The aim of this clinical study is to determine whether preoperative abdominal massage has an effect on the development of postoperative constipation. The main questions it aims to answer are:

• Does preoperative abdominal massage improve postoperative stool consistency? • Does preoperative abdominal massage prevent constipation? To see if abdominal massage is effective in preventing constipation, researchers will not apply any treatment to the second group and will compare the two groups.

Participants will:

• Provide researchers with information about their preoperative and postoperative stool consistency and constipation status.
• Inform the researchers if the group that received the massage experiences any adverse effects from the massage.

Abdominal massage, being a low-cost, non-invasive procedure with no known harmful side effects, and one that nurses can integrate into clinical practice, plays an important role in the management of constipation.

This study is a single-center, randomized controlled experimental trial planned to be conducted in the General Surgery Department of a Training and Research Hospital in Istanbul. Standard operating procedures for patient recruitment, data collection, data management, adverse event reporting, and change management processes have been predefined. The experimental group will receive abdominal massage twice daily for 15 minutes, while the control group will continue with routine care. Adverse events will be recorded after each session, and necessary protocol changes will be documented in accordance with formal change management procedures. The sample size was determined based on a power analysis performed with G*Power 3.1; 30 participants were planned for each group (total n=60; α=0.05, power=0.80). A complete case analysis approach will be adopted for missing data resulting from data inconsistencies, out-of-range results, or unanswered items, and group assignments will continue until data is complete. In accordance with the statistical analysis plan, the Mann-Whitney U test will be used for between-group comparisons and the Wilcoxon test for within-group comparisons for the Bristol Stool Scale (BSS) score, which is the primary outcome measure; For the secondary outcome measure, stool type distribution, the Chi-square test will be applied. Effect size will be reported using Cohen's d and odds ratio, and the statistical significance threshold will be set at p<0.05.

Inclusion criteria:

• Being hospitalized in the General Surgery Department
• Experiencing constipation
• Being 18 years of age or older
• Having the cognitive ability to answer questions
• Voluntary participation in the study

Exclusion criteria:

• Being under 18 years of age
• Not experiencing constipation
• Having a condition that contraindicates abdominal massage (active intra-abdominal pathology, open wound, thrombocytopenia, etc.)
• Insufficient cognitive ability