Intestinal Obstruction: Types and Causes

Intestinal Obstruction Definition

• Interruption in the normal flow of intestinal contents along the intestinal tract
• Occurs when intestinal contents cannot pass through the GI tract
• Can occur in the small intestine or colon
• Can be partial, complete, simple, or strangulated
• Partial obstructions usually resolve with conservative treatment
• Complete obstructions usually require surgery
• Simple obstructions have an intact blood supply
• Strangulated obstructions do not

Mechanical Obstruction

• Detectable occlusion of the intestinal lumen
• Physical block to passage of intestinal contents without disturbing blood supply of bowel
• High small-bowel (jejunal) or low small-bowel (ileal) obstructions occur four times more frequently than colonic obstructions

Mechanical Obstruction Causes

• Extrinsic adhesions from surgery, hernia, and volvulus (loop of intestine that has twisted)
• Intrinsic hematoma, tumor, intussusception (telescoping of intestinal wall into itself), stricture or stenosis
• Intraluminal foreign body, fecal or barium impaction, polyp

Mechanical Obstruction Notes

• Approximately 90% of mechanical obstructions in postoperative patients are due to adhesions
• In non-surgical patients, hernia (most often inguinal) is the most common cause

Functional Obstruction (A dynamic, Neurogenic) Ileus

• Peristalsis is ineffective due to diminished motor activity from toxic or traumatic disturbance of the autonomic nervous system
• There is no physical obstruction, and blood supply is not interrupted
• Disappears spontaneously after 2 to 3 days

Functional Obstruction Causes

• Spinal cord injuries, vertebral fractures
• Postoperatively after any abdominal surgery
• Peritonitis, pneumonia
• Wound dehiscence (breakdown)
• Gastrointestinal tract surgery

Strangulation Obstruction

• Compromises blood supply
• Most common causes are emboli and atherosclerosis of the mesenteric arteries
• Leads to gangrene of the intestinal wall
• Caused by prolonged mechanical obstruction

Pathophysiology of Intestinal Obstruction

• Obstruction leads to accumulation of intestinal contents
• Accumulation leads to fluid and gas development above the obstruction
• Fluid and gas development leads to increased distention and pressure within the intestinal lumen, and increased venous and capillary pressure
• Increased pressure leads to edema, congestion, and necrosis
• This continues to perforation of the intestinal wall with toxin and bacteria leaking out
• Perforation leads to peritonitis

Types of Intestinal Obstruction

• Small bowel obstruction
• Large bowel obstruction

Small Bowel Obstruction Pathophysiology

• Abdominal distention and retention of fluid occurs
• Reduces fluid absorption and stimulates gastric secretion
• Increasing distention and pressure within the intestinal lumen occurs, decreasing venous and arteriolar capillary pressure
• Edema, congestion and necrosis occurs
• Eventual rupture or perforation of the intestinal wall, with resultant peritonitis

Small Intestinal Obstruction Causes

• Intussusception: Shortening of the colon caused by one segment of bowel moving into another
• Volvulus of the sigmoid colon: The twist is counterclockwise in most cases, with edematous bowel
• Hernia: The sac of the hernia is a continuation of the peritoneum of the abdomen, with hernial contents passing through the hernial opening into the hernial sac

Clinical Manifestations of Small Bowel Obstruction

• Crampy pain: Wavelike and colicky, with the site of pain usually pointing to the obstruction
• Pass blood and mucus, but no focal matter and no flatus
• Vomiting occurs
• For complete obstructions, peristaltic waves are initially extremely vigorous
• Intestinal contents eventually move toward the mouth instead of the rectum
• For ileum obstructions, fecal vomiting occurs

Small Bowel Obstruction Vomiting Progression

• Vomit stomach contents first
• Then, duodenum and jejunum bile-stained contents
• Finally, ileum fecal-like contents

Small Bowel Obstruction Dehydration Signs

• Intense thirst, drowsiness, generalized malaise
• Aching, and parched tongue and mucous membranes

Untreated Small Bowel Obstruction

• Hypovolemic shock occurs from dehydration and loss of plasma volume

Small Bowel Obstruction Assessment and Diagnostic Findings

• Diagnosis is based on the symptoms described previously and on x-ray findings
• Abdominal x-ray studies show abnormal quantities of gas, fluid, or both in the bowel
• Laboratory studies (electrolyte studies and a complete blood cell count) reveal a picture of dehydration, loss of plasma volume, and possible infection

Small Bowel Obstruction Medical Management

• Correction of fluid and electrolyte imbalances with sodium, potassium, and blood component therapy
• Ringer's lactate may be used to correct interstitial fluid deficit
• Dextrose/water may be used to correct intracellular fluid deficit
• Decompression of the bowel with a nasogastric or small bowel tube

Small Bowel Obstruction Surgical Intervention

• Surgical treatment depends largely on the cause of the obstruction
• Hernias and adhesions are repaired by repairing the hernia or dividing the adhesion
• The affected bowel portion may be removed, and an anastomosis performed in some instances

Small Bowel Obstruction Nursing Management

• Maintain the function of the nasogastric tube
• Assess and measure the nasogastric output
• Assess for fluid and electrolyte imbalance and monitor nutritional status
• Assess for improvement with return of normal bowel sounds and decreased abdominal distention
• Improvement in abdominal pain and tenderness and passage of flatus or stool
• Report alterations in intake and output, worsening pain or abdominal distention, and increased nasogastric output
• Prepare the patient for surgery

Large Bowel Obstruction Pathophysiology

• Accumulation of intestinal contents, fluid, and gas proximal to the obstruction
• Severe distention or perforation
• Unless some gas and fluid can flow back through the ileal valve
• Dehydration occurs more slowly because the colon can absorb its fluid contents and can distend to a size considerably beyond its normal full capacity

Large Bowel Obstruction If Blood Supply is Cut Off

• Strangulation and necrosis occurs

Large Bowel Obstruction Clinical Manifestations

• Symptoms develop and progress relatively slowly compared to small intestine obstructions
• Constipation may be the only symptom for days in patients with obstruction in the sigmoid colon or the rectum
• Eventually, the abdomen becomes markedly distended due to gases and fluid accumulation
• Loops of large bowel become visibly outlined through the abdominal wall
• Crampy lower abdominal pain
• Fecal vomiting and symptoms of shock may occur

Small vs Large Intestine Obstruction Manifestations

• Onset is rapid in small intestine obstruction, and is gradual for large intestine obstruction
• Vomiting is frequent and copious in small intestine, and are rare for large intestine obstruction
• Pain is colicky and cramp like for small intestine, and are low-grade and cramping for large intestine
• Bowel movement includes feces for a short time for small intestine obstruction, and are absent for large intestine obstruction
• Distention is great for small intestine obstruction, and is increased for large intestine obstruction

Large Bowel Obstruction Assessment and Diagnostic Findings

• Diagnosis is based on symptoms and on x-ray studies
• Abdominal x-ray studies (flat and upright) show a distended colon
• Barium studies are contraindicated

Large Bowel Obstruction Medical Management

• Colonoscopy to untwist and decompress the bowel
• Cecostomy: Surgical opening made into the cecum for patients who are poor surgical risks and urgently need relief; provides outlet for releasing gas and a small amount of drainage
• Rectal tube may be used to decompress an area that is lower in the bowel
• Surgical resection to remove the obstructing lesion
• Temporary or permanent colostomy may be necessary
• Ileoanal anastomosis may be necessary if the entire large colon needs removal

Nursing Management for Intestinal Obstruction

• Monitor the patient for worsening symptoms
• Provide emotional support and comfort
• Administer intravenous fluids and electrolytes as prescribed
• Prepare the patient for surgery including preoperative teaching
• If post operative, provide general abdominal wound care and routine postoperative nursing care

Nursing Process for Patient With Intestinal Obstruction: Nursing Assessment

• Describe the nature and location of the patient's pain
• Note the presence of distention and the absence of flatus or defecation in the nursing history
• Monitor and record bowel sounds in all four quadrants
• Conduct frequent checks of the patient's level of responsiveness
• Decreasing responsiveness may offer a clue to an increasing electrolyte imbalance or impending shock

Nursing Diagnoses for Intestinal Obstruction

• Pain related to obstruction, distention, and strangulation
• Risk for fluid volume deficit related to impaired fluid intake, vomiting, and diarrhea
• Altered nutrition less than body requirements related to intestinal obstruction and vomiting
• Ineffective breathing pattern related to abdominal distention, interfering with normal lung expansion
• Anxiety related to complications and severity of illness

Nursing Interventions for Intestinal Obstruction

• Administer prescribed analgesics for pain relief
• Provide supportive care during nasoenteral intubation to relieve discomfort
• Turn the patient from supine to prone position every 10 minutes until enough flatus is passed to decompress the abdomen and potentially relieve air-fluid lock syndrome
• Use a rectal tube to aid treatment

Maintaining Electrolyte and Fluid Balance for Intestinal Obstruction

• Measure and record all intake and output
• Administer IV fluids and blood as prescribed
• Monitor electrolytes, urinalysis, hemoglobin, and blood cell counts
• Minimize factors that would enhance gastric secretions to prevent fluid loss (through NG suction), such as avoiding conversation about meals
• Monitor urinary output to assess renal function and detect urinary retention
• Monitor vital signs; a drop in blood pressure may indicate decreased circulatory volume due to blood loss from strangulated hernia

Postoperative Nursing Interventions for Enterostomy

• Connect tube to drainage bottle at bedside
• Expect considerable amount of fecal drainage during the first 12 to 15 hours (500 to 1,000 mL)
• Observe drainage equipment frequently for patency
• Inject 15 mL of warm saline solution into the enterostomy tube every 2 to 4 hours with approval of health care provider if drainage is difficult
• Protect skin around enterostomy tube with a skin sealant or barrier preparation

Maintaining Normal Bowel Elimination for Intestinal Obstruction

• Save all stools to test for occult blood
• Maintain adequate fluid balance
• Record amount and consistency of stools
• Maintain NG or Miller-Abbott tube to decompress the bowel

Maintaining Normal Lung Ventilation for Intestinal Obstruction

• Keep the patient in Fowler's position to promote ventilation and relieve abdominal distention
• Monitor arterial blood gases for oxygenation levels

Preventing Complications for Intestinal Obstruction

• Prevent infarction by assessing the patient’s status; pain that increases in intensity or becomes localized may indicate strangulation
• Detect early signs of peritonitis (rigidity and tenderness)
• Avoid enemas, which may distort an x-ray picture or make a partial obstruction worse
• Observe for signs of shock (pallor, tachycardia, hypotension)
• Watch for signs of metabolic alkalosis (slow, shallow respirations, changes in sensorium, tetany)
• Watch for signs of metabolic acidosis (disorientation; deep, rapid breathing; weakness; and shortness of breath on exertion)

Relieving Fears

• Recognize the patient's concerns and secure patient's cooperation and confidence in the staff
• Encourage presence of support person and offer counseling

Evaluation

• Patient experiences minimal pain and vital signs are stable
• Relief of bowel obstruction is demonstrated (passes flatus, has first bowel movement, and has no signs of complications)