Pain Evaluation Across Robotic and Laparoscopic Surgery for Colorectal Procedures
Conditions: Minimally Invasive Surgical Procedures, Colon Cancer Patients
Sponsor: Hospital Central de la Defensa Gómez Ulla

 
Pain Evaluation Across Robotic and Laparoscopic Surgery for 
Colorectal Procedures  
 
(PEARL Study) 
 
 
 
IP: Patricia Tejedor Togores 
Código: CR001 
1st July 2025 
 
 
 
 

Study Protocol and Statistical Analysis Plan (SAP) 
Official Title: Pain Evaluation Across Robotic and Laparoscopic Surgery for Colorectal 
Procedures (PEARL Study) 
NCT Number: [To be filled after registry submission] 
Document Date: February 1, 2025 
Document Type: Study Protocol and Statistical Analysis Plan (SAP) 
1. Introduction 
Colorectal surgery has evolved significantly over the past few decades with the 
development and adoption of minimally invasive techniques aimed at improving both 
short- and long-term patient outcomes. Laparoscopic surgery has been established as the 
gold standard for many colorectal procedures, demonstrating clear benefits over open 
surgery, such as reduced postoperative morbidity, shorter hospital stays, lower rates of 
complications, and decreased postoperative pain. 
 
Robotic-assisted surgery has emerged more recently as a promising alternative to 
traditional laparoscopy. Robotic systems offer enhanced dexterity, improved ergonomics, 
three-dimensional visualization, and tremor filtration, which together allow for more 
precise surgical dissection and potentially less tissue trauma. Despite these theoretical 
advantages, there remains limited high-quality, prospective data comparing the impact of 
robotic versus laparoscopic surgery on postoperative pain in colorectal procedures. 
 
Given the critical importance of pain control in surgical recovery, this study seeks to 
address this evidence gap by prospectively comparing postoperative pain outcomes 
between these two minimally invasive surgical techniques. 
2. Justification 
Postoperative pain following colorectal surgery significantly impacts patient recovery, 
including early mobilization, return of bowel function, hospital length of stay, and overall 
quality of life. Inadequate pain control has been linked to increased rates of postoperative 
complications and delayed recovery. 
 
Although the robotic approach is increasingly used worldwide, evidence regarding its 
specific impact on pain control compared to laparoscopy remains scarce, especially in the 
field of colorectal surgery. Most existing studies have focused on technical feasibility and 
oncological outcomes, with pain outcomes often analyzed as secondary endpoints or within 
heterogeneous patient populations. 
 
This study is therefore justified by the need to generate prospective, controlled, and 
detailed data on postoperative pain following robotic versus laparoscopic colorectal 
surgery. Findings from this study may directly influence surgical decision-making, 

anesthetic protocols, and postoperative care pathways within enhanced recovery after 
surgery (ERAS) programs. 
3. Objectives 
Primary Objective: 
- To compare the intensity of postoperative pain at 24 hours after surgery between patients 
undergoing laparoscopic versus robotic colorectal surgery, using the Visual Analog Scale 
(VAS). 
 
Secondary Objectives: 
- To compare postoperative pain at 48 and 72 hours post-surgery. 
- To analyze intraoperative analgesic requirements, specifically the total doses of fentanyl 
and remifentanil administered. 
- To assess hospital length of stay between both surgical groups. 
- To evaluate postoperative analgesic consumption during the hospital stay. 
- To compare postoperative complication rates, categorized by the Clavien-Dindo 
classification. 
- To analyze histopathological outcomes, including lymph node yield and margin status. 
- To assess conversion rates to open surgery. 
- To evaluate the systemic inflammatory response using laboratory markers (CRP, 
procalcitonin, fibrinogen). 
- To assess quality of life at 30 days, 3 months, 6 months, and 12 months postoperatively 
using validated questionnaires (QLQ-C30, EQ-5D, QLQ-CR29). 
4. Hypothesis 
Robotic colorectal surgery, by providing enhanced surgical precision and reduced tissue 
trauma, will result in significantly lower postoperative pain scores at 24 hours compared to 
laparoscopic surgery. 
5. Methodology 
Study Design: 
This is a prospective, single-center, observational cohort study conducted at Hospital 
General Universitario Gregorio Marañón in Madrid, Spain. 
 
Sampling Method: 
Consecutive sampling will be used to enroll all eligible patients over a 2-year period. 
 
Sample Size Calculation: 
Based on a two-sided alpha level of 0.05 and a power of 80%, and assuming a standard 
deviation of 3, a total of 80 patients (40 per group) will be required to detect a clinically 
relevant difference of at least 2 points in VAS pain scores. Accounting for a 10% dropout 
rate, the final target enrollment will be adjusted accordingly. 
 
Population and Eligibility Criteria: 

 
Inclusion Criteria: 
- Adults aged 18 years or older. 
- Signed informed consent. 
- ASA physical status classification I-III. 
- Adequate cognitive status to complete study questionnaires. 
- Scheduled for elective right or left colon surgery for malignant disease. 
- Eligibility for participation in the hospital’s ERAS (RICA) program. 
 
Exclusion Criteria: 
- Indication for open surgery during preoperative planning. 
- Rectal surgery (mesorectal excision without protective stoma). 
- Inflammatory bowel disease requiring resection. 
- Intraoperative need for multivisceral resection not previously identified. 
- Non-Pfannenstiel extraction incisions. 
- Chronic opioid or benzodiazepine use or abuse. 
- Chronic use of analgesics for other medical conditions. 
- Recreational drug use history. 
- Non-compliance with the RICA protocol. 
 
Intervention: 
Both groups will receive standard perioperative care including preincision local anesthetic 
infiltration using mepivacaine and bupivacaine at trocar sites and Pfannenstiel incisions. 
Pneumoperitoneum pressure will be standardized at 10 mmHg. 
 
Follow-Up: 
Pain assessments will be conducted at multiple time points: upon arrival in the recovery 
room, on transfer to the surgical ward, and at 24, 48, and 72 hours postoperatively, as well 
as at hospital discharge. 
 
Quality of life assessments will be conducted at 30 days, 3 months, 6 months, and 12 
months postoperatively using validated instruments. 
 
Data Collection and Management: 
Data will be collected and managed using the REDCap electronic data capture system, 
ensuring confidentiality and data integrity. 
 
Study Duration: 
Total duration of 2 years for patient enrollment and follow-up. 
6. Statistical Analysis Plan 
Descriptive Statistics: 
- Categorical variables will be summarized using frequencies and percentages. 

- Continuous variables will be described using means and standard deviations (SD) or 
medians and interquartile ranges (IQR), depending on data distribution (evaluated using 
the Kolmogorov-Smirnov test). 
 
Comparative Statistics: 
- Continuous variables will be compared using Student’s t-test for normally distributed data 
and Mann-Whitney U test for non-normal data. 
- Categorical variables will be analyzed using Chi-square test or Fisher’s exact test when 
expected frequencies are low. 
- Correlation between continuous variables will be assessed using Spearman's correlation 
coefficient. 
- Relative risks (RR) with 95% confidence intervals (CI) will be calculated for dichotomous 
outcomes. 
 
Multivariate Analysis: 
- Logistic regression analysis will be used to identify independent predictors of 
postoperative pain and complications, including variables with p<0.25 in univariate 
analysis. 
 
Statistical Software: 
All analyses will be conducted using SPSS software version 22 (SPSS Inc., Chicago, IL). 
Statistical significance will be set at p<0.05. 
7. Participating Center 
Hospital General Universitario Gregorio Marañón, Madrid, Spain. 
8. Ethical and Legal Considerations 
The study will adhere to all relevant ethical and legal guidelines, including the Declaration 
of Helsinki, Spanish biomedical research laws, and data protection regulations (LOPD 
03/2018 and GDPR 679/2016). 
 
The study protocol has been or will be approved by the hospital’s Ethics Committee (CEIm). 
All participants will provide written informed consent before enrollment. 
 
Patient confidentiality will be strictly maintained. Data will be stored in REDCap, a secure 
electronic database with access limited to authorized study personnel. 
 
No personal identifiers will appear in any publication or presentation resulting from this 
study. 
9. Material Resources 
All necessary clinical, surgical, and anesthetic resources required for study implementation 
are available at the Hospital General Universitario Gregorio Marañón. The study does not 
require additional diagnostic tools or modifications to standard patient care pathways. 

10. Study Timeline 
Recruitment Phase: 24 months. 
Follow-Up Phase: Up to 12 months postoperatively for each patient. 
Data Analysis and Reporting: Expected within 6 months after completion of follow-up. 
11. Additional Considerations 
No economic incentives will be provided to study participants or investigators. There are no 
commercial interests associated with this study. 
 
Results will be submitted for publication in peer-reviewed journals, and all principal 
investigators will be listed as co-authors according to their level of contribution. 
12. Annex List (Referenced but not included in this document) 
- Patient Information Sheet and Informed Consent Form. 
- ERAS (RICA) Protocol. 
- Institutional Anesthesia Protocol. 
- Visual Analog Scale (VAS) Assessment Tool. 
- Quality of Life Questionnaires (QLQ-C30, EQ-5D, QLQ-CR29). 
- Case Report Form (CRF). 
- REDCap Confidentiality Certification.