Studies have estimated that cecal intubation failure occurs with conventional colonoscopy in about 10% of cases. Various methods have been adopted to improve the cecal intubation rate, including a transparent cap and special colonoscopes.

To assess the efficacy of using a cap-assisted gastroscope (E-cap) compared with a cap-assisted colonoscope (C-cap) for the complete examination of the colon in nonsedated patients with technically difficult sigmoid colons.

Randomized, controlled study.

Tertiary-care referral center.

One hundred thirty-nine patients with technically difficult sigmoid colons were studied.

Colonoscopy with either an E-cap (n = 69) or a C-cap (n = 70).

Cecal intubation rate, cecal intubation time, patient-assessed pain score, and endoscopist-assessed pain score.

The cecal intubation rate was significantly higher in the E-cap (65/69, 94.2%) than in the C-cap group (50/70, 71.4%; P < .0001). Patient-assessed pain (moderate to severe) was more frequently reported in the C-cap (14/70, 20.0%) than in the E-cap group (5/69, 7.2%; P = .029). Endoscopist-assessed pain (moderate to severe) was more frequently reported in the C-cap (13/70, 18.6%) than in the E-cap group (3/69, 7.2%; P = .009). For patients with a low body mass index (≤22 kg/m²), the cecal intubation rate was significantly higher in the E-cap (37/38, 97.4%) than in the C-cap group (15/29, 51.7%; P < .0001).

Single-center experience, lack of a gastroscope control group without a cap.

The cap-assisted gastroscope is more tolerable and effective than cap-assisted colonoscope for the complete examination of the colon in patients with technically difficult sigmoid colons. (Clinical trial registration number: KCT0000744.)