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Procedure
Practice 05/15/98 - Coding
Recommendations
Feature
Article 05/15/98
The
Lower Gastrointestinal Tract
This month we continue our study of the digestive organs
with a review of the anatomy and physiology of the lower gastrointestinal
tract. We also examine lower GI disease processes and some
of the common procedures performed to diagnose and treat them.
The small intestine is a coiled, narrow tube located
below the stomach in the lower abdomen. The small intestine
extends from the duodenum, where it accepts the contents
of the stomach via the pyloric sphincter, to the jejunum
and ileum and finally to the ileocecal orifice
where it passes semifluid food by-products to the large intestine.
The major part of digestion occurs in the small intestine.
Predigested material supplied by the stomach (chyme)
is further subjected to the action of three powerful digestive
fluids within the small intestine: pancreatic fluid, intestinal
enzymes, and bile. These fluids neutralize gastric acid, ending
the gastric phase of digestion. The food passes along the
intestinal tract by wave-like peristaltic contractions
of the smooth muscles of the intestinal walls. Peristalsis
is activated by the parasympathetic nervous system. After
the various foods have been broken down into soluble, easily
diffusable products, they are absorbed by the millions of
villi (projections) lining the inside walls of the
small intestine. Proteins and carbohydrates are absorbed into
capillaries, and lymphatic nodules absorb fats. The villi
pass the proteins and carbohydrates to the liver for metabolic
processing, and the lymphatic nodules pass the fats through
the lymphatic system into the bloodstream. The small intestine
is anchored to the spinal column by a vascular membrane called
the mesentery.
At the junction of the small and large intestines is a circular
muscle called the ileocecal sphincter. When it relaxes,
the contents of the ileum pass successively through the portions
of the large intestine: the cecum, ascending colon
(right colon), transverse colon, descending
colon (left colon), sigmoid colon, rectum,
and anus. (The appendix is a nonfunctional vestigial
appendage of the lower part of the ascending colon). In the
large intestine water is absorbed from the remains of the
digested food and mucus is secreted from the epithelial cells
along the intestinal walls. The feces are formed and stored
in the rectum. The anus is the sphincter muscle that regulates
the lower orifice of the digestive tract.
Infectious Gastroenteritis
Gastroenteritis is a generic term applied to nonspecific
inflammation of the GI tract. Infectious gastroenteritis
is caused by a number of bacteria and viruses. Campylobacter
is the most common bacterial cause of diarrheal illness.
Second in prevalence only to the common cold, the Norwalk
virus causes about 40% of nonbacterial diarrhea in children
and adults. During winter months, rotaviruses are major
causes of serious diarrheal illnesses that result in hospitalization
of infants and children under the age of 2 years. Giardiasis
is caused by the parasite Giardia lamblia, which invades the
intestinal mucosa and causes nausea, vomiting, diarrhea, and
malaise.
Gastroenteritis syndromes of many types can follow exposure
to contaminated food or water. Some types, for example shigellosis
and Norwalk virus infections, are also easily transmitted
from one infected person to another.
Inflammatory Bowel Diseases
(IBD)
Inflammatory bowel disease is the general name for several
distinct diseases that cause intestinal inflammation. Two
of the most common inflammatory bowel diseases are:
- Crohn's disease -
Crohn's disease causes inflammation in the small intestine.
The disease usually occurs in the ileum, but it can affect
any part of the digestive tract, from the mouth to the anus.
The inflammation extends deep into the lining of the affected
organ. The inflammation can cause pain and can make the
intestines empty frequently, resulting in diarrhea. Crohn's
disease can be difficult to diagnose because its symptoms
are similar to other intestinal disorders such as irritable
bowel syndrome and ulcerative colitis. However, Crohn's
disease differs from ulcerative colitis, because it causes
inflammation deeper within the intestinal wall. Crohn's
disease affects males and females equally and may have a
familial component. About 20 percent of people with Crohn's
disease have a blood relative with some form of IBD. Crohn's
disease may also be called ileitis or enteritis.
The most common symptoms of Crohn's disease are abdominal
pain, often in the lower right quadrant, and diarrhea. Rectal
bleeding, weight loss, and fever may also occur. Bleeding
may be serious and persistent, leading to anemia. Children
with Crohn's disease may suffer delayed development and
stunted growth.
The most common complication is intestinal blockage. Blockage
occurs because the disease tends to thicken the intestinal
wall with swelling and scar tissue, narrowing the lumen.
Crohn's disease may also cause ulcers that tunnel through
the affected area into surrounding tissues such as the bladder,
vagina, or skin. The areas around the anus and rectum are
often involved. These tunnels, called fistulas, are
a common complication and often become infected.
Nutritional complications are common in Crohn's disease.
Deficiencies of proteins, calories, and vitamins may occur.
These deficiencies may be caused by inadequate dietary intake,
intestinal loss of protein, or poor absorption (malabsorption).
- Ulcerative colitis
causes inflammation and ulcers in the top layers of the
large intestinal lining. The inflammation usually occurs
in the rectum and lower part of the colon, but it may affect
the entire colon. Ulcerative colitis rarely affects the
small intestine except for the ileum. Other terms synonymous
with ulcerative colitis are colitis, ileitis, and proctitis.
The inflammation caused by ulcerative colitis causes diarrhea.
Ulcers form on the intestinal walls at sites where the inflammatory
process has destroyed the cells lining the interior of the
lumen, and the ulcers then bleed and produce mucus and pus.
Diverticular Disease
A diverticulum is a sacculation (pouch) that bulges outward
through weak spots in the intestinal lining. About half of
all Americans between the ages of 60-80 have diverticulosis.
When the pouches become infected or inflamed, the condition
is called diverticulitis. The exact etiology of diverticulitis
is not known, but doctors suspect that it may begin when stool
or bacteria are trapped within a diverticulum. Diverticulitis
occurs in about 10-25% of people with diverticulosis.
Most people with diverticulosis have few or no symptoms.
If diverticulitis develops, however, a number of symptoms
occur. Left lower quadrant abdominal pain is the most frequent
problem, and if infection ensues, fever, chills, nausea, vomiting,
and constipation may also be present. Diverticulitis can lead
to complications such as intestinal abscesses or perforations,
obstruction, or bleeding.
Meckel's diverticulum is a congenital sacculation
of the distal ileum. Unless the diverticulum becomes inflamed
or infected, people with this congenital abnormality are generally
asymptomatic.
Irritable Bowel Syndrome
(IBS)
IBS is a common disorder of the intestines that leads to
crampy pain, gassiness, bloating, and changes in bowel habits.
Symptoms of IBS may be constipation, diarrhea, or both, and
lower abdominal pain. IBS has been called by many names: mucous
colitis, spastic colon, spastic bowel, and functional bowel
disease. Most of these terms are somewhat inaccurate, however,
because IBS does not cause bowel inflammation. The cause of
IBS is not known. It is referred to as a functional disorder
because there is no sign of disease when the colon is examined.
Proctitis
Proctitis is inflammation of the lining of the rectal mucosa.
Proctitis can be an acute or chronic problem. Proctitis may
be a side effect of medical treatments like radiation therapy
or antibiotics. Diseases like ulcerative colitis, Crohn's
disease, and sexually transmitted diseases may also cause
proctitis. Other causes include rectal injury, bacterial infection,
allergies, and malfunction of the nerves in the rectum. Symptoms
include constipation, a feeling of rectal fullness, left-sided
abdominal pain, passage of mucus through the rectum, rectal
bleeding, and anorectal pain.
Short Bowel Syndrome
Short bowel syndrome is a group of problems affecting people
who have had half or more of their small intestine removed.
The most common reason for removing part of the small intestine
is treatment of Crohn's disease. Diarrhea is the main symptom
of short bowel syndrome. Other symptoms include cramping,
bloating, and heartburn. Many people with short bowel syndrome
are malnourished because their remaining small intestine is
unable to absorb enough water, vitamins, and other nutrients
from food. They may also become dehydrated, which can be life
threatening. Problems associated with dehydration and malnutrition
include weakness, fatigue, depression, weight loss, bacterial
infections, and food sensitivities.
Arteriovenous Malformations
(AVMs)
Gastrointestinal AVMs are abnormal mucosal or submucosal
blood vessels. Their diameters vary from 1 to 30 mm. Often
GI AVMs are associated with other diseases such as valvular
heart disease, chronic renal failure, chronic liver disease,
and collagen vascular diseases. A common source of acute or
chronic GI bleeding, AVMs are seen on endoscopy as red vascular
mucosal or submucosal lesions. Once GI bleeding from AVMs
occurs, recurrent bleeding, chronic anemia, or severe acute
GI bleeding is common. Gastrointestinal AVMs are usually found
in the stomach, proximal small bowel, and right colon.
Neoplasia of the Small
Intestine
- Benign neoplasms arising
in the jejunum and ileum include leiomyomas, lipomas, neurofibromas,
and fibromas. Tumors in the small intestine account for
only 1-5% of all gastrointestinal neoplasms. Polyps are
more common in the colon than in the small bowel. Angiodysplasias
or arteriovenous malformations occur most often in the distal
ileum or cecum.
- Malignant tumors in
the small intestine are fairly uncommon. When they do occur,
adenocarcinomas usually arise in the proximal jejunum. Malignancies
occur most often in patients with Crohn's disease, where
the tumors tend to occur distal to the area affected by
Crohn's, or in bypassed or inflamed loops of bowel. The
ileum is the second most common site (after the appendix)
of carcinoid tumors. About 30% of small bowel carcinoids
cause symptoms of obstruction, pain, bleeding.
Colonic Neoplasia
- Colonic polyps are
masses of tissue arising from the bowel wall and protruding
into the lumen. Polyps may be sessile (attached to the bowel
by a base), or pedunculated (attached to the bowel by a
stalk), and vary considerably in size. Such lesions are
classified histologically as tubular adenomas, tubulovillous
adenomas (villoglandular polyps), villous (papillary) adenomas
(with or without adenocarcinoma), hyperplastic polyps, hamartomas,
juvenile polyps, polypoid carcinomas, pseudopolyps, lipomas,
leiomyomas, or other rarer tumors.
- Familial polyposis is
an inherited disease of the colon in which 100 or more adenomatous
polyps carpet the colon and rectum. Malignancy develops
before age 40 in nearly all untreated patients.
- Other polyps include
hyperplastic polyps, which are common in the colon and rectum.
Inflammatory polyps and pseudopolyps occur in chronic ulcerative
colitis and in Crohn's disease. Juvenile polyps outgrow
their blood supply at puberty and essentially auto-amputate
at that time.
- Colon and rectal cancers
account for more new cancer cases each year than any
other anatomic site except the lung. In the USA about 75,000
people died of these cancers in 1989; about 70% occurred
in the rectum and sigmoid colon, and 95% were adenocarcinomas.
Carcinoma of the colon is more common in women; carcinoma
of the rectum is more common in men. Cancer of the colon
and rectum spreads by (1) direct extension through the bowel
wall, (2) hematogenous metastases, (3) regional lymph node
metastases, (4) perineural spread, and (5) intraluminal
metastases.
Intestinal Obstruction/Infarction
Intestinal obstruction consists of two types: simple, in
which there is no interference with blood supply, and strangulating,
in which all blood flow to the affected bowel segment is cut
off. Common causes of small bowel obstruction are adhesions,
hernias, tumors, foreign bodies, and inflammatory bowel disease.
The chief causes of large bowel obstruction are tumors, diverticulitis,
volvulus, and fecal impaction. Tumors may be either malignancies
that block the intestinal lumen or large lipomas or polyps
that cause intussusception. Obstructing cancers most often
occur at the splenic and sigmoid flexures. Diverticulitis
usually obstructs in the sigmoid, and volvulus most commonly
occurs in the sigmoid and cecum.
Ileus
Ileus is a temporary cessation of intestinal peristalsis.
Various causes of ileus include scarring and adhesions due
to prior infection, mesenteric ischemia, arterial or venous
injury, intraabdominal hematomas, abdominal surgery, and metabolic
disturbances such as hypokalemia. Ileus is diagnosed by abdominal
distention, vomiting, obstipation, and cramping. Auscultation
of the GI tract reveals a silent abdomen or minimal peristalsis.
Hirschprung's Disease;
Megacolon
People with Hirschprung's disease lack the nerve cells that
enable intestinal muscles to move stool through the colon.
Stool becomes trapped, filling the colon and causing it to
distend. Hirschprung's disease is a congenital condition mainly
affecting infants and children.
Although symptoms usually begin within a few days after birth,
some people don't develop them until childhood or even adulthood.
In infants, the primary symptom is not passing meconium within
the first 24 to 48 hours of life. Other symptoms include constipation,
abdominal swelling, and vomiting. Symptoms in older children
include passing small watery stools, diarrhea, and a lack
of appetite.
Disorders of the Appendix
Except for hernia, acute appendicitis is the most common
cause for an attack of acute abdominal pain and for abdominal
operations in the U.S. Because symptoms and signs vary widely,
and because a delay in surgery may lead to a ruptured appendix
and peritonitis, it is accepted that nearly 15% of operations
with this diagnosis lead to other findings or even to finding
no pathology at all
Although acute appendicitis is by far the most common disease
of this organ, other pathology may be caused by swallowed
foreign bodies, pinworms, fecaliths, carcinoid tumors, cancer,
villous adenomas, and diverticula; it may also be involved
in idiopathic ulcerative colitis or the ileocolitis of Crohn's
disease.
Hemorrhoids
Hemorrhoids are swollen veins in and around the anus and
lower rectum that normally stretch under pressure. Hemorrhoidal
varicosities result from prolonged increased pressure due
to chronic constipation or diarrhea, pregnancy, heredity,
or aging.
Varicosities are often complicated by inflammation, thrombosis,
and bleeding. External hemorrhoids are located below the dentate
line (the junction of the rectum and anus), and are covered
by squamous epithelium. Internal hemorrhoids are located above
the dentate line. Hemorrhoids typically occur in the right
anterior, right posterior, and left lateral positions.
Both external and internal hemorrhoids can protrude and then
regress spontaneously or be reduced manually. Only ulcerated
or thrombosed hemorrhoids are painful. A thrombosed hemorrhoid
presents as a perianal protrusion in which pain may vary from
nonexistent to severe and incapacitating. Ulcerated, edematous,
or strangulated hemorrhoids can cause severe pain.
Anal Fissure; Fissure in
Ano; Anal Ulcer
Anal fissures are acute longitudinal tears or chronic oval-shaped
ulcers in the stratified squamous epithelium of the anal canal.
The exact cause of anal fissures is unclear. They are believed
to be due to a traumatic laceration from a hard or large stool
with secondary infection. The fissure rests on the internal
anal sphincter and causes it to go into spasm. The fissure
usually lies in the posterior midline, but may occur in the
anterior midline. An external skin tag (the "sentinel
pile") may be present at the lower end of the fissure.
Anorectal Fistula; Fistula
in Ano
An anorectal fistula is a tube-like tract with one opening
in the anal canal and the other usually in the perianal skin.
Fistulas usually arise spontaneously and occur secondary to
drainage of a perirectal abscess. Usually, there is no recognized
predisposing cause. Most fistulas originate in the anorectal
crypts; others may result from diverticulitis, neoplasm, or
trauma. Rectovaginal fistulas may be secondary to Crohn's
disease, obstetric injuries, radiotherapy, or malignancy.
Angiography is a technique
that uses dye to highlight blood vessels. This procedure is
most useful in situations when a patient is acutely bleeding.
The dye leaks out of the blood vessel and identifies the bleeding
site. In selected situations, angiography allows injection
of coagulants into arteries to stop the bleeding.
Radionuclide scanning
is a noninvasive screening technique to locate sites of acute
bleeding, especially in the lower GI tract. This technique
involves injection of small amounts of radioactive material.
Then a special camera produces images of the organs, allowing
the doctor to isolate a bleeding site.
Enteroscopy (per oral
endoscopy of the small bowel with a gas-sterilized pediatric
colonoscope) is used to visualize and biopsy tumors and to
coagulate bleeding lesions of the duodenum and proximal jejunum.
Arteriography or technetium bleeding scans help locate intestinal
bleeding points.
Lower GI endoscopy allows
direct visual examination of the intestinal tract with a flexible
tube containing light-transmitting glass fibers or a video
transmitter that returns a magnified image. A diagnostic colonoscopy
may be done to further evaluate an abnormality seen on barium
enema; to determine the source of GI bleeding or unexplained
anemia; to evaluate patients with colon cancer, or to determine
the extent of inflammatory bowel disease. Therapeutic indications
include removal of polyps, coagulation of bleeding sites,
and reduction of volvulus or intussusception.
Polypectomy is performed
in a variety of ways. One of the most common methods employs
a flexible wire loop attached to a grounded electrosurgical
cautery unit. The polyp is snared around its neck and current
is applied as the loop is tightened enough to cut through
the base of the polyp. Bleeding lesions are coagulated with
electrocautery or by laser.
Rigid and flexible sigmoidoscopy
and anoscopy: Examination of the perianal area
and distal rectum can be performed with a 7 cm anoscope. The
entire rectum may be examined with either the rigid 25 cm
or flexible 60 cm instrument, and examination of the sigmoid
colon is performed with a flexible sigmoidoscope.
Percutaneous catheter drainage
is done to drain intraluminal intestinal abscesses. Using
a needle and small catheter, the physician inserts the needle
through the skin of the abdomen and drains fluid from the
abscess via the catheter.
Rubber band ligation
of hemorrhoids is a simple procedure in which a rubber band
is placed around the base of the hemorrhoid inside the rectum.
The band cuts off circulation and the hemorrhoid withers away
within a few days.
Sclerotherapy employs
injection of a chemical solution around the hemorrhoidal vein
to shrink it.
Laser coagulation and photocoagulation
both are techniques that use special devices to burn hemorrhoidal
tissue.
Intestinal resections and ostomy
procedures are performed to excise diseased portions
of the intestine. The remaining portions of intestine may
be connected (anastomosis), or an opening (ostomy)
between the skin and intestine may be performed. Different
types of ostomy are performed depending on how much and what
part of the intestines are removed. The surgeries are called
ileostomy, colostomy, and ileoanal reservoir surgery.
If the colon and rectum are removed, the surgeon performs
an ileostomy to attach the ileum to the external stoma. If
the rectum is removed, the surgeon performs a colostomy to
attach the colon to the stoma. A temporary colostomy may be
performed if part of the colon has been removed and the rest
of the colon needs to heal.
Ileoanal reservoir surgery is an alternative to a permanent
ileostomy. It is completed in two steps. In the first surgery,
the colon and rectum are removed and a temporary ileostomy
is done. In the second surgery, the ileostomy is closed and
part of the small intestine is used to create an internal
pouch to hold stool. This pouch is then attached to the anus.
The muscle of the rectum is left in place so the stool in
the pouch does not leak out of the anus.
Practice Makes Perfect!
Are you ready for some hands-on practice?
Read the operative reports on our procedure
practice page. Then assign ICD-9-CM diagnosis
and ICD-9-CM and CPT-4 procedure codes. Compare your answers
with our coding
recommendations. Good luck!
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