Urine Gram Stain in the Early Detection of an Enterovesical Fistula

Enterovesical fistula (EVF) is a rare condition that can be difficult to diagnose due to its nonspecific symptoms, such as recurrent urinary tract infections (UTIs), pneumaturia, and fecaluria. We report a case of EVF in which early diagnosis was facilitated by clinically integrated interpretation of urine Gram stain findings in the context of the patient's overall presentation. An 89-year-old woman with a history of rheumatoid arthritis and long-term corticosteroid use presented with fever and right knee pain, initially suspected to be a rheumatoid flare. However, synovial fluid analysis was negative for infection or crystals, prompting further evaluation. Urinalysis revealed bacteriuria and leukocyturia, and urine Gram stain demonstrated a polymicrobial pattern with numerous polymorphonuclear leukocytes. Given the patient's clinical status and lack of common risk factors for polymicrobial colonization, the findings raised suspicion for fecaluria and a possible EVF. A contrast-enhanced computed tomography (CT) scan subsequently confirmed an EVF due to mucinous adenocarcinoma of the cecum invading the bladder. The patient underwent successful ileocecal resection and bladder fistula closure. Although not routinely used to diagnose EVF, urine Gram stain can provide early diagnostic clues when interpreted in real time alongside clinical findings. When polymicrobial patterns are observed in urine, especially in patients with recurrent or atypical UTIs, they may offer a critical diagnostic clue to EVF. In this case, the integration of polymicrobial patterns with bedside assessment led to early suspicion and imaging. The case also highlights how serious infections in older patients may present with atypical or misleading symptoms, emphasizing the need for diagnostic vigilance. This case highlights the potential utility of urine Gram stains as a rapid, cost-effective tool for the early detection of EVF. Clinicians should consider EVF in older adult patients with atypical UTIs, and interpret polymicrobial Gram stain findings in the clinical context to guide timely diagnosis and appropriate management.