that may remain asymptomatic until incidental discovery. This accessory ovary was unexpectedly identified during a cesarean section in an otherwise asymptomatic pregnant woman. Intraoperative assessment demonstrated a normal ipsilateral ovary and separate accessory ovarian tissue. Conservative management was chosen because no suspicious features of malignancy were identified. The case highlights the importance of recognizing adnexal anatomical variations during obstetric surgery. HIGHLIGHTS An accessory ovary is a rare congenital anomaly that may remain asymptomatic until incidental discovery. This accessory ovary was unexpectedly identified during a cesarean section in an otherwise asymptomatic pregnant woman. Intraoperative assessment demonstrated a normal ipsilateral ovary and separate accessory ovarian tissue. Conservative management was chosen because no suspicious features of malignancy were identified. The case highlights the importance of recognizing adnexal anatomical variations during obstetric surgery. The understanding of the etiology of accessory ovaries remains incomplete. Most cases are considered congenital and may result from the separation of migrating ovaries during embryogenesis. Less commonly, an accessory ovary may be acquired following pelvic surgery, ovarian trauma, or inflammatory processes that lead to implantation of displaced ovarian fragments [ 3 ] . Accessory ovaries have been reported in association with congenital anomalies of the genitourinary tract, highlighting the importance of evaluating affected patients for associated abnormalities whenever feasible [ 3 ] . Most accessory ovaries are asymptomatic and remain undetected until incidental discovery during surgery, imaging studies, or investigation of infertility and pelvic pain. Although usually benign, ectopic ovarian tissue may undergo the same physiological and pathological changes as those of normally located ovaries, including cyst formation, endometriosis, torsion, and, rarely, neoplastic transformation. Preoperative diagnosis is uncommon because imaging findings are often nonspecific, particularly when the accessory ovary is small [ 4 – 6 ] . We report a rare case of an accessory ovary incidentally identified during cesarean section in an asymptomatic pregnant woman with no preoperative suspicion of adnexal pathology. This case report highlights the diagnostic challenges associated with this rare anomaly, discusses its embryological origin and clinical significance, and reviews the available literature regarding diagnosis, management, and follow-up. This case report is presented in line with the SCARE criteria [ 7 ] .

Accessory ovaries are uncommon congenital anomalies that may be associated with genitourinary and Müllerian abnormalities in 23% of cases. These anomalies include a bicornuate or unicornuate uterus, bifid fallopian tubes, accessory tubal ostia, agenesis of the kidney or ureter, duplicated ureter, bladder diverticulum, accessory adrenal glands, and a lobulated liver [ 1 , 2 ] . In our patient, no other associated gross congenital anomalies were seen during the operation. We reviewed the WEBLINE (PubMed, Google Scholar, Web of Science, the Science Citation Index, and the Social Sciences Index) database, which was searched using the following MeSH terms: ((Accessory ovary) AND (diagnostic OR clinical)) AND (treatment OR management), and (Accessory ovary) alone, from 1963 to 2025. Each article’s abstract was screened, and the relevant original English-language articles were read. Relevant articles were cross-referenced and summarized to identify related publications over the last 62 years. The inclusion criteria were author, year of publication, age of the patient and/or parity, preoperative diagnosis, incidental intraoperative findings, surprise histological diagnosis, and management. Only 11 cases were identified (Table 1 ). Table 1 Summary of accessory ovaries from 1963 to 2025 from WEBLINE Timeline Results by year. Author, & year of publication Age of the patient Preoperative diagnosis Incidental intraoperative findings Surprise histological diagnosis Management Vendeland et al 2000 [ 7 ] 16 years Ovarian cyst Yes No Ovarian conservation Andrade et al 2001 [ 8 ] 18-year-old woman Pelvic tumor Yes No Oophorectomy Liu et al 2005 [ 2 ] 30-year-old Ovarian tumor Yes No Oophorectomy Temiz et al 2008 [ 9 ] 22-year-old nulliparous Mesenteric cyst Yes No Cystectomy and fimbrioplasty Sharatz et al 2008 [ 4 ] 11 years Giant adnexal mass No Yes Left salpingectomy (tumour involved the tube) Fei Ngu et al 2011 [ 10 ] 39-year-old nulliparous Ovarian torsion Yes No Oophorectomy Zang et al 2017 [ 11 ] 46-year-old Left adnexa mass No Yes Left adnexectomy Toshio et al 2019 [ 3 ] A 46‑year‑old, nulliparous Uterine myoma Yes Yes Total hysterectomy and oophorectomy Zhou et al 2020 [ 6 ] Nulliparous Ovarian torsion Yes No Cystectomy with ovarian conservation Yeping et al 2024 [ 5 ] 18-year-old girl Ovarian tumor torsion and an accessory ovary No No Release of the ovarian torsion and oophoroplasty Qinhua Li et al 2025 [ 12 ] 13-year-old Ovarian cyst Yes Yes Cystectomy with ovarian conservation Summary of accessory ovaries from 1963 to 2025 from WEBLINE Timeline Results by year. Evidence supporting effective preoperative imaging diagnosis has been reported. However, the preoperative diagnosis of an accessory ovary is difficult. It is usually an incidental finding or an unexpected histological diagnosis after resection of a clinically relevant mass [ 4 , 5 ] . In this case, the diagnosis was incidental during a cesarean section. Reports of incidentally diagnosed accessory ovaries during cesarean delivery in asymptomatic pregnant women are extremely rare in the available literature. On the one hand, the accessory ovary is considered to have a physiological function and can be preserved for future fertility in women who still want to bear children [ 6 ] . On the other hand, the accessory ovary is often excised during surgery due to its potentially malignant behavior [ 6 ] . Therefore, no clear guidelines exist for the management of an accessory ovary. In the literature, all accessory ovaries were managed according to associated ovarian diseases, and no cases of malignancy were reported. Therefore, in asymptomatic patients with a normal intraoperative appearance, conservative management may be appropriate. However, awareness of this anomaly is important because the accessory ovary may undergo the same pathological processes as the normal ovary, including cystic, inflammatory, and neoplastic changes [ 2 – 6 , 8 – 12 ] (Table 1 ). In our patient, no associated disease was found, and we opted for conservative management. The patient was clearly informed and counseled to undergo further investigations, including pelvic and renal follow-up ultrasounds. Since accessory ovaries are often asymptomatic, they may be underreported. This condition is associated with a high risk of pelvic and renal anomalies and should prompt further evaluation to enable physicians to provide advice about future reproductive function and management of congenital anomalies [ 8 ] . Our patient had an unremarkable medical history and declined to undergo further investigation, citing the absence of symptoms and cost. Consequently, due to ethical and financial constraints, we were unable to perform further investigations to rule out congenital abnormalities of the urinary system.

This case illustrates the incidental diagnosis of an accessory ovary during a cesarean section in an asymptomatic pregnant woman. Recognition of this rare anatomical variation is important to avoid misdiagnosis and unnecessary surgical intervention. Careful assessment for associated congenital anomalies and appropriate follow-up should be considered when resources permit.