A 60-year-old Asian man was referred by a nephrologist with bilateral hydronephrosis on an ultrasound scan with a creatinine of 500 μmol/litre. The initial diagnosis from the referring doctor was of high-pressure chronic retention as he felt there was a palpable bladder. The patient was admitted and catheterised but only had a residual of <100 ml. His temperature and basic observations were normal and there was no evidence of infection on urine culture and routine blood tests. A non-contrast CT scan was suggestive of bilateral small kidneys, air in the bladder, ureters and kidneys (fig 1A,B). Air in any part of the urinary tract is usually seen in relation to an infective process from gas forming organisms,1 as a result of a fistula between the gastrointestinal tract and the urinary tract or as a result of recent instrumentation (eg, endoscopic surgery, urethral catheterisation). In this case there was no clinical/laboratory evidence of sepsis or history to suggest a fistula. Therefore we considered the possibility that the patient may have had undiagnosed bilateral vesicoureteric reflux (VUR) as the cause of his chronic renal impairment. We suspected this because air, as a result of urethral catheterisation on admission, had reached the upper tracts. We were able to confirm this by a subsequent cystogram (fig 2), which was also suggestive of a duplex system on the right. In retrospect, the bilateral hydronephrosis seen on an initial ultrasound (not shown) was likely to be reflux-related dilatation of the pelvic calyceal system. The approximate incidence of VUR in adults is 4%.2 Adults with VUR often deny a history of urinary tract infections (UTIs) in childhood, as in our case. Primary VUR occurs without any obvious pathology but in adults secondary VUR may be related to bladder outflow obstruction, neurological disorders or surgery (eg, renal transplant or ileal conduit formation).2

• Download figure
• Open in new tab
• Download powerpoint

Figure 1

A,B. Non-contrast CT scan showed presence of air in the upper tracts in both kidneys (straight arrows) and the right ureter (curved arrow). The kidney outlines show presence of scarring.

• Download figure
• Open in new tab
• Download powerpoint

Figure 2

Cystogram with evidence of bilateral grade 4 vesicoureteric reflux and duplex system on right.