Retained products of conception complicated by hemoperitoneum: a case report

Abstract

Background

Hemoperitoneum, a well-documented manifestation of various gynecological conditions, is herein presented in the first documented case secondary to retained products of conception (RPOC) following a medical abortion. This condition can pose significant diagnostic challenges and carry a high risk of misdiagnosis.

Case presentation

A 33-year-old woman presented with acute-onset heavy vaginal bleeding and mild lower abdominal pain 33 days after a first-trimester medical abortion (mifepristone and misoprostol). Transvaginal ultrasonography (TVS) revealed an intrauterine mass and significant hemoperitoneum. Emergency dilation and curettage was performed, and histological examination confirmed RPOC with degenerated gestational villi.

Conclusion

This case highlights an unusual but critical mechanism of hemoperitoneum—retrograde transtubal bleeding from RPOC—expanding the differential diagnosis of hemoperitoneum in women of reproductive age.

Background

Retained products of conception (RPOC) are residual trophoblast-derived tissue in the uterus following miscarriage, abortion, or delivery, with a reported frequency of 1 to 6% [1–4].This condition can result in complications including abnormal uterine bleeding, intrauterine adhesions, infection, secondary infertility, and secondary arteriovenous fistula [5, 6]. Hemoperitoneum is a well-documented manifestation of various gynecological conditions, such as ruptured ovarian cysts [7, 8] or ectopic pregnancies [9]. However, to our knowledge, no prior cases have linked hemoperitoneum to RPOC. We report an exceptionally rare case of massive vaginal bleeding accompanied by hemoperitoneum secondary to RPOC. Given its atypical presentation, this condition poses significant diagnostic challenges and carries a high risk of misdiagnosis.

Case presentation

A 33-year-old woman presented to our institution on February 27,2025, with a chief complaint of massive vaginal bleeding and mild lower abdominal pain persisting for approximately 12 h. The patient was previously healthy with no significant medical or surgical history. She had regular menstrual cycles (30-day interval, 5-day duration) with mild dysmenorrhea. Her last menstrual period was December 15, 2024. She had undergone three medical abortions with no prior deliveries. Condoms were her primary contraceptive method. The patient reported undergoing medical abortion 33 days prior to admission. Initial transvaginal ultrasonography (TVS) performed on January 23, 2025, demonstrated an intrauterine gestational sac (10 × 11 × 7 mm) containing a yolk sac but no discernible fetal pole. Both adnexa were normal on imaging. Following standard protocol, the patient received combined oral mifepristone and misoprostol for medical termination of pregnancy, which resulted in successful expulsion of the gestational sac two days later. She experienced intermittent scant vaginal bleeding following expulsion of the gestational sac. On February 11, 2025, the patient presented for follow-up evaluation. TVS demonstrated a slightly hyperechoic area (21 × 18 × 11 mm) at the left side of the fundus of the uterine cavity with ill-defined demarcation from the posterior myometrium. Color Doppler Flow Imaging (CDFI) detected intralesional vascularity. The patient was initiated on oral mifepristone 25 mg twice daily for 14 days. One week later, surveillance TVS revealed persistent slightly hyperechoic area (16 × 12 × 10 mm) at the original site with prominent linear vascularity on CDFI. Ovaries appeared normal bilaterally. Serum β-human chorionic gonadotropin (β-hCG) level was 813.83 mIU/mL, and mifepristone was continued. After an additional week, TVS showed evolution to a mixed-echogenicity intracavitary mass (20 × 20 × 12 mm) with better-defined margins but persistent vascularity. Serum β-hCG declined to 564.46 mIU/mL. The patient received 0.6 mg oral misoprostol, resulting in vaginal bleeding with small clots but no tissue expulsion.

On the night of February 26, 2025, the patient developed acute-onset heavy vaginal bleeding with blood clots, accompanied by mild lower abdominal pain and tenesmus. She presented to our gynecologic emergency department the following morning (February 27). Emergency TVS revealed a 26-mm heterogeneous avascular mass with ill-defined margins extending from the uterine cavity to the cervical canal, a 20-mm vaginal hematocele, significant hemoperitoneum (78 × 26 × 21 mm free fluid in the rectouterine pouch and 76 × 19 × 43 mm free fluid in the right anterior aspect of the uterus), and unremarkable bilateral adnexa (Fig. 1). The patient’s serum β-hCG level was 154 mIU/mL, with accompanying hemoglobin of 111 g/L and normal coagulation function at presentation.

Fig. 1.

Transvaginal ultrasonography image. A Intrauterine mass (black star). B Vaginal hematocele (white star). C, D Free fluid in the rectouterine pouch (white star and white arrow). E, F Free fluid in the right anterior aspect of the uterus (white star and white arrow)

The patient was urgently admitted to our gynecology department. Upon admission, physical examination revealed lower abdominal tenderness together with tachycardia (112 beats/minute). Pelvic examination revealed active vaginal bleeding with a closed cervical os and marked cervical motion tenderness. Diagnostic culdocentesis yielded 3 mL of dark-red, non-coagulating blood with a β-hCG level of 2,725 mIU/mL, confirming intraperitoneal hemorrhage of gestational origin. Emergency dilation and curettage was performed, evacuating organized products of conception. Histopathological analysis identified degenerated gestational villi with necrotic changes and focal villous edema, consistent with RPOC. The endometrial lining showed characteristic proliferative-phase morphology. Postoperative surveillance on March 3, 2025, demonstrated complete resolution on TVS with normalization of serum β-hCG levels, confirming successful management. Hemoglobin was 87 g/L. This result suggests that the previously recorded hemoglobin value of 111 g/L on February 27 may have reflected hemoconcentration rather than the patient’s true baseline hematologic status. The patient was discharged on March 3. Figure 2 provides a summary of the patient’s clinical progression following the medical abortion.

Fig. 2.

A summary of the patient’s clinical progression following the medical abortion. β-hCG = β-human chorionic gonadotropin; TVS=transvaginal ultrasonography; CDFI=Color Doppler Flow Imaging

Discussion

Hemoperitoneum of gynecological etiology most commonly results from ruptured ovarian cysts or ectopic pregnancies. Less frequent causes include endometriosis [10, 11] and uterine leiomyoma [12, 13], where the bleeding stems from outside the uterine cavity. Notably, blood within the uterine cavity may also enter the peritoneal cavity through the fallopian tubes causing hemoperitoneum [14]. RPOC represent a common gynecological condition. However, no published cases have established an association between RPOC and hemoperitoneum. Our case represents the first reported instance of hemoperitoneum secondary to RPOC, expanding the differential diagnosis of hemoperitoneum in women of reproductive age. The mechanism of hemoperitoneum in this case is attributed to retrograde flow of intrauterine bleeding through the fallopian tubes into the peritoneal cavity.

This case presents a unique constellation of clinical findings, including acute lower abdominal pain, massive vaginal bleeding, β-hCG positivity, and hemoperitoneum, accompanied by an intrauterine lesion on TVS without adnexal involvement. The patient’s recent RPOC history suggests that substantial intrauterine blood accumulation from RPOC led to hemoperitoneum. Prolonged retention of gestational tissue may result in tissue organization and adhesion formation, thereby impairing uterine cavity blood drainage. When substantial intrauterine hemorrhage occurs, obstructed outflow may increase intracavitary pressure, forcing blood through the fallopian tubes into the peritoneal space. Notably, the patient’s peritoneal fluid β-hCG level markedly exceeded serum levels, suggesting continued hCG secretion by retained villi into the uterine blood pool - a finding corroborated by histopathological identification of villous tissue post-curettage.

The fallopian tubes serve as anatomical conduits between the uterine cavity and peritoneal space, allowing potential passage of intrauterine blood into the abdominal cavity. This mechanism is exemplified by the well-established phenomenon of retrograde menstruation, where endometrial blood refluxes through the fallopian tubes into the peritoneal cavity. Approximately 90% of reproductive-aged women experience physiological retrograde menstruation [15]. Pathological conditions causing reproductive tract obstruction may exacerbate this phenomenon, potentially leading to clinically significant hemoperitoneum [16]. A documented case attributed substantial hemoperitoneum to coitus-induced retrograde menstrual flow during menses [17]. Retrograde menstruation also represents an important etiological factor for hemoperitoneum in women undergoing peritoneal dialysis [18]. We propose that acute elevation of intrauterine pressure secondary to intrauterine bleeding led to transtubal reflux of blood, ultimately culminating in hemoperitoneum in this patient. A similar phenomenon was observed in a cesarean patient with postpartum hemorrhage managed by Hwu-Hayman sutures. Due to uterine atony, bleeding occurred at the placental attachment site on the right anterior uterine wall. The accumulated blood in the right uterine cavity progressively increased intracavitary pressure. This elevated intracavitary pressure caused the suture to slide to the left, and subsequent retrograde blood flow through the fallopian tube into the abdominal cavity, ultimately resulting in hemoperitoneum [14]. Di Serio et al. [19] reported a case of hemoperitoneum secondary to a hypervascularized placental polyp three months post-medical abortion. The patient similarly presented with acute vaginal bleeding and an intrauterine mass, yet emergency laparoscopy failed to identify any intra-abdominal bleeding source. We postulate that the hemoperitoneum likely resulted from retrograde tubal flow of intrauterine bleeding.

In reproductive-aged women presenting with acute abdominal pain and intra-abdominal fluid, ruptured ectopic pregnancy must remain the primary diagnostic consideration. Heterotopic pregnancy (HP), characterized by the coexistence of intrauterine and extrauterine gestations, presents particular diagnostic challenges. The visible intrauterine pregnancy frequently leads to diagnostic overshadowing of the concurrent ectopic component, with several reported cases of ectopic rupture following intrauterine pregnancy miscarriage [20, 21]. Notably, the biochemical finding of hemoperitoneum β-hCG levels exceeding corresponding serum concentrations - as observed in our case - has also been documented in ruptured ectopic pregnancies [22]. These shared diagnostic features underscore why HP is one of the differential diagnoses we need to consider.

Conclusion

In clinical practice, gynecologists should maintain a high index of suspicion for potential retrograde flow of intrauterine blood into the peritoneal cavity when evaluating patients presenting with hemoperitoneum, particularly those demonstrating concurrent intrauterine lesion and massive vaginal bleeding. This diagnostic consideration is crucial to prevent unnecessary laparoscopic or laparotomic intervention while ensuring appropriate management.

Abbreviations

RPOC

Retained products of conception

TVS

Transvaginal ultrasonography

CDFI

Color Doppler Flow Imaging

β-hCG

β-human chorionic gonadotropin

HP

Heterotopic pregnancy

Authors’ contributions

Qian Zhu: Conceptualization, Supervision and Writing - review & editing; Xiaoyan Huang: Writing - original draft. All authors reviewed the manuscript.

Funding

None.

Data availability

The data is presented within the manuscript and accompanying figures.

Declarations

Ethics approval and consent to participate

The Ethics Committee of the Affiliated Jiangning Hospital of Nanjing Medical University has granted approval for the ethical application (Clinical Trial Number: 2025-03-021-K01) and the patient has provided informed consent.

Consent for publication

All authors have read and understood the journal’s submission guidelines and consented to the manuscript’s publication. Written informed consent was obtained from the patient, ensuring no identifying details compromise her anonymity.

Competing interests

The authors declare no competing interests.