Variaciones anatómicas en la vascularización del colon derecho y su implicancia en la escisión completa del mesocolon con linfadenectomía D3. Estudio de corte transversal / Anatomical variations in right colon vascularization: its implication in complete mesocolic excision with D3 lymphadenectomy. A cross-sectional study

Introducción: La escisión completa del mesocolon con linfadenectomía D3 (CME-D3) mejora los resultados de los pacientes operados por cáncer del colon. Reconocer adecuadamente la anatomía vascular es fundamental para evitar complicaciones. Objetivo: El objetivo primario fue determinar la prevalencia de las variaciones anatómicas de la arteria mesentérica superior (AMS) y sus ramas en relación a la vena mesentérica superior (VMS). El objetivo secundario fue evaluar la asociación entre las distintas variantes anatómicas y el sexo y la etnia de lo pacientes. Diseño: Estudio de corte transversal. Material y métodos: Se incluyeron 225 pacientes con cáncer del colon derecho diagnosticados entre enero 2017 y diciembre de 2020. Dos radiólogos independientes describieron la anatomía vascular observada en las tomografías computadas. Según la relación de las ramas de la AMS con la VMS, la población fue dividida en 2 grupos y subdividida en 6 (1a-c, 2a-c). Resultados: La arteria ileocólica fue constante, transcurriendo en el 58,7% de los casos por la cara posterior de la VMS. La arteria cólica derecha, presente en el 39,6% de los pacientes, cruzó la VMS por su cara anterior en el 95,5% de los casos. La variante de subgrupo más frecuente fue la 2a seguida por la 1a (36,4 y 24%, respectivamente). No se encontró asociación entre las variantes anatómicas y el sexo u origen étnico. Conclusión: Las variaciones anatómicas de la AMS y sus ramas son frecuentes y no presentan un patrón predominante. No hubo asociación entre las mismas y el sexo u origen étnico en nuestra cohorte. El reconocimiento preoperatorio de estas variantes mediante angiotomografía resulta útil para evitar lesiones vasculares durante la CME-D3. (AU)

Background: Complete mesocolic excision with D3 lymphadenectomy (CME-D3) improves the outcomes of patients operated on for colon cancer. Proper recognition of vascular anatomy is essential to avoid complications. Aim: Primary outcome was to determine the prevalence of anatomical variations of the superior mesenteric artery (SMA) and its branches in relation to the superior mesenteric vein (SMV). Secondary outcome was to evaluate the association between these anatomical variations and sex and ethnicity of the patients. Design: Cross-sectional study. Material and methods: Two hundred twenty-fivepatients with right colon cancer diagnosed between January 2017 and December 2020 were included. Two independent radiologists described the vascular anatomy of computed tomography scans. The population was divided into 2 groups and subdivided into 6 groups (1a-c, 2a-c), according to the relationship of the SMA and its branches with the SMV. Results: The ileocolic artery was constant, crossing the SMV posteriorly in 58.7% of the cases. The right colic artery, present in 39.6% of the patients, crossed the SMV on its anterior aspect in 95.5% of the cases. The most frequent subgroup variant was 2a followed by 1a (36.4 and 24%, respectively). No association was found between anatomical variants and gender or ethnic origin. Conclusions: The anatomical variations of the SMA and its branches are common, with no predominant pattern. There was no association between anatomical variations and gender or ethnic origin in our cohort. Preoperative evaluation of these variations by computed tomography angi-ography is useful to avoid vascular injuries during CME-D3. (AU)

Laparoscopic right hemicolectomy with CME: standardization using the "critical view" concept.

BACKGROUND: Complete mesocolic excision is gradually becoming an established oncologic surgical principle for right hemicolectomy. However, the procedure is technically demanding and carries the risk of serious complications, especially when performed laparoscopically. A standardized procedure that minimizes technical hazards and facilitates teaching is, therefore, highly desirable. METHODS: An expert group of surgeons and one anatomist met three times. The initial aim was to achieve consensus about the surgical anatomy before agreeing on a sequence for dissection in laparoscopic CME. This proposal was evaluated and discussed in an anatomy workshop using post-mortem body donors along with videos of process-informed procedures, leading to a definite consensus. RESULTS: In order to provide a clear picture of the surgical anatomy, the "open book" model was developed, consisting of symbolic pages representing the corresponding dissection planes (retroperitoneal, ileocolic, transverse mesocolic, and mesogastric), vascular relations, and radicality criteria. The description of the procedure is based on eight preparative milestones, which all serve as critical views of safety. The chosen sequence of the milestones was designed to maximize control during central vascular dissection. Failure to reach any of the critical views should alert the surgeon to a possible incorrect dissection and to consider converting to an open procedure. CONCLUSION: Combining the open-book anatomical model with a clearly structured dissection sequence, using critical views as safety checkpoints, may provide a safe and efficient platform for teaching laparoscopic right hemicolectomy with CME.

The length of the large intestine in children determined by computed tomography scan.

Little information is available on the length of the normal large intestine and its component parts in children. This information would be useful for procedures such as colonoscopy. The aim of this study was to investigate the length of the large intestine and its component parts in New Zealand children. Archival deidentified pediatric supine abdominopelvic computed tomography (CT) scans were retrospectively analyzed. After exclusion criteria, a total of 112 scans (57 males and 55 females) were included in the study and divided into three age groups: 0-2 years (n = 33), 4-6 years (n = 40), and 9-11 years of age (n = 39). The length of the large bowel increased from a mean of 52 cm in children aged <2 years to 73 cm at 4-6 years and 95 cm at 9-11 years. In all age groups, the transverse colon was the longest segment, contributing ∼30% of the total length of the large bowel. In comparison to total large bowel length, the mean proportional length of the rectum (9-12%), sigmoid colon (23-27%), descending colon (19-22%), transverse colon (27-32%), and ascending colon (14-17%) varied little between the three age groups. There were no significant differences between males and females in all age groups. The cecum was located in the right upper quadrant in 27% of children aged 0-2 years but in the right lower quadrant in all 9-11 year olds. These data provide useful information on the length of the large intestine and its component parts in living children, which are particularly relevant to pediatric colonoscopy and surgery. Clin. Anat. 30:887-893, 2017. © 2017 Wiley Periodicals, Inc.

An unusual case of colon vascularization by the inferior mesenteric artery / Um caso incomum de vascularização do cólon pela artéria mesentérica inferior

Abstract In this article we present a rare variant in which the large intestine was vascularized by the inferior mesenteric artery. It was encountered during macro and microscopic dissection of the cadaver of a 63-year-old woman at a university department of human anatomy. In this case, the ascending, transverse, descending, and sigmoid colon and rectum were vascularized by the inferior mesenteric artery, whereas the small intestine, cecum and appendix were supplied by the superior mesenteric artery.

Resumo Neste artigo apresentamos uma variação rara em que o intestino grosso era vascularizado pela artéria mesentérica inferior. A variação foi descoberta durante a dissecção macro e microscópia de um cadáver do sexo feminino, 63 anos de idade, em um departamento universitário de anatomia humana. Neste caso, o cólon ascendente, transverso, descendente e sigmoide e também o reto eram vascularizados pela artéria mesentérica inferior, ao passo que o intestino delgado, ceco e apêndice eram vascularizados pela artéria mesentéria superior.

Mesocolic Lymph Node Number, Size, and Density: An Anatomical Study.

BACKGROUND: Lymph nodes play a critical role in the staging, treatment, and prognosis of colon cancer. However, the normal number and morphology of lymph nodes in the normal mesocolon is unknown. OBJECTIVE: This study aimed to investigate the number and size of lymph nodes in the ascending and sigmoid mesocolons. DESIGN: This is a descriptive anatomical cadaver study of 10 sigmoid mesocolons and 5 ascending mesocolons, resected in a standardized manner and examined systematically after serial histological sectioning. The number, maximum length, and appearance of lymph nodes were analyzed, and the 2 mesocolons were compared by using the Mann-Whitney U test, the Wilcoxon signed rank test, and the χ test. PATIENTS: Ten cadavers (mean age, 82.9 years; 5 male) with no evidence of colorectal disease were examined. MAIN OUTCOME MEASURE: The number, maximum length, and appearance of lymph nodes and fat-associated lymphoid clusters were the primary outcomes measured. RESULTS: The median number of lymph nodes in the sigmoid and ascending mesocolons was 71 (range, 24-116) and 61 (range, 33-71). More than 90% of lymph nodes were less than 5 mm in maximum length. Sigmoid mesocolic nodes were significantly smaller than ascending mesocolic nodes (median maximum lymph nodes length, 1.6 mm vs 2.1 mm; p < 0.001), but there was no statistically significant difference in the density of lymph nodes between the sigmoid and ascending mesocolon. Fatty replacement was seen in almost 30% of lymph nodes. A few fat-associated lymphoid clusters were observed in both mesocolons. LIMITATIONS: Only 15 mesocolic specimens could be examined because of the detailed labor-intensive methodology, and younger cadavers were not available for analysis. CONCLUSIONS: In this descriptive anatomical study, the median number of lymph nodes in the sigmoid and ascending mesocolon was 71 and 61. Ascending mesocolic nodes were significantly larger than sigmoid mesocolic nodes. These anatomical findings are relevant to the interpretation of lymph node yields after the surgical resection of colon cancer.

Lateral pouch appendix associated with retroperitoneal terminal part of the ileum: a potential diagnostic and surgical challenge.

Knowledge of development and various possible positions of the appendix is important in understanding the pathophysiology of appendicitis. In the present case, we report on a lateral pouch type of appendix in a formalin-embalmed male cadaver. The appendix was found to be situated in a space between the caecum and the lateral abdominal wall. A short band of peritoneum extended from the right iliac fossa to the base of the appendix. The terminal part of the ileum was retroperitoneal and it was vertically situated in the right iliac fossa. Both the ileocaecal junction and the base of the appendix were located at the posterolateral wall of the caecum. The mesoappendix was unusual in position, and it extended from the appendix to the anterolateral wall of the caecum and commencement of the ascending colon. Documentation of rare anatomical variants of the appendix may hold significant clinical importance in diagnosis as well as surgical treatment of appendicitis.

Laparoscopic and endoscopic exploration of the ascending colon wall based on a cadaver sectioned images.

For realistic virtual dissection, the sectioned images of a cadaver are a desirable material because of their high resolution and real body color. After a volume model is made of the sectioned images, it can be piled or peeled at the intended thickness as if a structure's surface is expanded and shrunken. The purpose of our study was to confirm whether laparoscopic and endoscopic exploration of the processed volume model plays a part in anatomy investigation. The ascending colon was outlined in serially sectioned images and accumulated to build a volume model. While the volume model was being piled or peeled, the ascending colon was observed laparoscopically and endoscopically in comparison with the original sectioned image. The trial efficiently demonstrated layers of the colon wall and surrounding tissues which could not be visualized by conventional macroscopic or microscopic techniques. The availability and contribution of this new method will be confirmed by application to other various organs.

Retrocolic spaces: anatomy of the surgical planes in laparoscopic right hemicolectomy for cancer.

To explore the regional anatomy of the fasciae and spaces around the right-side colon from laparoscopic perspective, we observed the location, extension, and boundaries of the spaces around the right-side colon in seven cadavers and in 49 patients undergoing laparoscopic right hemicolectomy for cancer, and reviewed computed tomography images from patients and healthy individuals. Between the ascending mesocolon and prerenal fascia (PRF), there was a right retrocolic space (RRCS), which extended in all directions. The anterior, posterior, medial, lateral, cranial, and caudal boundaries of the RRCS were the ascending mesocolon, PRF, superior mesenteric vein, right paracolic sulcus, inferior margin of the duodenum, and inferior margin of the mesentery radix, respectively. Between the transverse mesocolon and the pancreas and duodenum, there was a transverse retrocolic space, which was enclosed cranially by the radix of the transverse mesocolon. In CT images, healthy PRF was noted as slender line of middle density, continuing to the transverse fascia. The retrocolic spaces was unidentifiable, unless they were filled with retroperitoneal lesions. The RRCS and transverse retrocolic space are natural surgical planes for laparoscopic right hemicolectomy for cancer. The boundaries of these fusion fascial spaces are the best access, and the PRF is the best guide.

Spatial organization of intestinal microbiota in the mouse ascending colon.

Complex microbial populations are organized in relation to their environment. In the intestine, the inner lining (mucosa) is a potential focal point for such organization. The proximal murine colon contains mucosal folds that are known to be associated with morphologically distinct microbes. To identify these microbes, we used the technique of laser capture microdissection (LCM) to sample microbes associated with these folds (interfold region) and within the central lumen (digesta region). Using 16S rRNA gene tag pyrosequencing, we found that microbes in the interfold region were highly enriched for the phylum Firmicutes and, more specifically, for the families Lachnospiraceae and Ruminococcaceae. Other families such as Bacteroidaceae, Enterococcaceae and Lactobacillaceae were all enriched in the digesta region. This high-resolution system to capture and examine spatial organization of intestinal microbes should facilitate microbial analysis in other mouse models, furthering our understanding of host-microbial interactions.

Sympathovagal balance fluctuates during colonoscopy.

BACKGROUND AND STUDY AIM: Colonoscopy is a common gastroenterological procedure for investigation of the bowel. The main side effects of colonoscopy are pain during investigation, cardiovascular complications and very rarely even death. The aim of this study was to compare the continuous fluctuation of heart rate variability (HRV) components during colonoscopy under normal conditions, analgesia/sedation, and total intravenous anesthesia. PATIENTS AND METHODS: 37 consecutive patients (aged 35 - 65), were randomly allocated to three groups: no sedation (control group 1); analgesia/sedation (group 2); and total intravenous anesthesia (group 3). Holter electrocardiography and subsequent frequency domain analysis were undertaken. The low-frequency (LF, 0.04 - 0.15 Hz) and the high-frequency (HF, 0.15 - 0.40 Hz) components were estimated using spectral analysis in the usual way. Normalized units (nu) were calculated from the following equations: LFnu = LF/(LF + HF), and HFnu = HF/(LF + HF). RESULTS: Groups 2 and 3 were found to have a significantly lower HFnu and higher LFnu than group 1 essentially throughout the procedure. A one-way analysis of variance and t-test confirmed that the differences were significant when the colonoscope reached the splenic flexure as were the LF/HF balances at the splenic and hepatic flexures and the cecum. The percentage change in LF/HF was also analyzed, and it was found that in group 3 the mean change was over 136 % when the colonoscope reached the sigmoid flexure, which was significantly higher than in the other two groups. CONCLUSION: Most changes in HRV components occurred during colonoscopy of the left side of the bowel. Analgesia/sedation and total intravenous anesthesia increased HRV by increasing the LF component.