In recent years, with the continuous advancement of digestive endoscopy techniques, how to improve the adenoma detection rate (ADR) by optimizing endoscopic procedural details has become a research hotspot. Colonic spasm can lead to narrowing of the intestinal lumen, deepening of mucosal folds, and limited field of view, thereby affecting lesion exposure and reducing examination quality. Although traditional intravenous antispasmodic drugs (such as scopolamine) can alleviate intestinal spasms, they may cause side effects such as increased heart rate, blood pressure fluctuations, and other systemic adverse reactions. In contrast, menthol is a natural monoterpene compound derived from peppermint oil. It can inhibit L-type calcium channels on the cell membrane of smooth muscle through local application, thereby reducing intracellular calcium concentration and inducing smooth muscle relaxation. This helps to relieve intestinal spasms and patient discomfort during colonoscopy. On the other hand, simethicone, a commonly used defoaming agent, can reduce surface tension, eliminate foam, and improve mucosal visualization. Theoretically, combining antispasmodic menthol with defoaming simethicone may further optimize the visual field during colonoscopy and increase the ADR through a synergistic "antispasmodic + defoaming" mechanism. Therefore, this study plans to conduct a prospective randomized controlled trial to evaluate the antispasmodic effect, safety, and impact on the ADR of a novel irrigation solution (0.1% menthol combined with simethicone suspension) in colonoscopy, providing evidence-based medical support for optimizing endoscopic procedures.

Inclusion Criteria:

1. Age between 18 and 75 years, regardless of gender;
2. Scheduled to undergo colonoscopy (for screening, diagnostic, or follow-up purposes);
3. Adequate bowel preparation quality (Boston Bowel Preparation Scale score ≥ 6);
4. Voluntarily signed informed consent and able to cooperate with completing study-related assessments.

Exclusion Criteria:

1. Allergy to menthol, cyclodextrin, or related substances;
2. History of severe intestinal diseases (such as ulcerative colitis, Crohn's disease, intestinal perforation, intestinal obstruction, intestinal tumors, etc.);
3. Presence of severe dysfunction of vital organs such as the heart, liver, kidneys, or lungs, or coagulation disorders;
4. Pregnant or lactating women;
5. Use of anticholinergic drugs, calcium channel blockers, or other spasmolytic agents within one week prior to the examination;
6. Psychiatric disorders or cognitive impairment that prevent cooperation with the study;
7. History of contraindications to colonoscopy or serious adverse reactions during previous procedures.