Gastrointestinal System and Diagnostics

Chapter 44: Gastrointestinal Diagnostic Procedures

Key Terms and Procedures

  • Barium Enema: Radiologic examination of the colon using barium to visualize abnormalities.

  • Barium Swallow: Imaging of the esophagus and stomach by swallowing barium.

  • Cholangiography: Imaging technique for viewing bile ducts using contrast material.

  • Cholecystography: Radiologic examination of the gallbladder after contrast medium ingestion.

  • Colonoscopy: Endoscopic examination of the lower gastrointestinal (GI) tract, including the colon.

  • Enteroclysis: Special type of small bowel study with a tube inserted into the small intestine for imaging.

  • Esophagogastroduodenoscopy (EGD): Visual examination of the esophagus, stomach, and duodenum.

  • Flexible Sigmoidoscopy: Exam of the sigmoid colon using a flexible scope.

  • Gallbladder Series: Series of x-rays to assess gallbladder function and structure.

  • Lower Gastrointestinal Series: X-ray examination of the large intestine after a barium enema.

  • Panendoscopy: Examination of the upper digestive tract (esophagus, stomach, duodenum) using a scope.

  • Percutaneous Liver Biopsy: Procedure to obtain liver tissue via needle for examination.

  • Peristalsis: Involuntary muscle contraction that moves food through the digestive tract.

  • Proctosigmoidoscopy: Examination of the rectum and lower colon using a sigmoidoscope.

  • Radionuclide Imaging: Technique using radioactive materials to visualize organ function.

  • Ultrasonography: Imaging method using sound waves to visualize internal organs.

  • Upper Gastrointestinal Series: X-ray of the upper GI tract after swallowing barium.

  • Virtual Colonoscopy: CT scan used to visualize the colon non-invasively.

Learning Objectives

Upon completing this chapter, the student will be able to:

  1. Identify major organs and structures of the gastrointestinal system.

  2. Discuss important information about gastrointestinal health.

  3. Identify pertinent historical facts regarding the present illness in clients.

  4. Discuss key physical assessments related to gastrointestinal function.

  5. Describe common diagnostic tests for gastrointestinal disorders.

  6. Explain nursing measures following a liver biopsy.

  7. Discuss nursing management for clients undergoing diagnostic testing for gastrointestinal disorders.

Gastrointestinal System Overview

  • The gastrointestinal (GI) system is divided into three sections:
      1. Upper GI Tract: Begins at the mouth and ends at the pyloric sphincter.
      2. Small Intestine: Includes the duodenum, jejunum, and ileum.
      3. Lower GI Tract: Starts at the cecum and finishes at the anus.

  • Accessory Structures: Include the peritoneum, liver, gallbladder, and pancreas.

  • Primary Functions: The primary functions of the GI tract are digestion and food distribution.

Major Digestive Enzymes and Their Actions

Enzymes/Secretions for Carbohydrate Digestion

  • Ptyalin (salivary amylase) (Source: Salivary glands)
       - Action: Starch → dextrin, maltose, glucose

  • Amylase (Source: Pancreas and intestinal mucosa)
       - Action: Starch → dextrin, maltose, glucose; Dextrin → maltose, glucose

  • Maltase (Source: Intestinal mucosa)
       - Action: Maltose → glucose

  • Sucrase (Source: Intestinal mucosa)
       - Action: Sucrose → glucose, fructose

  • Lactase (Source: Intestinal mucosa)
       - Action: Lactose → glucose, galactose

Enzymes/Secretions for Protein Digestion

  • Pepsin (Source: Gastric mucosa)
       - Action: Protein → polypeptides

  • Trypsin (Source: Pancreas)
       - Action: Proteins and polypeptides → polypeptides, dipeptides, amino acids

  • Aminopeptidase (Source: Intestinal mucosa)
       - Action: Polypeptides → dipeptides, amino acids

  • Dipeptidase (Source: Intestinal mucosa)
       - Action: Dipeptides → amino acids

  • Hydrochloric Acid (Source: Gastric mucosa)
       - Action: Protein → polypeptides, amino acids

Enzymes/Secretions for Fat Digestion

  • Pharyngeal Lipase (Source: Pharynx mucosa)
       - Action: Triglycerides → fatty acids, diglycerides, monoglycerides

  • Steapsin (Source: Gastric mucosa)
       - Action: Triglycerides → fatty acids, diglycerides, monoglycerides

  • Pancreatic Lipase (Source: Pancreas)
       - Action: Triglycerides → fatty acids, diglycerides, monoglycerides

  • Bile (Source: Liver and gallbladder)
       - Action: Fat emulsification

Gerontologic Considerations

  • Assessment: Include patters of defecation in older adults as dietary changes or muscle tone reduction can lead to constipation or incontinence.

  • Nursing Measures:
      - Encourage fiber-rich fruits and vegetables.
      - Maintain adequate fluid intake, mobility, and scheduled defecation times post-meal.

  • Reducing Anxiety: Explain procedures thoroughly to alleviate anxiety about pain or positioning.

  • Fluid Management: Be cautious of fluid balance; older adults face a high risk of dehydration especially pre- and post-GI testing due to dietary restrictions and testing procedures.

  • Provide nourishment promptly post-examination and assist with ambulation as necessary to prevent dizziness or confusion.

Anatomy and Physiology

Mouth

  • Primary entry point for food where it is masticated (chewed).

  • Initial digestion of starch occurs with ptyalin (salivary amylase).

Esophagus

  • Approximately 25 cm long, located behind the trachea.

  • Composed of striated (upper), mixed (middle), and smooth muscle (lower).

  • Peristalsis: Coordinated muscle contractions that move food down to the stomach.

  • Sphincters:
      - Upper Esophageal Sphincter: Prevents air entry during respiration.
      - Lower Esophageal Sphincter: Prevents backflow from the stomach.

Stomach

  • Temporary storage of food, mixing via mechanical and chemical action to form chyme.

  • Sphincters:
      - Lower Esophageal Sphincter (Cardiac Sphincter): Controls entry from the esophagus.
      - Pyloric Sphincter: Controls exit to the duodenum.

  • Digestive secretions are acidic due to hydrochloric acid (HCl).

Small Intestine

  • Divided into three parts: Duodenum, Jejunum, Ileum.

  • Functions: Primary site for nutrient absorption; influenced by bile and pancreatic secretions.

  • The ileocecal valve regulates flow into the large intestine and prevents reflux.

Large Intestine

  • Approximately 4 to 5 feet long, responsible for waste propulsion and absorption of water and electrolytes.

  • Structures include the cecum, colon, rectum, and anal canal.

  • The appendix is a non-functional blind-ended tube extending from the cecum.

Nursing Process for Diagnostic Testing in Gastrointestinal Disorders

Assessment

  • Interview: Establish past familiarity with tests and previous experiences.

  • History Review: Focus on hypersensitivity or allergies related to test preparations.

  • Vital Signs: Take baseline vitals and weight; encourage bladder emptying prior to tests.

Diagnosis, Planning, and Interventions

  • Acute Anxiety: Related to test knowledge deficits; expected outcome is knowledge of the procedure and relief from anxiety.
      - Provide explanations and printed instructions.
      - Allow expression of fears.

  • Acute Pain: Following procedures, expected outcome is minimal discomfort.
      - Use support for positioning and administer analgesics if necessary.

  • Hypovolemia Risk: Monitor fluid balance during preparation and testing; report any signs of dehydration.

  • Constipation Risk: Due to barium; encourage fluid intake and administer laxative/enema as prescribed.

Evaluation of Expected Outcomes

  • Confirm findings of minimal anxiety, pain management, and normal bowel function.

Pharmacologic Considerations

  • Medication adjustments may be needed pre- and during tests based on procedures and orders.

Key Points

  • GI anatomy and physiology encompasses all digestive structures and functions.

  • Comprehensive assessments should address appearance, skin, mouth, abdomen, and anus.

  • A range of diagnostic tests and laboratory analyses assist in evaluating GI health and disorders.

Clinical Judgment Exercises

  1. Evaluate precautions before an EGD procedure.

  2. Post-EGD assessment considerations.

  3. Abdominal assessment areas for epigastric pain complaints.

  4. Anticipated tests for suspected colon cancer patients.

Next-Generation NCLEX-Style Review Questions

  1. Assessing absent bowel sounds in the right lower quadrant (RLQ).

  2. Optimal positioning for abdominal assessment.

  3. Understanding and following barium enema instructions.

  4. Essential allergy inquiry for cholecystography preparation.

  5. Post-liver biopsy nursing actions.

  6. Signs of complications following a colonoscopy.