What is the optimal ER to hospital admission pathway for a patient presenting with suspected Small Bowel Obstruction (SBO)?

ER to Hospital Admission Pathway for Small Bowel Obstruction

All patients presenting to the ER with suspected SBO should undergo immediate resuscitation with IV fluids, nasogastric decompression, and CT abdomen/pelvis with IV contrast (no oral contrast), followed by urgent surgical consultation within hours—not days—as delays in surgical evaluation significantly increase mortality from 2% to 27%. 1, 2, 3

Initial Assessment and Triage (First 30-60 Minutes)

Immediate Clinical Evaluation

• Assess for emergency surgical indications: peritonitis, signs of strangulation/ischemia (fever, tachycardia, tachypnea, confusion, intense unremitting pain, diffuse tenderness with guarding/rebound, absent bowel sounds) 1
• Examine all hernia orifices including groin hernias and previous surgical incision sites, as these are critical reversible causes 1
• Obtain focused history: previous abdominal surgeries (85% sensitivity for adhesive SBO), recent constipation, absence of flatus/stool passage, vomiting pattern, rectal bleeding, weight loss 4, 5
• Physical examination findings to document: abdominal distension (present in 65%, positive likelihood ratio 16.8), abnormal bowel sounds (hyperactive early, absent suggests ischemia), visible peristalsis in thin patients 4, 5

Immediate Resuscitation (Parallel to Assessment)

• Start aggressive IV crystalloid resuscitation immediately—these patients are profoundly dehydrated from third-spacing and vomiting 2, 6
• Insert Foley catheter to monitor urine output as resuscitation marker 2
• Place nasogastric tube for gastric decompression to reduce aspiration risk, improve respiratory status, and remove proximal contents 2, 6
• Initiate broad-spectrum IV antibiotics if fever, leukocytosis, or systemic illness present 2

Laboratory Tests (Stat Orders)

• Complete blood count: assess for leukocytosis with left shift indicating ischemia 1
• Lactate level: elevated lactate suggests bowel ischemia (critical for surgical decision-making) 1, 2
• Electrolytes, BUN/creatinine: evaluate dehydration and guide resuscitation 1
• CRP: elevated levels may indicate peritonitis/ischemia 1
• Coagulation profile: necessary for potential surgical intervention 1
• Note: Normal laboratory values cannot exclude ischemia—imaging is mandatory 1

Diagnostic Imaging (Within 1-2 Hours of Presentation)

Primary Imaging Modality

• CT abdomen/pelvis with IV contrast is the diagnostic standard with >90% accuracy for detecting SBO, identifying the site/cause (87-90% accuracy), and detecting complications 1, 2, 7
• Do NOT administer oral contrast in suspected high-grade SBO—it delays diagnosis, increases aspiration risk, worsens patient discomfort, and can mask abnormal bowel wall enhancement indicating ischemia 2
• CT identifies critical surgical indicators: bowel ischemia (abnormal wall enhancement, pneumatosis, mesenteric edema), closed-loop obstruction, volvulus, perforation, transition point location 2, 7

Alternative Imaging (Limited Scenarios)

• Ultrasound has 91% sensitivity and 84% specificity, useful in pregnancy or when CT unavailable, but provides less anatomic detail than CT 1, 4, 5
• Plain abdominal radiographs have only 60-70% sensitivity and cannot exclude SBO or detect ischemia—they delay definitive diagnosis and should be avoided 1, 2

Surgical Consultation and Admission Decision (Within 2-4 Hours)

Immediate Surgical Consultation Required For:

• Any signs of peritonitis, strangulation, or ischemia (mortality reaches 25% when ischemia present) 2, 6
• CT findings of: bowel wall thickening, abnormal enhancement, mesenteric edema, pneumatosis, closed-loop obstruction, lack of small-bowel feces sign, fat stranding, significant free fluid 2, 7
• High-grade or complete obstruction on imaging 2, 6
• Clinical deterioration during observation 2, 6
• Hemodynamic instability despite resuscitation 2

Critical Timing Issue

• Patients admitted to medical services have 27% mortality versus 2% mortality when admitted to surgical services due to delays in surgical intervention 3
• All SBO patients should be admitted under surgical service or have immediate surgical co-management, as delay from admission to surgery significantly increases morbidity and mortality 3

Admission Pathway Algorithm

Path 1: Emergency Surgery (Immediate OR)

Indications: Signs of peritonitis, strangulation, ischemia, perforation, or hemodynamic instability despite resuscitation 2, 6, 3

• Admit directly to surgical service with OR notification 3
• Continue aggressive resuscitation en route to OR 2
• Laparotomy preferred over laparoscopy in high-grade obstruction with instability for better visualization 2

Path 2: Urgent Surgical Admission (Within Hours)

Indications: High-grade partial or complete SBO without immediate signs of ischemia, but requiring close monitoring 2, 6

• Admit to surgical service (NOT medical service) 3
• Continue NPO, NG decompression, IV fluids 2, 6
• Serial abdominal examinations every 4-6 hours 6
• Repeat lactate and clinical assessment if any deterioration 2
• Surgical intervention if: no improvement within 24-48 hours of conservative management, clinical deterioration, or development of ischemia signs 2, 6

Path 3: Conservative Management with Surgical Oversight

Indications: Low-grade partial SBO with passage of some flatus/stool, no signs of ischemia, and clear improvement with initial resuscitation 6

• Admit to surgical service with daily surgical evaluation 3
• Water-soluble contrast study may be considered: if contrast reaches colon within 24 hours, 96% sensitivity for resolution with conservative therapy 1
• Advance to surgery if: no contrast in colon at 24 hours, clinical deterioration, or persistent symptoms beyond 48-72 hours 1, 6

Common Pitfalls to Avoid

• Never admit SBO patients to medical service without immediate surgical consultation—this single factor increases mortality from 2% to 27% 3
• Never delay CT imaging in favor of plain radiographs—plain films have inadequate sensitivity and cannot detect ischemia 1, 2
• Never give oral contrast in suspected high-grade SBO—it delays diagnosis and risks aspiration 2
• Never rely on physical examination or laboratory tests alone to exclude ischemia—CT imaging is mandatory 2
• Never mistake incomplete obstruction with watery diarrhea for gastroenteritis—this leads to dangerous delays 4
• Never overlook SBO in elderly patients where pain may be less prominent 4
• Never delay surgical consultation when peritoneal signs, strangulation, or ischemia suspected—this significantly increases mortality 2, 3

Special Considerations

Virgin Abdomen (No Prior Surgery)

• Consider alternative etiologies: malignancy (10-41%), hernias, gallstone ileus, Meckel's diverticulum, intussusception, bezoar 1
• CT accuracy may be lower (52-76% versus operative findings) in virgin abdomen, requiring higher index of suspicion 1
• Surgical exploration threshold should be lower as adhesive etiology cannot be assumed 1

Intermittent or Low-Grade SBO

• Standard CT may have only 48-50% sensitivity for low-grade obstruction 1
• Consider CT enterography with bowel distention if standard CT negative but clinical suspicion high 1
• Water-soluble contrast follow-through can help predict need for surgery 1