The Extraperitoneal Approach to Left-Sided Colorectal Resections: A Human Cadaveric Study

Technical challenges during laparoscopic and robotic anterior resection include identification of key retroperitoneal structures and obtaining clear views of the inferior mesenteric artery (IMA) pedicle and total mesorectal excision (TME) plane. Steep head-down position improves surgical exposure but is associated with cerebral oedema, high intrapulmonary pressures, and rare neurological complications. In this article we describe the key steps of an anterior resection performed via the extra-peritoneal (XP) space in the supine position.

The technique of same-side lateral-to-medial XP dissection has been developed and refined in serial cadaveric workshops. A standard periumbilical port is inserted for initial laparoscopic exploration. Dissection is then performed in the left XP space via a 5 cm skin incision (later used as the extraction site) to allow for insertion of four (latterly three) working ports. The colon is mobilized along its lateral attachments, reflecting retroperitoneal structures down and away. The IMA pedicle is taken proximally, next to the duodenum. If required, TME dissection can be continued in the same plane. A short intraperitoneal phase is then required to complete the procedure.

Eight cadavers were studied (seven males; median 78 y). Four operations were performed laparoscopically and four robotically. Excellent views of the key retroperitoneal structures were achieved early in the procedure. Anatomical identification was performed sequentially for left-sided structures-psoas tendon, gonadal vessel, ureter, common iliac artery, IMA, and duodenum before ligation of the IMA pedicle. High ligation of IMA on the aorta and splenic flexure mobilization were performed in all eight procedures.

This novel study shows it is feasible to perform the key steps of an anterior resection using the XP space in the supine position. This will reduce the need for steep head-down positioning which may have meaningful clinical benefits. Prospective clinical studies are required to validate the technique within a patient population.