Hydronephrosis

Hydronephrosis describes urine-filled dilation of the renal pelvis and/or calyces as a result of obstruction.CT scan of bilateral hydronephrosis due to a bladder cancerMassive hydronephrosis as marked by the arrow.Renal ultrasonography of hydronephrosisStone causing hydronephrosisStone causing hydronephrosisUrine jetsPeripelvic renal cysts may look like hydronephrosis on non-contrast CT (left image). However, CT urography (at right) reveals non-dilated calyces and pelvises. Hydronephrosis describes urine-filled dilation of the renal pelvis and/or calyces as a result of obstruction. The signs and symptoms of hydronephrosis depend upon whether the obstruction is acute or chronic, partial or complete, unilateral or bilateral. Hydronephrosis that occurs acutely with sudden onset (as caused by a kidney stone) can cause intense pain in the flank area (between the hips and ribs). Historically, this type of pain has been described as 'Dietl's crisis'. Conversely, hydronephrosis that develops gradually will generally cause either attacks of a dull discomfort or no pain. Nausea and vomiting may also occur. An obstruction that occurs at the urethra or bladder outlet can cause pain and pressure resulting from distension of the bladder. Blocking the flow of urine will commonly result in urinary tract infections which can lead to the development of additional stones, fever, and blood or pus in the urine. If complete obstruction occurs, kidney failure may follow. Blood tests may show impaired kidney function (elevated urea or creatinine) or electrolyte imbalances such as hyponatremia or hyperchloremic metabolic acidosis. Urinalysis may indicate an elevated pH due to the secondary destruction of nephrons within the affected kidney. Physical examination may detect a palpable abdominal or flank mass caused by the enlarged kidney. Hydronephrosis is the result of any of several abnormal pathophysiological occurrences. Structural abnormalities of the junctions between the kidney, ureter, and bladder that lead to hydronephrosis can occur during fetal development. Some of these congenital defects have been identified as inherited conditions, however the benefits of linking genetic testing to early diagnosis have not been determined. Other structural abnormalities could be caused by injury, surgery, or radiation therapy.