Anatomic Problems 

of the Colon 

National Digestive Diseases Information Clearinghouse 

National 

Institute of 

Diabetes and 

Digestive 

and Kidney 

Diseases 

NATIONAL 

INSTITUTES 

OF HEALTH 

The colon, or large intestine, is part of the 

digestive system, which is a series of organs 

from the mouth to the anus. When the 

shape of the colon or the way it connects 

to other organs is abnormal, digestive 

problems result. Some of these anatomic 

problems can occur during embryonic 

development of the fetus in the womb and 

are known as congenital abnormalities. 

Other problems develop with age. 

Knowing how the colon develops and how 

it works provides a basis for understanding 

the specific anatomic problems that follow: 

•	 Malrotation 

•	 Small bowel and colonic


intussusception


•	 Fistulas 

•	 Colonic atresia 

•	 Volvulus 

•	 Imperforate anus 

Colon Anatomy and 

Development 

The adult colon is about 5 feet long. It 

connects to the small bowel, which is also 

known as the small intestine. The major 

functions of the colon are to absorb water 

and salts from partially digested food that 

enters from the small bowel and then send 

waste out of the body through the anus. 

What remains after absorption is stool, 

which passes from the colon into the rectum and out through the anus when a person has a bowel movement. 

The colon comprises several segments: 

•	 the cecum, the portion just after the 

small bowel 

•	 the ascending colon 

•	 the transverse colon 

•	 the descending colon 

Ascending 

colon 

Decending 

colon 

Sigmoid 

colon 

Rectum 

Cecum 

Transverse colon 

U.S. Department 

of Health and 

Human Services Anatomic Problems of the Colon 
•	 the sigmoid colon, an S-shaped portion near the end of the colon 

•	 the rectum, where stool is stored until 

evacuation 

The colon is formed during the first 3 

months of embryonic development. As the 

bowel lengthens, part of it passes into the 

umbilical cord, which connects the fetus to 

the mother. As the fetus grows and the 

abdominal cavity enlarges, the bowel 

returns to the abdomen and turns, or 

rotates, counterclockwise to its final position. The small bowel and colon are held in 

position by tissue known as the mesentery. 

The ascending colon and descending colon 

are fixed in place in the abdominal cavity. 

The cecum, transverse colon, and sigmoid 

colon are suspended from the back of the 

abdominal wall by the mesentery. 

Malrotation and Volvulus 

If the bowel does not rotate completely 

during embryonic development, problems 

can occur. This condition is called malrotaMesentery 

tion. Normally, the cecum is located in the 

lower right part of the abdomen. If the 

cecum is not positioned correctly, the bands 

of thin tissue that normally hold it in place 

may cross over and block part of the small 

bowel. 

Also, if the small bowel and colon have not 

rotated properly, the mesentery may be 

only narrowly attached to the back of the 

abdominal cavity. This narrow attachment 

can lead to a mobile or floppy bowel that 

is prone to twisting, a disorder called volvulus. (See the section on volvulus, page 5.) 

Malrotation is also associated with other 

gastrointestinal (GI) conditions, including 

Hirschsprung’s disease and bowel atresia. 

Malrotation is usually identified in infants. 

About 60 percent of these cases are found 

in the first month of life. Malrotation 

affects both boys and girls, although boys 

are more often diagnosed in infancy. 

The colon is held in place by the mesentery.	 In malrotation, the cecum is not positioned correctly. 

The tissue that normally holds it in place may cross over 

and block part of the small bowel. 

2	 Anatomic Problems of the Colon 
In infants, the main symptom of malrotation is vomiting bile. Bile is a greenishyellow digestive fluid made by the liver 

and stored in the gallbladder. Symptoms of 

malrotation with volvulus in older children 

include vomiting (but not necessarily vomiting bile), abdominal pain, diarrhea, constipation, bloody stools, rectal bleeding, or 

failure to thrive. 

Various imaging studies are used to diagnose malrotation: 

•	 x rays to determine whether there is a 

blockage. In malrotation, abdominal 

x rays commonly show that air, which 

normally passes through the entire 

digestive tract, has become trapped. 

The trapped air creates an enlarged, 

air-filled stomach and upper small 

bowel, with little or no air in the rest 

of the small bowel or the colon. 

•	 upper GI series to locate the point of 

intestinal obstruction. With this test, 

the patient swallows barium to coat 

the stomach and small bowel before 

x rays are taken. Barium makes the 

organs visible on x ray and indicates 

the point of the obstruction. This test 

cannot be done if the patient is 

vomiting. 

•	 lower GI series to determine the 

position of the colon. For this test, a 

barium enema is given while x rays are 

taken. The barium makes the colon 

visible so the position of the cecum 

can be determined. 

•	 computed tomography (CT) scan to 

help determine and locate the intestinal obstruction. 

Malrotation in infants is a medical emergency that usually requires immediate 

surgery. Surgery may involve 

•	 untwisting the colon 

•	 dividing the bands of tissue that


obstruct the small bowel


3	 Anatomic Problems of the Colon 

•	 repositioning the small bowel and


colon


•	 removing the appendix 

Surgery to relieve the blockage of the small 

bowel is usually successful and allows the 

digestive system to function normally. 

Small Bowel and Colonic 

Intussusception 

Intussusception is a condition in which one 

section of the bowel tunnels into an adjoining section, like a collapsible telescope. 

Intussusception can occur in the colon, the 

small bowel, or between the small bowel 

and colon. The result is a blocked small 

bowel or colon. 

Intussusception is rare in adults. Causes 

include 

•	 benign or malignant growths 

•	 adhesions (scarlike tissue) 

•	 surgical scars in the small bowel


or colon


•	 motility disorders (problems with


the movement of food through the


digestive tract)


•	 long-term diarrhea 

Some cases of intussusception have been 

associated with viral infections and in 

patients living with AIDS. It can also occur 

without any known cause (idiopathic). 

In infants and children, intussusception 

involving the small bowel alone, or the 

small bowel and the colon, is one of the 

most common causes of intestinal obstruction. Malrotation is a risk factor. Intussusception affects boys more often than girls, 

with most cases happening at 5 months and 

at 3 years of age. Most cases in children 

have no known cause, but viral infections or 

a growth in the small bowel or colon may 

trigger the condition. In the past, cases of 

intussusception appeared to be associated 
with a childhood vaccine for rotavirus, a 

common cause of gastroenteritis (intestinal 

infection). That vaccine is no longer given. 

In adults with intussusception, symptoms 

can last a long time (chronic symptoms) or 

they can come and go (intermittent symptoms). The symptoms will depend on the 

location of the intussusception. They may 

include 

•	 changes in bowel habits 

•	 urgency—needing to have a bowel


movement immediately


•	 rectal bleeding 

•	 chronic or intermittent crampy


abdominal pain


•	 pain in a specific area of the abdomen 

•	 abdominal distention 

•	 nausea and vomiting 

Children with intussusception may 

experience 

•	 intermittent abdominal pain 

•	 bowel movements that are mixed with 

blood and mucus 

•	 abdominal distention or a lump in the 

abdomen 

•	 vomiting bile 

•	 diarrhea 

•	 fever 

•	 dehydration 

•	 lethargy 

•	 shock (low blood pressure, increased 

heart rate requiring immediate 

attention) 

If intussusception is not diagnosed promptly, especially in children, it can cause serious damage to the portion of the bowel that 

is unable to get its normal blood supply. A 

range of diagnostic tests may be required. 

X rays of the abdomen may suggest a bowel 

obstruction (blockage). Upper and lower 

GI series will locate the intussusception 

and show the telescoping. CT scans can 

also help with the diagnosis. When intussusception is suspected, an air or barium 

enema can often help correct the problem 

by pushing the telescoped section of bowel 

into its proper position. 

Both adults and children may require surgery to straighten or remove the involved 

section of bowel. The outcome of this surgery depends on the stage of the intussusception at diagnosis and the underlying 

cause. With early treatment, the outcome is 

generally excellent. In some cases, usually 

in children, intussusception may be temporary and reverse on its own. If no underlying cause is found in these cases, no specific 

treatment is required. 

Fistulas 

A fistula is an abnormal passageway 

between two areas of the digestive tract. 

An internal fistula occurs between two 

areas of intestine or an area of intestine 

and another organ. An external fistula 

occurs between the intestine and the 

outside of the body. Both internal and 

external fistulas may be characterized by 

abdominal pain and swelling. External 

fistulas may discharge pus or intestinal 

contents. Internal fistulas can be associated with diarrhea. 

The most common types of fistulas develop 

around the anus, colon, and small bowel. 

These types are 

•	 ileosigmoid—occurs between the sigmoid colon and the end of the small 

bowel, which is also called the ileum 

•	 ileocecal—occurs between the ileum 

and cecum 

•	 anorectal—occurs between the anal 

canal and the skin around the anus 

•	 anovaginal—occurs between the rectum and vagina 

4	 Anatomic Problems of the Colon 
•	 colovesical—occurs between the colon 

and bladder 

•	 cutaneous—occurs between the colon 

or small bowel and the outside of the 

body 

Fistulas can occur at any age. Some fistulas 

are congenital, which means they occur 

during the development of a baby. They 

are seen in infants and are more common 

in boys. Other fistulas develop suddenly 

due to diseases or after trauma, surgery, or 

local infection. A fistula can form when 

diseased or damaged tissue comes into contact with other damaged or nondamaged 

tissue, as seen in Crohn’s disease (intestinal 

inflammation) and diverticulitis. Childbirth 

can lead to fistulas between the rectum and 

vagina in women. 

External fistulas are found during a physical examination. Internal fistulas can be 

seen by colonoscopy, upper and lower GI 

series, or CT scan. 

Fistulas may be treated by surgery to 

remove the portion of the intestine causing 

the fistula, along with antibiotics to treat 

any associated infection. 

Colonic Atresia 

Colonic atresia is a condition that occurs 

during embryonic development in which the 

normal tubular shape of the colon in the 

fetus is unexpectedly closed. This congenital abnormality may be caused by incomplete development of the colon or the loss 

of blood flow during its development. 

Colonic atresia is rare and may occur with 

the more common small bowel atresia. 

Infants with colonic atresia have no bowel 

movements, increasing abdominal distention, and vomiting. X rays will show a dilated colon above the obstruction, which can 

then be located using a barium enema. 

Surgery is necessary to open or remove 

the closed area and re-connect the normal 

sections of the colon. 

Volvulus 

Volvulus refers to the twisting of a portion 

of the intestine around itself or a stalk of 

mesentery tissue to cause an obstruction. 

Volvulus occurs most frequently in the 

colon, although the stomach and small 

bowel can also twist. The part of the digestive system above the volvulus continues to 

function and may swell as it fills with digested food, fluid, and gas. A condition called 

strangulation develops if the mesentery of 

the bowel is twisted so tightly that blood 

flow is cut off and the tissue dies. This 

condition is called gangrene. Volvulus is a 

surgical emergency because gangrene can 

develop quickly, cause a hole in the wall of 

the bowel (perforation), and become lifethreatening. 

In the colon, volvulus most often involves 

the cecum and sigmoid segment. Sigmoid 

volvulus is more common than cecal 

volvulus. 

Sigmoid Volvulus 

The sigmoid is the last section of the colon. 

Two anatomic differences can increase the 

risk of sigmoid volvulus. One is an elongated or movable sigmoid colon that is unattached to the left sidewall of the abdomen. 

Another is a narrow mesentery that allows 

twisting at its base. Sigmoid volvulus, however, can occur even without an anatomic 

abnormality. 

Risk factors that can make a person 

more likely to have sigmoid volvulus are 

Hirschsprung’s disease, intestinal pseudoobstructions, and megacolon (an enlarged 

colon). Adults, children, and infants can all 

have sigmoid volvulus. It is more common 

in men than in women, possibly because 

5	 Anatomic Problems of the Colon 
men have longer sigmoid colons. It is also 

more common in people over age 60, in 

African Americans, and in institutionalized 

individuals who are on medications for 

psychiatric disorders. In addition, children 

with malrotation are more likely to get 

sigmoid volvulus. 

The symptoms can be acute (occur suddenly) and severe. They include a bowel 

obstruction (commonly seen in infants), 

nausea, vomiting, bloody stools, abdominal 

pain, constipation, and shock. Other symptoms can develop more slowly but increase 

over time, such as severe constipation, lack 

of passing gas, crampy abdominal pain, and 

abdominal distention. A doctor may also 

hear increased or decreased bowel sounds. 

Several tests are used to diagnose sigmoid 

volvulus. X rays show a dilated colon above 

the volvulus. Upper and lower GI series 

help locate the point of obstruction and 

show whether malrotation of the rest of the 

colon is present. A CT scan may be used to 

show the degree of twisting and malrotation, and whether perforation has occurred. 

In most instances, a sigmoidoscope, a tube 

used to look into the sigmoid colon and 

rectum, can be used to reach the site, 

untwist the colon, and release the obstruction. However, if the colon is found to be 

twisted very tightly or is twisted so tightly 

that blood flow is cut off and the tissue is 

dead, immediate surgery will be needed to 

correct the problem and, if possible, restore 

the blood supply. Dead tissue will be 

removed during surgery, and a portion of 

the colon may be removed as well—a procedure called a resection. Sigmoid volvulus 

can recur after untwisting with the sigmoidoscope, but resection eliminates the 

chance of recurrence. Prompt diagnosis of 

sigmoid volvulus and appropriate treatment 

generally lead to a good outcome. 

Cecal Volvulus 

Cecal volvulus is the twisting of the cecum 

and ascending segment of the colon. Normally, the cecum and ascending colon are 

fixed to the internal abdominal wall. If not, 

they can move and become twisted. The 

main symptoms of cecal volvulus are 

crampy abdominal pain and swelling that 

are sometimes associated with nausea and 

vomiting. 

In testing, x rays will show the cecum out of 

its normal place and inflated with trapped 

air. The appendix may be filled with gas, 

but little or no gas is seen in other parts of 

the colon. Upper and lower GI series will 

locate the volvulus and the position of the 

colon. A CT scan may show how tightly the 

volvulus is twisted. A colonoscopy, which 

uses a small, flexible tube with a light and a 

lens on the end to see the inside of the 

colon, can sometimes be used to untwist 

the volvulus. If the cecum becomes gangrenous or holes develop in it, surgery will 

be needed. 

In volvulus, a portion of the intestine twists around 

itself. 

6 Anatomic Problems of the Colon 
Imperforate Anus 

(Anal Atresia) 

Imperforate anus or anal atresia is a congenital abnormality in which the anorectal 

region is abnormal or incompletely developed. In some cases, the rectum may end 

and not connect with the anus, or it may 

connect in the wrong spot. For example, 

it may connect to the urethra, bladder, or 

vagina. (See the section on fistulas, page 

4). In other cases, the anus may be very 

narrow or missing altogether. The result 

is that stool cannot pass out of the colon. 

Imperforate anus occurs in about 1 in 

5,000 infants. 

Another malformation that results in 

absence of a functioning anus is congenital 

cloaca. In patients with this abnormality, 

the anal muscles and vagina fail to form 

and the result is a large, ill-defined opening 

that represents the rectum as well as the 

vagina and bladder, depending on the 

extent of the defect. Cloaca deformity 

of the anus usually requires a colostomy 

but may be correctable with a surgical 

procedure that transfers a muscle from 

another part of the body to create a 

functioning sphincter at the anus. 

Symptoms of imperforate anus include 

•	 no bowel movement within 24 to 48 

hours after birth 

•	 a missing or misplaced anal opening 

•	 stool that comes out of the vagina or 

urethra 

•	 abdominal swelling (distention) 

Imperforate anus is usually found when the 

infant is first examined after birth. Imperforate anus is categorized on the basis of 

the location of the end of the rectum in 

relation to the muscles that support the 

rectum and other organs in the pelvis, 

called the levator ani muscles. These location categories are 

•	 high: the rectum ends above the


muscles


•	 intermediate: the rectum ends at the 

level of the muscles 

•	 low: the rectum ends below the


muscles


In all cases of imperforate anus, surgery is 

necessary to reconstruct the anus. Low 

imperforate anus is corrected through a 

minor procedure just after birth. High 

imperforate anus may require surgery to 

separate the rectum from the other organs 

if the rectum is connected with them. The 

outcome is usually very good, but some 

infants may not develop good bowel control 

after surgery because the anal muscles may 

not form. A child with high imperforate 

anus often has other GI problems, such as 

malrotation and intestinal atresia. 

Factors that affect the outcome of treatment include the location of the abnormality, the patient’s sex, and the age at which 

the surgery is done. Surgery to correct low 

imperforate anus in boys usually has an 

excellent outcome. Correcting cloaca in 

girls requires a more difficult procedure 

and is more prone to complications. 

Hope Through Research 

The National Institute of Diabetes and 

Digestive and Kidney Diseases, through its 

Division of Digestive Diseases and Nutrition, supports basic and clinical research 

into GI diseases, including GI structure; 

the growth of GI cells in normal and disease states; tissue injury, repair, and regeneration; and Crohn’s disease. Research 

includes new methods that will help physicians and researchers see inside the body, 

thereby increasing the detection rate for 

anatomic problems of the colon. 

7	 Anatomic Problems of the Colon 
• Anatomic problems of the colon are 

caused by changes in the shape of 

the colon or the way it connects to 

other organs. 

• Anatomic problems may be congenital or develop with age. 

• Anatomic problems can block the 

passage of food through the digestive 

system. Some problems can become 

life-threatening. 

• Symptoms of anatomic problems 

include abdominal pain, abdominal 

distension, vomiting, and diarrhea or 

constipation. 

• Some anatomic problems may 

resolve over time; others may need 

to be corrected with surgery. 

Points to Remember 

For More Information 

Crohn’s & Colitis Foundation of America 

(CCFA) 

386 Park Avenue South, 17th Floor 

New York, NY 10016–8804 

Phone: 1–800–932–2423 or 212–685–3440 

Fax: 212–779–4098 

Email: info@ccfa.org 

Internet: www.ccfa.org 

International Foundation for Functional 

Gastrointestinal Disorders (IFFGD) 

P.O. Box 170864

Milwaukee, WI 53217–8076 

Phone: 1–888–964–2001 or 414–964–1799 

Fax: 414–964–7176 

Email: iffgd@iffgd.org 

Internet: www.iffgd.org 

National Digestive Diseases 

Information Clearinghouse 

2 Information Way 

Bethesda, MD 20892–3570 

Phone: 1–800–891–5389 

Fax: 703–738–4929 

Email: nddic@info.niddk.nih.gov 

Internet: www.digestive.niddk.nih.gov 

The National Digestive Diseases Information 

Clearinghouse (NDDIC) is a service of the 

National Institute of Diabetes and Digestive 

and Kidney Diseases (NIDDK). The NIDDK 

is part of the National Institutes of Health 

under the U.S. Department of Health and 

Human Services. Established in 1980, the 

clearinghouse provides information about 

digestive diseases to people with digestive 

disorders and to their families, health care 

professionals, and the public. NDDIC answers 

inquiries, develops and distributes publications, 

and works closely with professional and patient 

organizations and Government agencies to 

coordinate resources about digestive diseases. 

Publications produced by the clearinghouse are 

carefully reviewed by both NIDDK scientists 

and outside experts. This fact sheet was 

reviewed by Robert Beart, M.D., University of 

Southern California; James W. Fleshman, M.D., 

Washington University and Barnes-Jewish 

Hospital; Kevan Jacobson, M.B.B.Ch, B.C.’s 

[British Columbia, Canada’s] Children’s 

Hospital; Joseph Levy, M.D., Children’s 

Hospital of New York-Presbyterian; and John 

H. Pemberton, M.D., Mayo Clinic. 

This publication is not copyrighted. The 

clearinghouse encourages users of this fact 

sheet to duplicate and distribute as many 

copies as desired. 

This fact sheet is also available at 

www.digestive.niddk.nih.gov. 

U.S. DEPARTMENT OF HEALTH 

AND HUMAN SERVICES 

National Institutes of Health 

NIH Publication No. 05–5120 

February 2005