Ans. is 'b' i.e. Postnatal scarring may occur even in the absence of urinary tract infections Also see Nov. 98 (Q. no. 117), June 2004 (Q. no. Ill) Nov 2004 (Q. No. 122)Although UTI is the most important cause for scarring and nephropathy in pts. of VUR, scarring can occur even in the absence of UTI due to pressure-effect of reflux on the renal tissue.Other optionsOption a : Renal scarring usually begins in the polar region of the kidneys.Option d: Trimethoprim - sulfamethoxazole (Septra, Bactrim) is the DOC for prophylaxis.* Prophylactic AntibioticAmoxycillin or ampicillin is DOC for prophylaxis for children upto 6 wks of age After 6 wks, trimethoprim-sulfamethoxazole is the prophylactic DOC [this is because after 6 wks, the biliary system of the newborn becomes mature enough to handle trimethoprim-sulfamethoxazole. Nitrofurantoin (Macrodantin) is another acceptable option for prophylaxis.Medications are usually given as suspensions once daily at one-half the standard therepeutic dose. Night-time dosing in toilet trained children is most effective because it precedes the longest period of urinary retention, when infection is most likely to develop.Options in children who develop allergy to above drugs are - nalidixic acid, trimethoprim alone and cephalosporium.Option c : Grade IV-V primary VUR is unlikely to resolve spontaneously particularly if detected in children more than 1 yr of age. A medical management in them is usually ineffective.