Caption =
DiseasesDB = 6145
ICD10 = ICD10|N|13|0|n|10-ICD10|N|13|3|n|10
ICD9 = ICD9|591
MedlinePlus =
eMedicineSubj =
eMedicineTopic =
MeshID = D006869

Hydronephrosis is distention and dilation of the renal pelvis and calyces, usually caused by obstruction of the free flow of urine from the kidney, leading to progressive atrophy of the kidney.Cite book | author=Kumar, Vinay; Fausto, Nelson; Fausto, Nelso; Robbins, Stanley L.; Abbas, Abul K.; Cotran, Ramzi S. | authorlink= | title=Robbins and Cotran Pathologic Basis of Disease | date=2005 | edition=7th| publisher=Elsevier Saunders | location=Philadelphia, Pa. | isbn=0-7216-0187-1 | pages=1012-1014]

igns and symptoms

The signs and symptoms of hydronephrosis depend upon whether the obstruction is acute or chronic, partial or complete, unilateral or bilateral. Unilateral hydronephrosis may occur without any symptoms, while acute obstruction can cause intense pain.

Blood tests can show raised creatinine and electrolyte imbalance. Urinalysis may show an elevated pH due to the secondary destruction of nephrons within the affected kidney.

Symptoms that occur regardless of where the obstruction lies include loin or flank pain. An enlarged kidney may be palpable on examination.

Where the obstruction occurs in the lower urinary tract, suprapubic tenderness (with or without a history of bladder outflow obstruction) along with a palpable bladder are strongly suggestive of acute urinary retention, which left untreated is highly likely to cause hydronephrosis.

Upper urinary tract obstruction is characterised by pain in the flank, often radiating to either the abdomen or the groin. Where the obstruction is chronic, renal failure may also be present. If the obstruction is complete, an enlarged kidney is often palpable on examination.


The obstruction may be either partial or complete and can occur anywhere from the urethral meatus to the calyces of the renal pelvis.

The obstruction may arise from either inside or outside the urinary tract or may come from the wall of the urinary tract itself. Intrinsic obstructions (those that occur within the tract) include blood clots, stones, sloughed papilla along with tumours of the kidney, ureter and bladder. Extrinsic obstructions (those that are caused by factors outside of the urinary tract) include pelvic or abdominal tumours or masses, retroperitoneal fibrosis or neurological deficits. Strictures of the ureters (congenital or acquired), neuromuscular dysfunctions or schistosomiasis are other causes which originate from the wall of the urinary tract.


Blood (U&E, creatinine) and urine (MSU, pH) tests should be taken. IVUs, ultrasounds, CTs and MRIs are also important tests. Ultrasound allows for visualisation of the ureters and kidneys and can be used to assess the presence of hydronephrosis and/or hydroureter. An IVU is useful for assessing the position of the obstruction. Antegrade or retrograde pyelography will show similar findings to an IVU but offer a therapeutic option as well.

The choice of imaging depends on the clinical presentation (history, symptoms and examination findings). In the case of renal colic (one sided loin pain usually accompanied by a trace of blood in the urine) the initial investigation is usually an intravenous urogram. This has the advantage of showing whether there is any obstruction of flow of urine causing hydronephrosis as well as demonstrating the function of the other kidney. Many stones are not visible on plain xray or IVU but 99% of stones are visible on CT and therefore CT is becoming a common choice of initial investigation. MRI is less commonly used, often when there is a reason to avoid radiation exposure, e.g. in pregnancy.


Left untreated, bilateral obstruction (obstruction occurring to both kidneys rather than one) has a poor prognosis.


Treatment of hydronephrosis focuses upon the removal of the obstruction and drainage of the urine that has accumulated behind the obstruction. Therefore, the specific treatment depends upon where the obstruction lies, and whether it is acute or chronic.

Acute obstruction of the upper urinary tract is usually treated by the insertion of a nephrostomy tube. Chronic upper urinary tract obstruction is treated by the insertion of a ureteric stent or a pyeloplasty.

Lower urinary tract obstruction (such as that caused by bladder outflow obstruction secondary to prostatic hypertrophy) is usually treated by insertion of a urinary catheter or a suprapubic catheter.


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Look at other dictionaries:

  • Hydronephrosis — Hy dro*ne*phro sis, n. [NL., Gr. y dwr water + ? a kidney.] (Med.) An accumulation of urine in the pelvis of the kidney, occasioned by obstruction in the urinary passages. [1913 Webster] …   The Collaborative International Dictionary of English

  • Hydronephrosis — Distention of the kidney with urine. Due to obstruction of urine outflow (for example, by a stone blocking the ureter, the tube going * * * Dilation of the pelvis and calices of one or both kidneys. This may result from obstruction to the flow of …   Medical dictionary

  • hydronephrosis — n. distension and dilatation of the pelvis of the kidney. This is due to an obstruction to the free flow of urine from the kidney. An obstruction at or below the neck of the bladder will result in hydronephrosis of both kidneys. The term primary… …   The new mediacal dictionary

  • hydronephrosis — /huy droh neuh froh sis/, n. Pathol. dilation of the branches and pelvic cavity of the kidney, caused by an accumulation of urine resulting from obstruction of normal outflow. [1840 50; HYDRO 1 + NEPHROSIS] * * * …   Universalium

  • hydronephrosis — noun distension of the kidneys due to obstruction in the flow of urine See Also: hydroureteronephrosis …   Wiktionary

  • hydronephrosis — hy·dro·ne·phro·sis …   English syllables

  • hydronephrosis — Abnormal enlargement of a kidney, which may be caused by blockage of the ureter (such as by a kidney stone) or chronic kidney disease that prevents urine from draining into the bladder …   English dictionary of cancer terms

  • hydronephrosis — noun accumulation of urine in the kidney because of an obstruction in the ureter • Hypernyms: ↑pathology …   Useful english dictionary

  • hydronephrosis of pregnancy — hydronephrosis due to pressure against the ureter by the pregnant uterus …   Medical dictionary

  • infected hydronephrosis — hydronephrosis that has become complicated by bacterial infection; see also pyonephrosis …   Medical dictionary