Can we predict surgical difficulty of rectal surgery ?

© Annals of Laparoscopic and Endoscopic Surgery. All rights reserved. Ann Laparosc Endosc Surg 2018;3:44 ales.amegroups. com In rectal surgery, the gold standard of surgical technique is total mesorectal excision (TME) (1). Treatment of rectal cancer has improved by the introduction of TME, which resulted in decreased postoperative local recurrence. Difficulties in TME are assumed to be due to the limited surgical maneuver in the narrow pelvic space: autonomic nerve conservation, sphincter preservation, and anastomosis. Compared with open surgery, laparoscopic surgery enables TME with greater precision by providing a better visibility even in a narrow space of the pelvic cavity. Although laparoscopic rectal surgery has been accepted by accumulated evidence, it remains technically difficult in patients with obesity, a narrow male pelvis, or bulky tumors. Recent large-scale randomized controlled trials (RCTs), such as COREAN and COLOR II, showed favorable outcomes of laparoscopic rectal surgery compared to open rectal surgery (2,3), although the results of other recent RCTs, such as ACOSOG Z6051 and ALaCaRT, were controversial (4,5). Recent studies have reported that surgical difficulties are affected not only by surgeon’s skill but also by the patient’s clinical and anatomical factors. However, the objective numerical rating indexes to help surgeons assess the estimated surgical difficulty are not developed yet. Escal et al. recently conducted a retrospective study aimed to evaluate the predictability of clinical and MRI-based anatomical factors for surgical difficulty in rectal surgery (6). In their cohort, 164 patients were categorized into the two groups based on the surgical difficulty criteria: low risk group (n=143, 87.2%) and high-risk group (n=21, 12.8%). To measure the surgical difficulty grading, they chose six factors: operation time, intraoperative blood loss, conversion to open surgery, transanal approach added to transabdominal TME, length of hospital stay, and postoperative morbidity. They employed multivariable logistic regression analysis, and found that body mass index (BMI) (>30 kg/m), coloanal anastomosis (vs. colorectal anastomosis), intertuberous distance (<10.1 cm), and mesorectal fat area (>20.7 cm) were significantly associated with a high grade of surgical difficulty. Finally, they proposed a four-item predictive score model in which each variable was scored 0 (absence) or 1 (presence). If patients have a score of 3 or more, they are considered to be at high risk of surgical difficulty. This study demonstrates that a combination of risk factors could affect the surgical difficulty of TME. This novel model could be useful for surgeons to predict the surgical difficulty of rectal surgery related to their experience and skill. The presence of some factors, including BMI, intertuberous distance, and mesorectal fat area, could reduce the pelvic space. Such limited space could cause insufficient counter traction, leading to an unfeasible operation. These results suggest that surgical space and counter traction are significantly related to the surgical difficulty of TME. High BMI, gender, low tumor location, tumor size, dimensions of the pelvic anatomy have been reported to be predictive factors associated with surgical difficulty. BMI is the most standard factor to evaluate the total body fat. Denost et al. analyzed the impact of BMI by classifying into 4 groups (i.e., BMI <20, 20–25, 25–30, and ≥30), and found that BMI influenced the conversion rate but not TME quality, surgical morbidity and long-term survival (7). Editorial