Your colon, also known as the large intestine, is part of your digestive system. It's a long, hollow tube at the end of your digestive tract where your body makes and stores stool. Many disorders affect the colon's ability to work properly. Some of these include

• Colorectal cancer
• Colonic polyps - extra tissue growing in the colon that can become cancerous
• Ulcerative colitis - ulcers of the colon and rectum
• Diverticulitis - inflammation or infection of pouches in the colon
• Irritable bowel syndrome - an uncomfortable condition causing abdominal cramping and other symptoms

Treatment for colonic diseases varies greatly depending on the disease and its severity. Treatment may involve diet, medicines and in some cases, surgery.

Ulcerative colitis (UC) is a disease that causes inflammation and sores, called ulcers, in the lining of the rectum and colon. It is one of a group of diseases called inflammatory bowel disease.

UC can happen at any age, but it usually starts between the ages of 15 and 30. It tends to run in families. The most common symptoms are pain in the abdomen and blood or pus in diarrhea. Other symptoms may include

• Anemia
• Severe tiredness
• Weight loss
• Loss of appetite
• Bleeding from the rectum
• Sores on the skin
• Joint pain
• Growth failure in children

About half of people with UC have mild symptoms.

Doctors use blood tests, stool tests, colonoscopy or sigmoidoscopy, and imaging tests to diagnose UC. Several types of drugs can help control it. Some people have long periods of remission, when they are free of symptoms. In severe cases, doctors must remove the colon.

What is ulcerative colitis?

Ulcerative colitis is a chronic disease in which abnormal reactions of the immune system cause inflammation and ulcers on the inner lining of your large intestine.

Ulcerative colitis can begin gradually and become worse over time. However, it can also start suddenly. Symptoms can range from mild to severe. In between periods of flares—times when people have symptoms—most people have periods of remission—times when symptoms disappear. Periods of remission can last for weeks or years. The goal of treatment is to keep people in remission long term.

Does ulcerative colitis have another name?

Ulcerative colitis is an inflammatory bowel disease (IBD). Crohn’s disease and microscopic colitis are other common types of IBD.

How common is ulcerative colitis?

Research suggests that about 600,000 to 900,000 people in the United States have ulcerative colitis.

Who is more likely to have ulcerative colitis?

Ulcerative colitis is more likely to develop in people

• between the ages of 15 and 30, although the disease may develop in people of any age
• who have a first-degree relative—a parent, sibling, or child—with IBD
• of Jewish descent

Irritable bowel syndrome (IBS) is a problem that affects the large intestine. It can cause abdominal cramping, bloating, and a change in bowel habits. Some people with the disorder have constipation. Some have diarrhea. Others go back and forth between the two. Although IBS can cause a great deal of discomfort, it does not harm the intestines.

IBS is common. It affects about twice as many women as men and is most often found in people younger than 45 years. No one knows the exact cause of IBS. There is no specific test for it. Your doctor may run tests to be sure you don't have other diseases. These tests may include stool sampling tests, blood tests, and x-rays. Your doctor may also do a test called a sigmoidoscopy or colonoscopy. Most people diagnosed with IBS can control their symptoms with diet, stress management, probiotics, and medicine.

Irritable bowel syndrome (IBS) is a group of symptoms that occur together, including repeated pain in your abdomen and changes in your bowel movements, which may be diarrhea, constipation, or both. With IBS, you have these symptoms without any visible signs of damage or disease in your digestive tract.

IBS is a functional gastrointestinal (GI) disorder. Functional GI disorders, which doctors now call disorders of gut-brain interactions, are related to problems with how your brain and your gut work together. These problems can cause your gut to be more sensitive and change how the muscles in your bowel contract. If your gut is more sensitive, you may feel more abdominal pain and bloating. Changes in how the muscles in your bowel contract lead to diarrhea, constipation, or both.

Does IBS have another name?

In the past, doctors called IBS colitis, mucous colitis, spastic colon, nervous colon, and spastic bowel.

How common is IBS?

Studies suggest that about 12 percent of people in the United States have IBS.

An intestinal obstruction occurs when food or stool cannot move through the intestines. The obstruction can be complete or partial. There are many causes. The most common are adhesions, hernias, cancers, and certain medicines.

Symptoms include

• Severe abdominal pain or cramping
• Vomiting
• Bloating
• Loud bowel sounds
• Swelling of the abdomen
• Inability to pass gas
• Constipation

A complete intestinal obstruction is a medical emergency. It often requires surgery.

What is diverticulosis?

Diverticula are small pouches, or sacs, that bulge outward through weak spots in your colon. They mostly form in the lower part of the colon. Diverticulosis is a condition in which you have these pouches. Most people who have diverticulosis do not have symptoms or problems. But sometimes the pouches can cause symptoms or become inflamed.

What is diverticulitis?

Diverticulitis is the name for the condition you have when one or more of the pouches get inflamed. Diverticulitis may come on suddenly. It can sometimes cause serious health problems.

What is diverticular disease?

Diverticular disease is a condition that happens when the pouches cause:

• Chronic (long-term) symptoms
• Diverticular bleeding
• Diverticulitis or diverticulitis complications

What causes diverticulosis and diverticulitis?

Researchers aren't sure what causes diverticulosis and diverticulitis. They think certain factors may play a role in causing or increasing the risk for these conditions, including:

• Your genetics. Certain genes may make some people more likely to develop the conditions.
• Lifestyle factors such as:
  • Diets low in fiber and high in red meat
  • Lack of physical activity
  • Taking certain medicines, such as nonsteroidal anti-inflammatory drugs (NSAIDs) and steroids
  • Having obesity
  • Smoking

Researchers are also looking at other possible factors that may play a role in these conditions. Those factors include bacteria or stool (poop) getting caught in a pouch in your colon and changes in the microbiome in the intestines. Your microbiome is made up of the bacteria and other organisms in your intestines.

Who is more likely to develop diverticulosis and diverticulitis?

Diverticulosis is common, especially as people age. More than one-third of U.S. adults between the ages of 50 and 59 have diverticulosis. More than two-thirds who are over age 80 have it. Most of those people will not have symptoms or problems. But some of them will develop diverticulitis.

What are the symptoms of diverticulosis and diverticulitis?

Diverticulosis usually doesn't cause symptoms. But some people can have chronic symptoms such as:

• Bloating
• Constipation or diarrhea
• Cramping or painin the lower abdomen (belly)

Diverticulitis may cause acute symptoms such as:

• Abdominal pain, most often in the lower left side of your abdomen
• Constipation or diarrhea
• Fevers and chills
• Nausea or vomiting

The pain caused by diverticulitis is usually severe and comes on suddenly. Less often, the pain may be mild and worsen over several days.

What other problems can diverticulosis and diverticulitis cause?

Some people with diverticulosis and diverticulitis may develop serious health problems (complications). Diverticular bleeding happens when a small blood vessel within the wall of a pouch bursts. The bleeding may be severe and sometimes even life-threatening.

People with diverticulitis can also develop serious problems such as:

• Abscess, a painful, swollen, pus-filled area caused by infection
• Fistula, an abnormal opening or passage between the colon and another part of the body, such as the bladder or vagina
• Intestinal obstruction, a partial or total blockage that keeps food, fluids, air, or stool from moving through your intestines
• Perforation, or a hole, in your colon
• Peritonitis, an infection of the lining of the abdominal cavity

How are diverticulosis and diverticulitis diagnosed?

Diverticulosis may be found when your health care provider is doing tests for another reason. Diverticulitis is usually found when you are having an acute attack.

To make a diagnosis, your provider will review your medical history, do a physical exam, and order tests. The tests may include:

• Blood tests
• Stool tests
• Imaging tests such as CT scan, ultrasound, or MRI
• Colonoscopy

What are the treatments for diverticulosis and diverticulitis?

f your diverticulosis is causing chronic symptoms, your provider may recommend:

• High-fiber foods or fiber supplements
• Antibiotics
• Medicines to reduce inflammation
• Probiotics

If you have diverticulitis without complications, your provider may recommend treatment at home. However, you probably need treatment in the hospital if you have severe diverticulitis, diverticulitis with complications, or a high risk for complications.

Treatments for diverticulitis may include:

• Antibiotics, except for very mild cases.
• A clear liquid diet for a short time to rest the colon. Your provider may suggest slowly adding solid foods to your diet as your symptoms improve.
• Medicines for pain. This is usually acetaminophen instead of nonsteroidal anti-inflammatory drugs (NSAIDs). NSAIDs may increase the chance of diverticulitis complications.
• Antispasmodic medicines to relieve spasms.

If your diverticulitis doesn't improve with treatment or if it causes complications, you may need surgery to remove part of your colon.

Can diverticulitis be prevented?

Your provider may recommend lifestyle changes to prevent diverticulitis:

• Eating a diet high in fiber and low in red meat
• Being physically active on a regular basis
• Not smoking (and quitting smoking if you are a smoker)
• Reaching and maintaining a healthy weight

What is Crohn's disease?

Crohn's disease is a chronic disease that causes inflammation in your digestive tract. It can affect any part of your digestive tract, which runs from your mouth to your anus. But it usually affects your small intestine and the beginning of your large intestine.

Crohn's disease is an inflammatory bowel disease (IBD). Ulcerative colitis and microscopic colitis are other common types of IBD.

What causes Crohn's disease?

The cause of Crohn's disease is unknown. Researchers think that an autoimmune reaction may be one cause. An autoimmune reaction happens when your immune system attacks healthy cells in your body. Genetics may also play a role, since Crohn's disease can run in families.

Stress and eating certain foods don't cause the disease, but they can make your symptoms worse.

Who is at risk for Crohn's disease?

There are certain factors which can raise your risk of Crohn's disease:

• Family history of the disease. Having a parent, child, or sibling with the disease puts you at higher risk.
• Smoking. This may double your risk of developing Crohn's disease.
• Certain medicines, such as antibiotics, birth-control pills, and nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin or ibuprofen. These may slightly increase your chance of developing Crohn's.
• A high-fat diet. This may also slightly increase your risk of Crohn's.

What are the symptoms of Crohn's disease?

The symptoms of Crohn's disease can vary, depending where and how severe your inflammation is. The most common symptoms include:

• Diarrhea
• Cramping and pain in your abdomen
• Weight loss

Some other possible symptoms are:

• Anemia, a condition in which you have fewer red blood cells than normal
• Eye redness or pain
• Fatigue
• Fever
• Joint pain or soreness
• Nausea or loss of appetite
• Skin changes that involve red, tender bumps under the skin

Stress and eating certain foods such as carbonated drinks and high-fiber foods may make some people's symptoms worse.

What other problems can Crohn's disease cause?

Crohn's disease can cause other problems, including:

• Intestinal obstruction, a blockage in the intestine
• Fistulas, abnormal connections between two parts inside of the body
• Abscesses, pus-filled pockets of infection
• Anal fissures, small tears in your anus that may cause itching, pain, or bleeding
• Ulcers, open sores in your mouth, intestines, anus, or perineum
• Malnutrition, when your body does not get the right amount of vitamins, minerals, and nutrients it needs
• Inflammation in other areas of your body, such as your joints, eyes, and skin

How is Crohn's disease diagnosed?

Your health care provider may use many tools to make a diagnosis:

• A medical history, which includes asking about your symptoms
• A family history
• A physical exam, including
  • Checking for bloating in your abdomen
  • Listening to sounds within your abdomen using a stethoscope
  • Tapping on your abdomen to check for tenderness and pain and to see if your liver or spleen is abnormal or enlarged
• Various tests, including
  • Blood and stool tests
  • A colonoscopy
  • An upper GI endoscopy, a procedure in which your provider uses a scope to look inside your mouth, esophagus, stomach, and small intestine
  • Diagnostic imaging tests, such as a CT scan or an upper GI series. An upper GI series uses a special liquid called barium and x-rays. Drinking the barium will make your upper GI tract more visible on an x-ray.

What are the treatments for Crohn's disease?

There is no cure for Crohn's disease, but treatments can decrease the inflammation in your intestines, relieve symptoms, and prevent complications. Treatments include medicines, bowel rest, and surgery. No single treatment works for everyone. You and your health care provider can work together to figure out which treatment is best for you:

• Medicines for Crohn's include various medicines that decrease the inflammation. Some of these medicines do this by reducing the activity of your immune system. Medicines can also help with symptoms or complications, such as nonsteroidal anti-inflammatory drugs and anti-diarrheal medicines. If your Crohn's causes an infection, you may need antibiotics.
• Bowel rest involves drinking only certain liquids or not eating or drinking anything. This allows your intestines to rest. You may need to do this if your Crohn's disease symptoms are severe. You get your nutrients through drinking a liquid, a feeding tube, or an intravenous (IV) tube. You may need to do bowel rest in the hospital, or you may be able to do it at home. It will last for a few days or up to several weeks.
• Surgery can treat complications and reduce symptoms when other treatments are not helping enough. The surgery will involve removing a damaged part of your digestive tract to treat
  • Fistulas
  • Bleeding that is life threatening
  • Intestinal obstructions
  • Side effects from medicines when they threaten your health
  • Symptoms when medicines do not improve your condition

Changing your diet can help reduce symptoms. Your provider may recommend that you make changes to your diet, such as:

• Avoiding carbonated drinks
• Avoiding popcorn, vegetable skins, nuts, and other high-fiber foods
• Drinking more liquids
• Eating smaller meals more often
• Keeping a food diary to help identify foods that cause problems

Some people also need go on special diet, such as a low-fiber diet.

The colon and rectum are part of the large intestine. Colorectal cancer occurs when tumors form in the lining of the large intestine. It is common in both men and women. The risk of developing colorectal cancer rises after age 50. You're also more likely to get it if you have colorectal polyps, a family history of colorectal cancer, ulcerative colitis or Crohn's disease, eat a diet high in fat, or smoke.

Symptoms of colorectal cancer include

• Diarrhea or constipation
• A feeling that your bowel does not empty completely
• Blood (either bright red or very dark) in your stool
• Stools that are narrower than usual
• Frequent gas pains or cramps, or feeling full or bloated
• Weight loss with no known reason
• Fatigue
• Nausea or vomiting

Because you may not have symptoms at first, it's important to have screening tests. Everyone over 50 should get screened. Tests include colonoscopy and tests for blood in the stool. Treatments for colorectal cancer include surgery, chemotherapy, radiation, or a combination. Surgery can usually cure it when it is found early.

Colorectal cancer is cancer that occurs in the colon or rectum. Sometimes it is called colon cancer, for short. As the drawing shows, the colon is the large intestine or large bowel. The rectum is the passageway that connects the colon to the anus.

Sometimes abnormal growths, called polyps, form in the colon or rectum. Over time, some polyps may turn into cancer. Screening tests can find polyps so they can be removed before turning into cancer. Screening also helps find colorectal cancer at an early stage, when treatment works best.

Cancer is a disease in which cells in the body grow out of control. When cancer starts in the colon or rectum, it is called colorectal cancer. Sometimes it is called colon cancer, for short.

Of cancers that affect both men and women, colorectal cancer is the second leading cancer killer in the United States, but it doesn’t have to be. Colorectal cancer screening saves lives. Screening can find precancerous polyps—abnormal growths in the colon or rectum—that can be removed before they turn into cancer. Screening also helps find colorectal cancer at an early stage, when treatment works best. About nine out of every 10 people whose colorectal cancers are found early and treated appropriately are still alive five years later.

If you are 45 years old or older, get screened now. If you think you may be at increased risk for colorectal cancer, speak with your doctor about when to begin screening, which test is right for you, and how often to get tested.

What Is Colorectal Cancer?

Colorectal cancer is cancer that occurs in the colon or rectum. Sometimes it is called colon cancer, for short.

What Are the Risk Factors for Colorectal Cancer?

Your risk of getting colorectal cancer increases as you get older, and there are other risk factors.

What Can I Do to Reduce My Risk of Colorectal Cancer?

The most effective way to reduce your risk of colorectal cancer is by having regular colorectal cancer screening tests beginning at age 45.

What Are the Symptoms of Colorectal Cancer?

Colorectal cancer doesn't always cause symptoms, especially at first.

What Should I Know About Screening?

Screening tests can find precancerous polyps, so that they can be removed before they turn into cancer. Screening tests can also find colorectal cancer early, when treatment works best.

Questions to Ask Your Doctor

Several screening tests can be used to find polyps or colorectal cancer. The benefits and risks of these screening methods vary. Discuss with your doctor which test is best for you.

The Digestive System

The digestive system is like a long tube that runs from the mouth to the anus and includes organs that help the body digest and absorb food and nutrients. The organs that make up the digestive system include the mouth, esophagus, stomach, small intestine, large intestine (or colon), rectum, and anus. Inside these organs is a lining called the mucosa. The digestive tract also contains a layer of smooth muscle. The muscle moves food through the tract in a wavelike movement called peristalsis, helping to mix it and break it down.

The liver and the pancreas also belong to the digestive system. They produce digestive juices that empty into the small intestine through ducts. The gallbladder stores the liver's digestive juices.

Digestion begins in the mouth. Chewed food is swallowed and moves into the pharynx, and then is pushed down the esophagus into the stomach. There, food is churned by smooth muscle contractions and mixed with digestive juices produced by the stomach. The stomach slowly empties its contents into the small intestine, where food dissolves into juices secreted from the pancreas, liver, and intestine. As the digested food moves through the small intestine, its nutrients are absorbed into the intestinal wall and into the bloodstream, where it is transported throughout the body for distribution. The colon removes water from the digested matter and converts it into a mostly solid mass of waste material, consisting largely of indigestible elements of the food, called fiber, and older cells that have been shed from the mucosa. Waste material is then expelled as feces.

The Colon

The small intestine joins the large intestine, or colon, in the right lower abdomen. The colon is a muscular tube about 5 feet long. It's made up of four sections: the ascending colon, which extends upward on the right side of the abdomen; the transverse colon, which goes across the body from the right to the left side in the upper abdomen; the descending colon, which continues downward on the left side; and the sigmoid colon (called this because of its "S" or "sigmoid" shape). The sigmoid colon attaches to the rectum, which ends in the anus.

The colon is composed of a number of different layers of tissue:

• The mucosa, the innermost layer, includes a single layer of epithelial cells, a layer of connective tissue, and a thin muscle layer. It is lined with goblet cells, glands that secrete mucous to help the passage of material through the colon.
• The submucosa is a layer of connective tissue beneath the mucosa.
• The circular muscle is a band of muscle that wraps around the entire colon and helps move waste material through it.
• The longitudinal muscle runs lengthwise along the colon. It works in conjunction with the circular muscle to create the wavelike motion of peristalsis.
• The serosa is the outermost layer of the colon.

Colon Function

The major function of the colon is to extract water, salts, and nutrients from partially digested food, and to propel the residue to the rectum and anus for expulsion. When the contents of the small intestine reach the colon, they're liquid. By the time they are expelled as feces, they're solid. About 2 pints of liquid matter enter the colon each day; stool volume is about a third of a pint. The difference between these two amounts is what the colon has absorbed in the course of digestion. If the digested matter lacks enough water, the colon can also add water to it to soften the stool. Maintaining this balance is one of the colon's most important functions.

By the time the partially digested food enters the colon, most of its nutrients have been absorbed by the small intestine. However, the process of digestion isn't over. The colon contains large numbers of bacteria. The most important of these are the lactobacilli and bifidus bacteria, which live in a symbiotic (mutually beneficial) relationship with the colon. They ferment the soluble fiber in food, forming valuable short-chain fatty acids that nourish intestinal cells, help regulate production of cholesterol, and are thought to help prevent a variety of diseases (including cancer). Beneficial bacteria also help to keep harmful bacteria in check. In addition, intestinal bacteria synthesize vitamin K, important in blood clot formation.

Figure 23.21 Large Intestine The large intestine includes the cecum, colon, and rectum.

Rectal valve is one of three transverse folds in the rectum where feces is separated from flatus

Rectum is part of the large intestine between the sigmoid colon and anal canal

Rectum

Food residue leaving the sigmoid colon enters the rectum in the pelvis, near the third sacral vertebra. The final 20.3 cm (8 in) of the alimentary canal, the rectum extends anterior to the sacrum and coccyx. Even though rectum is Latin for "straight," this structure follows the curved contour of the sacrum and has three lateral bends that create a trio of internal transverse folds called the rectal valves. These valves help separate the feces from gas to prevent the simultaneous passage of feces and gas.

Large Intestine

The large intestine includes the cecum, colon, and rectum.

Absorption, Feces Formation, and Defecation

The small intestine absorbs about 90 percent of the water you ingest (either as liquid or within solid food). The large intestine absorbs most of the remaining water, a process that converts the liquid chyme residue into semisolid feces ("stool"). Feces is composed of undigested food residues, unabsorbed digested substances, millions of bacteria, old epithelial cells from the GI mucosa, inorganic salts, and enough water to let it pass smoothly out of the body. Of every 500 mL (17 ounces) of food residue that enters the cecum each day, about 150 mL (5 ounces) become feces.

Feces are eliminated through contractions of the rectal muscles. You help this process by a voluntary procedure called Valsalva's maneuver, in which you increase intra-abdominal pressure by contracting your diaphragm and abdominal wall muscles, and closing your glottis.The process of defecation begins when mass movements force feces from the colon into the rectum, stretching the rectal wall and provoking the defecation reflex, which eliminates feces from the rectum. This parasympathetic reflex is mediated by the spinal cord. It contracts the sigmoid colon and rectum, relaxes the internal anal sphincter, and initially contracts the external anal sphincter. The presence of feces in the anal canal sends a signal to the brain, which gives you the choice of voluntarily opening the external anal sphincter (defecating) or keeping it temporarily closed. If you decide to delay defecation, it takes a few seconds for the reflex contractions to stop and the rectal walls to relax. The next mass movement will trigger additional defecation reflexes until you defecate.If defecation is delayed for an extended time, additional water is absorbed, making the feces firmer and potentially leading to constipation. On the other hand, if the waste matter moves too quickly through the intestines, not enough water is absorbed, and diarrhea can result. This can be caused by the ingestion of foodborne pathogens. In general, diet, health, and stress determine the frequency of bowel movements. The number of bowel movements varies greatly between individuals, ranging from two or three per day to three or four per week.

What are colonoscopy and flexible sigmoidoscopy?

Colonoscopy and flexible sigmoidoscopy are procedures that let your doctor look inside your rectum and colon (large intestine). They use instruments called scopes. Scopes have a light and a tiny camera attached to a long, thin tube. These procedures let your doctor see problems such as inflamed tissue, ulcers, polyps, and cancer.

Colonoscopy checks your entire colon and rectum. Flexible sigmoidoscopy checks the rectum and the lower colon (sigmoid colon) only.

What is a virtual colonoscopy?

A virtual colonoscopy also looks inside your rectum and part of your colon. But it does not use a scope. Instead, it is an x-ray test. Another name for this test is CT colonography.

Who needs a colonoscopy, virtual colonoscopy, or flexible sigmoidoscopy?

You may need a colonoscopy, virtual colonoscopy, or flexible sigmoidoscopy to find the cause of unexplained symptoms such as:

• Bleeding from your anus (the opening of the rectum through which stool passes out of your body)
• Changes in your bowel activity, such as diarrhea
• Pain in your abdomen (belly)
• Unexplained weight loss

Doctors also use these procedures to screen for colon polyps and cancer. Screening is testing for diseases when you have no symptoms. It may find diseases at an early stage, when they are easier to treat. If aren't at higher risk for colorectal cancer, your health care provider will likely recommend you start getting screenings at age 45. If you at higher risk, you may need to start getting screened for colorectal cancer earlier.

There are also other tests to screen for colorectal cancer, including stool tests. Talk with your provider about which test is right for you and when and how often you should get it.

How do you prepare for a colonoscopy, virtual colonoscopy, or flexible sigmoidoscopy?

To prepare for a colonoscopy, virtual colonoscopy, or flexible sigmoidoscopy, you will need to:

• Talk with your doctor about any health problems you have and all of the medicines and supplements that you take. You may need to stop taking some of your medicines and/or supplements before the procedure.
• Follow the bowel prep instructions from your doctor. The bowel prep clears the stool out of your colon, so your doctor will be able to see the colon during the procedure:
  • You may need to follow a clear liquid diet, usually for about one day before the procedure. Avoid red or purple drinks or gelatin; the dye can look like blood in the colon. You probably need to stop eating and drinking the night before the exam.
  • You will need to take some laxatives. They may be pills, a powder that you dissolve in liquid, an enema, or a combination of these. The laxative will cause diarrhea, so you need to stay close to the bathroom.

For a virtual colonoscopy, you will also need to drink a contrast medium the night before. The contrast medium is a dye or other substance that is visible on x-rays. It can help your doctor tell the difference between stool and polyps.

How are colonoscopy, virtual colonoscopy, and flexible sigmoidoscopy done?

For a colonoscopy:

• You will have the procedure at a hospital or outpatient center. It usually takes 30 to 60 minutes.
• You will get IV (intravenous) sedatives or anesthesia, usually along with pain medicine, so you won't be awake or feel pain during the procedure.
• You'll lie on a table while the doctor inserts a colonoscope through your anus and into your rectum and colon. The scope inflates your large intestine with air for a better view. The camera sends a video image to a monitor so your doctor can see your colon.
• Once the scope reaches the opening to your small intestine, the doctor will slowly remove the scope. While doing so, your doctor will examine your colon again.
• If you have polyps, your doctor may remove them and send them to a lab for testing. Most polyps aren't cancer, but removing them can prevent them from becoming cancer later on.
• If you have abnormal tissue, your doctor may do a biopsy.
• The sedative or anesthesia takes time to wear off completely. You'll stay at the hospital or outpatient center for 1 to 2 hours after the procedure. Then you will need someone to drive you home.

For a virtual colonoscopy:

• You will have the procedure at a hospital or outpatient center. It usually takes about 10 to 15 minutes.
• You do not need anesthesia.
• You'll lie on a table while a specially trained x-ray technician inserts a thin tube through your anus and into your rectum. The tube inflates your large intestine with air for a better view.
• The table slides into a tunnel-shaped device where the technician takes the x-ray images. You will turn over on your side or stomach to get more images taken.

For a flexible sigmoidoscopy:

• You will have the procedure at a hospital, medical office, or outpatient center. It usually takes about 20 minutes.
• You do not need anesthesia.
• You'll lie on a table while the doctor inserts a thin tube through your anus and into your rectum. The tube inflates your large intestine with air for a better view. The camera sends a video image to a monitor so your doctor can see your lower colon.
• Once the scope has reached the top of the lower colon, the doctor will slowly remove the scope. While doing so, your doctor will examine your lower colon again.
• If you have polyps, your doctor may remove them and send them to a lab for testing. Most polyps aren't cancer, but removing them can prevent them from becoming cancer later on.
• If you have abnormal tissue, your doctor may do a biopsy.

What should I expect after a colonoscopy, virtual colonoscopy, or flexible sigmoidoscopy?

You may feel cramping in your abdomen or bloating during the first hour after the any of these procedures. If the doctor removed polyps or performed a biopsy, you may have light bleeding from your anus. This bleeding is normal.

For a virtual colonoscopy or a flexible sigmoidoscopy, you go back to your regular activities and diet right after the test. For a colonoscopy, you can expect a full recovery and return to your normal diet by the next day.

Your doctor will give you the results of your procedure. If you had a biopsy, it can take a few days to get those results.