The Role of Anatomical Dissection in Defining Colic and Small Bowel Artery Lymphovascular Bundles in the D3 Volume of Small and Large Bowel Mesentery

The D3 lymphadenectomy with extended mesenteric/mesocolic excision is becoming a standard in the surgery of small and large bowel carcinoma. The aim of this study is to present the feasibility of macro- and microdissection of the mesenteric lymphatics in the root of the mesentery with accompanying morphometry of the lymphatic clearances. The study was carried out on three embalmed cadavers from the body donor program. After the removal of the anterolateral abdominal wall, the greater omentum was retracted cranially, giving access to the mesentery, right, and transverse mesocolon. After marking the pertinent landmarks (ileocolic fold, middle colic fold, duodenojejunal angle), the visceral peritoneum was carefully incised along the approximate larger perimeter of the D3 volume and removed. The subperitoneal fatty and connective tissue was removed by gentle centrifugal scraping, revealing the underlying deep lymphatic and blood vessel network. We used narrow spatulas, micro-dissection scissors, small tweezers, curved forceps, and 5x magnifying lens with a fluorescent ring. The centrally positioned superior mesenteric vessels were pivotal in identifying their branches, affluents, and the accompanying lymphatic network. The lymph vessels were identified by continuity with the collector vessels and their link to the lymph nodes. Finally, the lymphatic clearances, i.e., distances between the mentioned arteries and their neighboring vessels, were measured by a digital caliper. In conclusion, the dissection of the mesenteric lymphatics gives a synoptic view of the lymph vessels network and provides valuable information for D3 surgery of small and large bowel tumors.