| Presentation | |
| Elderly patient seen 6 years ago for what appeared to be resolving haemorrhoidal bleed … 6 months prior [to the most recent visit] described narrow stools like a snake … [At the present visit] bowel frequency and some bleeding with examination of clear external piles no rectal masses on rectal examination. [Also] did some bloods but wasn't anaemic | System 1 dominance may explain the high threshold for vigilance in this age group |
| [I ignored] the older the patient the lower the threshold for colorectal cancer that we would have for referring … red flag that's there for a reason therefore it would be foolish to sort of dismiss… | No significant attempt to rule out and normal Hb wrongly used for rule out. Another example of the power of a perceived label in biasing process |
| Salience | |
| External piles with a normal PR … [6 years ago] with haemorrhoides seen by a colleague. | Salient feature was a normal examination 6 years earlier |
| Outcome | |
| 2 months after last visit … change in bowel habit with rectal bleeding and as part of investigation had a sigmoidoscopy and biopsy which found a malignant colonic tumour | Delay in diagnosis likely to System1 overpowering System 2, raising closure threshold |
| Summary | |
| System 1 single diagnosis based on the label immediately jumps to the diagnosis. Ignored expected natural history, and the presence of a red flag. Diagnosis was delayed until a new critical cue emerged. |