Implantation of a pregnancy outside of the endometrium, collectively referred to as an ectopic pregnancy, complicates approximately 2 % of pregnancies [2]. Nontubal ectopics are especially concerning since they may present late and/or be more vascularized with a higher risk of life threatening bleed- ing if they rupture. Primary ovarian ectopic pregnancy (OEP) is a rare form of ectopic pregnancy, estimated to occur in 3.6 % of all ectopic pregnancies [3]. The etiology of primary OEP remains unknown and can occur in the absence of risk factors.
Embryo migration from the fallopian tube has been described as a potential mechanism of an ovarian ectopic [4]. A review by Joseph and Irvine reported that contraceptive intrauterine devices and assisted reproductive technology each accounted for roughly 20 % of all ovarian ectopic pregnancies [5].
Since many women with ectopic pregnancies are asymptom- atic, early diagnosis of ectopic pregnancy, especially nontubal ectopic pregnancies, requires a high index of suspicion and a
skilled ultrasonographer. Abdominal pain and vaginal bleeding are presenting symptoms of an ectopic pregnancy regardless of the location, making it difficult to distinguish an OEP from both tubal and nontubal pregnancies. Failure to diagnose an OEP can be catastrophic due to potential rupture of the ovary and subsequent internal bleeding, dramatically increasing the likelihood of need- ing major surgical intervention alongside loss of the ovary. Indeed, ruptured ectopics may present with an acute abdomen, shoulder pain (secondary to diaphragmatic irritation), and even hypovole- mic shock secondary to the hemoperitoneum [5].
The classic diagnosis of an OEP was confirmed surgically by the original four Spiegelberg criteria (1878): (1) the ipsilateral fallo- pian tube and fimbria are intact and separate from the ovary, (2) the gestational sac is in the normal position of the ovary, (3) the ges- tational sac is connected to the uterus by the ovarian ligament, and (4) ovarian tissue must be attached to the specimen and within the gestational sac. Although the classic definitive diagnosis of an OEP depends on these histopathologic findings obtained surgically [6], advances in transvaginal sonography have led it to become a key diagnostic tool in ovarian, as well as other, ectopic pregnancies.
Ovarian pregnancies classically appear as a hypoechoic cyst on or within the ovary and are characterized by a wide echogenic (hyper- echoic) outside ring [7]. A yolk sac or fetal pole is less commonly seen. Interestingly, approximately 70 % of ovarian ectopic pregnan- cies are not diagnosed, instead being mistaken as a ruptured corpus luteum or a hemorrhagic cyst due to their similar clinical features [6]. In the case presented here, OEP was diagnosed by sonographic evidence of a gestational sac and fetal pole with a measurable heart rate within the left ovary.
Management
Management strategies used for OEPs are similar to those used in tubal pregnancies [5]. Hemodynamic stabilization with imme- diate surgical management is appropriate with clinical features
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suggestive of a ruptured ectopic pregnancy in the unstable patient. The surgical approach is both patient- and surgeon-de- pendent, consisting of laparoscopy and/or laparotomy with the ultimate goals of removal of ectopic pregnancy tissue, achiev- ing hemostasis, and preservation of healthy ovarian tissue [8].
Historically, OEPs were treated via removal of the entire ovary or by wedge resection attempting to conserve some remaining healthy ovarian tissue [9]. Postoperative methotrexate may be considered with concern for residual trophoblastic tissue fol- lowing surgery in appropriate patients [5].
Primary medical treatment can be considered in hemodynamically stable patients. Although medical manage- ment of OEP with systemic methotrexate has been successful [10], concern for treatment failure requiring emergent sur- gery exists [11]. This is especially true with the presence of a fetal heart suggesting an advanced pregnancy. Administer- ing intramuscular (IM) medical therapy may avoid surgical intervention; however, monitoring for resolution of the pro- cess may take a week or longer and this can be stressful for both provider and patient.
Evolution of care now often permits an earlier diagnosis, which allows for consideration of conservative nonsurgical management [1]. Local instillation of methotrexate, KCl, or hy- perosmolar glucose under ultrasound guidance provides many advantages including limited systemic toxicity, higher concen- tration of chemotherapy at the ectopic site, and direct visualiza- tion of immediate ectopic disruption [12]. Treatment of OEP by transvaginal ultrasound-guided aspiration of the pregnancy followed by local administration of methotrexate, may be espe- cially valuable in the presence of a fetal heart. Advantages are a shorter interval to establish treatment efficacy (with immediate cessation of fetal heart activity) alongside still avoiding a surgi- cal approach which, independent of the additional morbidity associated with a laparoscopy or laparotomy, might culminate in removing the ovary [1].
Outcome
Following a discussion of treatment options, with desired fertility in mind, the patient opted for a conservative nonsurgical interven- tion. Under intravenous sedation via transvaginal ultrasound guid- ance, the ovarian gestational sac was aspirated with a 17-gauge in vitro fertilization needle. A total dose of 50 mg of methotrexate was instilled locally into the ectopic after which the corpus luteum cyst was disrupted. Immediate cessation of fetal heart activity was noted. A follow-up transvaginal ultrasound 1 week later confirmed adequate treatment and serum hCG levels steadily declined to an undetectable level within 8 weeks [1]. The patient subsequently conceived an intrauterine pregnancy and delivered a healthy child.
Clinical Pearls/Pitfalls
• The original four Spiegelberg clinical criteria for the diagnosis of OEP are outdated because they require surgical intervention for evaluation and historical guidelines and treatment regimens should be reconsidered.
• Advances in transvaginal sonography may permit earlier diag- nosis of ovarian ectopic pregnancies.
• When ectopic pregnancy is suspected, a thorough sonographic evaluation for nontubal ectopics, including ovarian, interstitial, cesarean section (C-section), and cervical sites is indicated.
• Ovarian ectopic pregnancies are commonly mistaken for corpus luteum cyst.
• Nonsurgical treatments of ovarian ectopic in a hemodynami- cally stable patients are a safe and effective minimally invasive option to be considered
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