Sigmoid nodes

At a glance

English

Sigmoid nodes

Latin (TA2)

Nodi sigmoidei

System

Lymphatic

Region

Trunk

Side

Single, on the midline

About the sigmoid nodes

The sigmoid nodes are an intermediate group of the inferior mesenteric nodes. They follow the sigmoid arteries, usually two to four branches of the inferior mesenteric artery that fan out to the left through the sigmoid mesocolon to the S-shaped loop of colon between the pelvic brim and the rectum.

Because the sigmoid colon is suspended on its own mesentery, the nodes lie within that fold, in an inverted V-shaped root attached to the left pelvic wall and over the sacrum. Beneath the apex of the root, under the peritoneum, the left ureter crosses the division of the left common iliac artery, a landmark used in surgery. The paracolic nodes along the marginal artery lie further out, close to the bowel.

Lymph enters them from the paracolic nodes of the sigmoid colon and the lower part of the descending colon. They pass it inward along the sigmoid arteries to the inferior mesenteric nodes at the root of the artery, from where it reaches the pre-aortic group and the intestinal trunk.

Cancer of the sigmoid colon spreads to these nodes after the paracolic group, and sigmoid colectomy takes the mesocolon and its vessels together with the bowel so that they are removed. They may also swell in diverticulitis, a common inflammation of the sigmoid colon, which can make it harder to tell infection from tumour on a scan.

Course and drainage

Begins at

Efferent vessels of the paracolic nodes of the sigmoid colon and the lower descending colon.

Drains into

Efferent vessels pass to the inferior mesenteric nodes, then the pre-aortic nodes and the intestinal trunk.

Drains

Drain the sigmoid colon and the end of the descending colon. A second station for sigmoid cancer, removed with the mesocolon at colectomy; they may also enlarge in diverticulitis.