Spontaneous Unilateral Twin Live Ectopic Pregnancy: A Systematic Review of Reported Cases, Diagnostic Challenges, and...

Unilateral twin live ectopic pregnancy is a rare and potentially life-threatening obstetric condition, marked by the implantation of two viable embryos within the same fallopian tube. These cases pose significant diagnostic and therapeutic challenges, particularly when fetal cardiac activity is present. This systematic review consolidates existing literature to explore the clinical presentation, underlying pathophysiology, diagnostic modalities, and management strategies associated with this uncommon condition, with a focused discussion on maternal outcomes. A comprehensive literature search was conducted across PubMed, Embase, Scopus, and the Cochrane Database of Systematic Reviews for articles published from January 1945 to May 2025. Both MeSH terms and non-MeSH keywords, including "Unilateral," "Twin," "Live," and "ectopic pregnancy," were used, yielding 503 records. After applying inclusion and exclusion criteria and manual screening, 17 case reports published between 1994 and 2023 were included for final analysis. Eligible studies were limited to English-language reports describing spontaneous unilateral twin ectopic pregnancies with confirmed fetal cardiac activity and adequate clinical details. Studies lacking these elements were excluded. The Joanna Briggs Institute (JBI) Critical Appraisal Checklist for Case Reports was used to assess the risk of bias (ROB) in this study. Due to the descriptive nature of the included studies, formal grading of evidence was not applied. All 17 included cases described women aged 24 to 44 years, typically presenting between six and 12 weeks of gestation with abdominal pain, vaginal bleeding, and amenorrhea. Transvaginal ultrasonography (TVUS) was the most frequently used diagnostic modality, revealing two gestational sacs with cardiac activity within a single fallopian tube. Serum serial β-human chorionic gonadotropin (β-hCG) levels were consistently elevated above the discriminatory threshold. In one particular case, advanced imaging such as magnetic resonance imaging (MRI) was used to clarify anatomy or assess rupture risk. All cases except one were managed surgically, most commonly through laparoscopic salpingectomy or salpingostomy. Methotrexate therapy was attempted in one case and is generally deemed inappropriate due to the presence of viable embryos. No concurrent intrauterine pregnancies were observed. Favorable maternal outcomes were reported in all cases when diagnosis and treatment were timely. Findings from this review are limited by the rarity of the condition, reliance on isolated case reports, and the lack of standardized diagnostic or treatment protocols. There is also potential for publication bias and underreporting of negative outcomes. Nonetheless, this review emphasizes the importance of early and accurate diagnosis using TVUS, supplemented by MRI when indicated, followed by prompt surgical management to optimize maternal safety. Increased awareness, reporting, and documentation of such rare presentations are crucial to guiding future clinical decision-making and preventing catastrophic complications. No external funding was received for this review. This review was not registered in any database due to its retrospective, descriptive nature.