# Colocaval Fistula: A Unique Case Report

## TL;DR

A rare case of a fistula connecting the inferior vena cava and the sigmoid colon is reported for the first time in medical literature.

## Contribution

This is the first reported case of an intraperitoneal colocaval fistula.

## Key findings

- A fistula was diagnosed between the inferior vena cava and the sigmoid colon in an 82-year-old female.
- The case represents the first documented intraperitoneal colocaval fistula in medical literature.

## Abstract

Fistula formation is a connection between anatomic locations that is intrinsically abnormal. A variety of causative etiologies and involved structures exist for these anomalous developments. Fistulas between vasculature and the enteric system are rare. When present, anatomical proximity is the dominant factor in determining which structures are involved. Aortoenteric fistulas involving the esophagus, duodenum, and small bowel are well-known with the stomach also being involved in rare instances. Fistulas involving the inferior vena cava (IVC) and enteric system have also been seen with the stomach, small bowel, and intrathoracic colon following an interposition each represented in reported cases. We present a case of an 82-year-old female with multiple medical comorbidities including opioid dependence, chronic constipation, recurrent lower extremity deep venous thrombosis, recurrent upper gastrointestinal (GI) bleeding, and IVC filter dependence who developed a unique problem. Her presenting complaints were nonspecific, but ultimately a diagnosis of fistula formation between the IVC and sigmoid colon was made. The colocaval fistula described here is the first intraperitoneal case to be reported in the body of literature.