What is the recommended initial and subsequent management for an adult patient with suspected bowel obstruction, including resuscitation, nasogastric decompression, laboratory and imaging work‑up, criteria for non‑operative treatment, and indications for urgent surgery?

Management of Bowel Obstruction

Initial Resuscitation and Assessment

Begin immediate intravenous crystalloid resuscitation, nasogastric decompression, bowel rest (nil per os), and water-soluble contrast administration in all patients without signs of peritonitis, strangulation, or ischemia—this approach resolves 70–90% of obstructions and should continue for up to 72 hours before considering surgery. 1, 2

Critical Initial Steps

• Fluid resuscitation: Administer aggressive IV crystalloid therapy to correct the near-universal dehydration and electrolyte disturbances; monitor serum electrolytes, BUN, and creatinine continuously to detect acute kidney injury. 1, 2

• Nasogastric tube placement: Insert an NG tube for gastric decompression in patients with significant distension and active vomiting to reduce intraluminal pressure, prevent aspiration, and improve respiratory status. 1, 2, 3 Note that routine NG tube placement in patients without active emesis is associated with increased pneumonia, respiratory failure, and longer hospital stays, so selective use is appropriate. 4

• Physical examination priorities: Assess for abdominal distension, abnormal bowel sounds (either absent or high-pitched), examine all hernial orifices and previous surgical scars, and specifically look for signs of peritonitis (rebound tenderness, guarding, rigidity) or strangulation (fever, hypotension, persistent tachycardia, continuous rather than colicky pain). 1, 2, 3

Laboratory Work-Up

Order a minimum panel consisting of: 2, 5

• Complete blood count with differential: Leukocytosis (WBC >10,000/mm³) suggests peritonitis, though sensitivity and specificity are modest. 2, 5

• Serum lactate: Elevated lactate is the key marker for bowel ischemia—a high-mortality condition requiring urgent surgery. 2, 5

• Comprehensive metabolic panel: Identify hypokalemia, hyponatremia, hypochloremia (common from vomiting and third-spacing), and elevated BUN/creatinine (indicating dehydration-related acute kidney injury). 2, 5

• C-reactive protein: Values >75 mg/L suggest peritonitis, though with limited sensitivity and specificity. 2, 5

Critical interpretation: The combination of elevated lactate + leukocytosis + metabolic acidosis strongly indicates probable bowel ischemia and mandates immediate surgical consultation. 2, 5 However, normal laboratory values do not exclude ischemia—physical examination has only 48% sensitivity for detecting strangulation even in experienced hands. 5

Imaging Work-Up

Obtain contrast-enhanced CT scan as the preferred imaging modality—it has approximately 90% accuracy for diagnosing obstruction, determining the transition point, identifying the cause, and predicting the need for urgent surgery. 1, 2

CT Scan Interpretation

• Signs requiring urgent surgery: Closed-loop obstruction, mesenteric edema, abnormal bowel wall enhancement, bowel wall thickening, pneumatosis intestinalis, mesenteric venous gas, free intraperitoneal fluid with peritoneal enhancement, or free perforation with pneumoperitoneum. 1, 6

• Oral contrast is unnecessary: The intraluminal fluid and gas already present within obstructed bowel serve as excellent contrast agents. 1

• Alternative imaging: MRI is a valid alternative in children and pregnant women (95% sensitivity, 100% specificity). 1, 2 Ultrasound in experienced hands can provide more information than plain radiographs and is useful when radiation exposure is undesirable. 1, 7

• Plain radiographs have limited value: Sensitivity is only 60–70% and cannot exclude the diagnosis. 2, 7

Water-Soluble Contrast Administration

Administer 100 mL of water-soluble contrast (Gastrografin) via the nasogastric tube after adequate gastric decompression—this provides both diagnostic and therapeutic benefits, significantly reducing the need for surgery, shortening time to resolution, and decreasing hospital length of stay. 1, 2

• Diagnostic value: If contrast reaches the colon within 4–24 hours (assessed by abdominal radiograph), there is a 90–96% likelihood the obstruction will resolve without surgery. 2, 8

• Therapeutic mechanism: Water-soluble contrast has an active therapeutic role beyond simple diagnosis. 1

• Safety: This treatment shows no significant differences in complications or mortality compared to standard conservative management alone. 1

Criteria for Non-Operative Treatment

Continue conservative management for up to 72 hours in patients who remain hemodynamically stable without developing peritoneal signs, provided they have: 1, 2

• No signs of peritonitis (absence of rebound tenderness, guarding, or rigidity) 1, 2
• No clinical evidence of strangulation or ischemia (no fever, persistent tachycardia, continuous pain, or rising lactate) 1, 2
• No radiographic evidence of closed-loop obstruction, free perforation, or bowel ischemia 1, 2
• Hemodynamic stability despite adequate fluid resuscitation 2, 5

Monitor continuously for: Rising lactate levels, persistent fever, worsening leukocytosis, development of metabolic acidosis, or transition from localized to diffuse peritoneal signs—any of these mandate immediate surgical escalation. 2

Indications for Urgent Surgery

Proceed directly to operative management without a trial of conservative therapy when any of the following are present: 1, 2

Absolute Indications

• Peritoneal signs on examination: Diffuse rebound tenderness, guarding, or rigidity 1, 2
• Clinical evidence of strangulation or ischemia: Fever, hypotension, persistent tachycardia, continuous (not colicky) abdominal pain 1, 2, 3
• Radiographic evidence: Free perforation with pneumoperitoneum, closed-loop obstruction, or CT signs of bowel ischemia 1, 2, 6
• Hemodynamic instability: Hypotension despite adequate fluid resuscitation 2, 5
• Failed conservative management: No clinical improvement after 72 hours, or contrast fails to reach the colon within 24 hours 1, 2

Surgical Approach Selection

• Open laparotomy is preferred for most patients requiring surgery, particularly those who are hemodynamically unstable, have diffuse peritonitis, severely distended bowel loops, or multiple prior abdominal surgeries. 1, 2

• Laparoscopic adhesiolysis may be considered only in highly selected patients who are hemodynamically stable, have no peritoneal signs, present a single adhesive band with clear transition point on CT, display minimal bowel distension, and have ≤2 prior laparotomies (preferably appendectomy only). 1, 2 The risk of iatrogenic bowel injury is 6.3–26.9% with laparoscopy, and bowel resection rates may be higher (53.5% vs 43.4% open). 2

Special Considerations

Adhesive Small Bowel Obstruction

• Most common cause in adults: Adhesions account for approximately 65–75% of cases, even in patients with limited prior surgery. 1, 3, 7

• Recurrence rates: After non-operative management, 12% of patients are readmitted within 1 year and 20% within 5 years; after operative management, 8% recur at 1 year and 16% at 5 years. 1, 2

• Adhesion barriers: In young patients undergoing surgery, apply hyaluronate-carboxymethylcellulose barriers to reduce recurrence from 4.5% to 2.0% at 24 months. 2

Large Bowel Obstruction

• Colonoscopy role: Limited to diagnosis and biopsy when malignancy is suspected and emergency surgery is not indicated; use CO₂ insufflation to reduce bowel ischemia risk. 1

• Sigmoid volvulus: Colonoscopy allows assessment of viability and detorsion with 70–95% success rate; perform same-admission sigmoid colectomy with primary anastomosis if no necrosis is present. 2

• Malignant obstruction: For left-sided obstructing colon cancer, self-expanding metallic stents are preferred over colostomy for palliation. 2

Inflammatory Bowel Disease

• Medical trial first: Stenoses may be inflammatory or fibrostenotic; patients deserve a trial of anti-inflammatory medications before surgery. 1, 2

• Endoscopic balloon dilation: Successful in 89–92% of primary intestinal or anastomotic strictures in Crohn's disease. 1, 2

• Mandatory biopsy: Any colorectal stricture requires endoscopic biopsies to rule out malignancy. 2

Critical Pitfalls to Avoid

• Do not delay surgery beyond 72 hours when obstruction persists—delays increase morbidity and mortality significantly. 1, 2

• Do not attempt laparoscopy when bowel is markedly distended, as the risk of enterotomy and delayed perforation is high. 2

• Do not dismiss watery diarrhea as evidence against obstruction—it may be present in incomplete obstruction. 2

• Do not rely solely on physical examination to rule out strangulation, given its limited 48% sensitivity. 5

• Do not place routine NG tubes in patients without active vomiting—this increases pneumonia risk and hospital stay without benefit. 4

• Do not assume normal laboratory values exclude ischemia—clinical suspicion and imaging findings must guide management. 5