Lymphatic Drainage of the Splenic Flexure Defined by Intraoperative Scintigraphic Mapping.

Background: The optimal surgical management of splenic flexure cancer is debated, partly because of an incomplete understanding of the lymphatic drainage of this region.

Objective: This study aimed to evaluate the normal lymphatic drainage of the human splenic flexure using laparoscopic scintigraphic mapping.

Design: This was a clinical trial.

Settings: The study was conducted at a single tertiary care center.

Patients: Thirty consecutive patients undergoing elective colorectal resections without splenic flexure pathology were recruited.

Intervention: Technetium-99m was injected subserosally at the splenic flexure.

Main Outcome Measures: Lymphatic scintigraphic mapping was undertaken at 15, 30, and 60 minutes using a laparoscopic gamma probe at the left branch of the middle colic, left colic, inferior mesenteric, and ileocolic (control) lymphovascular pedicles.

Results: Lymphatic drainage at 60 minutes was strongly dominant in the direction of the left colic pedicle (96% of patients), with a median gamma count of 284 (interquartile range, 113-413), versus the left branch of the middle colic count of 31 (interquartile range, 15-49; p < 0.0001). This equated to a median 9.2-times greater flow to the left colic versus the middle colic. Counts at the left colic were greater than all of the other mapped sites at 15, 30, and 60 minutes (p < 0.001), whereas middle colic and inferior mesenteric artery counts were equivalent. The protocol increased operative duration by 20 to 30 minutes without complications.

Limitations: These results report lymphatic drainage from patients with normal splenic flexures, and caution is necessary when extrapolating to patients with splenic flexure cancers.

Conclusions: The lymphatic drainage of the normal splenic flexure is preferentially directed toward the left colic in the high majority of cases. Retrieving these nodes should be prioritized in splenic flexure cancer resections, with important secondary emphasis on left middle colic nodes, supporting segmental (left hemicolectomy) resection as the procedure of choice. Additional development of colonic sentinel node mapping using these techniques may contribute to individualized surgical therapy morbidity. See Video Abstract at http://links.lww.com/DCR/A495.