An emergency colonoscopy, also called an urgent or emergent endoscopy, is a specialized procedure used for the immediate assessment of the large intestine. It uses a long, flexible tube (colonoscope) inserted through the rectum to provide a visual examination of the colon lining. Unlike routine screenings, the emergency version is reserved for acute medical situations where a delay could lead to severe health consequences. This rapid diagnostic and therapeutic tool allows medical teams to intervene quickly.
Conditions that Demand Immediate Intervention
The need for an emergency colonoscopy is driven by acute, potentially life-threatening lower gastrointestinal issues requiring rapid diagnosis and intervention. The most common indication is acute lower gastrointestinal bleeding (LGIB), where a patient is losing a significant amount of blood, often presenting as bright red or maroon stools. The procedure locates the exact source of the hemorrhage, which is crucial for stabilization and determining the next steps of care.
Another urgent situation is acute colonic obstruction, where a mass or severe narrowing prevents the passage of stool and gas. The procedure diagnoses the cause of the blockage, such as a tumor, and may relieve the obstruction through decompression or temporary stent placement. Emergency procedures are also necessary for the urgent removal of a foreign body lodged in the colon or rectum, preventing complications like perforation or continued bleeding.
The Challenge of Emergency Bowel Preparation
The primary logistical hurdle distinguishing an emergency colonoscopy from an elective one is the lack of time for standard bowel cleansing, which usually takes 24 to 48 hours. Adequate preparation is necessary to ensure clear visualization of the colon lining, but an urgent timeline makes this impossible. The presence of residual stool, blood clots, or other debris can severely compromise the endoscopist’s view, significantly reducing the diagnostic yield and increasing the procedure’s duration.
Medical teams employ accelerated preparation protocols, such as a rapid purge using large volumes of polyethylene glycol (PEG) solution, sometimes averaging 5.5 liters, administered over just a few hours. In cases of massive bleeding, a quicker approach involves a hydroflush technique, where multiple one-liter tap water enemas are administered to clear the lower colon. If the patient is vomiting, the PEG solution may be delivered through a nasogastric tube.
Newer, low-volume preparations, such as one-liter PEG-Ascorbate solutions, are also utilized for faster and more tolerable cleansing in critically ill patients. During the procedure itself, the endoscopist uses specialized techniques like the water immersion method. Here, the colon is continuously flushed with water or saline through the scope’s channel, helping to dislodge remaining material and clear blood clots for a better view.
Procedural Adaptations and Heightened Risks
Performing a colonoscopy in an emergency setting requires significant procedural adaptations and carries a heightened risk profile. The procedure is frequently conducted in a hospital setting, such as an Intensive Care Unit or an operating room, rather than a standard outpatient suite. This is necessary due to the need for advanced monitoring and immediate access to surgical support. Patients are often hemodynamically unstable, requiring continuous monitoring by an anesthesiologist.
One of the most significant risks is bowel perforation, a tear in the colon wall, which is reported to be substantially increased in emergency procedures, with some data suggesting a four-fold increase in risk compared to elective cases. The risk is compounded by the underlying inflammatory state or obstruction that necessitated the procedure.
Another concern is aspiration pneumonia, which is elevated because the patient often has not followed the required fasting protocol due to the urgency of their condition. The use of deep sedation or general anesthesia, often required for unstable patients, further increases the risk of aspiration because protective airway reflexes are suppressed. Endoscopists may use specialized colonoscopes with larger suction channels to clear the field of vision more effectively, allowing a quick transition from diagnosis to therapeutic intervention.
Immediate Treatment Decisions Following the Scope
The primary objective of an emergency colonoscopy is to fix the problem immediately, making it a combined diagnostic and therapeutic procedure. Once the source of acute bleeding is identified, the medical team initiates immediate hemostasis. This is often achieved using endoscopic clips, thermal cauterization, or injections of epinephrine to constrict the blood vessels. This action can be life-saving and may prevent the need for emergency surgery.
If the procedure was performed for acute colonic obstruction, the next decision often involves placing a self-expanding metallic stent (SEMS) to bypass the blockage. Stenting immediately relieves symptoms and serves as a bridge to surgery, allowing the patient to stabilize before a definitive operation. If the scope reveals a non-endoscopically repairable complication, such as a perforation or a massive tumor, the patient is immediately transitioned to the surgical team.