Comparison of the Effects of Fentanyl, Oxycodone, Butorphanol on Gastrointestinal Function

Inclusion Criteria:

1. patients who were scheduled for laparoscopic hysterectomy from W\&C BRANCH HOSPITAL OF JIANGSU PROVINCE HOSPITAL
2. American Society of Anesthesiologists (ASA) physical status classification 1 to 2,
3. Women aged 40-65
4. Weight 50-80 kg

Exclusion Criteria:

1. History of opioids abuse and allergy and contraindication to opioid drugs
2. bronchial asthma; coronary heart disease; severe hypertension; diabetes mellitus;
3. hepatic, and renal dysfunction (glutamyl aminotransferase\> 40U or aspartate aminotransferase\> 35U; urea nitrogen\> 8.2 μmol / L, creatinine\> 133 μmol / L),
4. History of brain damage or psychiatric disease
5. Patients with coagulopathy (PT\> 17 seconds or activated partial thromboplastin time (APTT)\> 47 seconds);
6. pregnant or lactating women;
7. Those with long-term constipation;
8. History of digestive diseases;
9. history of gastrointestinal disease (peptic ulcer disease, Crohn's disease, or ulcerative colitis)
10. Participants in other drug trials in the past three months. （11）After randomization and allocation, patients were withdrawn if laparoscopy was converted to open surgery or if they required reinvestigation for postoperative bleeding.