Acute Colonic Pseudo-Obstruction (ACPO), more commonly referred to as Ogilvie Syndrome, is a rare, acquired and potentially life-threatening condition that is characterized by sudden and severe colon dilatation without any structural or mechanical obstruction. This means that although the colon appears to obstruct, there is no actual obstruction. Signs and symptoms that closely resemble those of intestinal obstruction occur because the colon is functioning as if there was obstruction.

Ogilvie Syndrome was first discovered in 1948 by British surgeon Sir William Heneage Ogilvie and occurs predominantly in hospitalized or geriatric patients recovering from critical illness, trauma or surgery. This syndrome is classified as a functional obstruction because of the impaired autonomic nerves, and impaired smooth muscle responsible for peristalsis, or the rhythmic contractions of the intestine, to move contents through the colon.

Should Ogilvie Syndrome not be recognized or treated promptly, it can progress to bowel ischemia, perforation, sepsis and even death; however, with prompt medical management, the majority of patients will completely recover without any long-term sequelae.

The exact cause of Ogilvie Syndrome is not always clear understood. Although Ogilvie Syndrome is said to occur because of disruption of the autonomic nervous system, and even more specifically the loss of parasympathetic nerve activity and increased sympathetic stimulation to the colon, this disruption will cause decreased motility of the colon and produce a large amount of gas and feces, and eventually an abnormal dilation of the colon in the absence of an obstruction.

There have been multiple associating factors:

1. Surgical Procedures: Ogilvie Syndrome frequently occurs after a major surgical procedure. Major surgical procedures associated with Ogilvie’s Syndrome include:
   • Orthopedic surgeries (especially hip replacements)
   • Abdominal surgeries
   • Cesarean sections
   • Neurologic surgeries
   • Cesarean section and hip surgery are the most frequent surgeries associated with acute colonic pseudo-obstruction. Numerous postoperative factors can contribute to this process such as immobility, anesthesia, opioid use and altered autonomic tone.
2. Medications: Certain medications known to affect bowel motility may trigger or worsen Ogilvie Syndrome. These include:
   • Opiates (e.g., morphine, hydromorphone)
   • Anticholinergic
   • Calcium channel blockers
   • Tricyclic antidepressants
   • Phenothiazines
   • These drugs interfere with normal autonomic regulation of the bowel, often slowing or halting peristalsis.
3. Medical Conditions: There are many acute and chronic medical conditions that may predispose patients to colonic pseudo-obstruction, including:
   • Neurological disorders, such as Parkinsonism, multiple sclerosis, or stroke
   • Metabolic disorders, such as diabetes mellitus, uremia, and hypothyroidism
   • Severe infections, such as pneumonia or sepsis
   • Cardiac events, such as myocardial infarction or congestive heart failure
   • These conditions may create disturbances in an individual’s autonomic function, delay bowel motility or cause a systemic response, leading to colonic dilation.
4. Electrolyte Disturbances: Electrolytes are critical for neuromuscular function. Abnormally high or low levels of potassium, magnesium, or calcium, will alter activity in smooth muscle, thus affecting bowel function. In general, the most common electrolyte disturbances that contribute to bowel dysfunction include:
   • Hypokalemia
   • Hypomagnesemia
   • Hypocalcemia
   • These disturbances are primarily seen in critically ill patients or patients receiving certain medications or IV fluids that can contribute to alterations in electrolytes.
5. Severe Illness or Trauma: Patients who are critically ill or recovering from major trauma, particularly constraints involving the head or spinal cord, are also more likely. The stress response, immobility, and loss of normal autonomic regulation can lead to Ogilvie Syndrome.
6. Other Contributing Factors: Older age is an important risk factor, because the elderly frequently demonstrate lower baseline colonic motility and may receive medications that affect bowel function. 
7. Pregnancy: Pregnancy, particularly during the third trimester or postpartum period, is a known risk factor for Ogilvie Syndrome. Several factors may contribute to this increased risk:
   • Dietary changes, including constipation from increased iron supplementation
   • Prolonged gastrointestinal transit time
   • Elevated progesterone levels, which relax smooth muscle
   • Reduced physical activity

Ogilvie syndrome is neither infectious nor inherited. You cannot catch it from another person, and you cannot inherit it from another person. It mainly occurs as a secondary complication of disease, surgical event or any procedure that alters the colon’s ability to move stool. 

Ogilvie syndrome itself is not a primary disease; rather it occurs when the colon loses its peristaltic activity, often because of a dysfunction in the autonomic nervous system, medication side effects, or a systemic illness. There is abnormal dilation of the colon without the presence of an obstruction. You may be at increased risk for Ogilvie Syndrome if any of the following apply:

• You are hospitalized, especially in an intensive care unit (ICU).
• You have undergone major surgery, particularly abdominal, pelvic, orthopedic or neurologic procedures.
• You are taking medications that slow bowel motility, such as opioids or anticholinergics.
• You have a neurological condition, such as Parkinson’s disease, multiple sclerosis or a spinal cord injury.
• You have a metabolic or systemic illness, such as diabetes, uremia or hypothyroidism.
• You are physically inactive, immobile or confined to bed for extended periods.
• You have an electrolyte imbalance, especially low potassium levels (hypokalemia).

It is imperative to realize that any condition that affects the regulation of colonic movement (e.g., nerve cell dysfunction, systemic disease, medication use), has the potential to lead to Ogilvie Syndrome. For this reason, Ogilvie Syndrome is more frequently seen in elderly individuals who often have multiple concurrent medical problems and are at a higher risk for the factors in the hospital setting.

Ogilvie Syndrome symptoms are similar to the symptoms of a mechanical bowel obstruction, which makes the diagnosis difficult. As gas and partially digested foods build up in the colon due to impaired motility, the following symptoms develop:

• Abdominal Distention (Hyper-resonant): This may be the earliest and prominent symptom. It can appear welling, tense and firm on palpation. On percussion, the abdomen may be hyper-resonant, due to gas.
• Abdominal Pain or Discomfort: Usually classified as mild to moderate and crampy. Severe or constant pain may signal complications such as bowel ischemia or perforation and warrant urgent evaluation. 
• Nausea and Vomiting: More likely to be present in late stages, especially if the colon is severely distended. In extreme cases vomiting, may include bile or fecal material.
• Constipation or Obstipation: Patients may report an inability to pass either stool or gas. This is a result of profoundly decreased colonic motility without an obvious, mechanical obstruction.
• Decreased or Absent Bowel Sounds: A physical examination may reveal decreased or absent bowel sounds, indicating a functional stop in colon peristalsis, with or without any signs of acute abdomen.
• Systemic Symptoms in Patients with Complications: Fever, tachycardia, and hypotension are late warning signs. Symptoms suggest complications and/or presence of significant complications:
  • Bowel ischemia (loss of blood supply to the colon)
  • Perforation (hole in bowel)
  • Sepsis (life-threatening systemic infection)

When not addressed, Ogilvie Syndrome can cause the following complications that may be serious or deadly:

Colonic perforation: The excessive dilation (in particular of the cecum) may stretch the bowel wall to the point of perforation. 

Bowel necrosis: Damage to the tissue from absent blood supply may cause the tissue to die.

Peritonitis: Inflammation of the peritoneum from leaking intestinal contents into the abdominal cavity.

Sepsis: A systemic infection can rapidly turn fatal without emergency treatment.

Electrolyte Imbalance and Hypovolemia: Larger amounts of fluid may collect in the distended colon, leading to loss of fluid, hypovolemia, dehydration, and electrolyte derangements.

Recognizing these signs of Ogilvie Syndrome and referring patients for medical intervention in a timely manner is necessary to avoid the risk of potentially fatal complications.

Timely and correct diagnosis allows for appropriate treatment, which reduces the risk of complications.

The major diagnostic dilemma is distinguishing Ogilvie Syndrome from a mechanical bowel obstruction.

1. Clinical history and physical examination:

A thorough past medical and surgical history, current medications, comorbidities, is required.

Examination of the abdomen includes examining for distension, bowel sounds, tenderness and signs of peritonitis.

2. Imaging Studies:

• Abdominal X-ray Bedside or Emergency Department Care: Bedside or emergency department care can obtain an abdominal x-ray that will show colonic distention, commonly in the cecum and ascending colon. No air-fluid levels or obstructing masses may suggest a mechanical obstruction. 
• CT scan of the abdomen and pelvis OR MRI abdomen and pelvis: The imaging study that tells you are you are definitively acutely constipated is a CT scan of the abdomen and pelvis as it will brook no doubt. The CT scan of the abdomen and pelvis rules out mechanical obstruction, ischemia, or perforation of any part of the colon. The CT scan of abdomen and pelvis may reveal colonic dilation > 10–12 cm. 
• Water-soluble Contrast Enema: A water-soluble contrast enema can help rule out large bowel obstruction (potentially from a tumor), and may in some instances have a therapeutic effect by enhancing colonic motility. 

3. Laboratory Test: Typical lab work includes: 

• Lactate, (lactate > 2 may indicate ischemia).
• Electrolytes
• Renal
• CBC, to look for infection or anemia

Ogilvie Syndrome is managed with a combination of conservative treatment, medications, and if indicated endoscopic or surgical intervention, depending on the severity of the Ogilvie Syndrome and the patient’s overall status.

1. Conservative treatment (Supportive Treatment):
   • Conservative treatment is the first line for stable patients who show no signs of ischemia or perforation. Conservative measures in the management of Ogilvie Syndrome include:
     • Treat the underlying cause. This may include managing infections, recent surgery, and immobility.NPO (Nothing per Oral). This will rest the bowel and decrease its workload.Nasogastric Tube. In the case of vomiting or significant distention, a nasogastric tube may be installed for decompression.Rectal Tube. A rectal tube is installed to relieve gas and lessen colonic pressure.Intravenous (IV) fluids and electrolyte replacement. Use only if the patient is dehydrated or has an electrolyte imbalance.
     • Discontinue offending medications. It is particularly important to discontinue narcotic agents, anticholinergic agents, and other drugs that slow motility.
     • Early mobilization. In order to encourage bowel movement and improved gastrointestinal motility.
     • Monitoring. Frequent abdominal exams, imaging, and laboratory testing are beneficial as they monitor progress but they are also helpful for complication management.
2. Pharmacologic Therapy:
   • Neostigmine: A cholinesterase inhibitor that increases parasympathetic activity, promoting colonic activity.
     • Administered via slow IV infusion, usually in a monitored environment, as there is some risk for bradycardia and hypotension. High success rate (greater than 90%) in appropriate patient management.
     • Cardiac monitoring is required with usage.
3. Endoscopic Decompression: Consider if there is no response to conservative and pharmacologic therapy, or with significant colonic distension. A flexiglescope can be employed to relieve trapped gas to decompress the colon.
   • In select cases, a decompression tube might be left in, to lessen the risk of persistence. This offers rapid relief, and we might be able to prevent him from needing a subsequent surgery.
4. Surgical Intervention: Surgical intervention is most appropriate with individuals who show evidence of significant complication, including: bowel perforation, peritonitis, ischemia, and failure of conservative and endoscopy.
   • Surgical options include:
     • Cecostomy (surgically creating a diversion or ostomy in the cecum for decompression to occur)
     • Segmental Colectomy (surgically remove the affected/diverted portion of bowel)
     • Colostomy (as appropriate, with extended bowel injury)

Surgery has a greater risk in older or critically ill patients, and should be circumspectly considered.

Acute colonic pseudo-obstruction (also known as Ogilvie Syndrome) is a real complication that can arise in sick people. Occasionally it occurs in patients with comorbidities, which can complicate management. Ogilvie syndrome is typically seen in elderly, hospitalized and/or post-operative patients and is due to loss of autonomic control or coordination of colonic motility.

Recognition through assessment of potential precipitating factors, clinical assessment, and imaging are key to prevent potentially life-threatening complications such as perforation, sepsis, and death. Often a conservative approach can be successful if established early. Neostigmine therapy, endoscopic decompression, or perhaps surgery for more advanced or refractory cases.

Improving awareness and the recognition of risk factors, early symptoms, and treatment will go a long way to improving outcomes for our patients. As awareness of the condition improves in the healthcare community the majority of morbidity and mortality associated with Ogilvie Syndrome are due to delayed recognition and treatment.

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• UpToDate. (2024). Acute colonic pseudo-obstruction (Ogilvie’s syndrome). In B. E. Lacy (Ed.), UpToDate.