Improved antenatal ultrasonography techniques have clearly been a factor in identifying collecting system dilation in the neonatal period. Obstruction is not necessarily the cause of hydronephrosis in the neonate; however, ureteropelvic junction (UPJ) obstruction is the most common cause of significant renal pelvis dilation in this age group (1). An exact etiology of UPJ obstruction has yet to be determined, but multiple hypotheses exist as to the cause of the obstruction. Incomplete recanalization of the proximal ureter, functional or anatomic obstruction, and developmental arrest are a few theories as to why obstruction occurs at the UPJ. Although the etiology of the obstruction may be unknown, the classification of obstruction can be divided into three categories: intrinsic, extrinsic, and secondary. Intrinsic UPJ obstruction is usually characterized by a stenotic or adynamic segment of ureter. Less commonly, intrinsic obstruction can be caused by mucosal folds or “flaps” (2). It has been estimated that 60% to 80% of persistent hydronephrosis in infants is secondary to intrinsic obstruction. Extrinsic obstruction most often occurs from an aberrant crossing vessel typically traveling to the lower pole of the kidney. This is a more common presentation in older children and adults. Secondary obstruction is rarer than extrinsic or intrinsic obstruction. It occurs when the ureter is severely dilated and tortuous from vesicoureteral reflux causing a “kink” in the ureter that acts as an impediment to urine flow. Over time, this area can become the site of significant periureteral scarring requiring surgical correction.


Indications to proceed to pyeloplasty at our institution include the following: severe hydronephrosis (Society for Fetal Urology grade III or IV) detected postnatally accompanied by <40% differential renal function with no response to furosemide on renal scan, worsening hydronephrosis on serial ultrasound, symptomatic UPJ obstruction, loss of relative renal function on serial renal scans (>10%), or persistent delay in drainage on serial diuretic renography in a child with severe hydronephrosis.


Multiple treatment options currently exist for the treatment of UPJ obstruction ranging from endopyelotomy to robotic pyeloplasty. At this time, endopyelotomy is not commonly performed in neonates and infants but has been used in preadolescent and adolescent children with some degree of success. It has also been demonstrated that endopyelotomy appears to be more successful as a secondary technique for failed pyeloplasty in children. However, more recent data suggest that redo pyeloplasty or ureterocalicostomy are more successful secondary treatments than endourologic procedures (4,5).

Pure laparoscopic or robotic-assisted laparoscopic pyeloplasty has gained significant popularity in the last decade, as the success rates, operative times, and hospital length of stay of these procedures are becoming comparable to open pyeloplasty (6,7). Robotic assistance has significantly decreased the learning curve for minimally invasive pyeloplasty by making intracorporeal knot tying a much simpler process. Although robotic pyeloplasty in small infants has been shown in the literature to be a successful operation, the open Anderson-Hynes pyeloplasty continues to be the gold standard for clinically significant UPJ obstruction in neonates and small infants with reported success rates consistently >90% to 95%. The most important factors in a successful pyeloplasty of any technique include formation of a funnel at the UPJ with dependent drainage and a tension-free anastomosis.

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Apr 24, 2020 | Posted by in UROLOGY | Comments Off on Pyeloplasty

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