A Rare Case of Sequential Contralateral Tubal Pregnancies

Bilateral tubal ectopic pregnancies are the rarest form of extrauterine pregnancy, with an incidence higher in women who are undergoing ovulation induction or assisted reproductive techniques. With an unpredictable clinical course and similar presentation to unilateral ectopic pregnancies, it is important to explore the possibility of bilateral tubal pregnancies with known risk factors. Early recognition is essential to prevent morbidity. We report a case of a 26-year-old gravida 3 para 2 female patient who presented to the emergency department with right lower pelvic pain and vaginal bleeding several weeks after a routine Papanicolaou (Pap) smear. The patient is sexually active, with a history of chlamydia and prior dilation and curettage for a medical abortion in 2023. Although she previously had a negative urine pregnancy test at her obstetrician-gynecologist (OBGYN), repeating testing in the emergency department revealed a positive urine pregnancy test and a serum human chorionic gonadotropin (β-hCG) of 1673.14 mIU/mL, with normal laboratory values. Review of systems is positive for abdominal pain and vaginal bleeding, and her physical exam is unremarkable with a soft, nontender, nondistended abdomen. The patient is discharged with resolved symptoms and a positive pregnancy test, with instructions to follow up with her OBGYN. Two days later, the patient returned for repeat testing, demonstrating a β-hCG 1795.46 mIU/mL, with a transvaginal ultrasound recording an ovoid structure adjacent to the right adnexa measuring 2.4 x 2.2 x 2.0 cm. Concern for ectopic pregnancy was raised given the <50% rise in β-hCG over 48 hours, and she underwent laparoscopic right salpingectomy for a confirmed right tubal ectopic pregnancy. Five days later, she returned to the emergency room for evaluation of weakness, dizziness, and increased vaginal bleeding. Repeat evaluation revealed an elevated β-hCG at 2,410.89 mIU/mL. A pelvic ultrasound was performed, which was unremarkable at the time with no evidence of intrauterine pregnancy or adnexal masses. Three days later, the patient received a repeat β-hCG, remarkable at 2,647.88 mIU/mL. A second β-hCG was recorded a day later, along with a follow-up transvaginal ultrasound. The hormone level is reported at 2,568.93, and the ultrasound showed a left adnexal mass separate from the ovary of variable echogenicity with a ring of vascularity, consistent with a left tubal pregnancy. This contralateral tubal pregnancy was successfully treated with methotrexate, and the patient recovered fully. This is a rare clinical presentation that is not well-reported in recent literature. For this patient, the sequential presentation of two tubal pregnancies suggests separate implantation events or delayed fertilization timing, resulting in an atypical bilateral ectopic course requiring different management strategies for each side. This case presents a rare instance of sequential contralateral tubal ectopic pregnancies, initially requiring surgical management on one side and subsequent medical management on the other. The case highlights the importance of maintaining a high index of suspicion for bilateral or sequential tubal pregnancies in at-risk patients, even after treatment of a confirmed unilateral ectopic pregnancy. This report highlights a rare presentation of sequential contralateral tubal ectopic pregnancies and discusses diagnostic and management considerations.