Hydronephrosis

Hydronephrosis is a medical condition where the kidney becomes enlarged due to a complete or partial obstruction in the outflow of urine. This results in the dilation of parts of the kidney that function to collect urine (renal pelvis and calyces). Hydronephrosis can affect one or both kidneys and can develop suddenly or gradually over time. This condition affects individuals of all ages including in fetuses during pregnancy.

Hydronephrosis can be caused by a wide variety of conditions, including congenital abnormalities of the urinary tract, kidney stones, tumors, narrowing of the ureters, bladder outlet obstruction, or pressure from nearby structures such as an enlarged prostate or the uterus during pregnancy. Hydronephrosis in children is most often caused by a structural abnormality while in adults, hydronephrosis is commonly caused by kidney stones, prostate enlargement, or cancer.

Symptoms of hydronephrosis differ among individuals depending on how quickly urine flow is blocked and whether the blockage is slowly or suddenly. Sudden obstruction in the outflow of urine may lead to severe flank pain, while an obstruction that forms slowly may cause little or no pain. Possible complications of hydronephrosis include urinary tract infections and kidney damage. Severe or prolonged obstructions can lead to irreversible kidney failure.

Diagnosis of hydronephrosis is usually made using a combination of clinical history, physical exam, and diagnostic bloodwork and imaging. Most commonly an ultrasound or CT scan may be used to confirm hydronephrosis and determine the cause of obstruction. Additionally, blood and urine tests may be used to assess kidney function and identify possible infection. Treatment focuses on removing the obstruction and may include anything from observation to catheter placement or surgery.

The outlook for hydronephrosis depends on the cause, severity, and duration of obstruction, as well as whether one or both kidneys are affected. When treated promptly, kidney function often recovers fully. However, long-standing or severe hydronephrosis, especially during early kidney development, can result in permanent kidney damage.