Prenatal Hydronephrosis

I am a 245 days / 8 months & 5 days old baby

The term prenatal hydronephrosis refers to dilation of the renal collecting system. The collecting system is the structure that collects urine directly from the kidney tissue and routes it by way of the ureter to the bladder. Hydronephrosis is also known as "swelling of the kidney".

Routine use of maternal ultrasound has become more prevalent during the past decade allowing for urologists and pediatricians alike to be informed of possible kidney defects before birth.[1]

Causes of prenatal hydronephrosis can include a ureteropelvic junction (UPJ) obstruction (most common), vesicoureteral reflux, megaureter, or posterior urethral valves (found in males who may also have a dilated bladder on prenatal ultrasound).[2]


Hydronephrosis is typically diagnosed before birth in a prenatal ultrasound. It also may be suspected in a child who experiences a urinary tract infection or abdominal pain.

The most important diagnostic test is the ultrasound. This can show how dilated the kidney is, whether both kidneys are involved, and whether the ureter is also dilated or the bladder is distended. Additionally, the ultrasound can give valuable information about the appearance of the functioning part of the kidney.[3]

Treatment Options

Sometimes, hydronephrosis goes away without treatment. Often, mild cases do not adversely affect kidney function and require only monitoring. Treatment is required only when kidney function is impaired or the kidney becomes greatly enlarged. The underlying cause of hydronephrosis determines the course of treatment.[4]

[4] ibid