Hydronephrosis: Symptoms, Causes, Diagnosis and Treatment

It is literally “water inside the kidney”

This condition refers to distension and dilation of the renal calyces and pelvis, usually caused by obstruction of the free flow of urine from the kidney.

Signs and symptoms of hydronephrosis

These depend on whether the obstruction is acute or chronic, partial or complete, unilateral or bilateral. Intense pain in the flank area (between the hips and ribs). Nausea and vomiting. An obstruction that occurs at the exit of the bladder or urethra, may feel pain and pressure resulting from the distention of the bladder. Blood and fever or pus in the urine. If a complete obstruction occurs,

Blood tests may show renal failure (elevated creatinine) or electrolyte imbalances such as hyperchloremic metabolic acidosis or  hyponatremia .


  • Abnormalities in the structures that make up the junctions between the kidneys, the ureter and the bladder, this anomaly can happen during the development of the fetus.
  • These congenital defects have been identified as hereditary conditions, however the benefits of linking genetic tests for early diagnosis have not been determined.
  • The compression of one or both ureters can be caused by other developmental defects such as a vein, artery, or abnormally placed tumor. This bilateral compression of the ureters can occur in pregnancy because of the enlarged uterus.
  • Sources of obstruction that can arise from various other causes including kidney stones, blood clots or retroperitoneal fibrosis .
  • The reverse flow of urine from the bladder to the kidneys can also cause hydronephrosis. This reflux can be caused by some of the factors previously discussed, as well as compression of the exit of the bladder inside the urethra due to the enlargement of the prostate or the impaction of feces in the colon.


  • Prenatal diagnosis is possible, through ultrasounds obtained during pregnancy.
  • The diagnostic test depends on the age of the patient, as well as whether the hydronephrosis was detected prenatally, incidentally or is associated with other symptoms.
  • Blood tests (measurement of creatinine) are typically indicated, they must be interpreted with caution.
  • Urinalysis is usually performed to determine if blood is present, which is typical for kidney stones.
  • Imaging studies – intravenous urography (IVU), ultrasound, computed tomography or resonance.
  • Ultrasound allows visualization of the ureters and kidneys (determines the presence of hydronephrosis).
  • Finally, if hydronephrosis is significant and obstruction is suspected, such as a pyelourethral junction or urethrovesical junction, a nuclear imaging study such as a MAG-3 tomography is justified.

Treatment for Hydronephrosis

It focuses on eliminating the blockage and draining the accumulated urine behind the blockage. Therefore, the specific treatment depends on where the obstruction is located, and whether it is acute or chronic.

Acute obstruction of the upper urinary tract is commonly treated by inserting a nephrostomy tube . Obstruction of the chronic upper urinary tract is treated by inserting a Urethral Stent.
Surgery is not necessary in all cases.