Hydronephrosis is not an illness in and of itself. Rather, it usually is a symptom of an illness or another underlying factor that causes hydronephrosis. Hydronephrosis can result from any of the following conditions:

• Blockage that is present at birth
• Blood clot
• Enlarged prostate (from benign prostatic hypertrophy (BPH) or prostate cancer)
• Kidney stone
• Pregnancy
• Scar tissue from a surgery or injury in the past
• Tumor, benign or cancerous, in the pelvic region
• Pelvic organ prolapses
• Unilateral obstructive uropathy, either acute (a sudden onset) or chronic (recurring over time)
• Urinary tract infection (UTI)
• Vesicoureteral reflux (urine that flows backward from the bladder to the kidney).
• Symptoms of hydronephrosis
• Symptoms of hydronephrosis vary in severity depending on how long a person has had the condition. As fluid buildup increases, symptoms are likely to become more severe.

Initially, people might notice they are urinating more often. Some people also feel an increased urge to urinate.

The main symptom of hydronephrosis is pain in the side and back (called flank pain), as well as groin and/or abdomen pain.

Other symptoms may include:

• UTI
• Increased urge to urinate or increased frequency of urination
• Pain during urination
• Incomplete urination
• Incontinence
• Queasiness or vomiting
• Abdominal mass (a lump and/or heaviness in the abdomen)
• Diagnosis of hydronephrosis

To diagnose hydronephrosis, a physician asks about a person’s symptoms and medical history. The doctor may feel (palpate) the patient’s back, side and abdomen and may be able to feel that the kidney is swollen.

Often hydronephrosis is diagnosed with an ultrasound test. This test uses sound waves to create an image of internal organs, such as the kidney. The ultrasound scan can tell the doctor whether the kidney is shaped unusually, whether obstructions are visible and whether unusual fluid is present.

Treatment of hydronephrosis

The treatment for hydronephrosis will depend on what has caused the kidney swelling. Some cases are resolved fairly simply. For instance, a UTI may be treated with antibiotics. If a kidney stone or other urinary stone is causing a blockage, the kidney stone may pass by itself, or may require other removal to eliminate the blockage.

It is especially important to seek treatment quickly if the person has only one kidney or such immune system disorders as HIV or diabetes. These individuals are at risk of requiring dialysis or a kidney transplant if hydronephrosis permanently damages the remaining kidney.