Research on the Efficacy and Mechanism of Shouhui Tongbian Capsules in Treating Postoperative Constipation of Benign Anal and Rectal Diseases Based on Gut Microbiota Analysis

• Shouhui Tongbian Capsules (Drug): Participants assigned to the Shouhui Tongbian Capsule group will receive routine postoperative care together with oral Shouhui Tongbian Capsule for 14 consecutive days. The dose will be two capsules per administration, three times daily, taken with warm water approximately 30 minutes after breakfast, lunch, and dinner. Each capsule contains 0.35 g of the approved marketed product. During the treatment period, other laxatives, probiotics, Chinese herbal medicines, or drugs that may affect intestinal motility or gut microbiota will generally be prohibited unless clinically necessary. Medication use, treatment adherence, drug dispensing, returns, adverse events, and any rescue treatment will be recorded throughout the study.
• Lactulose Oral Solution Control Group (Drug): Participants assigned to the lactulose group will receive routine postoperative care together with lactulose oral solution for 14 consecutive days. Lactulose will be administered orally at a dose of 15 mL once daily in the morning. Participants will receive both verbal and written instructions on the dose, administration method, and treatment schedule. During the study, other laxatives, probiotics, Chinese herbal medicines, or medications that may affect intestinal motility or gut microbiota will generally be prohibited unless clinically necessary. Treatment adherence, concomitant medications, adverse events, and any rescue treatment for severe constipation, pain, or postoperative discomfort will be recorded in the case report form.

Primary outcomes

• Change in Patient Assessment of Constipation-Symptoms Total Score From Baseline to Day 14 [From baseline before treatment to the end of treatment on Day 14.]: The Patient Assessment of Constipation-Symptoms questionnaire is a 12-item participant-reported measure used to assess the severity of constipation symptoms. The questionnaire includes four abdominal symptom items, three rectal symptom items, and five stool symptom items. Each item is rated on a 5-point scale from 0 to 4, where 0 indicates "absent," 1 indicates "mild," 2 indicates "moderate," 3 indicates "severe," and 4 indicates "very severe." The overall score is calculated as the mean of the completed item scores and ranges from 0 to 4. Higher scores indicate more severe constipation symptoms. The questionnaire will be completed before treatment and on Day 14. Change from baseline will be calculated as the Day 14 score minus the baseline score; a larger negative change indicates greater improvement.

Sex: All, ages: 18 Years to 75 Years

Inclusion Criteria:

Surgical indication for a benign anorectal disease, including hemorrhoids or anal fistula Diagnosis of postoperative constipation after benign anorectal surgery Postoperative constipation symptoms such as difficulty defecating, reduced bowel movement frequency, hard or lumpy stools, incomplete evacuation, anorectal obstruction, or abdominal distension Ability to tolerate the planned anorectal surgical procedure without related contraindications Consciousness and ability to cooperate with treatment, follow-up, and questionnaire assessments Written informed consent provided by the participant or legally authorized representative Age 18 to 75 years, inclusive

Exclusion Criteria:

Severe systemic disease, including serious psychiatric or immune disorders Severe infection Malignant tumor Severe organic disease of a major organ, including the heart, liver, or kidneys Pregnancy Breastfeeding Postpartum period Coagulation dysfunction Other anorectal disease that may affect outcome assessment Known allergy to either study treatment or any treatment component Any other condition considered by the investigators to make participation unsuitable