Ans. is 'b' i.e., Pyeloplasty Pelvi-ureteral junction (PUJ)/ureteropelvic (UPJ) o UPJ obstruction is the most common obstructive lesion in childhood and is the most common cause of hydronephrosis found on prenatal and early postnatal ultrasonography. o It 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. Presentation o Hydronephrois revealed by maternal USG (Dilated renal pelvis but normal ureter). o Palpable renal mass in new borns or infants. o Abdominal flank or back pain typically exacerbated by drinking large volumes of liquid. o UTI/Haematuria after minimal trauma. Epidemiology Left side more commonly involved than right (Bilateral = 10%). Male more commonly involved than females (M : F = 2 : 1). Initial Diagnosis by Ultrasonography o Hydronephrosis with dilated renal pelvis. Ureter i f visualized is of normal caliber (not dilated). Renal Differential function Nuclear Renography is used to determine Renal Differential function o A differential function of < 40% is considered significant and often an indication for surgical management. Management Management depends on the differential renal function and AP diameter of PUJ : - 1)Differential renal function > 40% especially when AP diameter of PUJ < 30 mm --> Conservative treatment. 2)Differential renal function < 40% especially when AP diameter of PUJ > 30 MM Surgical treatment is indicated. Pyeloplasty is the surgical procedure of choice. Other surgical procedures used are external drainage (nephrostomy), endopyelotomy and nephrectomy. o Differential function of < 10% is often considered as an arbitary cut off for nephrectomy.