Comparison of intraperitoneal irrigation with sodium bicarbonate solution versus normal saline in operative gynaecological laparoscopy to reduce postoperative pain: a randomized control trial

RATIONALE: Postoperative pain after gynaecological laparoscopy is partly due to peritoneal irritation from residual CO2 and tissue handling. While normal saline irrigation is routinely used to reduce this pain, it does not neutralize the acidic environment created by CO2 insufflation. Sodium bicarbonate, an alkaline solution, may better counteract peritoneal acidity, potentially reducing postoperative pain more effectively. It has also demonstrated anti-inflammatory and analgesic effects in other clinical settings. Limited studies in gynaecological laparoscopy suggest a need for further evaluation of sodium bicarbonate irrigation compared to normal saline to improve postoperative outcomes. Therefore we propose to undertake this study.

AIM: To compare the efficacy of intraperitoneal sodium bicarbonate solution irrigation versus normal saline irrigation in reducing post operative pain in women undergoing Operative gynaecological laparoscopy.

OBJECTIVES:

Primary objective:

1. To compare the VAS scores for postoperative pain at various sites (Right and left shoulder tip, port sites, abdomen excluding port sites, back) between patients receiving sodium bicarbonate solution irrigation versus normal saline irrigation following operative gynaecological laparoscopy.

Secondary objectives:

1. To compare analgesic requirement in intervention and control groups.

2. To assess the incidence of postoperative nausea and vomiting (PONV) in intervention and control groups.

3. To compare inflammatory markers between intervention and control groups on post operative day (POD) 1 and POD 3.

4. To assess the impact on recovery metrics, including time to first oral intake, ambulation and duration of hospital stay from end of surgery.

MATERIALS AND METHODS

Study Design: Randomized Control Trial

Setting: The study will be conducted in the Department of Obstetrics and Gynaecology, Department of Anaesthesiology, University College of Medical Sciences and Guru Teg Bahadur Hospital, Dilshad Garden, Delhi.

Duration: 1st August 2025 to 30th November 2026

Inclusion criteria:

1. Women aged 18-65 years

2. American society of anesthesiologist physical status classification 1 or 2

3. Those undergoing elective operative laparoscopic surgery for benign gynaecological conditions.

Exclusion criteria:

1. History of chronic pain, psychiatric illness, opioid use, alcohol

2. Metabolic/ respiratory alkalosis

3. Electrolyte imbalances

4. Chronic kidney disease, liver disease, cardiovascular or respiratory diseases

5. Malignancy

6. Conversion to laparotomy

7. Diagnostic laproscopy

8. Pregnancy

9. Infection in post operative period

10. Known allergy to study solutions

SAMPLE SIZE: The minimum sample size is estimated based on study conducted by Agarwal et al (2023) reporting statistically significant average values of VAS score as 3.1+/-0.5 and 3.9+/-0.7 in intervention and control group respectively at abdomen excluding port sites after 12hrs post procedure. At 2 tail alternative hypothesis level of significance 5%, power of test 99% and with equal allocations in both groups, the minimum sample size came out to be 54 including both the groups. Additional 6 cases will be added to compensate for dropouts, with total enrollment of 60 cases, hence allocating 30 in each group.

METHODOLOGY: Sixty women aged 18–65 years undergoing elective operative gynaecological laparoscopy will be randomized into two groups (30 each) after informed consent. Baseline demographics, investigations (CBC, CRP, DLC, NLR, PLR, MLR), physical, and gynaecological examinations will be recorded. Preoperative arterial blood gas (ABG) analysis will be performed. Under general anesthesia (following standard protocol), pneumoperitoneum will be created with CO2 (12–15 mmHg). At end of surgery, intraperitoneal irrigation will be performed with either 50 mL of 7.5% sodium bicarbonate diluted in 1000 mL normal saline (Group A) or 1000 mL normal saline alone (Group B). The fluid will remain in the cavity for 5 minutes before complete aspiration. Trocar sites will be infiltrated with 0.25% bupivacaine before closure, and postoperative ABG sampling will be repeated 10 minutes after extubation. Postoperative pain will be assessed by VAS scores at 6, 12, 24, 48 hours and 1 week at right and left shoulder tip, port sites, abdomen excluding port sites and back. Analgesia will be provided based on VAS scores (>=4), with IV paracetamol infusion and IM diclofenac/ tramadol as needed. CBC, CRP, DLC, NLR, PLR, MLR will be reassessed on POD 1 and 3. Postoperative outcomes including PONV, abdominal distension, time to first oral intake, ambulation, and hospital stay duration will be recorded after the end of the procedure.

OUTCOME MEASURES

Primary Outcome Measure:

1. Post operative pain measured by visual analogue scale (VAS) (0-10) at Right and left shoulder tip, port sites, abdomen excluding port sites and back recorded as Mean±SD at 6, 12, 24, 48 hours and 1 week post-laparoscopy procedure in both the groups.

Secondary Outcome Measures

1. Total analgesic requirement in both the groups (Type, dose, and time to first request)

2. Incidence of PONV in both the groups.(Use of antiemetics)

3. Comparison of inflammatory markers (CBC, CRP, DLC, NLR, PLR, MLR) post laparoscopy in both the groups.

4. Mean time for first oral intake, ambulation and duration of hospital stay from end of surgery in both the groups.

STATSTICAL ANALYSIS

1. Descriptive statistics based on quantitative [mean(SD)] and qualitative [frequency(%)] variables.

2. The normality of the continuous data set will be assessed with Kolmogorov Smirnov test.

3. The comparison between the two groups will be done based on independent t-test / Mann-Whitney U test based on the result of novelty.

4. Categorical variables will be analyzed using the Chi-square test.

5. A p-value < 0.05 will be considered statistically significant.

6. All the analysis will be performed by using SPSS version 20.0.