Double inferior vena cava with azygous continuation: A rare anatomical variant demonstrated on contrast-enhanced CT

Duplicated inferior vena cava (DIVC) is a rare congenital vascular anomaly first described in 1916 during autopsy, with a reported incidence ranging from 0.2% to 3% and intraoperative detection rates between 0.2% and 0.6%. Although usually asymptomatic and discovered incidentally, DIVC has significant implications during surgery and interventional procedures. We report the case of a 49-year-old female with type 2 diabetes mellitus, end-stage renal disease on regular hemodialysis, and a history of failed renal transplants, who presented with fever, cough, and acute respiratory distress. She was diagnosed with Streptococcus pneumoniae pneumonia and required intensive care admission with mechanical ventilation, vasopressor support, and dialysis. During recovery, she developed abdominal pain and diarrhea. Contrast-enhanced computed tomography of the abdomen ruled out gastrointestinal pathology but incidentally revealed a DIVC. Imaging demonstrated a normal right-sided inferior vena cava (IVC) and an additional left-sided IVC draining the left common iliac vein. The left renal vein drained into the left IVC, which ascended cranially with azygous continuation, ultimately draining into the superior vena cava, while a rudimentary venous connection was also noted between the right and left IVCs. The intrahepatic segment of the right IVC drained normally into the right atrium. This case highlights the incidental detection of a duplicated IVC with azygous continuation, a rare but clinically significant venous anomaly, and emphasizes that awareness of such variations is essential for surgeons, radiologists, and intensivists, particularly in the context of retroperitoneal surgery, transplantation, or IVC filter insertion, where unrecognized anomalies may increase procedural risk.