Gastroenterology Bowel Obstruction Quiz

Bowel Obstruction Overview

• Bowel obstruction (intestinal obstruction) is a condition where intestinal contents cannot pass through the gastrointestinal (GI) tract. It can be partial (some passage possible) or complete (no passage), simple (intact blood supply) or strangulated (compromised blood supply).
• Location of obstruction (small intestine or large intestine) affects symptoms and treatment.

Types of Bowel Obstruction

• Mechanical Obstruction: A physical blockage of the intestinal lumen.
  • Small Bowel Obstruction (SBO): Most commonly caused by surgical adhesions (scar tissue), but also hernias, cancers, Crohn's disease strictures, and intussusception after bariatric surgery.
  • Large Bowel Obstruction (LBO): Most commonly caused by colorectal cancer (CRC), followed by diverticular disease. Other causes include adhesions, ischemia, volvulus, and Crohn's disease.
• Nonmechanical Obstruction: Reduction/absence of intestinal peristalsis (muscle contractions) due to nervous system issues.
  • Paralytic ileus: Lack of intestinal peristalsis and bowel sounds; common after abdominal surgery, also caused by peritonitis, inflammatory responses (like pancreatitis or appendicitis), electrolyte imbalances (especially hypokalemia), and spinal fractures.
  • Pseudo-obstruction: GI motility disorder mimicking a mechanical obstruction; patient has symptoms but no apparent cause.
• Vascular Obstruction: Rare; interference with blood supply to intestines.
  • Primarily caused by emboli and atherosclerosis (hardening and narrowing) of mesenteric arteries.
    • Emboli can originate from blood clots (thrombi) in individuals with chronic atrial fibrillation, diseased heart valves, or prosthetic valves.

Etiology and Pathophysiology

• Daily fluid intake in small intestine ~6-8 liters. Most is absorbed, leaving 75% of gas swallowed air.
• Obstruction causes fluid, gas, and contents to accumulate proximal to blockage.
• Initial distention stimulates secretions, reduces absorption, and empties & collapses distal bowel.
• Increased intraluminal pressure leads to fluid leakage, eventually causing fatigue and stopping peristalsis.
• Fluid retention in intestines and peritoneal cavity reduces blood volume & can cause hypotension/shock.
• Inadequate blood flow causes ischemia (reduced blood supply), necrosis (tissue death), eventual bowel perforation, and potential for dangerous conditions like strangulation, leading to infection and death.

Clinical Manifestations

• Hallmarks: Abdominal pain, nausea/vomiting, distention, constipation.
• Order and severity vary based on cause, location, and obstruction type.
• SBO: Sudden, colicky pain (4-5 min intervals), projectile, bile-containing vomiting (often temporary relief); high-pitched bowel sounds above obstruction, more gradual onset/foul-smelling vomit with distal obstruction.
• LBO: Persistent, cramping pain, obstipation (severe constipation) or change in bowel habits, lack of flatus; bowel sounds initially present but progressively decrease in activity; vomiting is rare.
• Strangulation: Severe, constant, rapid-onset pain.
• General Signs: Abdominal tenderness/rigidity, acute illness appearance, dehydration, sepsis (tachycardia, dry mucous membranes, hypotension, temperature >100°F).

Diagnostic Studies

• Thorough history and physical assessment are crucial.
• Imaging (abdominal X-rays, CT scans, contrast enemas) to identify obstruction and guide surgical decisions.
  • Endoscopic visualization (sigmoidoscopy/colonoscopy) helpful for LBO.
• Blood tests (CBC, blood chemistries) assess dehydration, infection potential/strangulation, and bleeding.
  • Monitor electrolytes, BUN, creatinine, etc.

Interprofessional Care

• Treatment goal: restore intestinal patency.
• Treatment depends on cause. Strangulated/perforated obstructions require emergency surgery.
• Non-surgical options:
  • NG tube decompression
  • Parenteral nutrition (PN) for bowel rest
  • Stents to allow time for fluid/electrolyte correction before surgery.
• Surgical options: resection (remove and reattach segments), partial/total colectomy, colostomy/ileostomy, colonoscopy to remove polyps/dilate strictures.

Nursing Management: Bowel Obstruction

• Assessment: Focused on patient's history (pain location, duration, intensity), changes in vomiting (onset, frequency, color), bowel function (flatus), bowel sounds, abdominal distention/tenderness.
• Monitoring Vital signs: Assess/record respiratory rate, heart rate, blood pressure, temperature. Report significant deviations.
• Intake and Output/Urinary Output: Monitor urine output (less than 0.5 mL/kg per hour may indicate decreased fluid volume/AKI) and record all relevant intake and outputs meticulously, including emesis and tube drainage.
• Lab Values: Monitor electrolytes, CBC, blood chemistries, and ABGs for acid-base imbalances and other complications.
• Collaboration: Work closely with healthcare providers, reporting changes in patient condition.

Clinical Problems

• Pain
• Impaired GI function
• Fluid imbalance

Planning

• Goals: relief of obstruction, return to normal bowel function, minimal discomfort, and normalization of fluid/electrolyte/acid-base balance.

Implementation

• Care prioritizes patient comfort and fluid/electrolyte balance. Post-op care similar to laparotomy patient care.