Anatomic Problems of the Lower GI Tract National Digestive Diseases Information Clearinghouse What are anatomic problems rectum—and anus. The intestines are some- times called the bowel. The last part of the of the lower gastrointestinal GI tract—called the lower GI tract—consists (GI) tract? of the large intestine and anus. U.S. Department Anatomic problems of the lower GI tract are The large intestine is about 5 feet long in of Health and structural defects. Anatomic problems that Human Services adults and absorbs water and any remain- develop before birth are known as congenital ing nutrients from partially digested food abnormalities. Other anatomic problems NATIONAL passed from the small intestine. The large INSTITUTES may occur any time after birth—from infancy intestine then changes waste from liquid OF HEALTH into adulthood. to a solid matter called stool. Stool passes The GI tract is a series of hollow organs from the colon to the rectum. The rectum joined in a long, twisting tube from the is 6 to 8 inches long in adults and is located mouth to the anus. The movement of mus- between the last part of the colon—called cles in the GI tract, along with the release the sigmoid colon—and the anus. The rec- of hormones and enzymes, allows for the tum stores stool prior to a bowel movement. digestion of food. Organs that make up the During a bowel movement, the muscles of GI tract are the mouth, esophagus, stom- the rectal wall contract to move stool from ach, small intestine, large intestine—which the rectum to the anus, a 1-inch-long open- includes the appendix, cecum, colon, and ing through which stool leaves the body. Transverse colon Descending Ascending colon colon Sigmoid colon Cecum Anus Rectum The lower GI tract What is malrotation? How does the lower GI Malrotation is when the intestines do not tract develop? rotate completely or correctly during gesta- tion. Malrotation can cause serious medical About 4 weeks into gestation—the problems in some infants and children, while 9-month period from conception to others may never develop problems. Sur- birth—the intestines of the developing geons estimate that problems with malrota- baby, or fetus, consist of a thin, straight tion occur in a small percentage of cases and tube that connects the stomach and are usually diagnosed in the first month of the rectum. Over the next 2 weeks, the life. Boys are more likely than girls to be rapidly developing intestines outgrow diagnosed with malrotation during infancy, the baby’s abdomen and move into but problems identified later in childhood the umbilical cord, which connects the are equally likely in boys and girls. Malrota- baby to the mother. During gestational tion rarely occurs in adults. weeks 10 to 12, the baby’s abdomen has grown large enough to hold the Malrotation can prevent the cecum—the intestines, which return to the abdo- beginning of the large intestine—from mov- men, rotating counterclockwise to their ing to its normal position in the lower right final position. The intestines are held in area of the abdomen. If this happens, bands place by tissue called mesentery. of mesentery can block the small intestine, creating an intestinal obstruction—also called bowel obstruction—a life-threatening event and a medical emergency. Malrotation Anatomic problems of the lower GI tract may also leave the mesentery only narrowly may involve parts of organs being in the attached to the back of the abdomen. This wrong place, shaped abnormally, or incor- incomplete attachment may result in the rectly connected to other organs. Anatomic intestine twisting—a serious condition called problems that affect the large intestine or volvulus—see “What is volvulus?” anus include Symptoms of Malrotation • malrotation Infants who have serious problems result- • volvulus ing from malrotation experience pain that • intussusception can be severe, and they often vomit bile—a greenish-yellow fluid. Other symptoms may • fistula include • imperforate anus • abdominal tenderness, swelling, or • colonic atresia bloating • bloody or dark-red stools • constipation—a condition in which a child has fewer than two bowel move- ments a week 2 Anatomic Problems of the Lower GI Tract • dehydration, or abnormal loss of body placed in the nose that runs into the fluids—decreased tears and little or stomach. Infants and children may be no urine or dark-yellow urine may be given a sedative to help them fall asleep observed for the test. Barium coats the small intestine, making signs of malrotation • signs of shock—paleness, sweating, show up more clearly on x rays. confusion, and rapid pulse The child may experience bloating and • weight loss nausea for a short time after the test. Older children with problems from malrota- For several days afterward, barium tion may have the above symptoms as well liquid in the GI tract causes stools to be as nausea, abdominal pain, diarrhea, or an white or light colored. A health care abnormal growth rate, as compared with provider will provide specific instruc- their peers. tions about eating and drinking after the test. Infants or children with any of the above symptoms should be evaluated immediately • Lower GI series. A lower GI series may by a health care provider. be done to look at the large intestine. A health care provider may provide writ- Diagnosis and Treatment of ten bowel prep instructions to follow at Malrotation home before the test. The child may be Doctors use x rays of the abdomen and imag- given a clear liquid diet for 1 to 3 days ing studies to diagnose intestinal problems before the procedure. A laxative or related to malrotation. enema may be used before the test. A laxative is medication that loosens stool • Computerized tomography (CT) scan. and increases bowel movements. An CT scans use a combination of x rays enema involves flushing water, laxative, and computer technology to create or sometimes a mild soap solution into three-dimensional (3-D) images. A the anus using a special plastic bottle. CT scan may include the injection of a special dye, called contrast medium. CT Infants and children may be given a scans require the child to lie on a table sedative to help them fall asleep for the that slides into a tunnel-shaped device test. For the test, the child will lie on a where the x rays are taken. CT scans table while the doctor inserts a flexible can help diagnose malrotation. Infants tube into the child’s anus. The large and children may be given a sedative to intestine is filled with barium, mak- help them fall asleep for the test. ing signs of malrotation show up more clearly on x rays. • Upper GI series. An upper GI series may be done to look at the small intes- For several days afterward, barium tine. No eating or drinking is allowed liquid in the GI tract causes stools to for 8 hours before the procedure, if be white or light colored. Enemas and possible. During the procedure, a child repeated bowel movements may cause is given barium—a chalky liquid—to anal soreness. A health care provider drink. An infant will lie on a table and will provide specific instructions about is given barium through a tiny tube eating and drinking after the test. 3 Anatomic Problems of the Lower GI Tract The above tests are all performed at a • abdominal adhesions, or bands of scar hospital or outpatient center by an x-ray tissue that form as part of the healing technician, and the images are interpreted process following abdominal injury, by a radiologist—a doctor who specializes in infection, or surgery medical imaging. Sigmoid volvulus—twisting of the sig- Surgery is almost always required to correct moid colon—accounts for the majority of problems resulting from malrotation. A cases, with cecal volvulus—twisting of the surgeon performs the procedure in a hospi- cecum and ascending colon—occurring less tal and the child is given general anesthesia. frequently. With early diagnosis and treatment, surgery is usually successful and may involve Sigmoid Volvulus Anatomic problems that increase a person’s • repositioning the large and small risk of developing sigmoid volvulus include intestines • dividing the bands of mesentery block- • an elongated or movable sigmoid colon ing the small intestine that is not attached to the left wall of the abdomen • removing the appendix, a 4-inch pouch attached to the cecum • a narrow mesentery connection at the base of the sigmoid colon • untwisting the large intestine if volvulus has occurred • malrotation that presents with problems in infancy What is volvulus? Sigmoid volvulus that occurs after infancy is more commonly seen in people who Volvulus occurs when the intestine twists around itself and the mesentery that sup- • are male ports it, creating an obstruction. The area • are older than age 60 of intestine above the obstruction continues to function and fills with food, fluid, and gas. • live in a nursing or psychiatric facility The mesentery may become so tightly twisted • have a history of mental health that blood flow to the affected part of the conditions intestine is cut off. This situation can lead to death of the blood-starved tissue and tear- Symptoms of Sigmoid Volvulus ing of the intestinal wall—a life-threatening Sigmoid volvulus symptoms can be severe event and a medical emergency. and occur suddenly. Symptoms may include Volvulus can be caused by malrotation or by • abdominal cramping other medical conditions such as • bloody stools • an enlarged colon • constipation • Hirschsprung disease, a disease of the • nausea large intestine that causes severe consti- pation or intestinal obstruction • signs of shock • vomiting 4 Anatomic Problems of the Lower GI Tract People with any of these symptoms should surgery will be needed.