Unique case of colovesical fistula in a renal allograft recipient

Colovesical fistula is commonly suspected in cases of diverticular disease, malignancy, trauma, iatrogenic injury or radiotherapy. In a case of allogenic live related transplant, this is rarely expected, especially after 20 years. The presence of gas in the bladder in the absence of history of instrumentation of urinary tract should prompt us to evaluate for colovesical fistula. Pneumaturia, faecaluria and recurrent urinary tract infection are tell-tale features of colovesical fistula, and when patients who are renal allograft recipient present with them, it should prompt a proper workup and swift surgical management, since the outcome is uniformly favourable. From our knowledge in this realm, we know that these are immunocompromised patients and have a high tendency to develop risk factors like malignancy and/or diverticular disease and eventually form colovesical fistula. An expected time period could be from 2 months to 6 years. But in our case, fistula formation occurred long after peak corticosteroid action, in the absence of conventional aetiologies.