Short interspinous diameter makes rectal surgery more difficult

Interspinous diameter seems to be an important factor affecting the difficulty of laparoscopic surgery in patients with mid-low rectal cancer, suggesting that magnetic resonance imaging (MRI) pelvimetry is helpful in gauging the technical difficulty of rectal surgery, a recent study has found.

The study included 221 patients who underwent sphincter-preserved total mesorectum excision (TME). Technical difficulty was defined according to the following criteria: quality of excision, operation time, intraoperative blood loss, distal margin, and circumferential resection margin. All participants underwent pelvic MRI.

Of the participants, 79 underwent laparoscopic procedures. Univariate analysis revealed that interspinous diameter (p=0.007), sacrococcygeal distance (p=0.037), and the angle of sacral promontory inclination (p=0.047) were all significant correlates of laparoscopic technical difficulty.

Multivariate analysis confirmed the significant role of interspinous diameter, such that surgery became more difficult with shorter diameters (odds ratio [OR], 0.602, 95 percent confidence interval, [CI], 0.389–0.934). While no other factors affected technical difficulty, the simulated troncar angle was found to be significantly and inversely correlated with laparoscopic operation time (OR, 0.961, 95 percent CI, 0.924–0.999).

In comparison, 100 patients underwent open surgery while 42 underwent transanal TME. In both subgroups, no factors significantly affected the overall technical difficulty of surgery. Instead, body mass index (p=0.017) and the ratio of the sacral promontory to the abdominal wall (p=0.021) were significantly associated operation time in the open surgery group. No such interactions were reported for transanal TME.