Editor,—Craig et al showed that timing of micturating cystourethrography (MCU) does not affect the detection and grading of vesicoureteric reflux (VUR) if the test is performed more than one week after diagnosis and treatment of a urinary tract infection (UTI).1 There is a view that early MCU may reveal a higher prevalence of VUR due to transient inflammatory changes at the level of the vesicoureteric junction.2 This is to some extent refuted by the work of Craig et al,1 however their study was unable to address the issue of VUR in the first week after diagnosis of UTI when the possibility of such a situation would seem greatest.

Further to the issue of transient VUR, it is assumed that its presence is insignificant, therefore justifying a policy of delaying MCU (whether for one week or six weeks). The logic which supports this strategy may be questioned. An opposing view could be that if UTI increases the likelihood of VUR at the time when the urine is infected, this may put the kidneys at risk in the same manner as more permanent VUR.2 Furthermore, such VUR will go undetected and the patient may not receive chemoprophylaxis. If such a child has another UTI, she or he may develop further temporary VUR putting the kidneys at risk once again. Perhaps this mechanism explains some of the renal scarring found in children investigated after UTI with normal MCU findings.

The issue of transient VUR needs to be progressed by further studies such as that of Craig et al, looking at MCU in the first week after UTI diagnosis, but not necessarily with the aim of dismissing transient VUR if it is found.