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Bowel Obstruction (Small and Large), Emergency Medicine

Basics

Description

- Obstruction of normal intestinal flow from mechanical or nonmechanical causes - Small-bowel obstruction (SBO): - 20% of acute surgical admissions - Adhesions: Most common cause (60%) - Neoplasms - Hernias - Strictures: Inflammatory bowel disease - Trauma: Bowel wall hematoma - Miscellaneous (e.g., ascaris infection)

- Vital signs: - Tachycardia, hypotension with significant volume depletion - Fever with strangulation or perforation - Hypothermia with sepsis

- Abdominal exam: - Distention - Variable tenderness, often diffuse - Hyperactive and high-pitched bowel sounds when early; hypoactive when late - Consider ischemic or gangrenous bowel if pain out of proportion to exam. - Peritoneal signs indicate strangulation or perforation.

- Pyloric stenosis: - Progressive, projectile, nonbilious postprandial vomiting - Male/female ratio: 5:1 incidence - Onset usually 2-5 wk of age

- CBC: - Electrolytes, BUN/creatinine, glucose: - Hypokalemia - Hypochloremic metabolic alkalosis - Prerenal azotemia

- Plain abdominal radiographs, supine and upright (75% sensitivity; 53% specificity): - Distended loops of bowel (normal small bowel <3 cm in diameter) - Distended cecum >13 cm indicates potential for perforation. - Air-fluid levels - "String of pearls" sign if small bowel loops nearly completely fluid filled - Less helpful for distinguishing strangulation

- Antibiotic choices (broad spectrum, for suspected ischemia): - Combination therapy: - Metronidazole (Flagyl): 1 g IV, then 500 mg IV q6h (peds: 7.5-30 mg/kg/24h IV div. q6-8h) - Ciprofloxacin (Cipro): 400 mg IV q12h - Ceftriaxone (Rocephin): 1-2 g (peds: 25-75 mg/kg/d IV up to 2 g div. q12-24h) IV q24h

- Single therapy: - Piperacillin-tazobactam (Zosyn): 3.375 g (peds: 150-400 mg/kg/24h IV div. q6-8h) IV q4-6h - Ampicillin-sulbactam (Unasyn): 1.5-3 g (peds: 100-400 mg/kg/24h IV div. q6h) IV q6h - Meropenem (Merrem): Adult: 1 g (peds: 60-120 mg/kg/24h IV q8h) IV q8h - Imipenem-cilastatin (Primaxin): 250-1,000 mg (peds: 50-100 mg/kg/24h IV q6-12h) IV q6-8h

  • Obstruction of normal intestinal flow from mechanical or nonmechanical causes
  • Small-bowel obstruction (SBO):20% of acute surgical admissionsAdhesions: Most common cause (60%)NeoplasmsHerniasStrictures: Inflammatory bowel diseaseTrauma: Bowel wall hematomaMiscellaneous (e.g., ascaris infection)
  • Large-bowel obstruction (LBO):Disease primarily of the elderlyCarcinoma (60%)Diverticular disease (20%)Volvulus (5%)Colitis (e.g., ischemic, radiation)Crohns diseaseForeign bodies
  • Functional, nonmechanical:Paralytic ileus (e.g., electrolyte abnormalities, injury)Pseudo-obstruction (i.e., Ogilvie syndrome [e.g., operative and nonoperative trauma] 11%)

Etiology

  • Obstruction leads to proximal dilatation of intestines due to swallowed air and accumulated GI secretions, leading to increased intraluminal pressures.
  • Retrograde peristalsis causes vomiting.
  • Distended bowel becomes progressively edematous, and additional intestinal secretions cause further distention and 3rd spacing of fluid into the intestinal lumen.
  • Obstruction may lead to intestinal wall ischemia (strangulated obstruction), resulting in increased aerobic and anaerobic bacteria, and methane and hydrogen production. Peritonitis, sepsis, and death may follow.
  • Mortality is 100% in untreated strangulated obstruction, 8% if treated surgically within 36 hr, but 25% if surgery delayed after 36 hr.

Diagnosis

Signs and Symptoms

History

  • Previous surgery, malignancy, hernias, colonoscopy history, significant family history
  • Abdominal pain:Intermittent when earlySymptoms may be vague in elderly or altered patientsConstant with strangulated obstruction
  • Vomiting:Bile-stained emesis with proximal obstructionFeculent emesis with distal obstruction
  • Obstipation, constipation, diarrhea
  • Stool caliber changes, weight loss

Physical Exam

  • Vital signs:Tachycardia, hypotension with significant volume depletionFever with strangulation or perforationHypothermia with sepsis
  • Abdominal exam:DistentionVariable tenderness, often diffuseHyperactive and high-pitched bowel sounds when early; hypoactive when lateConsider ischemic or gangrenous bowel if pain out of proportion to exam.Peritoneal signs indicate strangulation or perforation.
  • Hernia (ventral, inguinal, femoral)
  • Digital rectal exam:Rectal massBlood in stool, gross or occult
  • Abdominal pain variable in elderly, may be vague
  • Nausea/vomiting and abdominal pain are common symptoms in elderly patients with acute myocardial infarctions:Abdominal distention, obstipation, and colicky pain suggest GI cause.
  • Intussusception:Leading cause of intestinal obstruction in infantsMost common between 3 and 12 mo of age
  • Incarcerated inguinal/umbilical hernia
  • Malrotation with volvulus:Can occur as early as 3-7 days of age"Double bubble" sign seen on plain radiograph owing to partial obstruction of duodenum, resulting in air in stomach and in 1st part of duodenum
  • Pyloric stenosis:Progressive, projectile, nonbilious postprandial vomitingMale/female ratio: 5:1 incidenceOnset usually 2-5 wk of age
  • Other causes include duodenal atresia, Hirschsprung, and imperforate anus.

Essential Workup

Careful history and physical exam

Diagnosis Tests & Interpretation

Lab

  • CBC:
  • Electrolytes, BUN/creatinine, glucose:HypokalemiaHypochloremic metabolic alkalosisPrerenal azotemia
  • Lactate
  • Amylase/lipase
  • Liver enzymes/function to exclude hepatic/biliary pathology
  • Stool heme test
  • Urinalysis
  • Type and crossmatch
  • PT/PTT
  • ECG in patients at risk of coronary artery disease

Imaging

  • Upright CXR:Evaluate for pulmonary pathology.Check for free air beneath diaphragm.
  • Plain abdominal radiographs, supine and upright (75% sensitivity; 53% specificity):Distended loops of bowel (normal small bowel <3 cm in diameter)Distended cecum >13 cm indicates potential for perforation.Air-fluid levels"String of pearls" sign if small bowel loops nearly completely fluid filledLess helpful for distinguishing strangulation
  • Abdominal CT:Sensitivity:Detects neoplastic causes and stages malignancyEffective in defining location of obstructionMore helpful than plain radiographs in identifying early strangulation (with IV contrast)Exclude other incidental findings/causesHas decreased use of contrast enemas due to ease of use
  • MRI:Sensitivity approached that of CTAvailability variable
  • US:More sensitive and specific than plain films for SBO but not as accurate as CT

Diagnostic Procedures/Surgery

Upper GI/barium enemas/endoscopy:

  • If carcinoma or mass lesion suspected as cause
  • Use decreased with availability of CT scan
  • May be painful or difficult in sick patients

Differential Diagnosis

  • Paralytic ileus
  • Pseudo-obstruction (Ogilvie)
  • Perforated ulcer
  • Pancreatitis
  • Cholecystitis
  • Colitis
  • Mesenteric ischemia

Treatment

Pre-Hospital

Establish IV access for patients with dehydration, vomiting, or significant abdominal pain.

Initial Stabilization/Therapy

  • ABCs
  • 0.9% normal saline (NS) or lactated ringers (LR) IV fluid resuscitation for significant volume depletion and strangulated or perforated bowel:Adults: 1 L bolusPeds: 20 mL/kg bolus
  • Correct electrolyte abnormalities, especially hypokalemia.

Ed Treatment/Procedures

  • IV fluids (isotonic saline or lactated Ringer's)
  • Nasogastric tube (NGT)
  • Foley catheter to monitor urine output
  • Surgical consultation
  • Antibiotics for suspected strangulated/perforated bowel:Antibiotic choices should cover gram-negative aerobic and anaerobic organisms:
  • Analgesics
  • Antiemetics
  • Treat underlying etiology, appropriate steroids for inflammatory bowel disease, radiation enteritis

Medication

  • Antibiotic choices (broad spectrum, for suspected ischemia):Combination therapy:Metronidazole (Flagyl): 1 g IV, then 500 mg IV q6h (peds: 7.5-30 mg/kg/24h IV div. q6-8h)Ciprofloxacin (Cipro): 400 mg IV q12hCeftriaxone (Rocephin): 1-2 g (peds: 25-75 mg/kg/d IV up to 2 g div. q12-24h) IV q24hSingle therapy:Piperacillin-tazobactam (Zosyn): 3.375 g (peds: 150-400 mg/kg/24h IV div. q6-8h) IV q4-6hAmpicillin-sulbactam (Unasyn): 1.5-3 g (peds: 100-400 mg/kg/24h IV div. q6h) IV q6hMeropenem (Merrem): Adult: 1 g (peds: 60-120 mg/kg/24h IV q8h) IV q8hImipenem-cilastatin (Primaxin): 250-1,000 mg (peds: 50-100 mg/kg/24h IV q6-12h) IV q6-8h
  • Analgesics:Morphine: 2-10 mg/dose (peds: 0.1-0.2 mg/kg IV/IM/SC q2-4h) IV/IM/SC q2-6h PRN
  • Antiemetics:Ondansetron (Zofran): 4 mg (peds: 0.1 mg/kg IV div. q8h) IV q4-8h PRNPromethazine (Phenergan): 12.5-25 mg (peds: >2 yr: 0.25-1 mg/kg/d IV/IM/PR div. q4-6h PRN) IV/IM/SC q4h

Follow-Up

Disposition

Admission Criteria

All patients with suspected/confirmed intestinal obstruction should be admitted with early surgical consultation.

Discharge Criteria

Normal lab/radiology results with resolution of symptoms and no further suspicion for intestinal obstruction.

Issues for Referral

Surgery consult for patients with suspected bowel obstruction

Followup Recommendations

Discharged patients:

  • Normal lab and radiologic studies
  • Timely appointment for re-evaluation
  • Explicit instructions detailing signs/symptoms to return to emergency department

Pearls and Pitfalls

  • Carefully examine patient with history of vomiting for incarcerated hernias.
  • Failure to diagnose strangulated bowel obstruction:Symptoms potentially vague in very old and very young and in altered patients
  • Failure to adequately replete fluid losses and electrolyte imbalances

Additional Reading

  • Batke M. Cappell MS. Adynamic ileus and acute colonic pseudo-obstruction. Med Clin North Am. 2008;92(3):649-670.
  • Diaz JJ Jr, Bokhari F, Mowery NT, et al. Guidelines for management of small bowel obstruction. J Trauma. 2008;64(6):1651-1654.
  • Hopkins C. Large-bowel obstruction workup. Available at http://emedicine.medscape.com/article/774045-workup#aw2aab6b5b5aa. Updated Nov 11, 2011. Accessed February 2013.
  • Noble BA. Small-bowel obstruction. Available at http://emedicine.medscape.com/article/774140-overview. Updated Oct 5, 2011. Accessed February 2013.
  • Walker GM, Raine PA. Bilious vomiting in the newborn: How often is further investigation undertaken? J Pediatr Surg. 2007;42(4):714-716.

See Also (Topic, Algorithm, Electronic Media Element)

  • Abdominal Pain
  • Gastric Outlet Obstruction
  • Pyloric Stenosis
  • Vomiting

Codes

ICD9

  • 560.9 Unspecified intestinal obstruction
  • 560.81 Intestinal or peritoneal adhesions with obstruction (postoperative) (postinfection)
  • 560.89 Other specified intestinal obstruction
  • 560.1 Paralytic ileus
  • 560.2 Volvulus
  • 560.8 Other specified intestinal obstruction

ICD10

  • K56.5 Intestinal adhesions w obst (postprocedural) (postinfection)
  • K56.60 Unspecified intestinal obstruction
  • K56.69 Other intestinal obstruction
  • K56.0 Paralytic ileus
  • K56.2 Volvulus
  • K56.6 Other and unspecified intestinal obstruction

SNOMED

  • 81060008 Intestinal obstruction (disorder)
  • 281255004 small bowel obstruction (disorder)
  • 281254000 large bowel obstruction (disorder)
  • 67766009 Intestinal adhesions with obstruction (disorder)
  • 23065003 Stenosis of intestine (disorder)
  • 55525008 Paralytic ileus (disorder)