1. The utility of DMSA scans in culture positive febrile urinary tract infections (UTI) has been well documented for diagnosing acute pyelonephritis (APN) (2-4). In our study 32 children had first episode of UTI and 10 had recurrent infections with positive urine cultures. Of the 33 children with VUR, 11 had grade I-II VUR and 22 had grade III-V VUR, 17 children were less than 2-years-old.

The gold standard investigation for documenting APN is DMSA scan. Renal ultrasonogram (RUS) can be normal in the presence of APN. The sensitivity of RUS for APN is low, in all age groups between 5-7%. The advantage of a DMSA scan in the early stages of infection is to document pyelonephritis and institute appropriate antibiotics. It gives an edge to the clinician to detect early the children at risk for renal damage and recurrent infection thereby preventing future sequelae(6). It has been shown in our study that early diagnosis of APN by the DMSA helped to diagnose vesicoureteric reflux (VUR) in a good percentage.

The association of renal dysplasia with VUR and UTI has been well documented particularly in children less than 2 years. DMSA done in the acute phase can help differentiate between dysplastic kidney with VUR and UTI, and APN with VUR in a structurally normal kidney(7). Delayed DMSA may lead to mistaken impression that a scarred kidney could be due to improperly treated APN where in reality it could have been a dysplastic kidney.

2. We have stated in our article that DMSA scan is a relatively inexpensive investigation needing no preparation to diagnose a serious infection like APN. On diagnosing APN with DMSA, full therapy is given for 14 days followed by chemo-prophylaxis. In the absence of DMSA evidence of APN, physicians may be reluctant to give the full course of antibiotic therapy and not convinced to give chemoprophylaxis resulting in progressive renal damage and sequelae of ESRD. The benefits of longer intravenous therapy in those patients with DMSA abnormalities during acute phase of infection(8). Management of ESRD is not economically viable and stress is being laid on utmost priority for preventive measures. It is agreed that the IPNG does not recommend routine VCUG in 2-5 years age group(9). However, in our study, out of 19 children less than 2 years of age, 17 had VUR and of 13 children between 2 and 5 years 12 had VUR. This strongly favors that this group needs further evaluation. For the same reason evaluating a child with both DMSA scan and VCUG above 5 years with an abnormal ultrasound in a first attack of febrile UTI or following recurrent UTI even with a normal ultra-sound is justified. Contrastingly, studies done in this group with first symptomatic UTI have shown high frequency of scintigraphic abnormalities and a strategy based only on ultrasound data would miss about 50% of the abnormal kidneys(10). It is only a conjecture that most patients with some scarring on an acute DMSA scan may not have any long term implication. This new experience gained away from the consensus statement will help in future to modify or to be considered for modification of the existing consensus statement. No consensus can be alive if experience is not added to the existing guidelines. We differ from the view of the reader that nuclear scan is highly radio-toxic. It is relatively less radiotoxic compared to intravenous urography and VCUG. DMSA scan has replaced IVU as a standard technique for the detection of renal inflammation and scarring for many years and its gonadal toxicity is negligible.

3. Regarding the need for DMSA scan in culture negative fever of unknown origin (FUO) it is mentioned in our study that the entry into the study was the DMSA positivity and hence 100% positivity of DMSA in the study group and it can be considered as an inclusion criteria. It is also mentioned that children were evaluated for FUO in the medical units and had DMSA scan on the basis of the clinicobiological features. No attempt was made to study the number of children who had DMSA scan prior to referral to the nephrology department. Hence it is difficult to state the number of children who were initially evaluated. It is stated by the reader from the literature that the prevalence of UTI in children <2 years without any focus for fever is about 4%(11). This is what we also stress through our article on including pyelonephritis as a possibility in FUO especially when clinical and biological features as mentioned in our study were present. In culture negative APN all 9 children who had normal ultrasound did not have normal VCU. Out of 26 children in the group of culture negative APN, 17 had VUR. Grading of reflux in them and the age group is given in Table I. Though the advantage of resolution of VUR is more in lower grades, the renal damage is not always proportionate to the degree of reflux from our experience.