This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pediatrics
[{'content': 'A child presented with intermittent episodes of left sided flank pain. Ultrasonography reveals large hydronephrosis with dilated renal pelvis and cortical thinning with a normal ureter. Kidney differential function was observed to he 19% which of the following is the best management – \nSelect and explain. \nA. Nephrectomy, B. Pyeloplasty, C. External drainage, D. Endopylostomy', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Pelvi-ureteral junction (PUS)/ureteropelvic IUPJ) \n\nUPJ obstruction is the most common obstructive lesion in childhood and is the most common cause of hydronephrosis found on prenatal and early postnatal ultrasonography. •\nIt is most commonly caused by intrinsic stenosis of a segment of ureter which is usually localized to the region of pelviureteric junction. Other causes include ureteric folds & extrinsic obstruction by crossing lower pole vessels.\n\nPresentation\n\nHydronephrois revealed by maternal USG (Dilated renal pelvis but normal ureter).\nPalpable renal mass in new horns or infants.\nAbdominal flank or back pain typically exacerbated by drinking large volumes of liquid.\nUTUHaemanuia after minimal trauma.\nEpidemiology\nLeft side more commonly involved than right (Bilateral = 10%).\nMale more commonly involved than females (M : F = 2 : 1). \n\tInitial iagnosis by Ultrasonography\nHydronephrosis with dilated renal pelvis.\nUreter if visualized is of normal caliber (not dilated).\n\nRenal Differential function\nNuclear Renography is used to determine Renal Differential function\n\nA differential function of < 40% is considered significant and often an indication for surgical management. Management\nManagement depends on the differential renal function and AP diameter of PUJ :-\n\n\nDifferential renal function > 40% especially when AP diameter ofPILI <30 min -3 Conservative treatment.\nDifferential renal function < 40% especially when AP diameter of PUI > 30 MM —4 Surgical treatment is indicated. Pyeloplasty is the surgical procedure of choice. Other surgical procedures used are external drainage (nephrostomy), endopyelotomy and nephrectomy.\n\n\nDifferential function of < 10% is often considered as an arbitary cut off for nephrectomy.', 'role': 'assistant'}]