The Incidence of 30-Day Adverse Events After Colonoscopy Among Outpatients in the Netherlands

Vincent de Jonge, BSc; Jerome Sint Nicolaas, BSc; Onno van Baalen, MD; Johannes T. Brouwer MD, PhD; Mark F.J. Stolk, MD, PhD; Thjon J. Tang, MD, PhD; Antonie J.P. van Tilburg, MD, PhD; Monique E. van Leerdam, MD, PhD; Ernst J. Kuipers MD, PhD


Am J Gastroenterol. 2012;107(6):878-884. 

In This Article


During the study period, 1,528 out of 1,800 patients (84.9%) gave permission in the pre-procedure questionnaire to be called 30 days after the procedure for the adverse event registration. A total of 1,144 persons (response rate: 74.9%) were successfully contacted and included in the study cohort. The number of patients included per endoscopy department ranged from 4.4 to 11.3% (mean: 9.0%). Patients were contacted after a mean of 32 days (s.d.: 4). Table 1 shows the characteristics of the final study cohort. No differences were found between the responders and non-responders.

Direct complications, extracted from the colonoscopy reports, were (minor) bleeding in nine patients (0.8%), hypoxia in two patients (0.2%), and bradycardia in two patients (0.2%).

Major Adverse Events

Table 2 shows the reported major adverse events in the 30 days after colonoscopy and the range between the participating departments. No mortality was observed in this study cohort. Definite-related major adverse events were reported by nine patients (0.8%), while another six patients had possible-related adverse events (0.5%). All patients with major definite-related events had received conscious sedation and had undergone a complete colonoscopy.

Patients who reported any major adverse event (n=34) were seen at the emergency department or admitted to the hospital for a median of 3.9 days (interquartile range: 1.0–5.5 days). Patients who reported definite-related major adverse events were admitted for a median of 4.0 days (interquartile range: 1.0–2.5).

Minor Adverse Events

Table 3 shows the reported minor adverse events in the 30 days after colonoscopy and the range between the participating departments. A total of 336 patients (29.4%) experienced definite-related minor adverse events, 36 patients (3.1%) had possible-related minor adverse events. Most common definite-related minor adverse events were abdominal discomfort (n=195, 17.0%), rectal blood loss (n=64, 5.6%), and change in bowel habits (n=62, 5.4%).

Of the patients who reported abdominal discomfort, 73 patients (37.4%) reported that abdominal discomfort had been absent before the procedure, 100 patients (51.3%) said that their complaints of discomfort was worse than before, and 12 patients (6.2%) said that they had less discomfort than before the colonoscopy. Forty-two patients (21.5%) scored their pain as severe, while the other 153 patients (78.5%) reported mild-to-moderate pain. Patients reported that the abdominal discomfort persisted for a median of 2.0 days (interquartile range: 1.0–4.0 days).

Of the patients who reported rectal blood loss at home, five patients (7.8%) reported much blood loss and 59 patients (92.2%) reported little blood loss. Blood loss was reported for a median of 1.0 day (interquartile range: 1.0–3.0).

Of all patients who were not retired (n=749), 64.1% went to work the day after the procedure, 24.8% missed 1 extra day from work, 4.1% 2 days, and 6.9% ≥ 3 days (mean: 1.4 days). Among the patients who were not retired and who reported definite-related minor adverse event (n=226), 59.1% went to work the day after the procedure (P=0.15), 26.1% missed 1 day from work, 5.9% 2 days, and 8.8% ≥ 3 days.

Predictors of Adverse Events

Table 4 shows the predictors of the occurrence of any adverse event. Any definite-related adverse event was significantly more often reported by female patients (odds ratio (OR): 1.5, 95% confidence interval (CI): 1.1–2.0), patients who were <50 years of age (OR: 1.5, 95% CI: 1.1–2.1), when the colonoscopy was performed for colorectal cancer screening or surveillance (OR: 1.5, 95% CI: 1.2–2.2) and when the colonoscopy was performed by a fellow (OR: 1.7, 95% CI: 1.2–2.5).


The colonoscopy was more often perceived as more discomforting than expected by patients who reported definite-related adverse events compared with patients who did not experience definite-related adverse events (59.4 vs. 70.5%, P<0.01). Furthermore, patients with definite-related adverse events found the colonoscopy less often comfortable (40.0 vs. 51.1%, P<0.01), and less often acceptable (60.9 vs. 76.7%, P<0.001), compared with patients who were free of adverse events.

Patients who had experienced any definite-related adverse event were also less willing to return for colonoscopy (80.6 vs. 87.6%, P<0.01) and were less often positive about the entire colonoscopy experience (83.9 vs. 88.9%, P=0.04). These results were the same when only minor adverse events were taken into account.


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