Case Report: Concurrent left pyosalpinx and acute suppurative appendicitis after IVF-FET: a case initially misdiagnosed as heterotopic pregnancy.

Background: Patients conceived via Case presentation: A 24-year-old pregnant woman after IVF-FET presented with persistent hypogastric pain, and transvaginal ultrasound identified an adnexal complex mass. Heterotopic pregnancy (HP) and ovarian torsion were top differential diagnoses, prompting emergency laparoscopic exploration. Intraoperative findings ruled out ectopic gestation and confirmed an extremely rare concurrent lesion: left pyosalpinx combined with acute suppurative appendicitis. Intervention & outcome: The patient received laparoscopic left salpingectomy, appendectomy and extensive pelvic adhesiolysis, accompanied by perioperative antibiotics and tocolytic agents. Postoperatively, she developed hypertensive disorders of pregnancy (HDP), which may have been associated with the preceding severe pelvic suppurative infection and its systemic inflammatory response, although a causal relationship cannot be established from a single case and IVF-FET itself is a known risk factor for HDP. She finally delivered a healthy male neonate by cesarean section at 37⁺⁴ weeks of gestation without neonatal adverse outcomes. Conclusion: Gestational pyosalpinx is a rare entity that shares overlapping clinical and sonographic features with heterotopic pregnancy, leading to frequent misdiagnosis. Timely laparoscopic surgery safely eliminates infectious lesions while maintaining intrauterine pregnancy, representing an effective therapeutic strategy for such complicated cases. The observed temporal association between severe pelvic infection and subsequent HDP warrants further investigation.