Hydronephrosis is characterized by a warping or ballooning of the renal pelvis and calyxes in the kidney, caused by increased pressure inside the kidney due to a blockage to the free flow of urine. The renal pelvis is a funnel-like tube that forms the top of the ureter, the urine conduit from the kidneys to the bladder. The renal calyxes propel urine from the outside of the renal pelvis into the ureter.
Urine Blockage
Blockage of urine flow at any region of the ureter between the entrance to the bladder, to the renal pelvis and calyxes can lead to a build of pressure causing hydronephrosis. Flow of urine can be blocked by several artifacts within the kidney or ureter including blood clots, kidney stones, dead tissue and kidney or ureter tumors. External factors, including abdominal or pelvic tumors, can also cause this condition by applying pressure, blocking flow of urine through the kidneys and ureter, according to a 2007 article published in Merk Online Medical Library.
Symptoms and Complications
Although symptoms of hydronephrosis can be variable, kidney or flank pain is common in all instances. The kidney can become physically palpable from the skin of the abdomen in severe cases due the amount of enlargement. Hydronephrosis-induced damage to specialist kidney cells can alter levels of blood electrolytes, leading to changes in blood acidity, which in turn can cause heart failure. The severity of complications arising from hydronephrosis depends whether the blockage is complete or partial and if one or both kidneys are affected, according to the British National Health Service.
Treatment
Treatment of hydronephrosis often requires a two-pronged approach, involving drainage of urine from the urinary system and removal of the blockage. Blockages caused by tumors are removed predominately by surgical means, whereas blockages caused by kidney stones may be treated with drugs such as Allopurino. Locating the source of the blockage may take doctors some time, during which the pressure of urine in the kidney may be increasing with every passing hour, leading to an extremely poor prognosis. For this reason, urine is drained as quickly as possible using procedures such as nephrostomy, according to an article published in "Pediatric Nephrology."
Nephrostomy
When the location of the urine blockage is unknown, nephostomy is often used to drain urine directly out of the renal pelvis. In this procedure a catheter is inserted through the abdomen and directly into the renal pelvis via ultrasound guidance, according to an article published in "Urology."
Ureteral Stent
When the ureter becomes blocked or loses the capacity to propel urine to the bladder, a ureteral stent is sometimes inserted into the ureter, allowing free flow of urine and relief of pressure inside the kidney. A ureteral stent is a thin 24 to 30 cm tube lined with the anti-blood-clotting drug heparin to reduce the chances of stent blockage, according to the "Surgery Encyclopedia."
References
- Merk Online Medical Library: Hydronephrosis
- National Health Service: Hydronephrosis
- "Pediatric Nephrology"; Mechanisms of Renal Injury and Progression of Renal disease in Congenital Obstructive Nephropathy; R. Chevalier et al.; 2010
- "Urology" Effectiveness of Three-Dimensional Fluoroscopy in Percutaneous Nephrostomy: an Animal Model Study; F. Soria et al.; 2009
- Surgery Encyclopedia: Ureteral stenting
