Post Laparoscopy Pain Reduction Project I (POLYPREP I): intraperitoneal normal saline instillation—a randomised controlled trial

OBJECTIVES: To evaluate the effect of intraperitoneal normal saline instillation (INSI) of 15 mL/kg body weight on postoperative pain after a gynaecological laparoscopic procedure. DESIGN: Randomised controlled trial. SETTING: University Hospital in Kuala Lumpur, Malaysia. PARTICIPANTS: Patients aged 18-55 years, with American Society of Anaesthesiologists (ASA) classification I-II, scheduled for an elective gynaecological laparoscopic procedure for a benign cause. INTERVENTION: The patients were randomly allocated to two groups. In the intervention group, 15 mL/kg body weight of normal saline was instilled intraperitoneally, while the control group received the conventional combination of open laparoscopic trocar valves with gentle abdominal pressure to remove the retained carbon dioxide. MAIN OUTCOME MEASURES: The outcomes measured were the mean pain scores for shoulder and upper abdominal pain at 24 h, 48 h, and 72 h postoperatively. RESULTS: A total of 68 women completed the study, including 34 women in each group. There was no difference in the shoulder pain score at 24 h, 48 h, and 72 h postoperatively. However, a significant improvement in the upper abdominal pain score after 48 h (95% confidence interval [CI] 0.34-1.52, p = 0.019) and 72 h (95% CI 0.19-0.26, p = 0.007) postoperatively were observed. CONCLUSIONS: INSI of 15 mL/kg body weight does not lower postoperative shoulder pain compared to no fluid instillation. A modest pain score improvement was observed in the upper abdominal area at 48 h and 72 h after surgery. An INSI of up to 30 mL/kg body weight may be required to eliminate shoulder pain. Care must be taken before administering a higher amount of INSI, considering the potential risk of peritoneal adhesions. Clinical registration ISRCTN Identifier: 87898051 (Date: 26 June 2019) https://doi.org/10.1186/ISRCTN87898051.