Emergency Medicine

Ogilvie's Syndrome

First described more than 50 years ago, Ogilvie's syndrome of acute colonic pseudo-obstruction remains diagnostically elusive and clinically frustrating. The authors discuss how to recognize the condition, assess the patient, and choose the intervention most likely to achieve decompression without undue risk.

By R. Michael S. Mitchell, MB, BCh, MRCP, and Michael F. Byrne, MD, MA, MRCP

What is Ogilvie's syndrome?

Intestinal pseudo-obstruction, or Ogilvie's syndrome, is characterized by massive dilatation of the colon in the absence of demonstrable intestinal obstruction. It was initially described in 1948 by Sir William Ogilvie, who reported two patients with abdominal pain, constipation, and colonic distension due to invasion and destruction of the splanchnic nerves, superior mesenteric ganglion, and celiac nerve plexus by a retroperitoneal malignancy. Despite numerous subsequent clinical reports and accurate characterization of the syndrome, Ogilvie's syndrome remains difficult to diagnose and is still associated with significant morbidity and mortality.

Who is at risk for Ogilvie's syndrome?

Ogilvie's syndrome typically occurs in patients who are already hospitalized with serious illnesses. Many and varied possible etiologies have been described, including stroke, myocardial infarction, retroperitoneal neoplasia, metabolic disturbances (including hypokalemia, hypocalcemia, and hypomagnesemia), trauma, peritonitis, and sepsis. It may also develop after surgery, especially orthopedic, thoracic, or cesarean section procedures. Occasionally, systemic diseases that affect gastrointestinal neuromuscular function, such as amyloidosis, may present with acute pseudo-obstruction, although chronic intestinal pseudo-obstruction is more characteristic of these disorders. Drugs, including antidepressants, phenothiazines, antiparkinsonian agents, and narcotics, may cause or exacerbate the condition.

What is the pathophysiologic basis of Ogilvie's syndrome?

The sequence of events in Ogilvie's syndrome includes an early impairment of peristalsis, most marked in the distal colon, accompanied by progressive proximal colonic dilatation that results in retention of large quantities of air and fluid in the intestine. The explanation proposed by Ogilvie in his original case series was destruction of the distal colon's sympathetic nerve supply, with consequent unopposed parasympathetic activity causing spasticity of the distal colon and progressive dilatation of the colon proximal to this area of relative obstruction. There is also evidence that a transient impairment of lumbar nerve parasympathetic innervation may cause the colon distal to the splenic flexure to become atonic in some cases, thus leading to a functional distal obstruction. Finally, patients with Ogilvie's syndrome have demonstrable sympathetic overstimulation, as seen in such signs as tachycardia and sweating. This may be the result of a positive feedback loop involving colo-colonic sympathetic reflexes that are then responsible for maintaining colonic dilatation by impairing colonic motility.

How does Ogilvie's syndrome present clinically?

The characteristic feature is severe abdominal distension, which differentiates it from, for example, a postoperative ileus in which there is minimal abdominal distension. Passage of stool or gas is usually absent, but may still occur in up to 40% of patients. Some patients may experience diarrhea. Nausea or vomiting may be present but are not constant features. Bowel sounds may be absent, normal, or hyperactive and are generally not useful for diagnostic purposes. Although abdominal discomfort is common, severe pain or tenderness is unusual and may indicate ischemia or perforation. Frequent clinical assessment, serial abdominal radiographs, and white cell counts should detect these complications early.

What tests are useful for diagnosing Ogilvie's syndrome?

There are no specific laboratory tests that are helpful for diagnosing Ogilvie's syndrome. Serial measurements of serum electrolytes and white cell counts are useful for detecting severe complications, such as intestinal ischemia or perforation.

Plain abdominal x-rays demonstrate massive colonic dilatation and are essential for monitoring the progress of the condition. Cecal diameter has been shown to have prognostic significance: massive dilatation can occur and cecal diameters of up to 25 cm have been reported. Abdominal films are not sufficient by themselves to exclude obstruction unless there is air in the rectosigmoid colon, but pneumatosis intestinalis and free peritoneal air can be readily identified.

Single contrast barium or gastrograffin contrast examinations are excellent for excluding intestinal obstruction and should be performed, providing perforation has been ruled out first. The perforation rate for contrast imaging in Ogilvie's syndrome is around 1%, and air insufflation should be avoided if possible. Contrast enemas may also be occasionally therapeutic. Computed tomography is an acceptable alternative to barium examinations. Colonoscopy can also exclude obstruction, but great care should be taken with insufflation to avoid both local and remote (pneumatic) perforation.

What is the initial management for Ogilvie's syndrome?

Once obstruction and perforation have been excluded, the management strategy is initially conservative and includes nasogastric decompression, withdrawal of drugs that may worsen the condition such as opiates or anticholinergics, correction of fluid and electrolyte disturbances, and treatment of the underlying cause and comorbid conditions. Placement of a rectal flatus tube may be of benefit, and the patient should be turned regularly to facilitate passage of gas, particularly onto the right lateral position. If these measures are not successful after 48 to 72 hours, if the cecal diameter is greater than 12 cm, or if the patient has developed right iliac fossa tenderness, then other options need to be considered. These include pharmacologic or endoscopic decompression, percutaneous cecostomy, or surgery. The development of peritoneal signs is an indication for surgery.

How effective is pharmacologic decompression?

Acetylcholinesterase inhibitors, such as neostigmine, increase acetylcholine concentrations at the enteric nervous system neuromuscular junctions, enabling smooth muscle to contract. Neostigmine may be expected, therefore, to improve intestinal contractility and facilitate expulsion of gas in Ogilvie's syndrome. There have been two randomized controlled trials (RCTs) and several open-label trials comparing intravenous neostigmine with placebo for acute colonic pseudo-obstruction. Neostigmine is given as an intravenous bolus of 2 to 2.5 mg over 1 to 5 minutes or as an intravenous infusion of 0.4 mg/h for 24 hours. Due to the potential side effects, the patient should undergo cardiac monitoring, and atropine should be available for immediate use if profound bradycardia occurs. Rates of effectiveness in the RCTs of neostigmine were 73% and 79%; in the uncontrolled studies, response was somewhat better.

In the absence of contraindications, neostigmine should be considered the next line of treatment if the cecal diameter remains greater than 12 cm for several hours. After a bolus of neostigmine, gas, stool, or both are usually passed within an hour and often much more quickly. A second dosage may be given if necessary. Despite its relative efficacy, a reduction in the risk of perforation and mortality has not been demonstrated for this drug. Side effects of neostigmine include sweating, salivation, bradycardia, hypotension, abdominal pain, vomiting, and bronchospasm. The elimination of neostigmine is impaired in the presence of significant renal compromise.

Neostigmine is contraindicated by mechanical obstruction, perforation, baseline heart rate less than 60, systolic blood pressure less than 90 mm Hg, bronchospasm, serum creatinine less than 3 mg/L, acidosis, recent myocardial infarction, or recent use of beta blockers.

Are there other pharmacologic therapies that are of benefit?

There is some evidence that peripherally restricted opioid antagonists, such as alvimopan or methyl-naltrexone, may improve narcotic-induced postoperative ileus. The 5-HT4 receptor agonists, such as cisapride, tegaserod, and prucalopride, have been shown to be prokinetic in the colon, but only cisapride has been used in Ogilvie's syndrome, with mixed results. Erythromycin is a motilin receptor agonist that is known to be prokinetic in the stomach and small intestine, but it has only a marginal effect in the colon. Although there have been occasional case reports detailing its use, erythromycin does not currently have a place in the management of Ogilvie's syndrome.

What is the role of endoscopic decompression of the colon?

Endoscopic decompression of the colon relieves acute pseudo-obstruction in about 85% of patients but is associated with a perforation rate of up to 2%, and about 15% of patients may require a second colonoscopy because of recurrent dilatation. The reported overall morbidity and mortality of colonoscopy in this condition are 3% and 1%, respectively. These risks are related to the typically poor underlying condition of the patient and to the circumstance, common in this setting, of performing colonoscopy on an unprepared and possibly compromised bowel. Air insufflation must be kept to a minimum during the procedure to prevent further dilation. Complications of colonoscopy are higher in patients with a larger cecal diameter and in those in whom conservative measures have failed.

As long as the colonoscope is passed beyond the hepatic flexure, the colon can usually be successfully decompressed. A decompression tube should be inserted during colonoscopy and secured in place by taping the end of it to the patient's skin in order to facilitate continued passage of gas until the condition is completely resolved. Even with tube placement, colonoscopic decompression has not been shown to result in an improved outcome compared to conservative measures alone, and the overall mortality rate is unchanged at 10% to 20%.

What about surgical decompression?

Surgical decompression, including "blow hole" cecostomy, colostomy, or colonic resection, is associated with a poor outcome; the mortality rate of patients undergoing this kind of surgery approaches 30%. Indications for surgery include intestinal ischemia, perforation, peritonitis, and a failure of other measures to prevent increasing colonic dilatation. Unrelieved colonic dilatation can result in cecal ischemia and perforation, with high mortality. Percutaneous cecostomy performed by an interventional radiologist is a less invasive alternative than surgery if conservative measures and colonoscopy have been unsuccessful, but it still carries significant risk.

What is the prognosis for patients with Ogilvie's syndrome?

The prognosis varies with the underlying condition. Old age, multiple comorbidities, and surgical intervention for acute pseudo-obstruction are associated with a poor outcome. Intestinal ischemia or perforation occurs in approximately 15% of patients overall and is associated with a mortality rate of 50%. Generally, a cecal diameter of 12 cm is considered the threshold for high risk of perforation and necessitates intervention. This figure is based on data from mechanically obstructed colons, but also has gained widespread acceptance for pseudo-obstruction. In addition to cecal diameter, the duration of distension also appears to be an important factor in perforation risk, with risk lowest in patients who undergo decompression within less than four days of onset.