Objective Preoperative Parameters Predict Difficult Pelvic Dissections and Clinical Outcomes

Construction of a nomogram model to predict technical difficulty in performing laparoscopic sphincter-preserving radical resection for rectal cancer

BACKGROUND

Colorectal surgeons are well aware that performing surgery for rectal cancer becomes more challenging in obese patients with narrow and deep pelvic cavities. Therefore, it is essential for colorectal surgeons to have a comprehensive understanding of pelvic structure prior to surgery and anticipate potential surgical difficulties.

AIM

To evaluate predictive parameters for technical challenges encountered during laparoscopic radical sphincter-preserving surgery for rectal cancer.

METHODS

We retrospectively gathered data from 162 consecutive patients who underwent laparoscopic radical sphincter-preserving surgery for rectal cancer. Three-dimensional reconstruction of pelvic bone and soft tissue parameters was conducted using computed tomography (CT) scans. Operative difficulty was categorized as either high or low, and multivariate logistic regression analysis was employed to identify predictors of operative difficulty, ultimately creating a nomogram.

RESULTS

Out of 162 patients, 21 (13.0%) were classified in the high surgical difficulty group, while 141 (87.0%) were in the low surgical difficulty group. Multivariate logistic regression analysis showed that the surgical approach using laparoscopic intersphincteric dissection, intraoperative preventive ostomy, and the sacrococcygeal distance were independent risk factors for highly difficult laparoscopic radical sphincter-sparing surgery for rectal cancer (P < 0.05). Conversely, the anterior-posterior diameter of pelvic inlet/sacrococcygeal distance was identified as a protective factor (P < 0.05). A nomogram was subsequently constructed, demonstrating good predictive accuracy (C-index = 0.834).

CONCLUSION

The surgical approach, intraoperative preventive ostomy, the sacrococcygeal distance, and the anterior-posterior diameter of pelvic inlet/sacrococcygeal distance could help to predict the difficulty of laparoscopic radical sphincter-preserving surgery.

Establishment of Surgical Difficulty Grading System and Application of MRI-Based Artificial Intelligence to Stratify Difficulty in Laparoscopic Rectal Surgery

(1) Background: The difficulty of pelvic operation is greatly affected by anatomical constraints. Defining this difficulty and assessing it based on conventional methods has some limitations. Artificial intelligence (AI) has enabled rapid advances in surgery, but its role in assessing the difficulty of laparoscopic rectal surgery is unclear. This study aimed to establish a difficulty grading system to assess the difficulty of laparoscopic rectal surgery, as well as utilize this system to evaluate the reliability of pelvis-induced difficulties described by MRI-based AI. (2) Methods: Patients who underwent laparoscopic rectal surgery from March 2019 to October 2022 were included, and were divided into a non-difficult group and difficult group. This study was divided into two stages. In the first stage, a difficulty grading system was developed and proposed to assess the surgical difficulty caused by the pelvis. In the second stage, AI was used to build a model, and the ability of the model to stratify the difficulty of surgery was evaluated at this stage, based on the results of the first stage; (3) Results: Among the 108 enrolled patients, 53 patients (49.1%) were in the difficult group. Compared to the non-difficult group, there were longer operation times, more blood loss, higher rates of anastomotic leaks, and poorer specimen quality in the difficult group. In the second stage, after training and testing, the average accuracy of the four-fold cross validation models on the test set was 0.830, and the accuracy of the merged AI model was 0.800, the precision was 0.786, the specificity was 0.750, the recall was 0.846, the F1-score was 0.815, the area under the receiver operating curve was 0.78 and the average precision was 0.69; (4) Conclusions: This study successfully proposed a feasible grading system for surgery difficulty and developed a predictive model with reasonable accuracy using AI, which can assist surgeons in determining surgical difficulty and in choosing the optimal surgical approach for rectal cancer patients with a structurally difficult pelvis.

Validation of a pelvic surgery difficulty risk model to predict difficult pelvic dissection and poor outcomes

BACKGROUND

We previously developed the Pelvic Surgery Difficulty Index for predicting intraoperative events and postoperative outcomes associated with rectal mobilization with or without proctectomy ("deep pelvic dissection"). The aim of this study was to validate the scoring system as a prognostic tool for outcomes of pelvic dissection, regardless of the cause of dissection.

METHODS

Consecutive patients who underwent elective deep pelvic dissection at our institution from 2009 to 2016 were reviewed. Pelvic Surgery Difficulty Index score (0-3) was calculated from the following parameters: male sex (+1), prior pelvic radiotherapy (+1), and linear distance from sacral promontory to pelvic floor >13 cm (+1). Patient outcomes stratified by Pelvic Surgery Difficulty Index score were compared. The outcomes assessed included operative blood loss, operative time, length of hospital stay, cost, and postoperative complications.

RESULTS

A total of 347 patients were included. Higher Pelvic Surgery Difficulty Index scores were associated with significantly more blood loss, operative time, postoperative complications, hospital costs, and hospital stay. The model achieved good discrimination with area under the curve ≥0.7 for most outcomes.

CONCLUSION

Preoperative prediction of the morbidity associated with difficult pelvic dissection is possible with an objective, feasible, and validated model. Such a tool may facilitate preoperative preparation and allow for better risk stratification and uniform quality control across centers.

Usefulness of Endoscopic Tattooing Before Neoadjuvant Therapy in Patients with Clinical Complete Response in Locally Advanced Rectal Cancer for Providing a Safe Distal Surgical Margin

Background: Endoscopic tattooing of colorectal tumors enables tumor localization and determination of appropriate surgical margins. It becomes very difficult to detect the distal surgical margins (DSMs) of rectal tumors in patients who obtain clinical complete response (cCR) after neoadjuvant therapy. In this study, our aim is to examine the benefits of endoscopic tattooing of the tumor before neoadjuvant therapy in patients with locally advanced rectal cancer in accurate localization of the previous tumor and in providing appropriate DSMs in cases with cCR. Patients and Methods: The patients who were diagnosed with locally advanced rectal cancer, received neoadjuvant therapy and subsequently achieved cCR, and underwent surgery between January 2015 and October 2020 were included in the study. The patients were divided into two groups according to whether they were endoscopically tattooed before neoadjuvant chemoradiotherapy. Results: A total of 49 cases were included in the study. Significantly better DSMs were observed especially in female gender in the tattooed group. DSMs were found to be closer to the resection margins in the nontattooed group. It was found that endoscopic tattooing had a significant effect on the DSM in the regression analysis (P = .06, R² = 0.47). It was determined that laparoscopy or open surgery alone did not differ in terms of DSMs but open surgery together with tattooing was found to be strongly effective in providing larger DSMs. Conclusion: In locally advanced rectal cancer, endoscopic tattooing of the distal margin of the tumor before neoadjuvant therapy is a reliable and effective method for obtaining a safe DSM and not leaving the residual tumor at the lower end of anastomosis, especially in cases of cCR.

Robotic Ureteral Reconstruction in Patients with Radiation-Induced Ureteral Strictures: Experience from the Collaborative of Reconstructive Robotic Ureteral Surgery

Objectives: Management of radiation-induced ureteral stricture (RIUS) is complex, requiring chronic drainage or morbid definitive open reconstruction. Herein, we report our multi-institutional comprehensive experience with robotic ureteral reconstruction (RUR) in patients with RIUSs. Patients and Methods: In a retrospective review of our multi-institutional RUR database between January 2013 and January 2020, we identified patients with RIUSs. Five major reconstruction techniques were utilized: end-to-end (anastomosing the bladder to the transected ureter) and side-to-side (anastomosing the bladder to an anterior ureterotomy proximal to the stricture without ureteral transection) ureteral reimplantation, buccal or appendiceal mucosa graft ureteroplasty, appendiceal bypass graft, and ileal ureter interposition. When necessary, adjunctive procedures were performed for mobility (i.e., psoas hitch) and improved vascularity (i.e., omental wrap). Outcomes of surgery were determined by the absence of flank pain (clinical success) and absence of obstruction on imaging (radiological success). Results: A total of 32 patients with 35 ureteral units underwent RUR with a median stricture length of 2.5 cm (interquartile range [IQR] 2-5.5). End-to-end and side-to-side reimplantation techniques were performed in 21 (60.0%) and 8 (22.9%) RUR cases, respectively, while 4 (11.4%) underwent an appendiceal procedure. One patient (2.9%) required buccal mucosa graft ureteroplasty, while another needed an ileal ureter interposition. The median operative time was 215 minutes (IQR 177-281), estimated blood loss was 100 mL (IQR 50-150), and length of stay was 2 days (IQR 1-3). One patient required repair of a small bowel leak. Another patient died from a major cardiac event and was excluded from follow-up calculations. At a median follow-up of 13 months (IQR 9-22), 30 ureteral units (88.2%) were clinically and radiologically effective. Conclusion: RUR can be performed in patients with RIUSs with excellent outcomes. Surgeons must be prepared to perform adjunctive procedures for mobility and improved vascularity due to poor tissue quality. Repeat procedures for RIUSs heighten the risk of necrosis and failure.

Preoperative Predictive Model of Narrow Pelvis in Laparoscopic Radical Prostatectomy Through Computed Tomography

Objective: At present, prostate cancer radical surgery still lacks an objective standard for predicting the anatomic difficulty of surgery through preoperative examination. Due to the poor prognosis and surgical complications caused by "Narrow Pelvis," a pelvic model for prediction is urgently needed. The purpose of this study is to present objective preoperative assessing indicators to predict the surgical difficulty caused by pelvic anatomic abnormalities during laparoscopic radical prostatectomy (LRP). Methods: Patients undergoing LRP were retrospectively analyzed and separated into "Common Pelvis" or "Difficult Pelvis" groups according to the preset criteria. The clinical data and pelvic imaging data of the two groups were compared to obtain statistically significant differences. The results were compared and validated in 500 ordinary males. Logistic regression analysis was performed to optimize these indicators into a scoring model, "Laparoscopic Radical Prostatectomy Narrow Pelvic Predictive Index (LRP-NPPI)" for predicting "Difficult Pelvis." Results: Of the 145 patients undergoing LRP, 22 (15.2%) were included in the "Difficult Pelvis" group. Patients in the "Difficult Pelvis" group were more likely to have a narrower, shorter, deeper, more flattened pelvis, greater body mass index, more history of previous pelvic surgery, and greater prostate volume. Moreover, the larger amount of intraoperative blood loss and longer operation time were related. Compared with the "Common Pelvis" group, patients in the "Difficult Pelvis" have higher score of LRP-NPPI (p < 0.05). Conclusion: With the model we proposed, it is possible to predict patients with pelvic anatomical difficulties during LRP.