Vicarious urinary excretion of iodinated contrast in a Crohn's patient

Area of Science:

• Radiology
• Gastroenterology
• Urology

Background:

• Vicarious renal excretion of iodinated contrast from the bowel is an uncommon event.
• This phenomenon can be mistaken for pathology, particularly when evaluating for recto-vesical fistulas in patients with Crohn's disease.
• Accurate diagnosis is crucial to avoid unnecessary interventions.

Purpose of the Study:

• To report a case of Crohn's disease with suspected recto-vesical fistula.
• To highlight the potential for misinterpretation due to vicarious renal excretion of contrast.
• To demonstrate simple methods for correctly identifying and avoiding diagnostic errors.

Main Methods:

• A patient with Crohn's disease underwent a gastrografin enema to assess for a recto-vesical fistula.
• Initial interpretation of the imaging suggested a positive fistula.
• Elucidation methods were employed to clarify the findings.

Main Results:

• The initial interpretation of the gastrografin enema was a false positive for recto-vesical fistula.
• Subsequent analysis using simple techniques confirmed the absence of a fistula.
• The findings were attributed to vicarious renal excretion of contrast.

Conclusions:

• Vicarious renal excretion of bowel contrast can mimic recto-vesical fistulas in Crohn's disease.
• Awareness of this phenomenon and the use of simple diagnostic clarifications are essential.
• Correct diagnosis prevents misdiagnosis and inappropriate patient management.