What Are the Renal Calyces?

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  • Written By: Franklin Jeffrey
  • Edited By: Rachel Catherine Allen
  • Last Modified Date: 04 November 2018
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Renal calyces are parts of the kidney that collect urine before it passes further into the urinary tract. The calyces are part of the renal pelvis, a convex system of sinuses that connect the innermost part of the kidney to the ureters and, from there, to the bladder. There are two types of renal calyx: the minor calyx and the major calyx. In the human body, there can be two to three major calyces and eight to fourteen minor calyces. Basically, the renal calyces are sectional, hollow cavities that act as reservoirs and help the kidneys perform their duty.

The function of the kidney is to filter out waste and excess water from about 200 quarts of blood every day. Most of this processing takes place in the renal cortex and the renal medulla, the "meaty" parts of the kidney. Once this filtration process is complete, the waste is expunged into the renal calyces and collected. The calyces, branching vessels connected to the kidney interior, empty into the renal pelvis, forming the initial portion of the lower urinary tract.


The different lobes of the kidney each have a medullary pyramid that is capped by a renal papilla. Renal papilla function as strainers; as urine is processed through the renal cortex and then the renal medulla, drops of urine are sent through the papilla to collect in the cavities of the renal calyces. Initially, this will be through the minor calyces, but every minor calyx joins to a major calyx, and the major calyxes then funnel all collected urine into the renal pelvis and, from there, the ureter and finally the bladder.

Cancer of the upper urinary tract is rare, but three-fourths of all such cases form tumors in the renal calyces or the renal pelvis. The susceptibility of these parts of the kidney to malignant cell growth stems from a tissue layer called the urothelium. This tissue is found in the bladder and the upper urinary tract and helps prevent previously filtered wastes from getting back into the bloodstream. Due to constant bombardment by toxins filtered from the blood, the areas where urine waste is the most present, such as the renal pelvis and calcyes, are also vulnerable to tumor growth. In fact, cancer of the urothelium ranks fifth in the U.S. among all cancers if skin cancer is excluded, and the renal calyces and pelvis account for about three-fourths of all cancer occurring in the urothelium.


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Post 4

I don't understand what it means that my left kidney demonstrates prominent calyces. Does this mean they can form stones? Last week they said in A& E I had blood in my urine and they thought I had passed a stone through my urethra.

I had no UTI at the time but did three days later and more blood my urine. I was put on antibiotics by my GP yet again. I have had terrible pains my right lower back back flank legs and right pelvic (fossa?) for months and ended up in A&E six times, mostly with UTI s and pain. All they do is chuck you out and say go to your gp for pain control.

I'm now

waiting for a flexible colposcopy of my urethra. My right kidney ultrasound demonstrates a proximal extrarenal pelvis. I had my gallbladder out via keyhole in 1992, but when they gave me the stones in a jar, they fell apart like sand. They said these sorts of stones are more painful because you can pass small grains through your urethra.

I would like to know could this be the way I'm passing through my urethra as have been in terrible pain for at least eight months ad had been living off tramadol pain killers.

Also I have vaginal tape from a prolapsed vagina in 2006. What I can't understand is why it is attached to the neck of my bladder. It must have moved because this was not the way the surgeon showed me how he was going to perform this operation at another hospital.

I have been saying this may be the problem regarding my UTIs since a gynecologist told me last year they can corrode the tape and they have not been around that long. This method hasn't had enough use to know the long term effects. Had I known this tape might corrode, I would have gone for the normal process of an operation to repair my prolapse. I'm worried and fed up.

Post 3

@JackWhack – I had a stone lodged in one of my calyces, and it was a big one. It was too large for me to pass, and the doctor said I needed surgery instead of just a catheter.

He had to make a cut in my back to put a scope in there. He broke up the stone and took it out with the scope.

I had to be in the hospital for several days. It was a rough thing to go through, but in a way, I'm glad I didn't have to pass that stone on my own. It would have been incredibly painful and probably impossible because of its size.

Post 2

Do kidney stones ever get lodged in the renal calyces? If so, do they usually come out on their on, or do you have to have surgery?

Post 1

I have polycystic kidney disease, and my renal calyces look different than those of people with healthy kidneys. I have hundreds of cysts in both kidneys, and the kidneys are enlarged because of this.

My renal calyces are longer and more spread out than normal calyces. I am also at a higher risk of getting kidney cancer someday.

I have to have an MRI every three years to screen for kidney cancer. It can also tell my doctor if the disease is progressing by how much my cysts have grown, if they have grown at all.

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