Ileus resident survival guide

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Ileus Resident Survival Guide Microchapters

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Anahita Deylamsalehi, M.D.[2]

Synonyms and keywords:Approach to functional ileus, Approach to mechanical obstruction, Ileus workup, Ileus diagnostic approach


Ileus is defined as reduction in intestinal motility, which is either due to an obstruction (mechanical ileus) or due to intestinal paralysis (functional ileus). Reduction or cessation of intestinal peristalsis prevent effective transmission of intestinal content leading to constipation and abdominal distension. Nevertheless, onset and severity of symptoms depend on extent and location of obstruction in mechanical ileus. Although proximal obstructions are presented acutely with nausea, vomiting, abdominal pain and obstipation, distal involvements usually take longer to become symptomatic. It is critical to differentiate two types of ileus and determining the etiology when encountering a suspected patient, since different approaches are available for each. Surgical intervention is usually recommended for treatment of mechanical obstructions, specifically complete obstructions, whereas conservative management which has been effective in management of functional ileus and some of partial mechanical obstruction cases.


Life Threatening Causes

Untreated ileus can lead to intestinal tissue ischemia, which elevates the risk of perforation and subsequently life threatening peritonitis.[1][2]

Common Causes of Functional Ileus

Common Causes of Mechanical Ileus


Signs and Symptoms
Suggest Mechanical Ileus Suggest Functional Ileus
Obstination (patient cannot pass stool or gas Patient cannot pass gas and minimal or absent stool passage
Nausea and vomiting (especially billious vomiting) Nausea and vomiting
Abdominal distension Minimal to moderate abdominal distension
Increased bowel sounds Decreased or absent bowel sounds
Severe abdominal tenderness and guarding

¶Not if a partial mechanical obstruction.

†Although vomiting could be absent in functional ileus.

‡ Nevertheless chronic obstruction leads to intestinal hypoactivity and low bowel sounds.

Abbreviations: CBC: complete blood count; WBC: white blood cell; CRP: C reactive protein; BUN: blood urea nitrogen, ABG: arterial blood gas; IV: intravenous

Suspected Ileus
1) History taking:

2) Physical examination

3) Laboratory investigations:

Supine and erect plain abdominal x-ray
Distended large bowel (especially cecum)
Distended small bowel loops
Subdiaphragmatic air
Inconclusive findings
Ogilvie syndrome
Abdominal CT scan with oral or IV water soluble contrast (If mechanical obstruction: CT scan is able to detect the exact level and identify possible complications, such as perforation, necrosis and strangulation
Findings favor mechanical ileus
Findings favor functional ileus
•Air-fluid level
•Transition point (dilated proximal bowel and collapsed distal bowel
•No or minimal air in colon/rectum
•Evidences of fecal impaction
•No transition point
•Presence of air in colon/rectum
•Dilated loops of both small and large intestine


Shown below is an algorithm summarizing the treatment of ileus.[4][3][7][5][8][9]

Abbreviations: WBC: White blood cell; CRP: C reactive protein; IV: Intravenous; NGT: Nasogastric tube

Presence of these findings
Surgical intervention, such as exploratory laparotomy
Severe abdominal pain and vomiting
Physical findings of peritonitis, such as guarding
•Severely disturbed laboratory results (WBC>10.500 or CRP>75
Radiologic findings of perforation, such as free intraperitoneal or subdiaphragmatic air
Radiologic findings of strangulation, such as increased bowel wall density, localized mesenteric fluid accumulation (specifically>500ml) and mesenteric congestion
•Evidences of complete obstruction
•No resolution after 72 hours of conservative management
•Development of peritonitis, strangulation or worsening of patient's clinical or laboratory conditions within 72 hours of conservative management
Absence of these findings
Non operative managements
Fluid resuscitation (IV)
Bowel rest
•In the presence of vomiting, Consider decompression with NGT
•Correct any electrolyte disturbances
Antibiotic therapy if there is any clinical or laboratory finding of infection
•Consider neostigmine if Ogilvie syndrome
•Consider barium enema and/or digital fecal disimpaction if fecal impaction




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  7. 7.0 7.1 Taylor MR, Lalani N (2013). "Adult small bowel obstruction". Acad Emerg Med. 20 (6): 528–44. doi:10.1111/acem.12150. PMID 23758299.
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  9. 9.0 9.1 Story SK, Chamberlain RS (2009). "A comprehensive review of evidence-based strategies to prevent and treat postoperative ileus". Dig Surg. 26 (4): 265–75. doi:10.1159/000227765. PMID 19590205.
  10. Ten Broek RPG, Krielen P, Di Saverio S, Coccolini F, Biffl WL, Ansaloni L; et al. (2018). "Bologna guidelines for diagnosis and management of adhesive small bowel obstruction (ASBO): 2017 update of the evidence-based guidelines from the world society of emergency surgery ASBO working group". World J Emerg Surg. 13: 24. doi:10.1186/s13017-018-0185-2. PMC 6006983. PMID 29946347.