Pelvic anatomy as a factor in laparoscopic rectal surgery: a prospective study

The aim of this study was to evaluate factors affecting the difficulty of laparoscopic total mesorectal excision (L-TME), focusing on the pelvic anatomy.

Seventy-four patients who underwent L-TME were prospectively enrolled. Tumor and patient factors, including magnetic resonance imaging-based pelvic measurements (obstetric conjugate, sacral length, sacral depth, interspinous distance, and intertuberous distance), were analyzed with respect to pelvic dissection time. Variable significantly correlated with pelvic dissection time in linear regression were considered risk factors which we defined as lower or upper quartile of each significant variable. Patients were categorized into 3 groups: easy group, no risk factors; moderate group, 1 to 2 risk factors; and difficult group, ≥ 3 risk factors.

Multivariate analysis showed that long sacral length, shallow sacral angle, narrow intertuberous diameter, and large tumor size were significantly associated with longer pelvic dissection time (P=0.018, P<0.001, P=0.034, P=0.032, respectively). The cutoff values of the upper quartile were 11.5 cm and 4.5 cm for sacral length and tumor size, and cutoff values of the lower quartile were 3.0 cm and 8.9 cm for sacral depth and intertuberous diameter. Logistic regression analysis showed that difficult group significantly contributed to intraoperative complication (95% confidence interval: 1.364-122.313, P=0.026) but not postoperative complication.

Having a narrow, deep pelvis and a large tumor were not found to adversely affect postoperative outcomes. However, in terms of operation time and intraoperative difficulty, anatomical factors should be taken into consideration when planning L-TME.