Inferior vena cava agenesis: Clinical presentation, imaging characteristics, and midterm outcomes with a proposed diagnostic algorithm

Objective Inferior vena cava agenesis (IVCA) is a rare developmental venous anomaly associated with proximal deep vein thrombosis (DVT) in young patients. Evidence guiding diagnostic and therapeutic strategies remains limited. We evaluated clinical presentation, imaging characteristics, management approaches, and midterm outcomes of patients with IVCA. Methods We performed a retrospective review of patients diagnosed with IVCA between January 2020 and January 2025 at a tertiary referral center. Demographics, thrombotic events, imaging findings, associated anomalies, treatment strategies, and follow-up outcomes were analyzed descriptively. Results Eight patients were identified (87.5% male; mean age 35.8 ± 13.1 years). Six (75%) were symptomatic, most commonly with lower-extremity swelling (50%) and pain (37.5%). Iliofemoral DVT occurred in two patients (25%); superficial thrombophlebitis occurred in one (12.5%). Pulmonary embolism was not observed. Diagnosis was established primarily by computed tomography (87.5%). Anatomical subtypes included infrarenal (50%), complete (37.5%), and suprarenal agenesis (12.5%). One patient had thrombophilia with associated cardiac and renal anomalies. Over a mean follow-up of 3.5 ± 2.33 years, no recurrent DVT or new venous insufficiency occurred. Conclusions IVCA should be suspected in young patients presenting with unexplained proximal DVT. Cross-sectional imaging is essential for definitive diagnosis. Individualized, risk-adapted management appears safe in the midterm; however, standardized therapeutic guidelines are lacking.