Intestinal obstruction is a blockage of your small intestine or colon that prevents food and fluid from passing through. Intestinal obstruction can be caused by many conditions, but it's most often the result of fibrous bands of tissue in the intestine (adhesions), hernias or tumors.

Intestinal obstruction can result in an array of uncomfortable signs and symptoms, including abdominal pain and swelling, nausea, and vomiting. If left untreated, intestinal obstruction can cause the blocked parts of your intestine to die (become necrotic). This tissue death can lead to perforation of the intestine, severe infection and shock. However, with prompt medical care, intestinal obstruction can often be successfully treated.

Signs and symptoms of intestinal obstruction include:

• Crampy abdominal pain that comes and goes (intermittent)
• Nausea
• Vomiting or diarrhea
• Inability to have a bowel movement or pass gas
• Swelling of the abdomen (distention)
• Abdominal tenderness
• Fever

When to see a doctor
Because of the serious complications that can develop from intestinal obstruction, you should seek immediate medical care if you develop the signs or symptoms listed above.

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Digestive system

Many conditions can cause intestinal obstruction. The causes often differ, however, depending on whether the obstruction occurs in the small intestine or in the colon.

"Mechanical" obstruction occurs when something — such as a hernia or tumor — is physically blocking your intestine. Blockage of your intestine can be partial or complete. Paralytic ileus (pseudo-obstruction), a condition in which your intestines don't function properly, may have the same signs and symptoms as mechanical obstruction, but no physical obstruction is present.

Mechanical obstruction of the small intestine
Common causes of mechanical obstruction in the small intestine include the following:

• Intestinal adhesions. These bands of fibrous tissue in the abdominal cavity may be present at birth (congenital). But, more often, they form after abdominal surgery. Intestinal adhesions can bind sections of your intestine, blocking the passage of food and fluids.
• Hernias. Hernias occur when part of your intestine protrudes into another part of your body. If a loop of intestine becomes trapped due to a hernia, it will cause intestinal obstruction.
• Tumors. A tumor within your small intestine may block the passage of food and fluids, causing obstruction.

Adhesions, hernias and tumors account for about 90 percent of cases of mechanical small intestine obstruction. Other causes include:

• Telescoping of a portion of the intestine into another portion (intussusception)
• Twisting of the intestine (volvulus)
• Narrowing of the outlet from the stomach (stricture)
• Inflammation or scarring from Crohn's disease

Mechanical obstruction of the colon
Mechanical intestinal obstruction is less common in the colon than in the small intestine. Only 10 to 15 percent of mechanical obstruction cases occur in the colon. Adhesions and hernias rarely cause obstruction in the colon. The most common causes of mechanical colonic obstruction include the following:

• Cancer
• Diverticulitis — a condition in which small, bulging pouches (diverticula) in the digestive tract become inflamed or infected
• Twisting of the colon (volvulus)

Less common causes of intestinal obstruction in the colon include:

• Telescoping of a portion of the colon into another portion (intussusception)
• Impacted feces
• Narrowing of the colon (stricture)
• Foreign bodies — swallowed objects that block the colon

Paralytic ileus
Paralytic ileus can cause signs and symptoms of intestinal obstruction. In paralytic ileus, although there is no blockage, the intestines don't function properly; movement of the intestines is greatly reduced or absent. The intestines are unable to move food and fluid smoothly through the digestive system.

Paralytic ileus can affect any part of the intestine. The most common cause of paralytic ileus is abdominal surgery. Right after abdominal surgery, the intestines don't function normally. A nasogastric (NG) tube and intravenous fluids are often necessary until the intestines begin to function again. Postoperative paralytic ileus is not a form of mechanical obstruction.

You're at an increased risk of developing intestinal obstruction if you've had abdominal surgery of any kind, surgery to remove part of your intestine (bowel resection) or other pelvic surgery, previous surgery for obstruction, or surgery to remove your appendix (appendectomy). These surgeries can cause adhesions, which are one of the most common causes of intestinal obstruction.

Conditions that increase your risk of intestinal obstruction include:

• Abdominal or pelvic surgery
• Crohn's disease — an inflammatory condition that can cause the intestine's walls to thicken, narrowing its passageway
• Cancer within your abdomen, especially if you've had surgery to remove an abdominal tumor or radiation therapy
• A history of constipation
• Malrotation, a condition present at birth (congenital) in which your intestine doesn't develop correctly

If left untreated, intestinal obstruction can cause serious, life-threatening complications. As your intestine becomes congested, its ability to absorb food and fluids decreases. Decreased absorption may cause vomiting, dehydration and, eventually, can result in shock, which may cause kidney failure.

Intestinal obstruction can also cut off the blood supply to the affected portion of your intestine. If left untreated, lack of blood causes the intestinal wall to die. Tissue death can result in a tear (perforation) in the intestinal wall, which can lead to peritonitis, an infection of the lining of your abdominal cavity.

Peritonitis is a life-threatening condition that requires immediate medical and surgical attention. Signs and symptoms of peritonitis include:

• Abdominal pain or tenderness
• Abdominal swelling
• Nausea
• Vomiting
• Fever
• Chills
• Thirst
• Low urine output
• Fluid in the abdomen
• Inability to have a bowel movement or pass gas

Peritonitis may cause you to go into shock. Signs and symptoms of shock include:

• Cool, clammy skin that may be pale or gray
• A weak and rapid pulse
• Abnormal breathing that may be either slow and shallow or very rapid
• Dilated pupils in the eyes
• Lackluster eyes that seem to stare

A person who is in shock may be conscious or unconscious. Shock is an emergency condition that requires immediate medical care.

Emergency medical care is required to treat intestinal obstruction. As a result, you may not have much time to prepare for your appointment. If you have time before your appointment, make a list of your signs and symptoms so that you can better answer your doctor's questions.

What to expect from your doctor
Your doctor is likely to ask you a number of questions, including:

• When did you first begin experiencing abdominal pain or other symptoms?
• Did your symptoms come on all of a sudden or have you had symptoms like these before?
• Is your pain continuous?
• Have you experienced nausea, vomiting, fever, blood in your stool, diarrhea or constipation?
• Have you had surgery on your abdomen?
• Have you had radiation to your abdomen?

What you can do in the meantime
Seek medical attention immediately. Avoid pain medications and stop eating until you're able to see a doctor.

Your doctor will ask about your medical history and your symptoms. He or she will also do a physical exam to assess your situation. The doctor may suspect intestinal obstruction if your abdomen is swollen or tender, or if there's a lump in your abdomen.

To confirm a diagnosis of intestinal obstruction, your doctor may recommend abdominal X-ray, ultrasound or computerized tomography (CT) scans. These tests also help your doctor determine if the obstruction is paralytic ileus or if it's a mechanical obstruction, and if it's a partial or a complete obstruction.

Treatment for intestinal obstruction requires hospitalization. When you arrive at the hospital, the doctors will first stabilize your medical condition. This includes giving you fluids through an intravenous (IV) line, putting a nasogastric (NG) tube through your nose and into your stomach to suck air and fluid out to allow the intestines to decompress, and placing a thin, flexible tube (catheter) into your bladder to drain urine.

Specific treatment depends on the cause of your condition. If your doctor determines that your signs and symptoms are caused by paralytic ileus, he or she may monitor your condition for a day or two in the hospital. Paralytic ileus is often a temporary condition that gets better on its own. If paralytic ileus doesn't improve within several days, your doctor may prescribe medication that causes muscle contractions, which can help move food and fluids through your intestines.

If you have mechanical obstruction in which some food and fluid can still get through (partial obstruction), decompressing your intestine with an NG tube may improve the condition, and no further treatment is necessary. If the obstruction does not clear within a day or so, you may need surgery to relieve the obstruction.

Complete obstruction, in which nothing can pass through your intestine, is a medical emergency that requires immediate surgery to relieve the blockage.

Prevention of intestinal obstruction depends on the cause. Some causes, such as intussusception and volvulus, may not be preventable. However, treatment of conditions related to intestinal obstruction, such as hernias and tumors, may reduce your risk of developing obstruction.