Pathogenesis and symptom of early hemorrhage in extrafollicular ovarian pregnancy onset at 4weeks gestation: A case report

Abstract

Introduction: Ovarian pregnancy is a rare form of ectopic pregnancy, accounting for approximately 3 % of cases, with an incidence ranging from 1 in 2100 to 1 in 7000 pregnancies. Its diagnosis is challenging due to nonspecific symptoms and difficulty distinguishing it from corpus luteum cysts or tubal pregnancies. Delayed recognition can lead to life-threatening hemorrhage.

Presentation of case: A 34-year-old gravida 3 para 3 Japanese woman presented with acute abdominal pain and hypovolemic shock 33 days after her last menstrual period. Imaging revealed a right ovarian cystic mass, intra-abdominal bleeding, and an empty uterus. Emergency laparoscopy identified a 5-mm gestational sac-like lesion on the right ovary. Laparoscopic wedge resection was performed. Pathological analysis confirmed extravillous trophoblast invasion into ovarian stromal vessels. A corpus luteum was observed at a separate location, supporting the diagnosis of secondary extrafollicular ovarian pregnancy. The patient recovered uneventfully.

Discussion: Ovarian pregnancies are classified as primary or secondary, and intrafollicular or extrafollicular. This case demonstrated secondary extrafollicular implantation with vascular invasion. Updated diagnostic criteria emphasize intact fallopian tubes, hemorrhagic ovarian lesions, and pregnancy tissue identification. Early detection remains difficult, particularly before 5 weeks gestation, and diagnosis often requires surgical and pathological confirmation.

Conclusion: This case underscores the importance of early recognition and laparoscopic management of ovarian pregnancy. Pathological findings aid in understanding implantation mechanisms and differentiating from similar adnexal conditions. Minimally invasive surgery enabled successful hemostasis and fertility preservation. Improved clinical awareness is essential to reduce complications associated with this rare condition.

Keywords: Ectopic pregnancy; Extrafollicular ovarian pregnancy; Extravillous trophoblast; Intrafollicular ovarian pregnancy; Laparoscopy; Ovarian pregnancy.

Proposed Mechanism: Extrafollicular Ovarian Pregnancy from Tubal Fertilization to Ovarian Implantation.

Fig. 1

(A) Axial contrast-enhanced computed tomography scan through the pelvis showing bleeding from the right ovary (green arrow). Exploratory laparoscopic imaging reveals a huge amount of bleeding in the abdominal cavity, especially extending to the liver, and with the uterus visible within the hematoma (star). (D) Laparoscopic imaging showing the presence of the gestational sac on the surface of the ovary (arrow), with persistent bleeding from the ovary over a wide area (arrowhead). (E) Laparoscopic imaging of the wedge resection of the pregnancy tissue using forceps. (F) Laparoscopic imaging of the electrocoagulation of the surface of the excision site to prevent residual pregnancy tissue and the development of gestational trophoblast disease. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

Fig. 2

(A) Microscopic image of hematoxylin-eosin staining demonstrating extravillous trophoblast invasion (white star) into the blood vessels (arrow) of the ovarian stroma (clover) of resected tissue. Scale bar: 200 μm. (B) Immunohistochemical labelling of CD31 (arrows) for detection of the vascular endothelium of the affected ovary Scale bar: 200 μm. (C) Immunohistochemical labelling of cytokeratin (AE1/AE3) (white star) for the detection of extravillous trophoblasts. Scale bar: 200 μm. (D) Immunohistochemical labelling of vimentin for detection of the ovarian stroma (clover). Scale bar: 200 μm. (E) Hematoxylin-eosin staining demonstrating extravillous cytotrophoblasts in cell islands (arrowhead) invading the ovarian stroma with a corpus luteum (arrow). Scale bar: 1 mm. (F) Immunohistochemical labelling of inhibin for detection of the corpus luteum (arrows). Scale bar: 1 mm. (G, H) In the hematoxylin-eosin staining, the corpus luteum, detected using immunohistochemical labelling of inhibin, was composed of the granulosa-lutein (white arrows) and theca-lutein cells (black arrows). Scale bars: 200 and 100 μm, respectively.

Fig. 3

A diagram depicting the proposed mechanism underlying this case of extrafollicular ovarian pregnancy. It is speculated that oocyte ovulation in the right ovary and embryonic development and backflow from the fallopian tube resulted in invasion of the ipsilateral ovary.