Matsushita 1998.

Methods	Generation of allocation sequence: randomisation was carried out using closed envelopes. Allocation concealment: not applicable as not blinded. Blinding: Unblinded. Inclusion of all randomised patients: All randomised patients were included in data analysis.
Participants	Number: 24 Age: 58.6 (42‐77) years Source: 24 patients with colorectal polyps detected at previous barium enema examination in Tenri Hospital, Nara, Japan. Inclusion criteria: Previous polyps detected at barium enema examination. Exclusion criteria: Previous abdominal or pelvic surgery, or if it was considered their general medical condition was poor.
Interventions	Tandem colonoscopies were carried out, randomly either first without a transparent cap (Obliclear, Top, Tokyo, Japan) and then with the cap (without‐to‐with) or first with the cap and then without (with‐to‐without) in the 24 patients. All patients were initially prepared with Polyethylene glycol solution and they received no pre‐medications. The Olympus CF2001 scope was used for all procedures. All polyps were removed whilst removing the colonoscope, intubation of the terminal ileum was attempted in all cases, as was retroflexion in the rectum.
Outcomes	Included in review: Caecal intubation rate, caecal intubation time, polyp detection rate. Excluded from review: polyp miss rate, retroflexion within rectum, and terminal ileal intubation rates.
Notes	Location: Department of gastroenterology, Tenri Hospital, Nara, Japan Source of funding: Not stated Attempts to clarify information: not required Language of Publication: English
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Closed envelopes
Allocation concealment (selection bias)	High risk	Not concealed as not blinded
Blinding (performance bias and detection bias) All outcomes	High risk	Unblinded
Incomplete outcome data (attrition bias) All outcomes	Low risk	None
Selective reporting (reporting bias)	Low risk	Appropriate outcomes assessed
Other bias	Unclear risk	Source of funding not stated