Hello! Thank you for the query. Minimal hydronephrosis - is simply dilatation of the renal pelvis. Such situation appears when the urine flow is obstructed or impeded due to urinary tract stones or narrow ureter, or compression of the ureter. As your brother has only minimal hydronephrosis, most likely it wont be necessary to do anything with it, however urologist consultation and observation is recomended. Extrarenal pelvis - means that some part of your brother pelvis lies outside the kidney. If no obstruction is present, no correction is necessary. Depending of where the pain is located, your brother may suffer from urinary tract stones (lower abdominal pain, radiating to the one side back, frequent urinating, burning while urinating), peptic ulcer (upper middle abdominal pain - upper GI endoscopy is necessary to rule it out), appendicitis (upper middle abdominal pain which after few hours migrates to the lower right abdomen). I suggest you to consult urologist, have urine analysis and blood work performed. Hope this will help. Regards.