What is the most common cause of hydronephrosis in newborns?

From the Guidelines

The most common cause of hydronephrosis in newborns is ureteropelvic junction (UPJ) obstruction, accounting for approximately 10% to 65% of cases. This condition occurs when there is a blockage at the junction where the ureter connects to the renal pelvis, preventing normal urine flow from the kidney to the bladder 1. According to the study by the Journal of the American College of Radiology, UPJ obstruction is a significant cause of hydronephrosis, especially in cases with moderate or severe antenatal hydronephrosis 1.

Key points to consider:

• UPJ obstruction accounts for a significant percentage of hydronephrosis cases, ranging from 10% to 65% 1
• The risk of UPJ obstruction increases with the severity of hydronephrosis, with up to 35% of significant hydronephrosis cases attributable to UPJ obstruction 1
• Regular monitoring with ultrasound is essential to track the condition's progression and determine if intervention is necessary, especially in cases with abnormal findings on initial neonatal US 1

In clinical practice, it is crucial to exclude obstructive causes of hydronephrosis, including UPJ obstruction, especially when vesicoureteral reflux (VUR) is not present 1. The study highlights the importance of follow-up ultrasound between 1 and 6 months to re-evaluate a dilated urinary tract after bladder catheterization 1. By prioritizing the diagnosis and management of UPJ obstruction, clinicians can improve outcomes for newborns with hydronephrosis, reducing the risk of kidney damage and promoting optimal quality of life.

From the Research

Causes of Hydronephrosis in Newborns

• The most common cause of prenatally diagnosed hydronephrosis is ureteropelvic junction obstruction (UPJO) 2, 3, 4, 5, 6.
• UPJO is a condition where there is a blockage at the junction of the ureter and the renal pelvis, which can lead to a buildup of urine and cause hydronephrosis.
• Other causes of hydronephrosis in newborns include vesicoureteral reflux, which is a condition where urine flows backward from the bladder into the ureters 3.

Diagnosis and Management

• The diagnosis of hydronephrosis in newborns is typically made using ultrasonography, which can detect the presence of fluid in the renal pelvis and calyces 2, 3, 4, 5, 6.
• The management of hydronephrosis in newborns depends on the severity of the condition and the presence of any underlying causes, such as UPJO or vesicoureteral reflux 2, 3, 4, 5, 6.
• In some cases, surgery may be necessary to relieve the obstruction and prevent long-term damage to the kidney 3, 4, 6.
• In other cases, conservative management with regular monitoring and follow-up may be sufficient 2, 3, 4, 5, 6.