What is the difference between a urostomy and a nephrostomy?

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A urostomy replaces the function of the bladder.

There are two types of urostomy:

• Incontinent diversion: Healthcare professionals also call this an ileal conduit. It directs the urine out through a stoma to an external collection pouch.
• Continent diversion: This type involves an internal urinary reservoir with valves to prevent the urine from backing up into the kidneys.

An incontinent diversion features a continuous output of urine and mucus. People with this type of urostomy must wear a collection pouch called an ostomy bag.

A continent diversion uses an internal pouch to collect the urine. A person must drain the pouch at regular intervals using a catheter.

A nephrostomy is an opening a surgeon creates between the skin on the back and the kidney. They then insert a thin, flexible catheter that drains urine directly from a kidney into a bag outside the body.

A nephrostomy can involve one kidney or both kidneys. When it involves both, it is called a bilateral nephrostomy.

If the nephrostomy affects one kidney, the urine from the unaffected kidney will continue to travel through the intact ureter to the bladder.

The urine in the kidney with the nephrostomy will drain through the temporary tube to a collection pouch that a person wears outside their body, often on their leg.

There are several differences between a urostomy and a nephrostomy:

A person may need a urostomy or a nephrostomy for different reasons.

Urostomy

A person may need a urostomy if the bladder is not functioning or if surgeons must remove it.

Reasons for urostomy surgery include:

• bladder cancer
• a congenital disability such as spina bifida
• a spinal cord injury
• chronic infection

Nephrostomy

Doctors insert a nephrostomy tube when a kidney’s ureter is not working as it should.

A person may need a nephrostomy as a result of:

• a blockage such as a kidney stone
• an infection
• scar tissue
• cancer, including:
  • bladder cancer
  • colon cancer
  • rectal cancer
  • cervical cancer
  • uterine cancer
  • ovarian cancer
  • prostate cancer

The kidneys still produce urine as usual.

The sections below outline how a surgeon performs each procedure.

Urostomy

Ordinarily, each kidney’s ureter leads to the bladder, which connects to the urethra, where urine leaves the body. If the bladder no longer functions or must be removed, surgeons replace it with a type of urostomy.

For an incontinent diversion, doctors create a conduit using a portion of the ileum, or small intestine. They close one end of the conduit and attach it to both kidney ureters. They then attach the open end of the conduit to a stoma — an opening in the abdominal wall.

The kidneys continue to make urine, which travels through the ureters as usual. However, instead of arriving at the bladder, the urine passes through the conduit and exits the body via the stoma. It collects in a pouch that a person wears outside their abdomen.

For a continent diversion, surgeons create an internal storage pouch that fills with urine. A person must regularly empty the pouch using a catheter.

The type of continent diversion determines which types of tissue surgeons use to create the outlet, valves, and storage pouch:

• Kock pouch: To create this type, surgeons use the terminal ileum, which is the end of the small intestine.
• Indiana pouch: Surgeons use the natural ileocecal valve and the ascending colon for the pouch and the terminal ileum for the outlet.
• Mitrofanoff procedure: Surgeons may use any of several tissues for this type, including the bladder, bowel, ureter, appendix, and fallopian tube.
• Ileal neobladder: This pouch empties through the urethra rather than an ostomy. Surgeons make the pouch from a section of the ileum.

A urostomy is a permanent surgical restructure of the urinary tract.

Nephrostomy

A nephrostomy uses an external pouch to collect urine through a thin tube attached directly to one or both kidneys.

Surgeons use ultrasound to guide nephrostomy tube insertion. The tube enters the body through the back of the torso.

A nephrostomy tube is a temporary structure. If a person needs the support of a nephrostomy for an extended time, healthcare professionals change the drainage tube at regular intervals.

Urostomy surgery has several possible complications, including:

• infection
• wound issues
• skin irritation
• gastrointestinal issues such as obstruction and leakage
• stomal retraction or prolapse
• herniation

The ileum is an important site for the absorption of nutrients. Urostomy surgery using this part of the bowel may result in:

• nutritional deficiencies, including vitamin B12 deficiency
• electrolyte and metabolic disturbances
• bone disorders
• kidney stones

Some complications arise soon after surgery, but others can appear years later.

Nephrostomy

Nephrostomy complications can include:

• sepsis and septic shock
• catheter kinking, blockage, and leaking
• bleeding
• pain
• catheter dislodgement

A nephrostomy procedure may also affect a person’s mental health. A 2019 study found that people living with nephrostomy tubes experienced anxiety and mild to moderate pain.

Urostomy and nephrostomy procedures both help urine exit the body.

A urostomy replaces the bladder when it can no longer function properly because of conditions such as cancer or abdominal trauma. A urostomy is a permanent surgical change to the urinary tract.

Nephrostomy bypasses blocked or damaged ureters that usually move urine from the kidneys to the bladder. It is usually a temporary measure but may be in place long term.