Bowel Obstruction
Study guide:
Definition:
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Paralytic ileus/adynamic bowel: failure to move the luminal contents due to poor motility.
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Simple bowel obstruction: blockage of the bowel lumen at one area without complications (perforation, strangulation etc.).
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Closed-loop obstruction: afferent and efferent bowel blockage, which usually results in complicated bowel obstruction and strangulation.
Causes:

Clinical Presentation:
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Nausea, vomiting, abdominal pain or distention, obstipation, and decreased flatus:
- High SBO obstruction:
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Little evidence of dilated bowl loops on radiology
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Minimal distention.
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Bilious vomiting (early).
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Low SBO:
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Abdominal pain referred to periumbilical area.
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Vomiting is delayed
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Multiple dilated bowl loops on radiology
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LBO obstruction:
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Obstipation and abdominal distension (early).
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Abdominal pain referred to the lower abdominal area.
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Distended colon proximal to the obstruction on radiology
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- High SBO obstruction:
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Fever: might be seen with strangulation.
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Abdominal tenderness and guarding: seen with strangulation and perforation.
Bloody emesis/vomiting with the other bowel obstruction S&S strongly suggests strangulation!
Diagnosis:
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Mainly clinical.
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Abdominal series (Upright abdominal, supine abdominal, and upright chest plain film X-ray):
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Supine abdominal is the most important.
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Upright abdominal is usually used to check for Air-fluid level.
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Upright chest is done to check for Pneumoperitoneum.
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Barium Swallow or Enema.
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CT: usually for SBO.
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Lab tests:
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CBC: to check for leukocytosis, hemoglobin, and BUN.
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Blood chemistries: potassium & sodium.
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ABGs: to check for metabolic acidosis, or alkalosis.
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Cardinal features of ACUTE SBO: Ab. Pain (colicky, central) Distension Vomiting Absolute constipation
Metabolic alkalosis is usually seen with pyloric obstruction or SBO. Metabolic acidosis is seen with late presentation of bowel obstruction.
Management:
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Conservative medical therapy:
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Keep the patient NPO.
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IV hydration and correct the electrolyte imbalances.
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NG tube:
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To prevent aspiration of vomitus.
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To decompress the small bowel.
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Foley catheter: to monitor the urine output, and so monitor hydration.
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Surgical Management:
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True bowel obstruction is considered as a surgical emergency, and those patients are candidates for laparotomy.
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Early surgical intervention
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Obstructed external hernia
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Suspicion of strangulation
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Obstruction in a virgin (not operated on) abdomen
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Exceptions:
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Partial obstruction.
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History of multiple previous laparotomies.
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Severely debilitated patient.
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Antibiotic coverage for gram-negative organisms.
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Post-operative care:
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Continue NG tube until the bowel function is resumed.
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Continue antibiotics if the patient is septic, wound contamination, long-standing peritonitis.
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Start total parental nutrition (TPN) if the bowel function is not resumed after 5 days.
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The six questions you should know about any obstruction:
1- Is it obstruction or not? (presence of cardinal symptoms; e.g. vomiting, constipation, bowel obstruction...)
2- What is the likely level of obstruction? (prominent symptoms; e.g. vomiting -> proximal, abdominal distention -> distal)
3- What is the likely underlying cause of obstruction?
4- Is the obstruction complete (not passing gas or stool) or partial (only passing gas)?
5- Is the obstruction simple or complicated? (e.g. signs of strangulation)
6- Does the patient suffer from any physiological changes?(e.g. signs of dehydration, electrolyte disturbances...)
1- Is it obstruction or not? (presence of cardinal symptoms; e.g. vomiting, constipation, bowel obstruction...)
References:
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Reid M, Stehr W. The Mont Reid surgical handbook.
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Kumar P, Clark M. Kumar & Clark's clinical medicine.
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Bowel Obstruction - Causes and Pathophysiology [Internet]. YouTube. 2016 [cited 13 April 2016]. Available from: https://www.youtube.com/watch?v=sBm12CkNtAo
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Le T, Bhushan V, Singh Bagga H. First aid for the USMLE step 2 CK. New York: McGraw-Hill Medical; 2010.
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Baily and Love’s short practice
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Clinical surgery
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Essential surgery
Written by: Roaa Amer
Reviewed by: Areej Madani
Haifa Al Issa
Format Editor: Reem AlQarni
Web Publisher: Abdullah K. Al Johani
Bayan Alzomaili