• A colonoscopy is an endoscopic procedure performed with a fiberoptic camera to examine the colon, from the anus to the distal portion of the small bowel (e.g., terminal ileum).
• Colonoscopies are indicated for colorectal cancer screening, positive fecal occult blood, GI hemorrhage, removal or biopsy of small polyps, change in bowel habits (associated with inflammatory bowel disease or malignancy), or decompression (as with colonic pseudo-obstruction).
• Colonoscopies can be performed under topical anesthesia with or without conscious sedation (benzodiazepines and opioids) or deep sedation (typically propofol).

Lateral decubitus

15–45 minutes

None to minimal, unless associated with underlying condition (e.g., GI hemorrhage or coagulopathy).

• The majority of colonoscopies are outpatient procedures.
• for inpatients, the duration of the hospital stay depends on the underlying conditions.

• Endoscopic colonoscope
• Irrigation
• Suction
• India ink for tattooing polyp site

Incidence

• Incidence of colon cancer increases with age, beginning around 40 years of age, and is higher in men than in women (60.4 in men versus 40.9 in women, per 100,000, per year) (1).
• Propofol sedation is utilized in ~25% of routine endoscopic procedures, of which the majority are performed by anesthesia providers.
• In 2003, Medicare charges for code 00810 were $106 per case; this compared to an average of $400 per case from commercial insurers (2).
• In Medicare beneficiaries, the number of colonoscopy cases performed by anesthesia providers more than doubled between 2001 and 2003 to 700,000; this corresponded to $80,000,000 in charges (2).

Prevalence

The lifetime risk of being diagnosed with colorectal cancer is 5.9% for men and 5.5% for women. This amounts to ~145,290 new cases and 55,290 deaths annually.

• Colorectal cancer survival is correlated to the stage of the disease at the time of diagnosis. Approximately 65% of patients present with advanced disease.
• Colonoscopy is a low-risk surgical procedure, but it has the potential for perforation and bleeding.
• Anesthetic risks include those associated with sedation, allergies, and nausea.

• Colorectal cancer is the third most common cancer in both men and women and the third leading cause of cancer-related mortality in men and women in the US (3).
• Five-year survival for cancer limited to the bowel wall at the time of diagnosis approaches 90%. When lymph nodes were involved, the 5-year survival dropped to 35–60%; and in the presence of metastatic disease it became less than 10% (4).

History

• A full anesthetic evaluation is necessary; patients who present for anesthetic management often have significant comorbidities.
• Maintain a high index of suspicion for colon cancer in elderly patients that present with a change in bowel habits, a history of fatigue or weight loss, particularly if there is a strong family history of colorectal cancer.

Signs/Physical Exam

• A thorough airway exam is important in the event that the airway needs to be supported or secured.
• Auscultation of the heart and lungs at a minimum is necessary for each patient.

Labs/Studies

• Preoperative laboratory studies for routine screening and ambulatory cases are not typically needed. If available, however, they should be reviewed.
• for inpatients, a hemoglobin level, coagulation panel and electrolyte values may have already been obtained and should be reviewed; consider ordering if appropriate.

• Anxiolytics, analgesics as needed. Short acting medications (e.g. midazolam, fentanyl) should be utilized.
• GI prophylactic medications include acid reduction agents.

• Realistic sedation goals should be discussed, including the possibility of recall.
• If a patient has severe anemia, a blood transfusion may be necessary.

• Monitored anesthesia care (MAC) is commonly provided for screening and outpatient procedures using propofol; common adjuvants include midazolam and fentanyl. The goal is to maintain spontaneous ventilation.
• General anesthesia (GA). Despite maintaining spontaneous ventilation and not instrumenting the airway, some anesthetists consider the depth of "sedation" needed for a colonoscopy as falling under the criteria of a general anesthetic. Inpatients may need their airway secured with an endotracheal tube.

• Standard ASA monitors
• IV access

• MAC: Supplemental oxygen with nasal cannula or face mask. Titration of sedation can be performed with benzodiazepines, opioids, propofol, or ketamine.
• GA: Spontaneous ventilation, laryngeal mask airway, or endotracheal tube.

• Sedation is typically performed with IV medications and titrated to maintain spontaneous ventilation.
• Volatile agents may be administered via a face mask or an endotracheal tube.

• MAC and deep sedation: Re-orient the patient.
• GA with an endotracheal tube: Standard extubation criteria.