What is the morbidity of hydronephrosis and hydroureter?

Updated: Dec 16, 2020
  • Author: Dennis G Lusaya, MD; Chief Editor: Bradley Fields Schwartz, DO, FACS  more...
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Long-standing hydronephrosis may be associated with obstructive nephropathy and renal failure. Patients with complete or severe partial bilateral obstruction also may develop acute kidney injury or chronic kidney disease. In the latter setting, the patient is often asymptomatic and the urinalysis results may be relatively normal or reveal only a few white or red blood cells. [7] Thus, urinary tract obstruction should be considered in all patients with otherwise unexplained renal insufficiency. The history may be helpful in some cases, possibly revealing symptoms of prostatic enlargement or prior malignancy or renal calculi.

Urinary stasis may result in infection, renal scarring, calculus formation, and sepsis.

Hypertension is occasionally induced by obstruction. The mechanism responsible for the elevation in blood pressure varies with the duration and type of obstruction. What remains unclear, however, is why the factors described below result in hypertension in only a minority of obstructed patients:

  • Acute, unilateral obstruction can cause hypertension via activation of the renin-angiotensin system; renal vein renin studies lateralize the increase in renin secretion to the obstructed kidney, a finding similar to that in unilateral renal artery stenosis. [8]

  • Renin secretion is usually normal in patients with bilateral urinary tract obstruction or obstruction of a solitary functioning kidney. [8] In this condition, renal failure leading to volume expansion is typically present; the elevation in blood pressure is probably volume mediated and resolves with the diuresis following correction of the obstruction.

  • The plasma renin activity is also typically normal in chronic unilateral obstruction, and the presence of the contralateral healthy kidney prevents both renal failure and fluid retention. [8] Furthermore, relief of the obstruction may not correct the hypertension. These observations suggest that the kidney may have incurred some permanent damage and that the elevation in blood pressure is unrelated to the renal disease.

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