[Factors affecting the difficulty of laparoscopy-assisted triple-port anterior resection]

To explore the factors affecting the operative difficulty of triple-port laparoscopic surgery (TLS) in anterior resection.

A retrospective case-control study was carried out. Clinical and MRI imaging data of 106 colorectal cancer cases undergoing TLS anterior resection at Department of Colorectal Surgery of Ruijin Hospital between 2013 and 2016 were retrospectively analyzed.

(1) patients receiving TLS anterior resection (Dixon operation); (2) preoperative stageI( to III( malignant tumor;(3) distance of 5-15 cm from inferior margin of tumor to anal verge; and (4) available preoperative rectal MRI.

(1) patients receiving preoperative adjuvant therapy; (2) patients with low rectal cancer or with local advanced disease; (3) T4b tumor. Rectal MRI was introduced to measure the structure of pelvis. In sagittal view, superior margin of the first sacral vertebrae, superior margin of the third sacral vertebrae, apex of coccyx, and the line of superior margin of pubic symphysis were used to form a pentagon. The 5 lines were marked as N, O, P, Q, R, and the 5 included angles were marked as angle 1, 2, 3, 4, 5. Organs (uterus and prostate) and tumor (transverse diameter, longitudinal diameter, section area, lesion length, distance to circumference cutting edge) were also measured on MRI. The operative time was applied to be the indicator of operative difficulty and patients were divided into 2 groups according to median operative time. Baseline information (age, gender, BMI, distance from inferior margin of tumor to anal verge, operative history, length of tumor), preoperative tumor staging, and MRI measurements (pelvis, tumor, uterus, prostate), etc were compared between two groups. Factors affecting operative difficulty of TLS were analyzed with logistic regression model.

Of 106 enrolled patients, 73 were male and 33 female with mean age of (59.8±12.2) years and mean BMI of (22.8±3.3) kg/m²; 25 patients had previous abdominal surgery; distance from inferior margin of tumor to anal verge was (7.4±2.0) cm and the tumor diameter was (3.7±1.4) cm; 24, 36 and 46 patients were in stage I(, II( and III( respectively. All operations were completed successfully. The median number of harvested lymph node was 13(11-16); the median length of distal resection margin was 2.5(2.0-3.1) cm; the median operative time was 2.0(1.5-2.6) hours; the median intraoperative blood loss was 50(0-100) ml; the median time to liquid diet was 4(3-5) days; the median hospital stay was 7(6-10) days. Ten cases (9.4%) developed complications within 30 days after surgery. Patients were divided into ≤2 h group and > 2 h group according to median operative time, and both groups had 53 patients. As compared to ≤2 h group, >2 h group had shorter distance from inferior margin of tumor to anal verge [(6.8 ± 1.5) cm vs. (8.0 ± 2.4) cm, t = 3.174, P = 0.004], lower ratio of (R+N)/(O+P)(1.61±0.27 vs. 1.73±0.19, t = 2.494, P = 0.014), larger transverse distance of tumor [(3.45±0.72) cm vs. (3.05±0.89) cm, t = 0.224, P = 0.027]. Multivariate logistic regression analysis showed the distance from inferior margin of tumor to anal verge was the independent factor affecting operative difficulty(OR=0.584, 95%CI:0.429-0.796, P = 0.001).

Surgeons may have less difficulty in performing TLS anterior resection for patients with longer distance from inferior margin of tumor to anal verge. In preoperative assessment of operative difficulty of TLS, comprehensive evaluation should be performed. Distance from inferior margin of tumor to anal verge should be regarded as the main factor, and MRI (R+N)/(O+P) and transverse diameter of tumor should be used as important reference, leading to reasonable choice of cases for TLS and smooth pass of study curve.