Gut Motility Disorders: Failure of Transit through Bowel

First Things First (assess & treat for the following)

The first step in dealing w/ gut dysmotility is to differentiate ileus from obstruction. Whereas ileus typically resolves w/ supportive care only, & without sequelae, obstruction rarely resolves w/out surgical intervention & can have serious consequences if not aggressively managed.

  • Ileus is functional failure (no demonstrable obstruction) of the gut to propel contents & can be classified as:
    • Adynamic ileus is an inhibition of the neuromuscular complex, also referred to as pseudo-obstruction.
      • Primary adynamic ileus is idiopathic (ie, Ogilvie’s syndrome).
      • Most adynamic ileus is secondary to well-known causes:
        • Postop ileus related to CNS & neural reflexes, hormones, medication & anesthetic agents is normal when it involves the small bowel for up to 24 hrs, the stomach up to 48 hrs & the colon for up to 72 hrs.
        • When postop ileus is prolonged or recurrent, considerations should include:
          • Intra-abdominal inflammation
          • Systemic sepsis
          • Intra-abdominal or retroperitoneal hematoma
          • Occult wound infection
        • Commonly seen after trauma, including:
          • Spinal cord injury
          • Spine fracture
          • Rib fractures
          • Pelvic fracture
        • Common w/ pulmonary atelectasis or pneumonia in the basal segments
        • Drugs that inhibit gut motility include:
          • Narcotics
          • Anticholinergic agents
          • Antihistamines
          • Psychotropic drugs such as haloperidol or tricyclic antidepressants
          • Phenothiazines
          • Ganglionic blocking agents
        • Metabolic causes of ileus are common:
          • Hypokalemia
          • Hyponatremia
          • Hypomagnesemia
        • Other metabolic causes include:
          • Uremia
          • Diabetes
          • Hypoparathyroidism
        • Miscellaneous causes
          • Scleroderma
          • Amyloidosis
    • Spastic ileus is related to hypermotility where uncoordinated peristalsis fails to push contents through.
    • Ischemic ileus is related to vascular occlusion & infarction of the myoelectric components.
  • Obstruction is the physical barrier to movement of bowel contents. In general, the 3 categories include:
    • Extraluminal causes
      • Adhesions
      • Hernias
      • Carcinomas
      • Abscesses
    • Lesions intrinsic to the bowel wall
      • Primary tumors
      • Inflammatory bowel disease (Crohn’s disease)
    • Intraluminal causes
      • Gallstones
      • Enteroliths
      • Foreign bodies
      • Bezoars
    • 80% of bowel obstruction involves the small bowel; the most common etiologies are:
      • Postop adhesions (65-80%); pelvic procedures, specifically gynecologic, appendectomy & colorectal resection, account for 60% of obstructions due to adhesions
      • Hernia (15-25%)
        • Ventral hernia is the most common.
        • Inguinal & internal hernias are common.
        • Less common are femoral, obturator, lumbar & sciatic.
      • Tumors (10-15%)
        • The majority are metastatic lesions that implant through hematogenous spread to the peritoneum.
        • Large intra-abdominal tumors can cause obstruction from extraluminal compression.
        • Obstructing primary small bowel tumors are rare.
      • Crohn’s disease (5%) is the 4th leading cause of small bowel obstruction.
        • Inflammation & edema that resolves w/ nonoperative mgt
        • Stricture that may require resection & reanastomosis or stricturoplasty
      • Abscess can cause obstruction by involving a portion of the intestinal wall, by adhesion or as a result of localized ileus & functional obstruction. Common etiologies include:
        • Ruptured appendix
        • Diverticulitis
        • Dehiscence of abdominal anastomosis
      • Miscellaneous other etiologies include:
        • Intussusception, more common in children; in adults is usually associated w/ a lead point such as a polyp, tumor or Meckel’s diverticulum
        • Enteroliths from jejunal diverticula
        • Foreign bodies
        • Phytobezoars
    • 20% of obstructions involve the colon; the most common etiologies include:
      • Cancer (60%)
      • Diverticulitis (15%)
      • Volvulus (15%)

If obstruction is present, the second step is to determine whether & how urgently surgical intervention is needed.

  • Only about 20% of partial obstructions will require surgical intervention, which can usually be done on a semi-elective (planned) basis.
  • Complete obstruction almost always requires surgical intervention, usually on an emergency basis.
  • The vast majority of obstructions are classified as simple, implying an intact blood supply (ie, gallstone ileus).
  • Strangulated obstruction implies mesenteric vessel occlusion & is associated w/ a higher morbidity & mortality; therefore, early recognition is important.
  • Closed loop obstruction involves occlusion of both afferent & efferent limbs of bowel & is especially dangerous because of rapid progression to strangulation & perforation even before clinical evidence of obstruction. The following closed loop obstructions require emergent surgical intervention if bowel resection is to be avoided:
    • Volvulus
    • Incarcerated ventral hernia
    • Congenital bands
    • Adhesions
    • Malrotation
    • Internal hernia

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Last updated: May 2, 2010