The terminal ileum can be identified by a ridge of antemesenteric fat (crista galli/cock’s comb). The iliocecal valve, when competent, prevents reflux from colon to ilium and may result in massive colonic distention when a distal obstructing lesion creates a closed loop. The base of the appendix is found at the convergence of the three colonic taeniae at the apex of the cecum. The cecum and right side of the colon are large and the stool liquid, so right-sided carcinomas most often present with occult bleeding. Lesions in the narrow left side of the colon most often present with obstructive symptoms.
The appendix is variable in location depending on the mobility of the cecum, the length of the appendix and whether it is retrocecal (50%). Most retrocecal appendices simply lie behind a relatively mobile cecum, but some are actually behind the cecal fusion fascia and truly retroperitoneal. A classic McBurney’s incision for open appendectomy is made through McBurney’s point, 2/3 the way from umbilicus to anterior superior spine of ileum, 1/3 above the line, 2/3 below. Placing the incision a little more lateral avoids getting into the rectus sheath. A McBurney incision can be extended more easily than a transverse (Rocky-Davis) incision without cutting into the rectus. Laparoscopic appendectomy is becoming a popular, though not clearly superior alternative to open.
Digital localization of the appendix in the open procedure is carried out by sweeping the finger from the lateral peritoneal reflection medially toward the psoas. Since the appendiceal mesentery is on the medial side of the organ, it cannot be torn by this maneuver. Appendicitis is usually due to obstruction of the neck of the organ by hypertrophied submucosal lymphoid patches rather than by fecolith, which is rare. Children, the elderly and immunocompromised patients progress to perforation earlier and surgery should not be delayed.