Colonoscopy is routinely implemented for colorectal cancer screening and the investigation of lower gastrointestinal symptoms. In the United States, the procedure is usually performed under sedation—typically moderate sedation with a benzodiazepine and opioid combination, or with propofol sedation. In other healthcare settings, colonoscopy may regularly be performed without sedation. A review of the literature reveals that colonoscopy without sedation or with on-demand sedation may be appropriate for a carefully selected subset of patients, while sedation confers measurable quality benefits for the broader population.
A landmark paper from 1999 published the results of a randomized controlled trial comparing colonoscopy with routine intravenous sedation with meperidine and midazolam against as-needed sedation in 70 patients willing to consider the procedure without medication1. In the as-needed arm, 94% of patients completed colonoscopy without any sedation, satisfaction scores approached those of the routinely sedated group, and all patients stated they would return to the same endoscopist.
Patients who avoided sedation also had fewer episodes of hypoxemia, less blood pressure decline, and lower procedural charges. Multivariate analysis identified male gender, older age, and absence of abdominal pain as independent predictors of willingness to attempt unsedated colonoscopy. Although these results are compelling, the trial’s limitations warrant acknowledgement: it was conducted by a single, highly experienced colonoscopist at a tertiary center, and the sample size was modest.
A later prospective study was conducted in California on 2,091 patients who were offered colonoscopy with or without sedation2. Of the 578 patients (27.6%) who chose to begin without medication, 81.1% completed the examination unsedated. 97.4% of unsedated patients expressed willingness to repeat the procedure without sedation, and intraprocedural adverse events were significantly fewer in the unsedated group (0.43% versus 6.67%). These findings demonstrate the feasibility of unsedated colonoscopy in a U.S. healthcare context. However, it is important to recognize that patients self-selected into the two research arms.
Other data reported significant drawbacks to colonoscopy without sedation3. Teruzzi et al. randomized 249 patients to routine sedation with midazolam and meperidine versus on-demand sedation. The proportion reporting moderate or severe pain was nearly three times higher in the on-demand group (34% versus 12.1%), and significantly more patients in that group stated they would refuse future colonoscopy (22% versus 9.7%). Critically, 66% of the on-demand group ultimately required sedation during the procedure, and their outcomes were no better than those who never received it. The authors argue that administering sedation reactively, after pain has already been perceived, does not rehabilitate the patient experience.
The large retrospective cohort study adds an important quality dimension to this debate—across 63,417 colonoscopies performed at a single institution, sedation was independently associated with higher adenoma detection rates (ADR: 22.5% versus 17.0%) and higher cecal intubation rates (CIR: 94.7% versus 91.2%), with these differences persisting after multivariate adjustment for patient age, gender, bowel preparation quality, and endoscopist experience4. The finding that sedation conferred quality benefits even for experienced endoscopists challenges the assumption that technical skill alone can fully compensate for the absence of pharmacological comfort.
Taken together, data suggest that colonoscopy without sedation is a viable and safe option in selected patients when performed by experienced endoscopists in appropriately equipped settings. However, for the majority of patients, sedation improves tolerance, supports procedural completion, and likely enhances adenoma detection.
References
- Rex, D. K., Imperiale, T. F. & Portish, V. Patients willing to try colonoscopy without sedation: associated clinical factors and results of a randomized controlled trial. Gastrointest. Endosc. 49, 554–559 (1999). https://doi.org/10.1016/S0016-5107(99)70381-0
- Petrini, J. L., Egan, J. V. & Hahn, W. V. Unsedated colonoscopy: patient characteristics and satisfaction in a community-based endoscopy unit. Gastrointest. Endosc. 69, 567–572 (2009). https://doi.org/10.1016/j.gie.2008.10.027
- Terruzzi, V., Meucci, G., Radaelli, F., Terreni, N. & Minoli, G. Routine versus “on demand” sedation and analgesia for colonoscopy: a prospective randomized controlled trial. Gastrointest. Endosc. 54, 169–174 (2001). https://doi.org/10.1067/mge.2001.113923
- Zhang, Q. et al. The impact of sedation on adenoma detection rate and cecal intubation rate in colonoscopy. Gastroenterol. Res. Pract. 2020, 3089094 (2020). https://doi.org/10.1155/2020/3089094
