Dara Walsh

Terminology and nomenclature in colonic surgery: universal application of a rule-based approach derived from updates on mesenteric anatomy

Recent developments in colonic surgery generate exciting opportunities for surgeons and trainees. In the first instance, the anatomy of the entire mesenteric organ has been clarified and greatly simplified. No longer is it regarded as fragmented and complex. Rather it is continuous from duodenojejunal flexure to mesorectum, spanning the gastrointestinal tract between. Recent histologic findings have demonstrated that although apposed to the retroperitoneum, the mesenteric organ is separated from this via Toldt’s fascia. These fundamentally important observations underpin the principles of complete mesocolic excision, where the mesocolic package is maintained intact, following extensive mesenterectomy. More importantly, they provide the first opportunity to apply a canonical approach to the development of nomenclature in resectional colonic surgery. In this review, we demonstrate how the resultant nomenclature is entirely anatomic based, and for illustrative purposes, we apply it to the procedure conventionally referred to as right hemicolectomy, or ileocolic resection.

Mesenteric-Based Surgery Exploits Gastrointestinal, Peritoneal, Mesenteric and Fascial Continuity from Duodenojejunal Flexure to the Anorectal Junction--A Review.

Introduction: It is now well established that mesenteric-based colorectal surgery is associated with superior outcomes. Recent anatomic observations have demonstrated that the mesenteric organ is contiguous from the duodenojejunal to the anorectal junction. This led to similar observations in relation to associated peritoneum and fascia. The aim of this review was to demonstrate the relevance of the contiguity principle to resectional colorectal surgery. Methods: All literature in relation to mesenteric anatomy was reviewed from 1873 to the present, without language restriction. Results: Mesenteric-based surgery (i.e. complete mesocolic excision, total mesocolic and mesorectal excision) requires division of the peritoneal reflection (i.e. peritonotomy), and mesenteric mobilisation in the mesofascial plane. These are the fundamental technical elements of mesenterectomy. Mesenteric, peritoneal and fascial contiguity mean that in resectional surgery, these technical elements can be reproducibly applied at all levels from the origin at the superior mesenteric root, to the anorectal junction. Conclusions: The goals of complete mesocolic, total mesocolic and mesorectal excision can be universally achieved at any level from duodenojejunal flexure to anorectal junction, by adopting technical elements based on mesenteric, peritoneal and fascial contiguity.

The importance of selecting the appropriate reference genes for quantitative real time PCR as illustrated using colon cancer cells and tissue.

Quantitative real-time reverse-transcription polymerase chain reaction (RT-qPCR) remains the most sensitive technique for nucleic acid quantification. Its popularity is reflected in the remarkable number of publications reporting RT-qPCR data. Careful normalisation within RT-qPCR studies is imperative to ensure accurate quantification of mRNA levels. This is commonly achieved through the use of reference genes as an internal control to normalise the mRNA levels between different samples. The selection of appropriate reference genes can be a challenge as transcript levels vary with physiology, pathology and development, making the information within the transcriptome flexible and variable. In this study, we examined the variation in expression of a panel of nine candidate reference genes in HCT116 and HT29 2-dimensional and 3-dimensional cultures, as well as in normal and cancerous colon tissue. Using normfinder we identified the top three most stable genes for all conditions. Further to this we compared the change in expression of a selection of PKC coding genes when the data was normalised to one reference gene and three reference genes. Here we demonstrated that there is a variation in the fold changes obtained dependent on the number of reference genes used. As well as this, we highlight important considerations namely; assay efficiency tests, inhibition tests and RNA assessment which should also be implemented into all RT-qPCR studies. All this data combined demonstrates the need for careful experimental design in RT-qPCR studies to help eliminate false interpretation and reporting of results.Quantitative real-time reverse-transcription polymerase chain reaction (RT-qPCR) remains the most sensitive technique for nucleic acid quantification. Its popularity is reflected in the remarkable number of publications reporting RT-qPCR data. Careful normalisation within RT-qPCR studies is imperative to ensure accurate quantification of mRNA levels. This is commonly achieved through the use of reference genes as an internal control to normalise the mRNA levels between different samples. The selection of appropriate reference genes can be a challenge as transcript levels vary with physiology, pathology and development, making the information within the transcriptome flexible and variable. In this study, we examined the variation in expression of a panel of nine candidate reference genes in HCT116 and HT29 2-dimensional and 3-dimensional cultures, as well as in normal and cancerous colon tissue. Using normfinder we identified the top three most stable genes for all conditions. Further to this we compared the change in expression of a selection of PKC coding genes when the data was normalised to one reference gene and three reference genes. Here we demonstrated that there is a variation in the fold changes obtained dependent on the number of reference genes used. As well as this, we highlight important considerations namely; assay efficiency tests, inhibition tests and RNA assessment which should also be implemented into all RT-qPCR studies. All this data combined demonstrates the need for careful experimental design in RT-qPCR studies to help eliminate false interpretation and reporting of results.

Digital sculpting in surgery: a novel approach to depicting mesosigmoid mobilization.

BackgroundThe aim of the present study was to develop a unique anatomic replica of the mesocolon using digital graphical software in order to provide an educational template for mesosigmoidectomy.MethodsThe colon and mesocolon were fully mobilized from ileocecal to mesorectal levels in a cadaver. Both colon and mesocolon provided a template from which to generate a three dimensional replica in ZBrush. The model was deformed in ZBrush, to compare and contrast current and classic interpretations of mesosigmoidal topography. An animation was developed in which the replica was deformed to mimic operative mobilization. Contiguous shape changes were captured in two-and-a-half-dimensional (2.5D) screen snapshots. This was repeated for medial to lateral and lateral to medial mobilization of the mesosigmoid.ResultsTopographic differences between classic and current appraisals of mesocolic anatomy were evident in 2.5D format. Using the model generated, contiguous shape changes during mesosigmoidal mobilization (i.e., between the left mesocolon, mobile/apposed mesosigmoid, and mesorectum) were replicated in animation format. By extracting and compiling 2.5D screen grabs a pictorial chronology of mobilization was developed.ConclusionsRecent advances in mesocolic topography can be captured and rendered using advanced digital sculpting software with high-end graphics capabilities. This approach permits a depiction of contiguous changes in mesosigmoidal topography during mesosigmoidal mobilization. A compilation of images in either animation or screen grab format obviates the interpolation of shape changes required using standard educational approaches.

Using fluorescence lymphangiography to define the ileocolic mesentery: proof of concept for the watershed area using real-time imaging

Recent advances in mesenteric science have demonstrated that the mesentery is a continuous structure with a ‘watershed’ area at the mesenteric apex between the right colon and terminal ileum, where lymphatic flow can proceed either proximally or distally. With this new understanding of the anatomy, functional features are emerging, which can have an impact on surgical management. Fluorescence lymphangiography or lymphoscintigraphy with indocyanine green allows real-time visualization of lymphatic channels, which highlights sentinel lymph nodes and may facilitate identification of the ideal margins for mesenteric lymphadenectomy during bowel resection for colon cancer. By using this novel technology, it is possible to demonstrate a watershed area in the ileocolic region and may facilitate more precise mesenteric dissection. In the present study, we provide proof of concept for the ileocolic watershed area using fluorescence lymphangiography.

Anatomy of the mesentery: Current understanding and mechanisms of attachment

An understanding of the anatomy of the mesentery is necessary to undertake any appraisal of the literature on its development. The mesentery is the collection of tissues that maintain all abdominal digestive organs in position and connection with the rest of the body. Therefore, it is also necessary to detail the exact mechanisms that maintain the mesentery in position. We explore these mechanisms, including the supportive functions of structures such as Toldts fascia, the peritoneal reflection, and vascular connections, in this article.

3D modelling of non-intestinal colorectal anatomy

AbstractPurposeThere is a paucity of methods to model soft anatomical tissues. Accurate modelling of these tissues can be difficult with current medical imaging technology. MethodsThe aim of this research was to develop a methodology to model non-intestinal colorectal tissues that are not readily identifiable radiologically to enhance contextual understanding of these tissues and inform medical device design. The models created were used to inform the design of a novel medical device to separate the mesocolon from the retroperitoneum during resection of the colon. We modelled the peritoneum and the mesentery. The mesentery was used to indicate the location of Toldt’s fascia.ResultsWe generated a point cloud dataset using cryosection images as the target anatomy is more visible than in CT or MRI images. The thickness of the mesentery could not be accurately determined as point cloud data do not have thickness. A denser point cloud detailing the mesenteric boundaries could be used to address this.ConclusionsExpert anatomical and surgical insight and point cloud data modelling methods can be used to model soft tissues. This research enhances the overall understanding of the mesentery and Toldt’s fascia in the human specimen which is necessary for medical device innovations for colorectal surgical procedures.

Identification of the optimal visual recording system in open abdominal surgery - a prospective observational study.

Abstract Introduction: Current methodologies used to record and render the surgeon’s point of view in open operative surgery remain limited. Chief among these limitations is a failure to demonstrate, in high definition and magnification, the planar roadmap that surgeons utilise in colorectal surgery. The high magnification and high resolution views provided during laparoscopic surgery simultaneously capture the planar road map and surgeon’s point of view. We developed an arm-mounted external laparoscope (exoscope) system and compared its performance against multiple standard recording modalities. Methods: Following ethical approval and informed consent, open colorectal procedures were recorded using five separate methodologies. Each methodology was assessed and compared. Results: Most of the methodologies utilised scored poorly at one if not more levels. The arm-mounted external laparoscope (exoscope) scored highest in rendering the surgeon’s point of view while simultaneously achieving high resolution and high magnification rendition of operative field (p < .001). This methodology was tested in a number of operative contexts within which it reproducibly and consistently scored highly. Conclusions: The arm-mounted exoscope is the optimal means of rendering the surgeon’s point of view of anatomic planes during open colorectal surgery.