Introduction

The urinary system consists of different parts like, the kidneys, ureters, bladder, and urethra. Blood from the body is filtered inside the kidneys to free the body from toxic waste products. After this process of filtration, urine is formed. This urine which is formed in the kidney passes along fine tube-like organs called the ureters in to the bladder. In the urinary bladder, urine is stored and when the bladder gets full and one starts to pass urine, the bladder contracts to empty the urine into the urethra, which opens above the vaginal opening in females and at the tip of the penis in males. Patency all along this tract is important for passage of urine outside the body. Obstruction at any level starting from the kidneys to the urethra causes retention of urine leading to excessive back pressure, resulting in kidney damage.

Definition

Nephrostomy is a procedure done to artificially create a passage between the kidneys and the skin. The nephrostomy tube is put through the skin of the back into the kidneys. In urostomy, an artificial pathway is created between the bladder and the skin of the abdominal wall.

Technique

The nephrostomy tube is put through the skin of the back into the kidneys. The opening at the skin end is attached to a bag in which urine can be stored. To this bag is attached a tap with which urine can be emptied from the bag. While installing a urostomy tube, ureters are resected from the bladder and attached to the detached part of the small intestine called the ileum. The other opening of the ileum is brought out from the abdominal wall. To this abdominal opening a bag is attached to collect urine. There is yet another technique called the Indiana pouch, in which a segment of a small bowel loop is converted into a small pouch like bladder to store and discharge urine at intervals.

Difference in Utility

Nephrostomy serves to directly divert the urine from the kidneys to the opening at the back of the body via an opening through the skin. Urostomy entails shunting the urine from bladder via an opening in the abdominal wall.

Difference in Indications

When the ureters are blocked, the urine retained produces a back pressure on the kidney. Hence, pathologies involving the lower abdomen e.g. ovarian or cervical cancer in females or prostate cancer in males, bladder or colon cancer, wherein the cancer mass blocks the ureters, this procedure needs to be performed.

Urostomy is commonly performed in case a person whose drainage of urine from urethra or bladder is not possible. It is commonly indicated when urinary bladder has been removed (cystectomy). In addition to this, bladder cancer, incontinence of urine or any injuries to urinary organs causing retention of urine might need a urostomy to facilitate expulsion of urine.

Summary

Nephrostomy is performed whenever there is an obstruction to flow of urine from the kidneys into the bladder through the ureters, whereas urostomy is performed when urine flow is not possible through bladder and urethra. Nephrostomy involves the kidneys, whereas urostomy involves the bladder. The commonest indications for nephrostomy are colon or ovarian cancer, whereas the commonest indications for urostomy is cystectomy.

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