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Malrotation
Published in P Ronan O’Connell, Robert D Madoff, Stanley M Goldberg, Michael J Solomon, Norman S Williams, Operative Surgery of the Colon, Rectum and Anus Operative Surgery of the Colon, Rectum and Anus, 2015
This is often the setting in which a rotational/fixation defect is encountered in the adult. Abnormalities of fixation facilitate mesenteric and mesocolonic mobilization according to oncologic principles. Nonrotation or partial rotation pose significant difficulties unless the true anatomic conformation is first confirmed. Conversion to an open procecedure via a long midline laparotomy is likely the most appropriate approach in this circumstance. Given the topographic complexity of mesenteric structures, several anatomic points should be reiterated. As in the normal adult, the mesocolon is a continuous entity from small intestinal to mesorectal levels. It is separated from the retroperitoneum by Toldt’s fascia. When a right hemicolectomy is planned, in the setting of abnormalities of rotation, a medial to lateral approach seems appropriate (there is no literature available that informs on this topic). Entry to the mesofascial or retrofascial planes is obtained by first freeing the right mesocolon from adhesions, then dividing the peritoneum where the mesocolon appears to become apposed to the retroperitoneum. Alternatively, access to the appropriate planes can be gained by dividing the peritoneum overlying the ileocecal mesenteric confluence. This anatomic constant is readily identified permitting rapid access to the appropriate plane for mesocolonic mobilization.
Management of Toxic Colitis
Published in Peter Sagar, Andrew G. Hill, Charles H. Knowles, Stefan Post, Willem A. Bemelman, Patricia L. Roberts, Susan Galandiuk, John R.T. Monson, Michael R.B. Keighley, Norman S. Williams, Keighley & Williams’ Surgery of the Anus, Rectum and Colon, 2019
Sean T. Martin, Ravi Pokala Kiran
In the retrograde approach, with the patient in maximum Trendelenburg position, the dissection commences at the pelvic brim. A lateral to medial approach then allows mobilising the sigmoid and descending colon by dividing Toldt’s fascia. The ureter is identified quite easily, as these patients tend to be quite malnourished, with minimal intra-abdominal fat. The mesentry is ligated close to the bowel wall with an electrothermal bipolar vessel-sealing device, such as a Ligasure (Medtronic, Minneapolis, Minnesota) or harmonic scalpel (Ethicon, Cincinnati, Ohio, USA). The splenic flexure is liberated by a dual pronged approach; medial to lateral dissection of the descending mesocolon off the retroperitoneum beneath the inferior mesenteric vein and by lateral dissection of Toldt’s fascia. The distal transverse mesocolon is divided with the energy-sealing device. Attention is then turned to the right colon. With the patient in reverse Trendelenburg position, with right lateral tilt, the ileocolic vessels are approached. The mesentry beneath the ileocolic is divided; the right colonic mesentry is elevated off the retroperitoneum in a medial to lateral fashion. The duodenum and right ureter are identified and preserved. The ileocolic vessels are divided at their origin either with an energy-sealing device, clips or an endoscopic stapling device. The remainder of the right colon mesentry is divided. The caecum is left adherent in the right iliac fossa until the transverse mesocolon has been divided to prevent torsion of the ileum which inevitably occurs with repeated change in the patient position. The central portion of the transverse mesocolon (i.e. that portion containing the middle colic vessels) is addressed next, with care paid to divide the mesentry close to the bowel wall. Once the transverse mesocolon has been divided the caecum can be mobilised to complete the dissection.
The mesentery: an ADME perspective on a ‘new’ organ
Published in Drug Metabolism Reviews, 2018
Aneesh A. Argikar, Upendra A. Argikar
As we know it today, the layers of parietal peritoneum combine to form peritoneal folds called the mesentery (Williams and Warwick 1980; Martini 2006). These fan-shaped peritoneal folds arise from the root of the mesentery located centrally in the abdominal cavity. The mesentery attaches and supports the colon and is collectively known as the mesocolon. Anatomically, the mesocolon is further subdivided in different regions, namely the transverse mesocolon, the sigmoid mesocolon, the mesoappendix, and the mesorectum. The mesentery connects the convoluted small intestine to the posterior abdominal wall. The mesentery provides stability to the stomach and the intestines, and also allows independent movement of the small intestine. A schematic representation of the mesentery is shown in Figure 1. The microscopic anatomy of mesocolon has been previously discussed elsewhere (Culligan et al. 2014). A top layer of surface mesothelium and a bottom layer of retroperitoneum have been documented. Between these layers, a deep mesothelium layer, Toldt’s fascia (a connective tissue layer), and a layer of retroperitoneal mesothelium have been established. Lymphatic tissue has also been observed in the Toldt’s fascia. The adipose tissue and lipids present in the greater omentum are a source of energy and insulate against heat loss from the anterior abdominal wall. Further micro-anatomical details on the mesentery were not available. The connective tissue in the mesenteries contains blood vessels, nerves, and lymphatics to and from the intestinal tract. The possibility of metabolism and transport during this passage of blood could have been overlooked until now or may have been lumped in with intestinal clearance.