Paralytic ileus

Last updated: September 11, 2023

Summarytoggle arrow icon

Paralytic ileus (also called functional bowel obstruction) is the interruption of the normal passage of bowel contents due to reduced peristalsis in the absence of a mechanical obstruction. It is often transient. Postoperative ileus is one of the most common causes of paralytic ileus. Other etiologies include inflammation of abdominal, pelvic, or retroperitoneal viscera, metabolic disturbances, certain medications, and mesenteric ischemia. Paralytic ileus typically manifests with nausea, vomiting, abdominal pain, abdominal distention, and constipation; bowel sounds are often absent on auscultation. Bowel distention, if present, leads to third-space volume loss, resulting in dehydration and electrolyte abnormalities. Ileus is generally a clinical diagnosis. Imaging may be required to evaluate for the underlying diagnosis and to rule out mechanical bowel obstruction and complications. The characteristic imaging feature of paralytic ileus is diffuse dilatation of bowel loops with no transition point. Laboratory studies can be useful to identify the underlying cause and/or to assess for complications. Apart from treating the underlying cause, there are few specific treatment measures for paralytic ileus. Management is mainly supportive, involving IV fluid resuscitation, electrolyte repletion, and bowel rest. Surgical intervention is only indicated if necessary for the underlying cause (e.g., acute complicated appendicitis) or if complications arise. Complications such as intestinal ischemia and perforation are rare in paralytic ileus.

Acute colonic pseudoobstruction, also known as Ogilvie syndrome, is a distinct clinical entity that typically affects critically ill or postoperative patients. Like paralytic ileus, there is no mechanical obstruction to the passage of bowel contents. However, the risk of severe colonic dilation with potential perforation and ischemia is significant. For management of this condition, see “Ogilvie syndrome.”

Definitiontoggle arrow icon

Temporarily impaired peristalsis (hypomotility) of the gastrointestinal tract in the absence of mechanical obstruction

Etiologytoggle arrow icon

The 5 Ps: Peritonitis, Postoperative, low Potassium, oPioids, and Pelvic/spinal fractures are among the most common causes of paralytic ileus.


Pathophysiologytoggle arrow icon

References: [9][10]

Clinical featurestoggle arrow icon

  • Symptoms
  • Examination findings
    • Percussion: diffuse tympany
    • Palpation: usually no tenderness unless peritonitis is present [11]
    • Auscultation: Bowel sounds are absent (silent abdomen) or decreased (early paralytic ileus).

References: [7][8]

Diagnosticstoggle arrow icon

General principles

Paralytic ileus must be differentiated from diagnoses that require surgical intervention.

Diagnostic studies are not generally required for early postoperative ileus. However, the possibility of early postoperative obstruction or abdominal infection should always be considered. [8]

Imaging [7]

Abdominal ultrasound [11]

  • Indication: commonly performed as an initial test in patients with abdominal pain [12]
  • Findings

X-ray abdomen [9][11][13]

  • Indication: commonly performed as the initial imaging modality in patients with abdominal pain and/or suspected ileus [9]
  • Findings [9][13]
    • Diffuse small and large bowel gaseous distention without transition or cutoff point
    • The sentinel loop sign may be seen in localized paralytic ileus.
    • Visible gas shadows in the rectum
    • Free air if bowel is perforated (rare); note that intraabdominal free air is expected after recent abdominal surgery. [7]

CT abdomen and pelvis with or without IV contrast [13]

  • Indications
    • Gold standard for the evaluation of suspected bowel obstruction [3][12][14]
    • To diagnose the underlying pathology (e.g., suspected intraabdominal infection)
  • Findings

Laboratory studies [7][8][11]

Laboratory studies are primarily indicated to investigate the underlying cause of paralytic ileus and assess for dehydration and metabolic imbalances secondary to diffuse bowel distension and third-spacing.

Routine workup [7]

Further studies

Obtain further laboratory studies based on the pretest probability of the underlying etiology; examples include:

Differential diagnosestoggle arrow icon

Treatmenttoggle arrow icon

General principles [7][8]

If there is no suspicion of more severe conditions such as mechanical obstruction or Ogilvie syndrome, the treatment of paralytic ileus is mainly supportive.

Conservative management [3][9][11]

Conservative management is indicated in all patients without signs of infectious causes or complications of paralytic ileus (e.g., ischemia, peritonitis).

Initial measures for all patients [16]

Further measures

Improvement of symptoms and tolerance of enteral feeding are better predictors of the normalization of gastrointestinal motility than successful bowel movements. [16]

Obtain urgent surgery consult if the patient develops signs of peritonitis.


  • Indications: not routinely indicated, except in the following situations

Acute management checklisttoggle arrow icon

Postoperative ileustoggle arrow icon


  • Postoperative ileus (physiologic): : impaired gastrointestinal motility that occurs following abdominal or pelvic surgery and typically resolves spontaneously within 72 hours; one of the most common causes of paralytic ileus
  • Prolonged postoperative ileus: a form of paralytic ileus associated with prolonged impaired gastrointestinal motility for > 72 hours after surgery [2][10]

Risk factors for postoperative ileus [3][7][8]

Clinical features

  • Similar to paralytic ileus secondary to other etiologies (i.e., nausea, vomiting, abdominal distension, failure to pass flatus, absent/decreased bowel sounds).
  • Abdominal tenderness is difficult to assess in the immediate/early postoperative period.

Prevention of postoperative ileus

Prolonged postoperative ileus causes considerable discomfort to the patient and leads to longer hospital stays. The following perioperative measures can decrease the risk in patients undergoing abdominal and other high-risk surgery.

  • Minimally invasive surgery, whenever feasible [3][8][10]
  • Multimodal analgesic regimens [1][3]
  • Early initiation of enteral feeding and regular diet [10][21]
  • Sham feeding with chewing gum [10]
  • Restricted use of IV fluids perioperatively [1][10]
  • Selective use of nasogastric tubes [10]
  • Early mobilization is generally believed to be beneficial. [1][10]
  • Consider preoperative initiation of a peripherally-acting μ-opioid antagonist (e.g., alvimopan ) in patients undergoing open colorectal surgeries or other major abdominal surgeries. [3][21][22]


Postoperative ileus is managed in the same way as paralytic ileus secondary to other etiologies. See “Treatment of paralytic ileus” for details.

Complicationstoggle arrow icon

Severe complications of paralytic ileus are uncommon but may include: [23][24]

We list the most important complications. The selection is not exhaustive.

Referencestoggle arrow icon

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