Revista nº 815

Anatomic variations of the healthy colon | Fernando J, et al. 24 Actual Med.2022;107(815):18- 26 Specific radiological analysis has substantially improved anatomical study of the colon and is now considered a fundamental tool for the study of normal anatomy, modified anatomy, and pathology of this organ. (6,21) The application of three-dimensional reconstruction technology from radiological images has been an important development in this regard. This method offers improved diagnostic possibilities and permits comparative studies for evaluation of the potential influence of external factors on the anatomy of the colon. (9,22,23) The morphometric studies of the colon described in the literature to date have generally used different measurement variables depending on the aim of the study. The Khashab group described colon segment lengths and lumen diameters through the use of virtual colonoscopy in order to evaluate the existing variability and differences based on sex, age, and BMI. (23) In our study, we have considered the anatomical reference points proposed by the Bourgouin group, (7) adding an additional bone point (PUBIS) and the points of the vascular elements (SMA and IMA), to morphometrically define the characteristics of the colon. The pubis has been considered a fixed anatomical point, although it should be borne in mind that movements of nutation and counternutation of the sacroiliac joint could cause minimal displacement of the pubis that may not be considered significant. (24,25) Our results show that sex, age, and BMI have a significant influence on the normal anatomy of the colon, which is consistent with previous reports in the literature. The Khashab group previously reported a significantly greater total colonic length in women than in men and a significantly shorter colonic length in patients with a body mass index (BMI) greater than 25. They did not report differences in total colon length between patients over 60 years and younger patients; however, in this group, they identified a significant difference in the length of the transverse colon. (23) The Bourgouin group suggested creating different anatomical models based on different groups related to sex, age, and BMI by digitizing the colon anatomical reference points proposed. In this study, men showed a higher and deeper hepatic flexure of the colon than women, while the splenic flexure was more lateralized, with no differences in the ICJ or in the SDJ. (7) Regarding age, there were only differences in the transverse mesocolon, which is significantly shorter in patients under 60 years of age. When studying the influence of body volume, overweight patients have previously been found to have a shorter right colon due to greater lateralization and depth of the ICJ. (7) Sex was the primary factor identified in this study, with more influence on anatomical variability, especially with the colon flexures considered as fixation elements. All the measurements analyzed in our study were greater in men, except for the distances between the pubis and both mesenteric arteries and the angle formed by the IMA and both colon flexures. As in the studies described above (7,23) the hepatic and splenic flexures were located higher in men because of their greater distance from the pubis (using it as a fixed point); the splenic flexure was the only significantly different position. Both mesenteric arteries should be considered as being higher in women, although the IMA is the primary one responsible for significant differences compared to men. In our analysis based on age groups, there were no differences in the distances between the pubis and colon reference points, but there were differences in the angle formed by these three points. Furthermore, the correlation between age and this angle was also significant. It should therefore be understood that the fixation points of the colon at the flexures must be more lateralized in older patients; this is consistent with the proposals by the Bourgouin group, who attributed this finding to the different distributions and dispositions of intra- abdominal fat. (7,23) There were also differences in the distances when considering the vascular elements, and although the location of the origin of the mesocolon could not be considered—as it has not been measured—the distance to the vessel closest to the mesocolon (the SMA) is greater in older patients, consistent with previous studies. (7) This was confirmed by the negative correlation between age and both of the distances between the pubis and mesenteric arteries. The influence of BMI on the anatomy of the colon described in our study is important. The stratification scheme in this study—normal weight, overweight and obese—differs from that in the previous studies mentioned, in which only two groups were considered. The normal weight and overweight group and the normal weight and obese groups showed significant differences between the pubis and ICJ and between the pubis and SDJ, with these points identified as being more lateral and deeper in more obese patients. This confirms the previous results from the Bourgouin group, which hypothesized that intra-abdominal fat is distributed in lower areas of the abdomen in obese patients. (7) Our study results differ in the disposition of the hepatic flexure of the colon as we identified differences between both groups, which have not been described in previous studies.(7,23) In fact, when analyzing the correlation between BMI and morphometric variables, we observed that there was a greater distance from the pubis to all colon reference points in more obese patients, as well as greater distance between the arteries, which could also be explained by a greater amount of intra-abdominal fat. A potential limitation of the present study could be the proposed reconstruction method. The manual