Basic symptoms of gastroenterological
diseases and diagnostic methods in gastroenterology
ANATOMIC CONSIDERATIONS
S1
The gastrointestinal (GI)
tract extends from the mouth to the anus and comprises several organs with
distinct functions. The organs are separated by specialized independently
controlled thickened sphincters... The gut wall is organized into well-defined
layers that contribute to the functional activities in each region. The mucosa
serves as a barrier to luminal contents or as a site for transfer of fluids or
nutrients. Gut smooth muscle mediates propulsion from one region to the next.
Many GI organs have a serosal.
Interactions with other organ
systems serve the needs both of the gut and the body. Pancreaticobiliary conduits
send bile
and enzymes into the duodenum. A rich vascular supply is modulated by GI tract
activity. Lymphatic channels assist in gut immune activities. Gut wall nerves
provide the basic controls for propulsion and fluid regulation.
FUNCTIONS OF THE GASTROINTESTINAL TRACT
The GI tract serves two main
functions—assimilation of nutrients and elimination of waste. In the mouth,
food is processed, mixed with salivary amylase, and delivered to the luminal GI
tract. The esophagus propels the bolus into the stomach, and the lower
esophageal sphincter prevents oral reflux of gastric contents. The propulsive
activities of the esophagus are coordinated with relaxation of the upper and
lower esophageal sphincters upon swallowing.
The stomach acts in food
preparation by mixing the bolus with pepsin and acid. Gastric acid also
sterilizes the upper gut. Gastric motor activity propels processed meal bolus
into the duodenum. Also the stomach secretes internal factor for vitamin B12
absorption.
The small intestine serves the
nutrient absorptive function of the gut with specialized enzymes and
transporters. Food from the stomach is mixed with pancreatic juice and bile in
the proximal duodenum. Pancreatic juice contains the main enzymes for
carbohydrate, protein, and fat digestion as well as bicarbonate to optimize the
pH for activation of these enzymes. Bile secreted by the liver and stored in
the gallbladder is essential for intestinal lipid digestion. The proximal
intestine is optimized for rapid absorption of nutrient breakdown products and
most minerals, while the ileum is better suited for absorption of vitamin B12
and bile acids. The small intestine also aids in waste elimination. The small
intestine terminates in the ileocecal junction, a sphincteric structure that
prevents coloileal reflux and maintains small-intestinal sterility.
The colon prepares the waste
material for controlled evacuation. The colonic mucosa dehydrates the stool,
decreasing daily fecal volumes from the1500 mL delivered from the ileum to the
100 - 200 mL expelled from the rectum. The proximal colon serves to absorb
fluid, while the distal colon exhibits peristaltic contractions to expel the
stool.
OVERVIEW OF GASTROINTESTINAL DISEASES
GI diseases develop as a
consequence of abnormalities within or outside of the gut and range in severity
from mild symptoms to an adverse outcome. Diseases may be localized to a single
organ or exhibit diffuse involvement at a number of sites.
CLASSIFICATION OF GI DISEASES
S2
GI diseases are manifestations
of alterations in nutrient assimilation or waste evacuation or in the
activities supporting these main functions.
1. Impaired Digestion and Absorption
Diseases of the stomach,
intestine, biliary tree, and pancreas can disrupt nutrient digestion and
absorption. Lactase deficiency, produces flatus and diarrhea, celiac disease,
bacterial overgrowth, infectious enteritis, Crohn's ileitis, and radiation
damage produce anemia, dehydration, electrolyte disorders,
or malnutrition. Biliary obstruction from stricture or neoplasm may impair fat
digestion. Impaired release of pancreatic enzymes in chronic pancreatitis or
pancreatic cancer decreases intraluminal digestion and can lead to profound
malnutrition.
2. Changed Secretion
Selected GI diseases result
from dysregulation of gut secretion. Gastric acid hypersecretion occurs in
Zollinger-Ellison syndrome, G-cell hyperplasia, duodenal ulcer disease.
Conversely, patients with atrophic gastritis or pernicious anemia release
little or no gastric acid. Inflammatory and infectious small-intestinal and
colonic diseases produce fluid loss through impaired absorption or enhanced
secretion and diarrhea.
3. Changed Gut Transit
Changes in gut transit are
commonly secondary to mechanical obstruction. Esophageal occlusion often
results from acid-induced stricture or neoplasm. Gastric outlet obstruction
develops from peptic ulcer disease or gastric cancer. Small-intestinal
obstruction may also occur with Crohn's disease, radiation- or drug-induced
strictures, and malignancy. The most common cause of colonic obstruction is
colon cancer, although inflammatory strictures develop in patients with
inflammatory bowel disease, after certain infections, or with some drugs.
Retardation of propulsion also
develops from disordered gut motor function. Achalasia
is characterized by impaired esophageal body peristalsis and incomplete lower
esophageal sphincter relaxation. Gastroparesis is the
symptomatic delay in gastric emptying of solid or liquid meals. Intestinal
pseudoobstruction causes marked delays in small-bowel transit due to injury to
enteric nerves or intestinal smooth muscle. Slow transit constipation is
produced by diffusely impaired colonic propulsion. Constipation is also
produced by outlet abnormalities such as rectal prolapse, invagination, or failure
of anal relaxation upon defecation.
Disorders of rapid propulsion
are less common than those with delayed transit. Rapid gastric emptying occurs
in postvagotomy dumping syndrome and with gastric hypersecretion. Accelerated
transit with hyperdefecation is noted in hyperthyroidism.
4. Impaired Gut Blood Flow
Different GI regions are at
variable risk for ischemic damage from impaired blood flow. Rare cases of
gastroparesis result from blockage of the celiac and superior mesenteric
arteries. More commonly cases are intestinal and colonic ischemia due to
arterial embolus, arterial thrombosis, venous thrombosis, or hypoperfusion from
dehydration, sepsis, hemorrhage, or reduced cardiac output. These may produce
mucosal injury, hemorrhage, or even perforation. Some cases of radiation
enterocolitis exhibit reduced mucosal blood flow.
5. Neoplastic Degeneration
All GI regions are susceptible
to malignant degeneration to varying degrees. In the United States , colorectal cancer is
most common and typically presents after age 50. Worldwide, gastric cancer is
especially prevalent in certain Asian regions. Esophageal cancer develops with
chronic acid reflux or in those with an extensive alcohol or tobacco use
history. Small-intestinal neoplasms are rare and occur with underlying
inflammatory disease. Anal cancers may arise with prior anal infection or
inflammation. Pancreatic and biliary cancers shows with severe pain, weight
loss, and jaundice and have poor prognoses. Hepatocellular carcinoma usually
arises in the setting of chronic viral hepatitis or cirrhosis secondary to
other causes.
6. Disorders without Obvious Organic Abnormalities
The most common GI disorders
show no abnormalities on biochemical or structural testing and include
irritable bowel syndrome (IBS), functional dyspepsia, noncardiac chest pain,
and functional heartburn. These functional bowel disorders mostly exhibit changed
gut motor function. Symptoms in some patients result from changed processing of
visceral pain sensations in the central nervous system. Patients with
functional bowel abnormalities with severe symptoms may exhibit significant
emotional disturbances.
7. Genetic Influences
Although many GI diseases
result from environmental factors, others exhibit hereditary components. Family
members of inflammatory bowel disease (IBD) patients show a genetic
predisposition to disease. Colonic and esophageal malignancies arise in certain
inherited disorders. Hereditary pancreatitis is caused by mutation in the
cationic trypsinogen gene. Rare genetic dysmotility syndromes are described.
Familial clustering is even observed in the functional bowel disorders,
although this may be secondary to learned familial illness behavior rather than
a true hereditary factor.
SYMPTOMS OF GASTROINTESTINAL DISEASE
S3.
The most common GI symptoms
are abdominal pain, heartburn, nausea and vomiting, changed bowel habits, GI
bleeding, and jaundice (Table 1). Others are dysphagia,
anorexia, weight loss, fatigue, and extraintestinal symptoms.
TABLE
1 Common Causes of Common GI Symptoms
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Abdominal Pain
Abdominal pain results from GI
disease and extraintestinal conditions involving the genitourinary tract,
abdominal wall, thorax, or spine. Visceral pain is generally midline in
location and different in character, while parietal pain is localized and clearly
described. Common inflammatory diseases with pain include peptic ulcer,
appendicitis, diverticulitis, IBD, and infectious enterocolitis. Other
intraabdominal causes of pain include gallstone disease and pancreatitis.
Noninflammatory visceral sources include mesenteric ischemia and neoplasia. The
most common causes of abdominal pain are irritable bowel syndrome (IBS) and
functional dyspepsia.
Heartburn
Heartburn, a burning
substernal sensation, is reported intermittently by at least 40% of the
population. Classically, heartburn is felt to result from excess
gastroesophageal reflux of acid. However, some cases exhibit normal esophageal
acid exposure and may result from increased sensitivity of esophageal mucosal
nerves.
Nausea and Vomiting
Nausea and vomiting are caused
by GI diseases, medications, toxins, acute and chronic infection, endocrine
disorders, labyrinthine conditions, and central nervous system diseases. The
best-characterized GI etiologies relate to mechanical obstruction of the upper
gut; however, disorders of propulsion including gastroparesis and intestinal
pseudoobstruction also show prominent symptoms. As with abdominal pain, IBS and
functional dyspepsia commonly present with nausea and vomiting.
Changed Bowel Habits
Changed bowel habits are
common complaints of patients with GI disease. Constipation is reported as
infrequent defecation, straining with defecation, passage of hard stools, or a
sense of incomplete fecal evacuation. Causes of constipation
include obstruction, motor disorders of the colon, medications, and endocrine
diseases such as hypothyroidism and hyperparathyroidism. Diarrhea is reported
as frequent defecation, passage of loose or watery stools, fecal urgency, or a
similar sense of incomplete evacuation. The differential diagnosis of diarrhea
is broad and includes infections, inflammatory causes, malabsorption, and
medications. IBS produces constipation, diarrhea, or an alternating bowel
pattern. Fecal mucus is common in IBS, while pus characterizes inflammatory
disease. Steatorrhea develops with malabsorption.
GI Bleeding
Hemorrhage may develop from
any gut organ. Most commonly, upper GI bleeding presents with melena or
hematemesis, and lower GI bleeding produces passage of bright red or maroon
stools. However, intensive bleeding upper sites can show prominent red rectal
bleeding, while slowly bleeding ascending colon sites may produce melena.
Chronic slow GI bleeding may present with iron-deficiency anemia. The most
common upper GI causes of bleeding are ulcer disease, gastroduodenitis, and
esophagitis. Other etiologies include portal hypertensive causes, malignancy,
and vascular lesions. The most prevalent lower GI sources of hemorrhage include
hemorrhoids, anal fissures, diverticula, and arteriovenous malformations. Other
causes include neoplasm, IBD, ischemia, infectious colitis, and other vascular
lesions.
Jaundice
Jaundice results from
prehepatic, intrahepatic, or posthepatic disease. Prehepatic causes of jaundice
include hematological diseases such as hemolytic anemia. Intrahepatic causes of
jaundice include hepatitis, cirrhosis, and cancer. Posthepatic causes of
jaundice include biliary diseases such as choledocholithiasis, cholangitis,
stricture, and neoplasm and pancreatic disorders such as acute and chronic
pancreatitis, stricture, and malignancy.
Other Symptoms
Dysphagia, odynophagia, and
unexplained chest pain suggest esophageal disease. A globus sensation is
reported with esophagopharyngeal conditions but also occurs with functional GI
disorders. Weight loss, anorexia, and fatigue are nonspecific symptoms of
neoplastic, inflammatory, gut motor, pancreatic, small bowel mucosal, and
psychiatric conditions. Fever is reported with inflammatory illness, but
malignancies also evoke febrile responses. GI disorders also produce
extraintestinal symptoms. IBD is associated with hepatobiliary dysfunction,
skin and eye lesions, and arthritis. Celiac disease may present with dermatitis
herpetiformis. Conversely, systemic diseases can have GI consequences. Systemic
lupus may cause gut ischemia, presenting with pain or bleeding. Overwhelming
stress or severe burns may lead to gastric ulcer formation.
EVALUATION OF THE PATIENT WITH GASTROINTESTINAL DISEASE
S4.
Evaluation of the patient with
GI disease begins with a careful history and physical examination. Special
additional investigations to test the structure or function of the gut are
indicated in selected cases. Some patients exhibit normal findings on
diagnostic testing. In these individuals a functional bowel disorder can be
suspected.
HISTORY
The history of the patient
with suspected GI disease has several components. Symptom timing can suggest
specific etiologies. Symptoms of short duration commonly result from acute
infection, toxin exposure, or abrupt inflammation or ischemia. Long-standing
symptoms point to an underlying chronic inflammatory or neoplastic condition or
a functional bowel disorder. Symptoms from mechanical obstruction, ischemia,
IBD, and functional bowel disorders are worsened by eating. Conversely, ulcer
symptoms may be relieved by eating or antacids. The symptom pattern and
duration may suggest underlying etiologies. Ulcer pain occurs at intermittent
intervals lasting weeks to months, biliary colic has a sudden onset and lasts
up to several hours. Pain from acute inflammation, as with acute pancreatitis,
is severe and persists for days to weeks. Meals call diarrhea in some cases of
IBD and IBS, while defecation relieves discomfort in these conditions.
Functional bowel disorders are exacerbated by stress. Sudden awakening from
sleep suggests organic disease rather than a functional bowel disorder.
Diarrhea from malabsorption usually improves with fasting, while secretory
diarrhea persists without oral intake.
Symptom relation to other
factors narrows the list of diagnostic possibilities. Obstructive symptoms with
prior abdominal surgery raise concern for adhesions, whereas loose stools after
gastrectomy or gallbladder excision suggest dumping syndrome or
post-cholecystectomy diarrhea. Symptom onset after travel allows to think about
enteric infection. Medications produce pain, changed bowel habits, or GI
bleeding. Lower GI bleeding likely results from neoplasm, diverticula, or
vascular lesions in an older person and anorectal abnormalities or IBD in a
younger individual. Celiac disease is prevalent in people of Irish descent; IBD
is more common in certain Jewish populations. A sexual history may raise
concern for sexually transmitted diseases or immunodeficiency.
Over the past two decades,
working groups worked to collect symptom criteria to improve the diagnosis of
the functional bowel disorders and to minimize the number of unnecessary
diagnostic tests performed. The most widely accepted symptom-based criteria are
the Rome criteria.
PHYSICAL EXAMINATION
The physical examination
complements information from the history. Abnormal vital signs provide
diagnostic variants and determine the need for acute intervention. Fever
suggests inflammation or neoplasm. Orthostasis is found with significant blood
loss, dehydration, sepsis, or autonomic neuropathy. Skin, eye, or joint
findings may point to specific diagnoses. Neck examination with swallowing
assessment evaluates dysphagia. Cardiopulmonary disease may present with
abdominal pain or nausea; thus lung and cardiac examinations are important.
Pelvic examination tests for a gynecologic source of abdominal pain. Rectal
examination may detect blood, indicating gut mucosal injury or neoplasm, or a
palpable inflammatory mass in appendicitis. Metabolic conditions and gut motor
disorders have associated peripheral neuropathy.
Inspection
of the abdomen may reveal distention from obstruction, tumor, or ascites or
vascular abnormalities with liver disease. Ecchymoses develop with severe
pancreatitis. Auscultation can detect bruits or friction rubs from vascular
disease or hepatic tumors. Loss of bowel sounds signifies ileus, while
high-pitched, hyperactive sounds characterize intestinal obstruction.
Percussion assesses liver size and can detect shifting dullness from ascites.
Palpation assesses for hepatosplenomegaly as well as neoplastic or inflammatory
masses. Abdominal examination is helpful in evaluating unexplained pain.
Intestinal ischemia shows severe pain but little tenderness. Patients with visceral pain may exhibit generalized
discomfort, while those with parietal pain or peritonitis have directed pain
often with involuntary guarding, rigidity, or rebound. Patients with
musculoskeletal abdominal wall pain may note tenderness exacerbated by Valsalva
or straight leg lift maneuvers.
ADDITION EXAMINATIONS
Laboratory, radiographic, and
scintigraphic tests can assist in diagnosis of suspected GI disease. The GI
tract can be investigated with internal evaluation - upper and lower endoscopy,
and examination of luminal contents. Histopathologic examinations of
gastrointestinal tissues complement these tests.
Laboratory
Selected laboratory tests
facilitate the diagnosis of GI disease.
Blood test.
Iron-deficiency anemia
suggests mucosal blood loss, whereas vitamin B12 deficiency results
from small-intestinal, gastric, or pancreatic disease. Either can also result
from inadequate oral intake.
Leukocytosis and increased erythrocyte
sedimentation rates are found in inflammatory conditions, while leukopenia is
seen in viremic illness.
Biochemical serum tests.
Severe vomiting or diarrhea
elicits electrolyte disturbances, acid-base abnormalities, and elevated blood
urea nitrogen.
Pancreaticobiliary or liver
disease is suggested by elevated pancreatic or liver chemistries.
Thyroid chemistries, cortisol, and calcium
levels are obtained to exclude endocrinologic causes of GI symptoms. Hormone
levels are obtained for suspected endocrine neoplasia.
Pregnancy testing is
considered for young women with unexplained nausea.
Serologic tests are available
for rheumatologic diseases such as systemic lupus erythematosus or scleroderma.
Intraabdominal malignancies
produce tumor markers including carcinoembryonic antigen, while paraneoplastic
dysmotility is associated with antineuronal antibodies.
Ascitic fluid is analyzed for infection, malignancy, or
findings of portal hypertension.
Cerebrospinal fluid is obtained for suspected
central nervous system causes of vomiting.
Urine samples screen for carcinoid, porphyria, and heavy
metal intoxication.
Luminal Contents
Stool samples are cultured for
bacterial pathogens or examined for leukocytes or parasites.
Duodenal aspirates can be
examined for parasites or cultured for bacterial overgrowth.
Fecal fat is quantified in
possible malabsorption.
Stool electrolytes and
osmolarity can be measured in diarrheal conditions.
Gastric acid is quantified to
rule out Zollinger-Ellison syndrome.
Pancreatic juice is analyzed
for enzyme or bicarbonate content to exclude pancreatic exocrine insufficiency.
Instrumental
S5. Esophageal and intragastral pH testing are done for refractory
symptoms of acid reflux, acid gastral secretion.
S6. Endoscopy
Endoscopy can provide the
diagnosis of the causes of bleeding, pain, nausea and vomiting, weight loss, changed
bowel function, and fever. Table 2 lists the most common
indications for the major endoscopic procedures.
S7. Upper endoscopy evaluates the esophagus, stomach, and
duodenum, while colonoscopy assesses the colon and distal ileum. Upper
endoscopy is advocated as the initial structural test performed in patients
with upper GI bleeding, suspected ulcer disease, esophagitis, neoplasm,
malabsorption, and Barrett's metaplasia because of its ability both to
visualize the abnormality directly and to biopsy it.
Colonoscopy is the procedure of choice
for colon cancer screening and observation; diagnosis of colitis secondary to
infection, ischemia, radiation, and IBD; and characterization of causes of
lower GI bleeding.
Sigmoidoscopy examines the
colon up to the splenic flexure and is currently used to exclude distal colonic
inflammation or obstruction in young patients not at significant risk for colon
cancer. For GI bleeding secondary to arteriovenous malformations or superficial
ulcers, small-intestinal examination is performed with push enteroscopy or
capsule endoscopy.
Endoscopic retrograde
cholangiopancreaticography (ERCP) provides diagnoses of pancreatic and biliary disease.
Endoscopic ultrasound is useful for evaluating the
extent of disease in GI malignancy as well as exclusion of choledocholithiasis,
evaluation of pancreatitis, drainage of pancreatic pseudocysts, and assessment
of anal continuity.
TABLE 2
Common Indications for Endoscopy
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S8. IMAGING
Radiographic tests evaluate diseases of the gut and extraluminal structures. Oral or
rectal contrast agents such as barium provide mucosal definition from the
esophagus to the rectum. Contrast radiography also assesses gut transit and
pelvic floor dysfunction. Barium swallow is the initial procedure for
evaluation of dysphagia to exclude subtle rings or strictures and assess for
achalasia, whereas small-bowel contrast radiology reliably diagnoses intestinal
tumors and Crohn's ileitis. Contrast enemas are performed when colonoscopy is
unsuccessful or contraindicated.
Ultrasound and computed tomography (CT) evaluate regions not
accessible by endoscopy or contrast studies, including the liver, pancreas,
gallbladder, kidneys, and retroperitoneum. These tests are useful for diagnosis
of mass lesions, fluid collections, and organ enlargement. Ultrasound is the
initial test to evaluate for gallstone disease. Virtual CT colonoscopy is being evaluated
as a method of colon cancer screening.
Magnetic resonance imaging assesses the mesenteric
circulation to screen for arterial exclusion; the pancreaticobiliary ducts to
exclude neoplasm, stones, and sclerosing cholangitis; and the liver to
characterize benign and malignant tumors.
Angiography excludes mesenteric ischemia and determines spread of malignancy.
Angiographic techniques also access the biliary tree in obstructive jaundice.
Positron emission tomography may become useful in distinguishing malignant from
benign pancreatic disease.
Radionuclide bleeding scans localize bleeding sites in patients with brisk
hemorrhage so that therapy with endoscopy, angiography, or surgery may be
directed.
Radiolabeled leukocyte scans can show the intraabdominal abscesses not visualized
on CT.
Biliary scintigraphy is complementary to ultrasound in the assessment of cholecystitis.
Scintigraphy to quantify esophageal and gastric emptying are well established, while
techniques to measure small-intestinal or colonic transit are less widely used.
Histopathology
Gut mucosal biopsies obtained
at endoscopy evaluate for inflammatory, infectious, and neoplastic disease.
Deep rectal biopsies assist with diagnosis of Hirschsprung's disease or
amyloid. Liver biopsy is indicated in cases with abnormal liver chemistries,
unexplained jaundice, following liver transplant to exclude rejection, and to
characterize the degree of inflammation in patients with chronic viral
hepatitis prior to initiating antiviral therapy. Biopsies obtained during CT or
ultrasound can evaluate for other intraabdominal conditions not accessible by
endoscopy.
Functional Testing
Tests of gut function provide
important data when structural testing is nondiagnostic. In addition to gastric
acid and pancreatic function testing, functional testing of motor activity is
provided by regional manometric techniques.
S9. Esophageal manometry is useful for suspected achalasia, whereas
small-intestinal manometry tests for pseudoobstruction.
Anorectal manometry is employed for unexplained incontinence or constipation from outlet
dysfunction.
Biliary manometry tests for sphincter of Oddi dysfunction with unexplained biliary pain.
Electrogastrography measures gastric electrical activity in individuals with nausea and
vomiting, whereas electromyography assesses
anal function in fecal incontinence.