Editing Ileus

''Obstipation and intolerance of diet due to non-mechanical factors''

== Aetiology ==

* Post-op (especially laparotomy)
** About 15% of colectomy
** 3% of hysterectomy
** 10% of radical cystectomy
** 10% of open AAA
* Metabolic and electrolyte derangements (hypokalaemia, hyponatraemia, hypomagnesaemia, uraemia, diabetic coma, hypoparathyroidism)
* Drugs 
** Opioids
** Antihypertensive agents (calcium channel blockers including verapamil, clonidine)
** Antidiarrhoeal/spasmodic agents (loperamide, hyoscyamine)
** Phenothiazine antiemetics (prochlorperazine, promethazine)
** Oral iron preparations
** Zoledronic acid
** Anticholinergics (SSRIs, TCAs, antipsychotics, Parkinson disease medications, first-generation antihistamines, muscle relaxants, overactive bladder medications, atropine)
* Intra-abdominal inflammation
** Gastroenteritis
* Retroperitoneal haemorrhage or inflammation
** Pancreatitis
* Intestinal ischaemia
* Systemic sepsis (pneumonia)
* Multi-trauma (spinal injury, rib or pelvic fractures, severe burns)
* Systemic illness (renal failure, heart failure, critical illness, MI, stroke)
* Diabetes and ketoacidosis
* Acute intermittent porphyria
* Botulism
* Parkinson disease
* Epilepsy

== High-risk factors ==

* Particularly seen in prolonged abdominal or pelvic surgery, and lower GIT surgery
* Open procedures
* Delaying enteral nutrition
* Peri-operative complications including abscess, bleeding, transfusion, peritonitis/sepsis
* Hypoalbuminaemia and aggressive IV fluids
* Opioids

== Pathophysiology ==

* Inflammation
** Degree of manipulation is directly related to both the degree of leucocyte infiltration into muscularis, and the amount of intestinal dysmotility
** This effect is not limited to the manipulated segment - inflammation can even occur in non-abdominal surgery
* Neural reflexes
** Inhibitory neural reflexes appear to impede return of normal function
** Blockade of spinal afferents with epidural can improve post-op ileus
* Neurohumeral peptides
** Nitric oxide, VIP, and possibly substance P all slow gut motility
** Opioids increase resting tone while decreasing gastric motility and emptying, and decrease propulsive colonic movements

== Diagnosis of prolonged post-op ileus - two or more of the following on day 4 or after, with differential diagnoses excluded by imaging ==

* Nausea or vomiting
* Inability to tolerate an oral diet over the preceding 24 hours
* Absence of flatus over the preceding 24 hours
* Abdominal distension
* Radiologic confirmation

== Differential diagnosis ==

* Physiologic ileus
* Mechanical SBO
** SBO typically has return of bowel function and oral intake, followed by new onset of symptoms; whereas ileus never comes back
** Early post-operative adhesions are typically soft and likely to resolve spontaneously
** Consider likelihood of internal hernia, masses, peritoneal disease
**

{| class="wikitable"
|'''Sign or symptom'''
|'''Ileus'''
|'''SBO'''
|-
|Abdominal distention
|May be present
|May be present
|-
|'''Bowel sounds'''
|'''Usually quiet or absent'''
|'''May be high pitched, may be absent'''
|-
|Obstipation
|May be present
|May be present
|-
|'''Pain'''
|'''Mild and diffuse'''
|'''Moderate to severe, colicky'''
|-
|'''Peritoneal signs'''
|'''Absent'''
|'''May be present'''
|-
|'''Radiography'''
|'''Dilated loops of bowel, paucity of colonic gas'''
|'''Dilated loops of bowel, differential air-fluid levels, paucity or absence of colonic gas'''
|-
|'''Fever, tachycardia'''
|'''Absent'''
|'''Should raise suspicion'''
|-
|Vomiting
|May be present
|May be present, may be bilious or feculent
|}

* Colonic pseudo-obstruction

== Investigation ==

* CT
** With oral contrast, has a sensitivity and specificity >90% for differentiating ileus from complete SBO
** Can also identify secondary causes of ileus (abscess, bleeding)
** Diffuse dilation of the entire small bowel without a transition point
* Bloods
** Identify reversible factors that may be contributing
** Seek evidence of alternative diagnosis
* A post-op ileus after laparoscopic surgery should raise suspicion for occult injury (bowel, bladder, ureteral)

== Treatment ==

* Correct underlying abnormality
* NGT indications
** Moderate/severe vomiting
** Significant abdominal distension
* IVF and bowel rest
** Sips of clear fluids
** Once distension resolves and bowel sounds return, start free fluids
** When the patient is able to take in adequate oral fluids, restart normal diet
* Analgaesia - minimise opioids, regular paracetamol, regular NSAIDs if possible
* Nutritional support
* CT with oral contrast on day 5 post-op if persisting symptoms
* No resolution by two weeks is an indication for re-operation, although likely to be tough due to adhesions

=== Unproven treatments ===

* Gastrografin - may decrease time to stool, but not tolerance of oral diet or resolution of nausea/vomiting

[[Category:Small bowel]]
[[Category:Intern education]]