Bowel Obstruction (Small and Large)

[Section Outline]

Description
Etiology

Author:

Sean P.Dyer

Description

Obstruction of normal intestinal flow from either mechanical or nonmechanical causes, affecting either the small or large intestine
Can be classified into small bowel obstruction (SBO), large bowel obstruction (LBO), and nonmechanical or functional causes
Also classified as either partial, complete, or closed-loop obstruction
Obstruction leads to proximal dilatation of intestines due to swallowed air and accumulated GI secretions, leading to increased intraluminal pressures and vomiting
Distended bowel becomes progressively edematous, and additional intestinal secretions cause further distention and third spacing of fluid into the intestinal lumen
Obstruction may lead to intestinal wall ischemia (strangulated obstruction), resulting in increased aerobic and anaerobic bacteria possibly leading to peritonitis, sepsis, and possibly death
Closed loop obstruction: Distal and proximal obstruction leading to more rapid increase in intraluminal pressures and arterial/venous congestion making higher risk for bowel infarction
Mortality is 100% in untreated strangulated obstruction, 8% if treated surgically within 36 hr, but 25% if surgery delayed after 36 hr

Etiology

SBO:
- 20% of acute surgical admissions
- More common than LBO
- Adhesions: Most common cause (60%)
- Neoplasms
- Hernias
- Strictures: Inflammatory bowel disease
- Trauma: Bowel wall hematoma
- Miscellaneous (e.g., ascaris infection)
LBO:
- Disease primarily of the elderly
- Carcinoma (60%)
- Diverticular disease (20%)
- Volvulus (5%)
- Colitis (e.g., ischemic, radiation)
- Crohn disease
- Foreign bodies
Functional, nonmechanical:
- Paralytic ileus (e.g., electrolyte abnormalities, injury)
- Pseudo-obstruction (i.e., Ogilvie syndrome [e.g., operative and nonoperative trauma] 11%)

Diagnosis ⬆ ⬇

[Section Outline]

Signs and Symptoms
Essential Workup
Diagnostic Tests & Interpretation
Differential Diagnosis

Signs and Symptoms

History

Risk factors: Previous surgery, malignancy, hernias, colonoscopy history, significant family history
Abdominal pain:
- Intermittent when early
- Symptoms may be vague in elderly or altered patients
- Constant with strangulated obstruction
Vomiting:
- Bile-stained emesis with proximal obstruction
- Feculent emesis with distal obstruction
Obstipation, constipation, diarrhea
Stool caliber changes, weight loss

Physical Exam

Vital signs:
- Tachycardia, hypotension with significant volume depletion
- Fever with strangulation or perforation
- Hypothermia with sepsis
Abdominal exam:
- Distention, tympanic
- 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
- Look for hernias (ventral, inguinal, femoral)
Digital rectal exam:
- Rectal mass
- Blood in stool, gross or occult

Geriatric Considerations
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

Pediatric Considerations

Intussusception:
- Leading cause of intestinal obstruction in infants
- Most common between 3-12 mo of age
- US is diagnostic test of choice
Incarcerated inguinal/umbilical hernia
Malrotation with volvulus:
- Can occur as early as 3-7 d of age
- “Double bubble” sign seen on plain radiograph owing to partial obstruction of duodenum, resulting in air in stomach and in first part of duodenum
Pyloric stenosis:
- Progressive, projectile, nonbilious postprand ial vomiting
- Male/female ratio: 5:1 incidence
- Onset usually 2-5 wk of age
Other causes include duodenal atresia, Hirschsprung, and imperforate anus
CT is imaging test of choice to diagnose obstruction when etiology is thought to be other than intussusception/appendicitis

Essential Workup

Careful history and physical exam

Diagnostic Tests & Interpretation

Lab

CBC:
- Leukocytosis common
Electrolytes, BUN/creatinine, glucose:
- Hypokalemia
- Hypochloremic metabolic alkalosis
- Prerenal 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 filled
- Less helpful for distinguishing strangulation
Abdominal CT
Sensitivity
90% for SBO; 91% for LBO:
- Detects neoplastic causes and stages malignancy
- Should be considered in all patients with an obstruction as it provides more information than plain films by differentiating grade, severity and etiology that may lead to change in management
- More helpful than plain radiographs in identifying early strangulation (with IV contrast)
- Exclude other incidental findings/causes
- Has decreased use of contrast enemas due to ease of use
MRI:
- Sensitivity approached that of CT
- Availability variable
US:
- Look for decreased peristalsis (“whirling”) and dilated loops of bowel >2.5 cm
- Noninvasive, can be rapidly performed, limited by body habitus
- +LR of 9.6-14.1

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 ⬆ ⬇

[Section Outline]

Prehospital
Initial Stabilization/Therapy
ED Treatment/Procedures
Medication

Prehospital

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 bolus
- Peds: 20-mL/kg bolus
Correct electrolyte abnormalities, especially hypokalemia

ED Treatment/Procedures

IV fluids (isotonic saline or LR)
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/24 hr 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/24 hr IV div. q6-8h) IV q4-6h
  - Ampicillin-sulbactam (Unasyn): 1.5-3 g (peds: 100-400 mg/kg/24 hr IV div. q6h) IV q6h
  - Meropenem (Merrem): Adult: 1 g (peds: 60-120 mg/kg/24 hr IV q8h) IV q8h
  - Imipenem-cilastatin (Primaxin): 250-1,000 mg (peds: 50-100 mg/kg/24 hr 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 PRN
- Promethazine (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 ⬆ ⬇

[Section Outline]

Disposition
Follow-up Recommendations

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

Follow-up 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 ⬆ ⬇

DiazJJ Jr, BokhariF, MoweryNT, et al. Small-bowel obstruction, evaluation and management of . J Trauma. 2012;73(5):S362-S369.
HopkinsC. Large-bowel obstruction workup . Available at http://emedicine.medscape.com/article/774045-workup#aw2aab6b5b5aa. Accessed February 2013.
HryhorczukAL, LeeEY. Imaging evaluation of bowel obstruction in children: updates in imaging techniques and review of imaging findings . Semin Roentgenol. 2012;47(2):159-170.
http://coreem.net/core/small-bowel-obstruction/. Accessed February 2018.
NobleBA. Small-bowel obstruction . Available at http://emedicine.medscape.com/article/774140-overview. Accessed February 2013.
SmithDA, NehringSM. Bowel obstruction . http://www.ncbi.nlm.nih.gov/books/NBK441975/. Accessed February 2018.
TaylorMR, LalaniN. Adult small bowel obstruction . Acad Emerg Med. 2013;20:528-544.
WalkerGM, RainePA. 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)

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)

section name header

Basics ⬇

Diagnosis ⬆ ⬇

History

Physical Exam

Geriatric Considerations

Pediatric Considerations

Lab

Imaging

Diagnostic Procedures/Surgery

Treatment ⬆ ⬇

Follow-Up ⬆ ⬇

Admission Criteria

Discharge Criteria

Issues for Referral

Pearls and Pitfalls ⬆ ⬇

Additional Reading ⬆ ⬇

Codes ⬆