A case report of tubal-ovarian pregnancy: the fetus in the fallopian tube and the placenta attached to the ovary

Abstract

Introduction and importance:

Heterotopic pregnancy (HP), defined as the coexistence of intrauterine and ectopic pregnancies, is a rare occurrence following natural conception or assisted reproductive technology (ART) procedures. Diagnosing HP can be challenging due to its rarity and often asymptomatic presentation.

Case presentation:

We present a case of HP in a woman with unexplained infertility who underwent in vitro fertilization-embryo transfer (IVF-ET). The HP involved an intrauterine pregnancy and a tubal-ovarian pregnancy (OP), which was diagnosed through combined sonography and managed conservatively via laparoscopy.

Clinical discussion:

The incidence of HP is rare, with reported incidences ranging from 1 in 10,000 to 1 in 50,000 naturally conceived pregnancies. Early detection of HP after ART is crucial for preserving intrauterine pregnancies and fertility potential, highlighting the importance of improved sonography imaging techniques.

Conclusion:

This case underscores the importance of vigilant monitoring for gynecologists treating IVF patients, not only regarding intrauterine pregnancies but also pregnancies of unknown location. Early and regular ultrasound monitoring, along with expertise in sonography, is essential for accurate diagnosis.

Introduction

Ectopic pregnancies (EP) most frequently occur in the fallopian tubes (95–98%), while rare presentations include interstitial, cervical, ovarian, and abdominal sites^[1]. Among these, HP – simultaneous intrauterine and extrauterine implantation – is exceedingly rare (incidence ~ 1:30,000 in spontaneous conceptions) but significantly higher in assisted reproductive technology (ART) populations (1–3%)^[2,3]. This report details an atypical tubal-ovarian HP after IVF-ET, emphasizing diagnostic challenges and preventive strategies in ART settings. This case has been reported in line with CARE criteria^[4].

Case report

A 28-year-old woman (gravida 0, para 0) was admitted to our hospital with suspected HP 79 days after undergoing IVF-ET. Two months prior, she had undergone controlled ovarian hyperstimulation followed by the transfer of two fresh embryos. Her medical history included two laparoscopic surgeries for appendicitis and intestinal tuberculosis, as well as 6 months of oral anti-tuberculosis medication for pulmonary tuberculosis. Diagnostic laparoscopy prior to IVF revealed bilateral hydrosalpinges with peritubal adhesions, consistent with sequelae of pelvic tuberculosis.

Highlights

• This case report describes a rare tubal-ovarian heterotopic pregnancy (HP) in a 28-year-old woman after IVF-ET.

• HP involves both intrauterine and ectopic pregnancies. The woman had a history of infertility, surgeries, and pulmonary tuberculosis.

• Following IVF-ET, she was found to have both an intrauterine pregnancy and an ectopic pregnancy in the left ovary.

• Emergency laparoscopy confirmed the tubal-ovarian pregnancy (OP), and surgery successfully removed the affected ovary and fallopian tube.

• The case highlights the importance of early ultrasound monitoring in assisted reproductive technology (ART) patients, the challenges in distinguishing ovarian from tubal pregnancy, and the need for careful monitoring to manage such complex pregnancies.

Serial serum β-hCG levels post-ET rose appropriately (Day 14: 1200 mIU/mL; Day 21: 18 000 mIU/mL). Initial transvaginal scan (TVS) at 1 month after ET, in another hospital showed an intrauterine gestational sac, but another month later, an intrauterine pregnancy and a suspected abdominal pregnancy were obtained. A repeated TVS on admission revealed an enlarged uterus with an intrauterine gestational sac (equivalent to 13⁺ weeks gestation) and a hypoechoic mass (12.4 × 9.22 × 6.27 cm³) in the left posterior of the cervical canal with an ectopic gestational sac with fetal pole (equivalent to 13⁺ weeks gestation), and ovarian echo can be seen around the mass (Fig. 1). Upon her admission, there were no symptoms or signs, and she was hemodynamically stable. However, acute abdominal pain suddenly occurred. An urgent examination of TVS showed ascites and a low echo area around the mass. Then, emergent laparoscopic surgery was managed.

Figure 1.

Two-dimensional ultrasound imaging. (A) An intrauterine pregnancy equivalents to 13⁺ weeks gestation. (B) In the left posterior of the cervical canal, an embryo echo with active fetal heart movement (equivalent to 13⁺ weeks gestation). UT, uterus; CX, cervical; PL, placenta; BL, bladder.

At laparoscopy, dense omentum and bowel adhesion from previous incision, approximately 100 ml of hemoperitoneum. As shown in Fig. 2, the left oviduct ampulla looked larger and swollen. The amniotic fluid effluxed from the punctured ampulla, and the fetus disassociated from the tubal. The umbilical cord was from the tubal fimbria end to the left ovarian cortex. A placenta was attached to the left ovary. Then, the diagnosis of tubal-ovarian pregnancy (OP) was established. Laparoscopic ovarian wedge resection and left tubal resection were performed. Pathological examination (chronic tubal inflammation, decay villi of the ovary, and chorionic villi of the placenta) confirmed the diagnosis (Fig. 3). The patient experienced term delivery and then birth control.

Figure 2.

Laparoscopic findings. (A) The left oviduct ampulla looked larger and swollen and demonstrated there was a fetus in it. (B) The normal pregnant uterus large as 13⁺ weeks gestation. (C) The umbilical cord was connected between the tubal fimbria end and the left ovarian cortex.

Figure 3.

Pathology. (A) Microphotograph showing inflammatory lesion of tubal (HE, 100 ×). (B) Chorionic villus embedded into the ovarian stroma. (C) Abundant chorionic villus were visible in the placenta. T, tubal; O, ovary; P, placenta; V, chorionic villi.

Discussion

HP, the concurrent presence of both intrauterine and extrauterine pregnancy, remains a rare occurrence, with reported incidences ranging from 1 in 10 000 to 1 in 50 000 naturally conceived pregnancies^[5,6]. However, there has been a notable increase in HP incidence, reaching 1−3% in EP^[2], largely attributed to advancements in ART, heightened occurrences of pelvic inflammatory disease (PID), and increased instances of tubal surgery among women^[3,7,8].

HP can manifest in two primary forms − synchronous and nonsynchronous − although the latter is relatively uncommon. Synchronous HP occurs when two zygotes are fertilized simultaneously or when a single zygote undergoes early cleavage, resulting in the implantation of one embryo in the uterine cavity and the other in an extrauterine location. In contrast, nonsynchronous HP involves the sequential implantation of embryos, with the intrauterine pregnancy typically advancing further in development than the ectopic one. This sequential development can lead to the misdiagnosis or oversight of HP. In our case, given the simultaneous transfer of two embryos and the absence of gestational age disparity between the intrauterine and ectopic pregnancies, synchronous HP was suspected.

Our findings align with prior studies such as HP with superfetation following ovarian stimulation^[9], two rare phenomena coexisting and implications in the era of ART^[10], and so on. However, the combination of intrauterine pregnancy with tubal-OP following IVF is exceptionally rare, with no reported cases documented. The development of the extrauterine fetus to 13 weeks gestation necessitates a robust blood supply, which is predominantly provided by the ovary rather than the fallopian tube. Upon late blastocyst implantation, trophoblastic cells initiate proliferation and chorion frondosum formation, crucial for placental development. In our case, the presence of the placenta solely attached to the ovary underscores its role as the primary site for trophoblastic proliferation and placental formation. Additionally, considering the patient’s history of pulmonary tuberculosis and prior surgeries, there is a plausible link between EP implantation and the ovary, as supported by existing literature^[11-13]. On the other hand, studies in ART have found that frozen embryo transfers are associated with a lower incidence of EP compared to fresh embryo transfers^[14]. Blastocyst transfers are also linked to a lower EP rate than cleavage-stage embryo transfers^[15]. Additionally, the occurrence of EP significantly decreases when the endometrial thickness at transfer is between 8 and 12 mm^[16]. Opting for single embryo transfers and placing embryos at least 10 mm away from the uterine fundus during transfer can further minimize the risk of EP^[17,18].

The sensitivity of TVS in diagnosing EP can range from 73% to 93%, primarily depending on the expertise of the gestational age, type of EP^[19], and sonographer^[4]. The sonographic features of OP typically manifest as a wide echo ring with an internal echo area on the surface of the ovary, often with the ovary appearing smaller than the ring. Additionally, the ovarian cortex may display follicles or corpus around one mass. However, distinguishing OP from the more common tubal location can be challenging. In the case presented here, the patient had sought care at various hospitals, and ultrasound follow-ups yielded variable results, failing to provide a clear diagnosis. Nonetheless, ultrasound played a crucial role throughout the treatment process. As Li et al emphasized, early and regular ultrasound monitoring, along with the expertise of the sonologist, are essential for accurate diagnosis, especially in women undergoing ART^[20]. Furthermore, the potential of three-dimensional (3D) ultrasound in diagnosing early and precise EP has been suggested^[21,22]. Ghi et al reported the identification of an OP using 3D imaging^[23]. In this case, peculiar sonographic findings on standard two-dimensional (2D) ultrasonography raised suspicion of OP, with clear visualization of ovarian echo around the mass. Utilizing 3D ultrasound may offer a standardized approach to sonographic diagnosis.

In our opinion, for patients with a history of EP, selecting a single frozen blastocyst transfer at an appropriate endometrial thickness while considering the details of the transfer technique may be an effective primary prevention measure to reduce the incidence of HP/EP in ART. Adherence to single blastocyst transfer protocols and meticulous post-ET surveillance are critical to mitigate HP risk. Careful monitoring is imperative up to three months after ET, particularly for ART patients with high-risk factors for EP or those who undergo the transfer of multiple embryos simultaneously. Highlights the necessity of comprehensive pelvic ultrasound evaluation after double embryo transfer, even with confirmed intrauterine pregnancy. When conventional 2D ultrasound fails to determine the location of the ectopic sac, alternative methods such as 3D ultrasound may provide a more definitive diagnosis. This case underscores the importance for gynecologists treating in vitro fertilization patients to remain vigilant not only regarding intrauterine pregnancies but also pregnancies of unknown location.

Strengths and limitations

This case provides novel insights into tubal-ovarian HP pathophysiology, particularly placental ovarian implantation. However, limitations include its retrospective design and missing pre-IVF tubal patency data. Generalizability is further constrained by the patient’s complex surgical history, necessitating validation through multicenter studies.

Ethical approval

This report was conducted in accordance with the ethical standards of the Second Hospital of Hebei Medical University (Approval No. 2024-P019).

Consent

Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request

Sources of funding

None.

Author contributions

X.Z.: acquisition of data, data analysis and interpretation, drafting of manuscript, and critical revision. X.Z.: conception and design of study, data analysis and interpretation. C.W.: acquisition of data, drafting of manuscript, and critical revision. L.Z.: conception and design of study, data analysis and interpretation, drafting of manuscript, and critical revision.

Conflicts of interest disclosure

The authors declared no conflict of interest with respect to the research, authorship, and/or publication of this article.

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Data availability statement

Not applicable to this article.