What is the current management sometime referred to as (treatment) approach for a patient with suspected small bowel obstruction, considering their past medical history, including any previous abdominal surgeries, hernias, or underlying medical conditions?

Management of Small Bowel Obstruction

Begin immediate resuscitation with IV crystalloids, insert a nasogastric tube for decompression, and obtain CT abdomen/pelvis with IV contrast—which has >90% diagnostic accuracy—to determine if the patient requires emergency surgery based on signs of ischemia, strangulation, or complete obstruction. 1, 2

Initial Assessment and Stabilization

History Taking

• Ask specifically about previous abdominal surgeries (85% sensitivity, 78% specificity for predicting adhesive SBO, which accounts for 55-75% of all cases) 2
• Document timing of last bowel movement and passage of flatus 2
• Inquire about history of hernias, inflammatory bowel disease (particularly Crohn's disease), prior malignancy, or radiation therapy 1, 2
• Review medications that affect peristalsis (opioids, anticholinergics) as these can cause pseudo-obstruction mimicking mechanical SBO 2
• Note any rectal bleeding or unexplained weight loss suggesting malignancy (10-13% of SBO cases) 1, 2

Physical Examination

• Examine all hernia orifices and previous surgical incision sites (hernias cause 10-15% of SBO) 1, 2
• Assess for abdominal distension (positive likelihood ratio 16.8) 2
• Check for peritoneal signs (fever, rebound tenderness, guarding)—though physical exam has only 48% sensitivity for detecting strangulation 1, 2
• Perform digital rectal examination to detect masses or blood 2
• Evaluate vital signs for hypotension or tachycardia indicating shock, ischemia, or severe dehydration 3

Immediate Management

• Start aggressive IV crystalloid resuscitation immediately 1, 2, 3
• Insert nasogastric tube for gastric decompression to prevent aspiration pneumonia and reduce proximal bowel pressure 1, 2, 3
• Place Foley catheter to monitor urine output as marker of adequate resuscitation 2, 3
• Administer anti-emetics and maintain NPO status 2

Laboratory Evaluation

Order the following tests immediately 1, 2, 3:

• Complete blood count (WBC >10,000/mm³ suggests peritonitis, though sensitivity is limited) 1, 2, 3
• Serum lactate (elevated levels indicate bowel ischemia; critical for risk stratification) 1, 2, 3
• Comprehensive metabolic panel including electrolytes (hypokalemia is common and requires correction before surgery) 1, 2, 3
• BUN/creatinine (assess for acute kidney injury from dehydration) 1, 2, 3
• C-reactive protein (CRP >75 mg/L suggests peritonitis) 1, 2, 3
• Coagulation profile (PT/INR, PTT) due to potential need for emergency surgery 1, 3
• Type and screen (or crossmatch if bowel resection anticipated) 3

Critical interpretation: Elevated lactate combined with leukocytosis and metabolic acidosis indicates probable bowel ischemia and mandates immediate surgical exploration 3, 4. However, normal laboratory values cannot exclude ischemia 1.

Imaging Strategy

CT Abdomen/Pelvis with IV Contrast (First-Line)

This is the preferred initial imaging study with >90% diagnostic accuracy for diagnosing SBO, determining the site and cause, and identifying complications 1, 2, 5, 6:

• No oral contrast is needed—non-opacified fluid in dilated bowel provides adequate intrinsic contrast in high-grade obstruction 2
• IV contrast is essential to evaluate for bowel ischemia and identify the underlying etiology 2, 5

CT findings requiring immediate surgery 1, 2, 4:

• Abnormal bowel wall enhancement (decreased or increased)
• Intramural hyperdensity on non-contrast images
• Bowel wall thickening with mesenteric edema
• Closed-loop obstruction, volvulus, or internal hernia
• Pneumatosis intestinalis or mesenteric venous gas
• Free intraperitoneal air (perforation)
• Significant ascites

Plain Abdominal Radiography

Plain X-rays have limited diagnostic value (sensitivity 50-70%, with 20-30% inconclusive results) and should not delay CT imaging 1, 2. They may be misleading in 20-40% of cases 1.

Water-Soluble Contrast Studies

• Use in adhesive SBO when CT shows partial obstruction without signs of ischemia 1, 2
• Administer oral water-soluble contrast and obtain abdominal X-ray at 4-8 hours and 24 hours 1, 2, 4
• Contrast reaching the colon within 24 hours predicts successful non-operative management (96% sensitivity, 98% specificity) 1, 2, 4
• No contrast passage at 24 hours indicates need for surgery 1, 4
• Water-soluble contrast may reduce hospital stay and need for surgery in adhesive SBO 2

Ultrasound

• Bedside ultrasound has excellent diagnostic accuracy (90% sensitivity, 96% specificity; positive likelihood ratio 14.1) 2, 7
• Particularly useful in pregnant women, children, and patients with multiple prior CT scans 1, 2
• Limited by operator dependence and bowel gas artifact 1

Decision Algorithm: Operative vs. Non-Operative Management

Immediate Surgery Required 1, 2, 3, 4:

• Signs of peritonitis on physical examination
• CT evidence of bowel ischemia (abnormal enhancement, pneumatosis, mesenteric venous gas)
• Closed-loop obstruction, volvulus, or internal hernia on imaging
• Incarcerated or strangulated hernia
• Free intraperitoneal air (perforation)
• Hypotension with signs of bowel compromise
• Complete obstruction with no improvement after 24-48 hours of conservative management

Mortality increases from 10% to 25-30% with bowel necrosis/perforation, making prompt surgical intervention critical 2, 3.

Trial of Non-Operative Management 1, 2, 8:

• Partial or low-grade SBO without signs of ischemia
• Adhesive SBO in patients with multiple prior surgeries
• No peritoneal signs or hemodynamic instability
• CT shows transition point but no concerning features

Non-operative management includes 1, 2, 8:

• NPO status with IV fluid resuscitation
• Nasogastric tube decompression
• Serial abdominal examinations every 4-6 hours
• Repeat laboratory tests (lactate, WBC) to monitor for ischemia
• Water-soluble contrast challenge to predict resolution
• Reassess at 24-48 hours—if no improvement, proceed to surgery 1, 2

Etiology-Specific Considerations

Adhesive SBO (55-75% of cases) 1, 2:

• Most common cause, even with remote surgical history
• Trial of non-operative management appropriate if no signs of ischemia
• Water-soluble contrast studies particularly useful

Hernias (10-15% of cases) 1, 2:

• Examine all hernia orifices carefully (inguinal, femoral, umbilical, incisional)
• Incarcerated hernias require urgent surgical repair
• Highest risk of strangulation compared to other etiologies

Malignancy (10-13% of cases) 1, 2:

• Consider in patients with weight loss, rectal bleeding, or no prior surgery
• CT accuracy for identifying malignant obstruction is 76%
• May require palliative surgery or stenting depending on prognosis

Other Causes (10-15% collectively) 1, 2:

• Crohn's disease strictures (5% of cases)
• Gallstone ileus (look for pneumobilia on CT)
• Intussusception (more common in children but can occur in adults)
• Meckel's diverticulum complications
• Radiation enteritis in patients with prior pelvic radiation

Critical Pitfalls to Avoid

• Delaying surgical consultation when signs of ischemia are present—mortality reaches 25% with bowel necrosis 2, 3
• Mistaking incomplete obstruction with watery diarrhea for gastroenteritis—patients can still pass liquid stool with high-grade SBO 2
• Overlooking hernias during physical examination—examine all potential hernia sites including previous incisions 1, 2
• Failing to correct electrolyte abnormalities before surgery—particularly hypokalemia 2, 3
• Attempting prolonged non-operative management beyond 48 hours without improvement—increases risk of complications 1, 2
• Relying on plain radiographs alone—they miss the diagnosis in 20-52% of cases 1, 6
• Assuming normal lactate and WBC exclude ischemia—physical exam and labs have limited sensitivity for strangulation 1, 2

Monitoring During Non-Operative Management

• Serial abdominal examinations every 4-6 hours to detect development of peritonitis 3
• Repeat lactate and WBC if clinical deterioration 3, 4
• Monitor urine output as marker of adequate resuscitation 2, 3
• Monitor for intra-abdominal hypertension (IAP ≥12 mmHg) in patients with significant distension 3
• Reassess need for surgery if no improvement by 24-48 hours 1, 2