Ileus resident survival guide

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

Synonyms and keywords:

Overview

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 which leads to constipation and abdominal distension, which are known as typical symptoms of ileus. Nevertheless, onset and severity of symptoms are depended on extent and location of obstruction in mechanical ileus. Although proximal obstructions are presented acutely with nausea, vomiting, abdominal pain and obstination, more distal involvements usually take longer to become symptomatic.

Causes

Life Threatening Causes

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

Common Causes of Functional Ileus

• Reflectory ileus due to abdominal, pelvic or retroperitoneal surgeries
• Medications such as narcotics, anticholinergics, calcium channel blockers and antipsychotics
• General anaesthesia
• Electrolyte disturbance, such as hypokalemia, hyponatremia and hypocalcemia
• Diabetes Mellitus
• Intestinal hypoperfusion
• Pancreatitis
• Ogilvie syndrome

Common Causes of Mechanical Ileus

• Tumors
• Hernia
• Infections or inflammations that affect the bowel wall such as diverticulitis.
• Fecal impaction
• Intussusception
• Adhesion (eg, due to a previous surgery)
• Volvulus (eg, sigmoid volvulus)
• Gallstone ileus

Diagnosis

• Shown below is a table summarizing the clinical presentations of both mechanical and functional types of 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
Severe abdominal tenderness and guarding
Increased bowel sounds‡	Decreased or absent bowel sounds

_{¶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.}

• Shown below is an algorithm summarizing diagnosis of ileus.

Suspected Ileus

1) History taking: History of previous surgery (Development of symptoms weeks/years later is more common with mechanical ileus, whereas development of symptoms hours/days later which is more common with functional ileus) History of constipation Drug history 2) Physical examination 3) Labratory investigations: CBC with differential WBC count/CRP (to rule out any systemic infections) Electrolytes Serum BUN and creatinine (to rule out renal failure due to fluid shift) Liver function tests, lipase (to rule out oancreatitis and liver failure) Lactate/ABG (to evaluate intestinal hypoperfusion and ischemia)

Supine and erect plain abdominal x-ray

Distended large bowel (especially cecum)

Distended small bowel loops

Subdiaphragmatic air

Inconclusive findings

Ogilvie syndrome

Perforation

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

Treatment

Shown below is an algorithm summarizing the treatment of [[disease name]] according the the [...] guidelines.

Do's

• Administration of water soluble contrast for CT scan is preferred. Moreover, in conservative management administration of 100 mg of water-soluble, iodinated contrast medium per nasogastric tube is recommended for better evaluation.

Don'ts

• Don't use CT scan with barium contrast due to it's irritative nature, specifically in presence of perforation.
• Don't use vagolytic agents such as butylscopolamine for pain control, due to their antiperistaltic effect.