Superfetation and heterotopic pregnancy: Case report of two rare phenomena coexisting and implications in the era of assisted reproductive technologies.

KEY CLINICAL MESSAGE: To raise awareness about the increasing incidence of superfetation and heterotopic pregnancy in patients with ovarian induction, their insidious symptoms of abdominal pain, anemia, and hemodynamic instability in early pregnancy, and the usefulness of transvaginal ultrasound (TVUS) and quantitative beta human chorionic gonadotrophin (b-hCG) for diagnosis.

ABSTRACT: Superfetation, occurrence of ovulation, fertilization, and implantation during an ongoing pregnancy and heterotopic pregnancy (HP) simultaneous presence of intrauterine and extrauterine pregnancies are infrequent phenomena. We report a case where both coexisted, challenges in diagnosis and management and association with the widespread use of assisted reproductive technologies (ARTs). A 32-year-old woman, who previously underwent ovulation induction therapy, presented with abdominal pain at 8 weeks pregnancy according to her last menstrual period. The patient had high quantitative serum beta-human chorionic gonadotropin (b-hCG) (30,883 mIU/mL). She was vitally stable and not anemic. Transvaginal ultrasound (TVUS) revealed two pregnancies at different gestational ages: an intrauterine pregnancy at 5 weeks and 3 days, and a right intact tubal ectopic pregnancy at 10 weeks and 5 days. Superfetation resulting in HP was then diagnosed. Subsequently, the patient underwent right laparoscopic salpingectomy. The intrauterine pregnancy progressed normally, resulting in delivery of a healthy full-term neonate via Cesarean section at 38 weeks. Superfetation is typically rare from suppression of follicular development and ovulation during pregnancy. Various theories have been proposed to explain its etiology, including polyovulation, delayed blastocyst implantation, and abnormal estrogen and b-hCG surges. In superfetation, an embryo resulting from a previous conception coexists with another embryo, either intrauterine, resulting in diamniotic dizygotic twins with significantly different gestational ages, or extrauterine resulting in HP. Despite being particularly challenging to diagnose because its presenting symptoms can overlap with those of other more common clinical conditions in early pregnancy, HP is increasingly seen with ARTs. In addition, the treatment of HP is versatile, ranging from expectant management to laparoscopic surgery. High level of suspicion for HP and superfetation is crucial in patients who, after ART, present with abdominal pain, hemodynamic instability, or anemia. Additionally, patients planning to undergo subsequent ART cycles should be thoroughly screened with b-hCG and TVUS to exclude an ongoing intrauterine or extrauterine pregnancy.