An acute pelvic pain in high-altitude tourist: A case report of ruptured ectopic pregnancy with low β-human chorionic gonadotropin.

rationaleHigh-altitude acclimatization triggers physiological adaptations - such as increased ventilation, heart rate, and red blood cell production - to improve tissue oxygen delivery. These adaptations may obscure typical signs of hemorrhage, complicating the diagnosis of ruptured ectopic pregnancy in patients with low beta-human chorionic gonadotropin (β-hCG) levels. PATIENT CONCERNS: A 31-year-old woman developed sudden pelvic pain and mild vaginal bleeding on the third day of high-altitude travel (Qinghai-Tibet Plateau). DIAGNOSES: Initial evaluation at a local hospital indicated very low β-hCG and no intrauterine gestational sac, leading to a misdiagnosis of biochemical pregnancy. Hemoglobin stability and absence of red blood cell decline, combined with high-altitude physiological changes, further delayed diagnosis. A transvaginal ultrasound later identified a ruptured right fallopian tube ectopic pregnancy, confirmed surgically.

interventionsSurgical confirmation. OUTCOMES: The case underscores how high-altitude hematologic adaptations (e.g., masked anemia) and low β-hCG levels can mimic benign conditions, complicating timely detection. LESSONS: Ectopic pregnancy should remain a differential diagnosis in high-altitude travelers with abdominal pain, even with low β-hCG and stable hematologic parameters. Clinicians should be vigilant for ectopic pregnancy even with low β-hCG and stable hemoglobin in high-altitude travelers, as acclimatization may mask hemorrhagic signs.