Robot-assisted laparoscopic low anterior resection for rectal cancer with persistent descending mesocolon: A case report

Vascular anatomical study of persistent descending mesocolon in patients undergoing laparoscopic surgery for colorectal cancer

“…The IMA radiality is the IMA branching pattern defined as the existence of three or more branches of the IMA at the same point, which was also defined as an IMA branching pattern that includes Type 3 and a part of Type 4 in the classification described by Murono et al 5,13 IMA radiality is a well‐known IMA branching pattern that has been reported in previously as an anatomical feature of vessels in PDM and some studies even listed it as a diagnostic criterion for PDM 6,9 . However, the recent study on vascular anatomical examination of PDM using 3D‐CT angiography reported that the IMA radiality was not necessarily specific to PDM, 5 and in our study also, we found no significant difference in the frequencies of IMA radiality between PDM and non‐PDM cases.…”

“…3D‐CT angiography is believed to be superior to conventional CT in evaluating the vascular anatomy such as the running direction of vessels, 13 which may have been linked to the discovery of the running direction of the SA, which we newly reported in this study. Although 2D‐CT can show the running direction of blood vessels, many reports have recently shown the effectiveness of preoperative vascular 3D‐angiography in colorectal cancer surgery 5,8,9,11–14,17,18 . 3D angiography allows us to share complicated vascular anatomical images with the surgical staff 14 .…”

“…The exact cause of the variations in the vascular running direction in PDM cases remains unknown, but they may be related to the displacement of the left‐sided colon and the shortening of the colonic mesentery. In PDM, the lack of fixation of the descending mesocolon to the dorsal abdominal wall during the fifth month of gestation results in the medial movement of the descending colon 1–9 . This medial displacement of the descending colon is also expected to cause a concomitant displacement of the sigmoid colon to the right, therefore PDM is sometimes called a “right‐sided sigmoid colon”, 6 resulting in a right‐sided traveling deviation of the SA in such cases.…”

“…The anatomic features of PDM can clarify the importance of preoperative evaluation of vascular anatomy in patients with PDM. PDM is characterized not only by fixation abnormalities but also by anatomical variations, such as the shortening of the mesentery 1–12 . The shortening of the mesentery results in a closer than usual proximity of the marginal vessels with the arteries involved in lymph node dissection, that is, IMA, LCA, and SA 3,4,8–10,12 .…”

“…Persistent descending mesocolon (PDM), the surgical findings of which were initially reported in 1960 by Morgenstern, 1 is a rare congenital atypia of fixation of the descending colon. In a patient with PDM, the descending to sigmoid colon is displaced medially toward the right side of the abdomen and adheres to the small intestinal mesentery or right pelvic wall 1–12 . PDM shows no Toldt's fusion fascia because the descending mesocolon does not fuse with the retroperitoneum, which results in the shortening of the left‐sided colonic mesentery 8 .…”