Hydronephrosis – Symptoms and Causes

Overview

Hydronephrosis refers to the swelling that occurs in one or both kidneys when urine cannot properly drain and begins to build up.

This condition typically results from either a blockage in the urinary drainage tubes or from structural differences present since birth that affect proper urine flow.

Without treatment, some cases may lead to kidney damage over time. This condition can affect people of all ages.

Signs and Symptoms

Hydronephrosis often develops without noticeable symptoms, especially in mild cases. When symptoms do appear, they typically relate to the underlying cause of the kidney swelling.

Common symptoms may include:

• Pain in the side or back (flank pain)
• Abdominal pain that comes and goes
• Nausea and vomiting
• Urinary symptoms:
  • Painful urination
  • Frequent urination
  • Urgent need to urinate
  • Blood in urine

In severe cases, patients might experience:

• Fever and chills (if infection is present)
• Decreased urine output
• Complete inability to urinate

Symptoms in babies may be harder to detect but can include:

• Irritability
• Poor feeding
• Failure to thrive
• Urinary tract infections

The intensity of symptoms often relates to how quickly the condition develops. Sudden blockages typically cause more severe pain than slowly developing obstructions, which might go unnoticed until a healthcare provider discovers them during an examination for another issue.

If you experience persistent flank or abdominal pain, especially with urinary changes, contact your healthcare provider.

Causes

Hydronephrosis happens when urine can’t flow properly from the kidney to the bladder, causing urine to back up in the kidney.

Several issues can block the normal flow of urine. Kidney stones are hard mineral deposits that can get stuck in the ureter (the tube connecting the kidney to the bladder). These stones block urine flow, forcing it back into the kidney.

Ureteropelvic junction blockage is a condition where the connection between the kidney and ureter becomes narrow or blocked. This narrowing is often present from birth, but sometimes develops later in life.

Blood clots, tumors, or scar tissue can also cause blockages in the urinary tract. Pregnancy can lead to temporary hydronephrosis as the growing uterus puts pressure on the ureters.

Other common causes include:

• Enlarged prostate in men (especially those over 50)
• Urinary tract infections that cause swelling
• Neurogenic bladder where nerve problems affect bladder function
• Vesicoureteral reflux where urine flows backward from the bladder to kidneys

Sometimes, cancer of the bladder, prostate, or reproductive organs can press against the ureters and block urine flow. About 1 in 100 pregnancies develop some degree of hydronephrosis, though it usually resolves after delivery.

Risk Factors

Several factors can increase a person’s chance of developing hydronephrosis. These risk factors vary by age and other health conditions.

Age-Related Factors:

• Older adults face a higher risk due to prostate enlargement in men and pelvic organ prolapse in women
• Babies may develop this condition before birth due to urinary tract abnormalities

Health Conditions that Increase Risk:

• Kidney stones
• Blood clots in urinary tract
• Urinary tract infections (UTIs)
• Pregnancy
• Tumors in the abdomen or pelvis
• Enlarged prostate

People with a history of pelvic or abdominal surgery face a higher risk because scar tissue can block urine flow. Those with neurological disorders affecting bladder function may also experience this condition more frequently.

Complications

Hydronephrosis can lead to several serious problems if not treated promptly.

Kidney damage often occurs when urine backs up into the kidney, causing pressure that harms kidney tissues. This damage may become permanent with time.

Urinary tract infections happen more frequently in people with hydronephrosis. The trapped urine creates an ideal environment for bacteria to grow.

These infections can spread to the kidneys (pyelonephritis) and sometimes enter the bloodstream, causing a dangerous condition called sepsis.

Kidney stones may form or grow larger due to urinary stasis. When urine doesn’t flow properly, minerals can crystallize and form painful stones that further block drainage.

Some patients develop chronic pain that affects their quality of life. This pain typically occurs in the back or side and can range from mild discomfort to severe, debilitating pain.

Children with untreated hydronephrosis may experience growth problems and developmental delays. Pregnant women with hydronephrosis face additional risks, including an increased chance of preterm labor and pregnancy complications.