Health Alterations IIManagement of Clients with Problems of the Gastrointestinal System Lecture 1.2. Asessment of the Gastrointestinal, Biliary, and Exocrine Pancreatic Systems
Major Gastrointestinal, Biliary, and Exocrine Pancreas Blood and Urine Tests
Stool Examination • Stool specimens are collected for culture, determination of fat content, and examination for the presence of ova, parasites, and fresh or occult blood. Special collection procedures may be necessary to enhance the identification of bacteria (Salmonella, Shigella, and Staphylococcus aureus), ova, and parasites. A fresh, warm stool specimen is optimal for laboratory analysis. • Detection of occult blood in the stool is useful in identifying bleeding in the GI tract. Occult blood may be identified by one of three tests: guaiac (Hemoccult), benzidine, or orthotoluidine (Occultest). Meat, poultry, or fish eaten within 3 days before testing can cause a false-positive test as well as aspirin or antiinflammatory drugs taken within 7 days; vitamin C in quantities of greater than500 mg/day may cause a false-negative test if consumed 3 days before testing with benzidine or orthotoluidine. • Determination of fecal fat may be done as part of a workup for malabsorption. Elevations in fecal fat will be present with biliary or pancreatic obstructions and many intestinal malabsorption disorders.
Radiologic Tests • Visualization of the GI tract may be performed by barium swallow, upper GI series, or barium enema. Barium is a radiopaque substance that, when ingested or given by enema, outlines the passageways of the GI tract for viewing by fluoroscopy or x-ray films. • Nursing responsibilities commonly involve cleansing of the GI tract with enemas and laxatives. It is important for the nurse to monitor the patient's fluid and electrolyte status because extensive bowel cleansing may cause significant fluid losses, particularly in elderly persons. The nurse should provide psychologic support to the patient because the procedures can be intrusive and uncomfortable. The nurse must also address the educational needs of the patient, explaining the procedure, the rationale for use, and procedural steps, which will assist in reducing anxiety.
Upper Gastrointestinal Series • An upper GI series involves visualization of the esophagus, stomach, duodenum, and upper jejunum through the use of a contrast medium. It is a fluoroscopic x-ray test that permits the examination of the structure, position, peristaltic activity, and motility of the organs. It can assist in the detection of tumors, ulceration, inflammation, abnormal anatomy, or malposition. The upper GI series used to be the foundation of a diagnostic workup for many GI disorders, but the ready availability of endoscopy has now relegated the test to a seldom used status. • An upper GI series involves swallowing the contrast medium (usually barium), which is prepared in a flavored milk shake form. The barium is unpleasant tasting and may cause vomiting. It is administered cold. The barium outlinesthe structures as it flows by gravity through the esophagus and stomach into the intestinal loops. Films are taken at intervals during the test, and the entire test takes about 45 minutes. The procedure is termed a barium swallow if only the function of the esophagus is to be evaluated and takes about 15 minutes. If the small bowel is the primary focus of the test, it may be termed a small bowel series. • No special preparation is necessary before a GI series; however, the patient maintains nothing-by-mouth (NPO) status for at least 6 hours before the test. After an upper GI series, the patient is prescribed a laxative to hasten elimination of the barium; barium that remains in the colon may become hard and difficult to expel, leading to fecal impaction. The stool should return to its normal color (barium is white) after the barium is expelled.
Barium Enema • A barium enema clearly outlines most of the large intestine through the use of a contrast medium. It is used to detect colon polyps, tumors, and chronic inflammatory bowel disease. If both an upper GI series and a barium enema are to be performed, the barium enema is done first, before barium from the upper GI series reaches the colon. • The procedure involves the instillation of barium through a rectal tube with an inflatable balloon to hold the barium in the colon. The patient is then placed in various positions while the radiologist observes on a monitor as the barium flows through the colon. The procedure takes about 30 minutes, and the instillation and retention of the barium can cause the patient considerable embarrassment and discomfort. • Preparation for a barium enema involves thorough cleansing of the bowel by laxatives, enemas, or both. Thorough preparation is essential because retained fecal material obscures the normal bowel anatomy. The patient may be asked to restrict dairy products, follow a liquid diet for 24 hours before the test, and remain NPO for at least 8 hours before the test. Laxatives are frequently administered after the test to facilitate the removal of the barium. The stools may be white tinged for several days. Inpatients are closely monitored for complications after the test, such as perforation of the bowel. Outpatients are instructed to report the development of abdominal pain and to monitor carefully for constipation.
Ultrasonography • Ultrasonography involves the use of high-frequency sound waves that are transmitted into the abdomen and create echoes that vary with tissue density. The echoes bounce back to a transducer and are electronically converted into pictorial images of the organs. This reveals organ size, shape, and position and is extremely useful in diagnosing cysts, tumors, and stones. Ultrasonography has gradually become the procedure of choice for diagnosing gallbladder disease because it does not expose the patient to radiation. The procedure is both painless and safe. • Patient preparation is straightforward. The patient remains NPO for 8 to 12 hours before the test, because gas in the bowel may interfere with the results. If the gallbladder is the focus of the test, the patient is instructed to eat a low-fat meal theevening before the test so that bile will accumulate in the gallbladder, thereby enhancing visualization. The patient resumes a normal diet and activity after the test.
Computed Tomography • Computed tomography (CT) can also be used to assess patients with gallbladder, biliary ductal system, or pancreatic problems. It is helpful in identifying problems similar to those described for ultrasonography. Multiple x-rays are passed through the abdomen. A computer reconstructs the data into two-dimensional images on a television screen. Still photographs can also be taken of the images. Contrast medium can be used with the CT scan to better visualize the biliary tract or to accentuate differences in tissue density of the pancreas. The test is comparable to ultrasonography in effectiveness. It is used less often because of its significantly higher cost and moderate radiation exposure for the patient. It is extremely useful with obese individuals, however, because increased tissue density limits the effectiveness of ultrasound transmission. • The patient should remain NPO for 8 to 12 hours before the test. If contrast medium is to be used, the patient should be assessed for allergies to iodine, seafood, or contrast medium. Barium studies, if necessary, should be done at least 4 days before CT scan or after the scan, because the barium can interfere with test results. There are no special after-care considerations. The patient may resume pretest diet and activity.
Radionuclide Imaging • GI scintigraphy may be used to localize the site of GI bleeding. Endoscopy provides excellent visualization of gastric or esophageal bleeding, but other areas of the GI tract are much more difficult to visualize and pinpoint. An intravenous injection of 99mTc sulfur colloid is administered. Pooling of the radionuclide will occur at the bleeding site. No pretest preparation is required, and no discomfort is experienced. Patients in unstable condition may not be candidates for this test if they are unable to travel safely to the nuclear medicine department for the 30 minutes required for the test.
Cholecystography • Oral cholecystography involves the radiographic examination of the gallbladder after the administration of a contrast medium. A normal liver will remove radiopaque drugs, such as iodoalphionic acid (Priodax), iopanoic acid (Telepaque), and iodipamide methylglucamine (Cholografin Meglumine), from the bloodstream and store and concentrate them in the gallbladder. The dye-filled gallbladder shows on x-ray examination as a dense shadow. If no shadow is seen, this indicates a nonfunctioning gallbladder. Stones, which are not radiopaque, show as dark patches on the film. Ultrasonography has largely replaced this once commonly used test in the diagnosis of gallbladder disease. Cholecystography is primarily used today when the ultrasound picture is inconclusive. • Patient preparation involves instruction to eat a fat-free meal the evening before the test. The radiopaque substance (usually iopanoic acid) is administered orally 2 to 3 hours after the evening meal. The dose is based on body weight, andthe tablets are administered one at a time at 5- to 10-minute intervals with several swallows of water after each pill. The patient then maintains NPO status until the test. The patient is carefully assessed for allergies to contrast dyes, seafood, or iodine.
Cholangiography • Cholangiography involves x-ray examination of the bile ducts to confirm the presence of stones, strictures, or tumors. The radiopaque substance may be administered intravenously or injected directly into the common bile duct with a needle or catheter during surgery or endoscopy. After surgery on the common bile duct, a radiopaque drug such as iodipamide methylglucamine is instilled through a drainage tube such as the T tube to determine the patency of the duct before the tube is removed (T tube cholangiography). The dye also may be injected through the skin and abdominal wall directly into a bile duct within the main substance of the liver (percutaneous transhepatic cholangiography). The technique is useful in visualizing the location and extent of a pathologic process, such as obstructive jaundice, and permits decompression of the liver. Complications from the test are rare, but include bile leakage leading to bile peritonitis or bleeding caused by accidental rupture of a blood vessel. • The patient remains NPO for about 8 hours before the test. The injection of the contrast medium may cause temporary pain or a feeling of pressure or epigastric fullness. The patient is carefully monitored for bleeding or adverse reactions to the dye. Vital signs are monitored, and the patient typically rests in bed for about 6 hours after the test, lying on the right side as much as possible. The needle insertion site is carefully monitored for signs of bleeding or infection.
Special Tests Esophageal Function Tests • Several diagnostic tests may be used to evaluate the functioning of the esophagus and aid in the diagnosis of esophageal reflux or motility problems. These tests can be performed by having the patient swallow two or three tiny tubes that are attached to an external transducer. Once the tubes are located in the stomach, they are slowly pulled back into the distal esophagus at varying levels. Lower esophageal sphincter pressure, swallowing activity, pH, and effectiveness of clearance can all be measured in about 30 to 45 minutes. However, 24-hour pH monitoring may be performed because it is considered the "gold standard" for the accurate diagnosis of esophageal reflux. • In preparation for these tests, it is important to provide the following instructions to the patient: (1) remain NPO for 8 hours before the procedure(s), (2) avoid alcohol and smoking the day before, and (3) do not take medications such as antacids, H2-receptor antagonists, proton pump inhibitors and anticholinergics before the test(s). Sedation is not required but may be used if the patient experiences persistent choking or gagging during the procedure. After removal of the tubes, a mild sore throat is common.
Manometry • This test is used to measure the pressure in the lower esophageal sphincter and record the duration and sequence of peristaltic movements within the esophagus. Readings are taken at various levels in the esophagus with the patient at rest and during swallowing. Baseline sphincter pressure is normally about 20 mm Hg. The test is used primarily to diagnose esophageal reflux, but the graphic record of muscular activity during swallowing may also help document the presence of achalasia or esophageal spasm. pH Monitoring • This test evaluates the competency of the lower esophageal sphincter (LES) by obtaining a single measurement of the esophageal pH. An electrode is placed above the LES and attached to a manometry catheter. Normally, the esophagus maintains a pH of more than 6.0. Serial measurements may be obtained by maintaining the electrode in place for 24 hours. The probe must be inserted transnasally and connected to a recording box similar to a Holter monitor that is worn about the waist. The patient can then be monitored at home while eating a normal diet; 24-hour pH monitoring is the most sensitive and specific diagnostic test for the presence of abnormal acid reflux.
Esophageal Clearance Test • In conjunction with the previous two tests, esophageal clearance tests evaluate the function of both the upper and lower esophageal sphincters along with the body of the esophagus in response to swallowing. Normally, esophageal function allows for the complete clearance of acid material from the esophagus in less than 10 swallows. Readings are recorded from the catheter tip to determine the rate and efficiency of acid clearance. Acid Perfusion Test (Bernstein Test) • Confusion surrounding the origin of heartburn symptoms is often resolved with the Bernstein test, which attempts to reproduce the pain. Small quantities of HCl are instilled into the distal esophagus by nasogastric tube. The test is positive if the acid produces pain. Saline is instilled to rinse out the acid, and an antacid may be administered to relieve the discomfort.
Tests of Gastric Function Gastric Analysis (Basal Gastric Secretion and Gastric Acid Stimulation Tests) • Examination of the fasting contents of the stomach may be helpful in establishing a diagnosis of gastric disease. The purpose is to quantify gastric acidity in the fasting and stimulated states. Abnormal secretion may be related to ulcers, malignancy, pernicious anemia, or Zollinger-Ellison syndrome. A nasogastric tube is inserted, and gastric contents are aspirated. Gastric contents may then be aspirated every 15 minutes for 90 minutes. • The patient is instructed to restrict food, fluid, and smoking for 8 to 12 hours before the test. The flow of gastric acid is then stimulated by betazole hydrochloride, histamine phosphate, or pentagastrin given subcutaneously. The person may experience side effects from the medication, including flushing, a feeling of warmth, slight headache, or itching. Epinephrine is given to counteract the effects of histamine if sensitivity occurs.
Tubeless Gastric Analysis (Diagnex Blue Test) • Tubeless gastric analysis may be used for detection of gastric achlorhydria.The test will indicate the presence or absence of free hydrochloric acid but cannot be used to determine the amount of free hydrochloric acid that is present. A gastric stimulant such as caffeine is given and then a cation exchange resin containing azure A is given orally an hour later. If free hydrochloric acid is present in the stomach, introduction of the resin will cause a substance to be released in the stomach that will be absorbed from the small intestine and excreted by the kidneys as blue dye within 2 hours. Absence of detectable amounts of blue dye in the urine indicates that free hydrochloric acid probably was not secreted. Schilling Test • The Schilling test evaluates vitamin B12 absorption. In the normal GI tract, vitamin B12 combines with the intrinsic factor that is produced by the parietal cells in the gastric mucosa and is absorbed in the distal portion of the ileum. Pernicious anemia develops if intrinsic factor is lacking or malabsorption exists. This is a concern in patients who have had the terminal ileum removed for diseases such as Crohn's disease. • The patient is kept NPO for 8 to 12 hours before the test and then administered an oral preparation of radioactive vitamin B12, followed by an intramuscular injection of nonradioactive vitamin B12 to saturate the tissue-binding sites. Urinary B12 levels are measured after urine is collected for 24 to 48 hours. With normal absorption of vitamin B12, the ileum absorbs more vitamin B12 than the body needs and excretes the excess into the urine. With impaired absorption of vitamin B12, little or no vitamin B12 is excreted into the urine. Intrinsic factor preparations may also be administered to differentiate intestinal problems from pernicious anemia.
Urea Breath Test • Testing for H. pylori has been both technically difficult and expensive. The urea breath test (UBT) is based on the principle that the H. pylori organism is able to produce large amounts of urease, a surface enzyme that catalyzes the urea in gastric secretions into bicarbonate and ammonia. Patients are administered an oral solution of carbon isotope-labeled urea in water. If H. pylori is present in the stomach the urea is metabolized. The labeled bicarbonate is excreted in the form of labeled carbon dioxide, which can be collected and measured. The patient exhales into a balloon or other receptacle, and the carbon dioxide is measured with a scintillation counter. The sample can be collected 20 minutes after the solution is ingested. The test has minimal risks associated with radioactivity and is estimated to be 97% sensitive for H.pylori and 100% specific.
Biopsy Upper Gastrointestinal Biopsy • A biopsy of the oral cavity or tongue may be done on any lesion or ulcerated area that requires a differential diagnosis. This procedure is usually performed with a local anesthetic. After the biopsy, the biopsy site is assessed for bleeding. Biopsy of the stomach is typically performed during fiberoptic endoscopy. Intestinal Biopsy • Biopsy of the small or large bowel may also be performed during the course of endoscopic examination to allow tissue analysis of lesions, polyps, or masses. A knife blade or snare is typically used to obtain the tissue sample. The procedure is not usually painful, although a feeling of pressure may be experienced. Bleeding from the site of the biopsy is uncommon. If bleeding does occur, the patient is instructed to report this to the physician and to curtail physical activity until examined by a physician.
Endoscopy • Today most endoscopic procedures are performed on an ambulatory basis, even with the elderly. Oral fiberscope insertion is uncomfortable and may precipitate gagging or choking despite the use of topical anesthetic sprays or gargles. Premedication with an IV sedative such as midazolam (Versed) or diazepam (Valium) or an analgesic such as meperidine (Demerol) is used. Thus the patient is conscious but sedated; amnesia is often experienced when high doses of these drugs are used.
Esophagogastroduodenoscopy • Upper GI endoscopy may be limited to the esophagus (esophagoscopy), stomach (gastroscopy), or duodenum (duodenoscopy); or it may involve examination of the entire region (esophagogastroduodenoscopy [EGD]). It is particularly useful for identifying the source of upper GI bleeding and for differentiating gastric malignancies from benign ulcers, and gastric ulcers from duodenal ulcers. Other uses include visualization of esophageal strictures, varices, tumors, achalasia, and hiatal hernias; and surgical removal of gastric polyps. • Preparation for an EGD involves instructing the patient to remain NPO for 8 hours before the test. Because air is typically introduced as the endoscope is advanced to improve visibility, the patient should be told that a feeling of pressure or fullness will likely be experienced. The entire test lasts about 15 to 30 minutes unless additional treatments are planned. • After the procedure the patient is monitored carefully for signs of dyspnea, pain, bleeding, or acute dysphagia. Vital signs are taken every 30 minutes for 3 to 4 hours, and no oral food or fluids are administered until the nurse determines that the gag reflex is fully intact. Throat lozenges or saline gargles may be used to relieve sore throat after the test. Complications are rare but include aspiration, perforation, and bleeding.
Endoscopic Retrograde Cholangiopancreatography • Endoscopic retrograde cholangiopancreatography (ERCP) also involves the oral insertion of an endoscope, but this device has a side-viewing tip and a cannula that can be maneuvered into the ampulla of Vater. Dye may be injected to outline the pancreatic and biliary ducts. The procedure may be combined with papillotomy to enlarge the sphincter andrelease gallstones. Glucagon may be administered to minimize spasm in the duodenum and sphincter. • Care after the procedure is similar to that previously described for an EGD. The patient is monitored carefully for signs of abdominal pain, nausea, and vomiting, which might indicate the development of pancreatitis.
Colonoscopy • Fiberoptic colonoscopy allows the examination of the entire colon in most patients. It is used to evaluate benign and malignant growths, remove polyps, take biopsy specimens, and localize sites of bleeding. A colonoscopy is the current "gold standard" for diagnosing colorectal cancers. Screening colonoscopies for colorectal cancer are recommended after age 50. • Thorough bowel preparation is essential before the test, which is especially difficult for elderly persons. A 1-day preparation with an oral osmotic solution is now standard because it reduces overall fluid and electrolyte loss. A gallon (3,78 l) of polyethylene glycol (Colyte) solution is administered rapidly (8 ounces (237 ml) every 15 minutes) and induces a profuse watery diarrhea within 30 to 60 minutes, which lasts about 4 hours. In some cases, the patient may receive a 2- to 3-day preparation consisting of a clear liquid diet, strong laxatives, and an enema the day of the test. All patients are NPO for about 8 hours before the test. • Patients are sedated before the colonoscopy. The fiberoptic colonoscope, which is 105 to 185 cm (42 to 72 inches) long, is advanced through the colon and the colon is visualized simultaneously. Air is introduced as the colonoscope is inserted to increase visualization of the mucosa. The air commonly causes abdominal cramping. The procedure lasts from 20 to 60 minutes. • Afterward the nurse assumes responsibility for carefully monitoring the patient and ensuring full recovery from sedation. Any changes in vital signs or development of severe abdominal pain, rectal bleeding, or fever should be immediately reported to the physician. In addition, arrangements for transportation home are important because the patient should not drive.
Colonoscopy • Sigmoidoscopy may be performed rather than colonoscopy. The cost of a sigmoidoscopy is considerably less than a colonoscopy but only allows for visualization of the anus, rectum, and distal sigmoid colon. Approximately 75% of all polyps and tumors of the large intestine can be visualized with a flexible sigmoidoscope. Pretest preparation instructions vary widely. The patient may be instructed to prepare with a 2-day clear liquid diet and pretest fasting. Fleet enemas may be ordered, or a cleansing enema may be preferred. The knee-chest position and a strong urge to defecate that is produced by the larger-diameter sigmoidoscope make this an uncomfortable and unpopular procedure for patients. Sedation is not usually used. Aftercare involves monitoring for distention, increased tenderness, and bleeding. The patient may initially pass large amounts of flatus from the instillation of air duringthe procedure. Slight rectal bleeding may occur if biopsies have been taken.