What Is the Renal Pelvis?

A diagram of a kidney, including the renal pelvis in light yellow.
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  • Written By: Mike Calhoun
  • Edited By: J.T. Gale
  • Last Modified Date: 11 September 2014
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The human kidneys are two bean-shaped organs that are located near the middle of the back, immediately below the rib cage. Kidneys perform the essential function of removing waste products from the blood and regulating fluid levels. The waste and extra fluids become urine, which drains into the renal pelvis. It then collects the urine before it is passed on to the urinary bladder.

Generally, the renal pelvis is shaped like a funnel and collects urine from the thousands of nephrons found in the kidney — a filter that strains the blood. It is a large muscular cavity located in the middle of each kidney which enables it to collect the urine from all parts of the kidney. A network of intersecting smooth muscle fibers is found in the wall of the renal pelvis. Smooth muscles are involuntary muscles, meaning that they cannot be consciously controlled. The smooth muscle fibers are bound together into sheets or bundles by reticular fibers and are frequently elastic fiber nets that are somewhat stretchable.

In some individuals, the renal pelvis becomes enlarged and protrudes from the kidney. When this happens, it is called an extra-renal pelvis, which means sticking out. This is considered a normal anatomic variant, meaning that its function of urine collection and transport to the ureters is not affected.


There is, however, an abnormality that can affect the renal pelvis called transitional cell carcinoma. This type of cancer develops in cells, known as transitional cells, which form the lining of the bladder, ureters, and renal pelvis. Typically, only one part is affected.

The exact causes of this type of cancer are unknown. Like other cancers, is not infectious and cannot be passed on to other people. Also, it is not an inherited trait because of a faulty gene.


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Post 5

@snowywinter- Yes, it is true that smoking can increase your risks of developing renal cell cancer. Smoking can actually increase your risks of developing most kinds of cancers. There are several risk factors for developing renal cancer. However, just because it is a risk factor doesn’t mean that you will develop the cancer. You should always discuss all risk factors with your doctor, including smoking.

Post 4

Is it true that smoking can contribute to one's chances of getting renal pelvis carcinoma?

Post 3

Bacterial infection in the region of the renal pelvis and kidney may cause an inflammation called pyelonephritis. Symptoms may include chills and back pain.

Post 2

The cup-like collecting region of the renal pelvis is called the "calyx." This word comes to us from Greek via Latin, and means "case of a bud," and is related to the word for "to hide."

Post 1

The most common cause of kidney cancer is renal carcinoma, which is ani infection of the blood filters in the kidney. Signs of this disease are many and may be considered strange, including brown urine, excessive hair growth in females, or enlargement of the left testicle.

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