Pseudo-intestinal obstruction, or Ogilvie’s syndrome, refers to the presence of signs and symptoms of intestinal obstruction in a patient without associated organic lesions. Pseudo-intestinal obstruction of the colon is characterized by a markedly dilated cecum (>10 cm in diameter) and a markedly dilated right hemicolon on abdominal plain radiographs, and is a form of megacolon, sometimes called “acute megacolon” to distinguish it from toxic megacolon. Ogilvie’s syndrome can occur after surgery, especially after coronary artery bypass surgery and total joint replacement. Drugs that affect colonic dynamics can trigger the disease (e.g., anticholinergic drugs or opiate analgesics).
Etiology Pseudo-intestinal obstruction is often combined with other diseases and sometimes occurs after abdominal surgery. The incidence is higher in the elderly, and predisposing factors include disorders of electrolyte balance (potassium, sodium, phosphorus, calcium, magnesium, etc.), infections (e.g., EBV, cytomegalovirus), organ insufficiency (kidney, lung, heart, etc.), trauma such as surgery (e.g., after orthopedic joint replacement), malignancy (e.g., small cell carcinoma), and autoimmune diseases. Pseudo-intestinal obstruction is seen in almost every medical and surgical disease in the textbook.
Pathophysiology Pseudo-intestinal obstruction may be associated with myogenic or neurogenic disorders. decreased number of Cajal interstitial cells, increased nitric oxide synthase activity, alpha-actin deficiency, and autoimmune diseases are possible etiologies. In addition, impairment of intestinal electrophysiological activity as well as intestinal dysmotility can be caused by a variety of endogenous or exogenous substances, such as intestinal glucagon, glucagon, epinephrine, anticholinergic drugs and prostaglandins and vasoactive intestinal peptides.
Clinical manifestations The main clinical manifestations of patients are abdominal distension, which may be accompanied by abdominal pain or constipation, and in a few cases, diarrhea. Pseudo-intestinal obstruction is mostly seen in postoperative elderly patients and is often combined with other diseases. Symptoms will persist in most patients, except for a small proportion of patients with mild symptoms that may resolve on their own. Symptoms of distention can be very pronounced, and perforation of the cecum may occur in approximately 15% of patients.
Diagnosis The following diseases should be differentiated: congenital megacolon, toxic megacolon (caused by ulcerative colitis and Crohn’s disease), intestinal torsion, fecal obstruction, and distal intestinal obstructive lesions.
Pseudo-intestinal obstruction is diagnosed by imaging, and mechanical intestinal obstruction needs to be excluded to confirm the diagnosis. Endoscopy and imaging are very important, and care should be taken to avoid damage to the intestinal canal by hyperventilation during the examination. Clinically, water-soluble contrast enema should be considered when pseudo-intestinal obstruction is suspected, which has an important role in clarifying the presence or absence of mechanical intestinal obstruction. If there is no mechanical obstruction, colonoscopy should be performed to carefully observe whether there are lesions in the large intestinal mucosa and perform intestinal decompression at the same time.CT is of little value, but is still more often used clinically.
Treatment Conservative treatment For patients with pseudo-intestinal obstruction, drugs should be taken as the first choice of initial treatment and intestinal decompression should be performed. An anal tube may be placed, and decompression may be performed by transcolonoscopy when results are poor. Conservative treatment measures include nutritional support, fluid and electrolyte supplementation, inhibition of bacterial overgrowth in the intestinal lumen, and prokinetic agents to improve intestinal motility. In addition, treatment of specific conditions such as infections and management of primary conditions (e.g., endocrine disease). Placement of a nasogastric tube and discontinuation of medications that can cause constipation are recommended. After treatment by these measures, sometimes the patient’s symptoms can be relieved.
Medications Medications include anticholinergics, antibiotics, prokinetics, and growth inhibitor analogs. Intravenous neostigmine may provide rapid decompression by stimulating bowel movements, but care must be taken for possible complications, including cardiac arrhythmias. Antibiotics such as metronidazole or ciprofloxacin may reduce bacterial concentrations and decrease gas production, but have no significant effect on improving colonic motility. Certain antibiotics have prokinetic effects, such as erythromycin which can be used as a gastric actin antagonist. Cisapride can cause side effects such as cardiac arrhythmias and has been discontinued.
Surgery In patients with pseudo-intestinal obstruction, surgical treatment should be avoided unless absolutely necessary. Surgery should be considered only if the patient’s symptoms cannot be relieved after medical treatment or endoscopic decompression. The surgical option is either open or lumpectomy appendicostomy. Alternative treatment options are CT-guided percutaneous cecum stoma or endoscopic percutaneous cecum stoma. When the intestinal canal is ischemic or perforated, surgical resection and selective anastomosis of the intestinal canal are required.