The role of sigmoid colon anatomic dimensions in the development of sigmoid volvulus, North-Western Ethiopia.

INTRODUCTION: Sigmoid colon anatomic dimensions have been studied to have roles in the occurrence of sigmoid volvulus; however, these studies are few in number and failed to control the confounding effect of acute sigmoid obstruction on the anatomic dimensions. The main objective of this study was to assess the role of sigmoid colon anatomic dimensions in the development of sigmoid volvulus controlling the effect of acute sigmoid obstruction on the anatomic dimensions. MATERIALS AND METHODS: The study was carried out from Dec, 2019 to April, 2021 at Tibebe Ghion Specialized Hospital and Felege Hiwot Comprehensive Specialized Hospital, two referral hospitals in Bahir Dar city, North-Western Ethiopia to compare sigmoid anatomic dimensions among three independent groups of participants: patients with no history of sigmoid volvulus (I), those for whom elective surgery was done after non-surgical detorsion of sigmoid volvulus (II), and patients for whom emergency surgery was done for sigmoid volvulus (III). The anatomic dimensions were compared using fixed effects one-way ANOVA or Kruskal-Wallis H test at p-value ≤ .05 (two-sided) and Tukey method or Dunn-Bonferroni's test was used for post-hoc comparisons. RESULTS: A total of 66 consecutive eligible patients (22 for each of the three groups) were included and analyzed in the study. The means of anatomic dimensions (in cm) for groups (I, II, III) were: sigmoid colon length-SCL (35.91, 71.07, 80.86), meso-sigmoid height-MSH (17.11, 26.52, 28.86), meso-sigmoid maximal width-MSMW (9.70, 14.89,16.80), and meso-sigmoid root width-MSRW (8.34, 7.48, 8.11). SCL, MSH, MSMW, MSH/MSRW, and MSMW/MSRW were found to be statistically significantly different in patients with sigmoid volvulus. MSRW and MSH/MSMW were not different between the study groups. CONCLUSION: A long sigmoid colon with long and wide mesentery, but with a constant base is highly likely to predispose individuals to sigmoid volvulus.

The Sphincter of O'Beirne-Part 2: Report of a Case of Chronic Constipation with Autonomous Dyssynergia.

BACKGROUND: Chronic constipation can have one or more of many etiologies, and a diagnosis based on symptoms is not sufficient as a basis for treatment, in particular surgery. AIM: To investigate the cause of chronic constipation in a patient with complete absence of spontaneous bowel movements. METHODS: High-resolution colonic manometry was performed to assess motor functions of the colon, rectum, the sphincter of O'Beirne and the anal sphincters. RESULTS: Normal colonic motor patterns were observed, even at baseline, but a prominent high-pressure zone at the rectosigmoid junction, the sphincter of O'Beirne, was consistently present. In response to high-amplitude propagating pressure waves (HAPWs) that were not consciously perceived, the sphincter and the anal sphincters would not relax and paradoxically contract, identified as autonomous dyssynergia. Rectal bisacodyl evoked marked HAPW activity with complete relaxation of the sphincter of O'Beirne and the anal sphincters, indicating that all neural pathways to generate the coloanal reflex were intact but had low sensitivity to physiological stimuli. A retrograde propagating cyclic motor pattern initiated at the sphincter of O'Beirne, likely contributing to failure of content to move into the rectum. CONCLUSIONS: Chronic constipation without the presence of spontaneous bowel movements can be associated with normal colonic motor patterns but a highly exaggerated pressure at the rectosigmoid junction: the sphincter of O'Beirne, and failure of this sphincter and the anal sphincters to relax associated with propulsive motor patterns. The sphincter of O'Beirne can be an important part of the pathophysiology of chronic constipation.

The Sphincter of O'Beirne - Part 1: Study of 18 Normal Subjects.

BACKGROUND: Gastroenterologists have ignored or emphasized the importance of the rectosigmoid junction in continence or constipation on and off for 200 years. Here, we revisit its significance using high-resolution colonic manometry. METHODS: Manometry, using an 84-channel water-perfused catheter, was performed in 18 healthy volunteers. RESULTS: The rectosigmoid junction registers as an intermittent pressure band of 26.2 ± 7.2 mmHg, or intermittent phasic transient pressure increases at a dominant frequency of 3 cpm and an amplitude of 28.6 ± 8.6 mmHg; or a combination of tone and transient pressures, at a single sensor, 10-17 cm above the anal verge. Features are its relaxation or contraction in concert with relaxation or contraction of the anal sphincters when a motor pattern such as a high-amplitude propagating pressure wave or a simultaneous pressure wave comes down, indicating that such pressure increases or decreases at the rectosigmoid junction are part of neurally driven programs. We show that the junction is a site where motor patterns end, or where they start; e.g. retrogradely propagating cyclic motor patterns emerge from the junction. CONCLUSIONS: The rectosigmoid junction is a functional sphincter that should be referred to as the sphincter of O'Beirne; it is part of the "braking mechanism," contributing to continence by keeping content away from the rectum. In an accompanying case report, we show that its excessive presence in a patient with severe constipation can be a primary pathophysiology.

Ex vivo specimen MRI and pathology confirm a rectosigmoid mesenteric waist at the junction of the mesorectum and mesocolon.

AIM: Continuity of the mesentery has recently been established and may provide an anatomical basis for optimal colorectal resectional surgery. Preliminary data from operative specimen measurements suggest there is a tapering in the mesentery of the distal sigmoid. A mesenteric waist in this area may be a risk factor for local recurrence of colorectal cancer. This study aimed to investigate the anatomical characteristics of the mesentery at the colorectal junction. METHOD: In this cross-sectional study, 20 patients were recruited. After planned colorectal resection, the surgical specimens were scanned in a MRI system and subsequently dissected and photographed as per national pathology guidelines. Mesenteric surface area and linear measurements were compared between MRI and pathology to establish the presence and location of a mesenteric waist. RESULTS: Specimen analysis confirmed that a narrowing in the mesenteric surface area was consistently apparent at the rectosigmoid junction. Above the anterior peritoneal reflection, the surface area and posterior distance of the mesentery of the upper rectum initially decreased before increasing as the mesentery of the sigmoid colon. These anatomical properties created the appearance of a mesenteric 'waist' at the rectosigmoid junction. Using the anterior reflection as a reference landmark, the rectosigmoid waist occurred at a mean height of 23.6 and 21.7 mm on MRI and pathology, respectively. CONCLUSION: A rectosigmoid waist occurs at the junction of the mesorectum and mesocolon, and is a mesenteric landmark for the rectum that is present on both radiology and pathology.

The rectosigmoid junction: are limits important?

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The rectosigmoid junction: are limits important?

The rectosigmoid junction (RSJ) is the limit between the sigmoid colon and the rectum. The limits of this transition zone have been a source of controversy. There are multiple definitions that aim to establish the beginning of the rectum. Some organizations propose the use of more than one definition. Generally, these definitions use either radiological markings, endoscopic measurements or anatomical landmarks. However, no consensus exists currently.

Variation in landmarks for the rectum: an MRI study.

AIM: This study aimed to assess the reliability of measurements and bony landmarks for the rectosigmoid junction on MRI. METHOD: The staging MRI scans for 100 patients were reviewed. The junction of the mesorectum and mesocolon was used to identify the rectum and sigmoid. The performance of current metric measurements or bony landmarks was then compared against the actual anatomical bowel segment. RESULTS: The mean distance of the sigmoid take-off from the anal verge was 12.6 cm (SD 1.8 cm, range 9.4-19.0 cm). At a cutoff of 12 cm, the anatomical bowel segment was found to be sigmoid colon rather than rectum in 35% of patients. At 15 and 16 cm the bowel segment was sigmoid in 84% and 96% of patients, respectively. At the sacral promontory and the third sacral segment, the bowel segment was sigmoid in 28% and 100% of patients, respectively. CONCLUSION: Current definitions of the rectum that rely on arbitrary measurements or bony landmarks will not locate the correct point of transition between the rectum and sigmoid in the majority of patients. The sigmoid take-off offers an alternative, anatomically bespoke, landmark.

[Application of sigmoid colon anatomy to laparoscopic surgery].

Laparoscopic sigmoidectomy for cancer is considered as a simple surgical approach, which is suitable for primary laparoscopic surgery. However, the success of laparoscopic sigmoidectomy is closely related to the anatomical characteristics of the sigmoid colon. The length, adhesion and morphology of the sigmoid colon vary greatly. The differences of the length, width, adhesion and morphology of the mesentery are large. The distribution of vessels is diversified. The high ligation or the low ligation is still controversial. The location of the sigmoid colon cancer is also not constant. These problems have great influence on the operation. Before operation, the tumor must be accurately located and the anatomical characteristics of the sigmoid colon must be fully evaluated. The operation can be carried out smoothly and the complications during and after the operation can be reduced.

Clinical relevance of the arterial supply to the proximal rectum

Although the rectum is considered to be an organ rich in vascularity, the exact role of the middle rectal artery appears to be an area of much debate. Despite its principal supply from the superior rectal artery, there is a lack of information regarding the arterial supply to the fractionized proximal rectal regions. The approach to operative procedures in the case of recto-sigmoid carcinoma, intestinal embolization and haemorrhoidal disease are considered to be largely dependent on the intramural rectal anastomosis. Since the subsequent outcome of surgical intervention lies in the preservation of the respective rectal arteries, this study aimed to identify the proximal rectal arterial supply and the bilateral presence and/or variation of the middle rectal artery in ten fetal and ten adult cadaveric specimens (n=40). While the superior rectal artery presented as the principal arterial source to the proximal rectum, the respective regions of the proximal rectum were also found to be supplied by the median sacral and middle rectal arteries. The inconsistent morphological inconstant nature of the middle rectal artery confirmed that it does not represent the principal arterial source of the proximal rectum; however it was postulated that the middle rectal artery is regularly present in female individuals. As the regional arterial supply to the proximal rectum was investigated in accordance with appropriate anatomical landmarks, it may also be used to demarcate the specific regions of the proximal rectum. Furthermore, this may assist to preserve the rectal arterial supply during the Hartmann’s Procedure (AU)

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Is it possible to give a single definition of the rectosigmoid junction?

AIM: The rectosigmoid junction is the limit separating the sigmoid colon and rectum. This transition zone has different definitions. We want to highlight different landmarks of the rectosigmoid junction (RSJ), to help the clinicians to adopt a consensual definition. METHOD: We reviewed anatomical, endoscopic, physiological and surgical points of view concerning the rectosigmoid junction (RSJ). RESULTS: The rectosigmoid junction has a different definition depending on who is studying it. Nevertheless, it is a high pressure location, a place connecting different muscles organizations, neurological systems or vascular anastomosis. The clear pathophysiology of the RSJ is not yet determined with certainty, but its resection is essential for the therapeutic care of patients and also for the improvement of surgical skills. From a surgical point of view, anatomical landmarks has to be chosen: easily reproducible and identifiable. The disappearance of taenia coli (belonging to the colon) and the peritoneal reflection (recto-genital pouch), located below the upper rectum, seem the most reliable. The level of rectal section must, in any case, be below the promontory. CONCLUSION: There is not a single definition, but rather several definitions of the RSJ. Each one of them reflects one appearance of this region: embryological and anatomical evolution or clinical entity. From a surgical point of view, the criterion which seems to be the most reliable is the disappearance of taenia coli and the peritoneal reflection (recto-genital pouch).

Differences between genders in colorectal morphology on CT colonography using a quantitative approach: a pilot study.

PURPOSE: To explore quantitative differences between genders in morphologic colonic metrics and determine metric reproducibility. METHODS: Quantitative colonic metrics from 20 male and 20 female CTC datasets were evaluated twice by two readers; all exams were performed after incomplete optical colonoscopy. Intra-/inter-reader reliability was measured with intraclass correlation coefficient (ICC) and concordance correlation coefficient (CCC). RESULTS: Women had overall decreased colonic volume, increased tortuosity and compactness and lower sigmoid apex height on CTC compared to men (p<0.0001,all). Quantitative measurements in colonic metrics were highly reproducible (ICC=0.9989 and 0.9970; CCC=0.9945). CONCLUSION: Quantitative morphologic differences between genders can be reproducibility measured.

Clinical anatomy of fecal incontinence in women.

Fecal incontinence is a devastating condition that has a severe impact on quality of life. This condition disproportionately affects women and its incidence is increasing with the aging United States population. Fecal continence is maintained by coordination of a functioning anal sphincter complex, intact sensation of the anorectum, rectal compliance, and the ability to consciously control defecation. Particularly important are the puborectalis sling of the levator ani muscle complex and intact innervation of the central and peripheral nervous systems. An understanding of the intricate anatomy required to maintain continence and regulate defecation will help clinicians to provide appropriate medical and surgical management and diminish the negative impact of fecal incontinence. In this article, we describe the anatomic and neural basis of fecal continence and normal defecation as well as changes that occur with fecal incontinence in women. Clin. Anat. 30:901-911, 2017. © 2017 Wiley Periodicals, Inc.

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.

Matrix metalloproteases expression in different histological types of colorectal polyps

Introduction: Colorectal carcinoma (CC) may begin as benign polyps, which may be classified in different histological types with a different risk to develop cancer. Matrix metalloproteases (MMPs) are able to degrade all components in the extracellular matrix and are important tissue-remodeling enzymes and key elements in tumor invasion and metastasis. The aim of this study was to investigate the expression and clinical relevance of MMPs in different histological types of colorectal polyps. Methods: The expression levels of MMP-1, 2, 7, 9, 11, 13 and 14 were analyzed by real-time PCR, Western-blot and immunohistochemistry in 50 patients with different histological types of colorectal polyps, 28 of which developed CC. Results: The results indicate that hyperplastic polyps had the lowest levels of MMP-1 and MMP-7, tubular polyps showed higher levels of both MMP-7 and MMP-14, and tubulovillous adenoma showed higher levels of MMP-1, MMP-7 and MMP-14. Conclusion: MMP expression was decreased in hyperplastic, tubular and tubulovillous adenoma polyps from patients who developed CC. Our findings suggest that MMP expression may be a pathological marker of colorectal polyps and for cancer susceptibility, which may improve strategies for CC prevention based on screening colonoscopy (AU)

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An anatomical study of the intersigmoid fossa and applications for internal hernia surgery.

PURPOSE: To improve the knowledge of the morphometry and the surrounding anatomical structures of the intersigmoid fossa and to determine possible surgical applications. METHOD: Forty eight adult cadavers (29 female and 19 male; mean age 83 years) underwent dissection in the Laboratoire d'Anatomie des Alpes Francaises. Two injections in the right carotid resulted in a total body concentration of formalin of 1.3 %. The study parameters were the dimensions of the intersigmoid fossa orifice and the fossa's relationship to surrounding structures. Data were recorded and analyzed using Microsoft Office Excel (MS Cerp). A Pearson coefficient r was used to examine the correlation between the length of colon and the ISF volume. RESULTS: The intersigmoid fossa was present in 75 % of cases (n = 36). The average dimensions for the transverse diameter, longitudinal diameter, and the depth were, respectively, 20.5 ± 0.2, 20.3 ± 0.13, and 26.8 ± 0.2 mm. The primary and secondary roots bordering this fossa measured on average 59.1 ± 0.1 and 48.3 ± 0.13 mm. In 13.9 % of cases (n = 5), the maximum depth was >40 mm and in 16.7 % of cases (n = 6), one of the diameters of the orifice entry of the fossa was >40 mm. The ureter and external iliac artery were the most frequently encountered structures during the dissection of the fundus of the intersigmoid fossa. CONCLUSION: The intersigmoid fossa remains present in most of the reported dissections of cadavers. It constitutes an essential landmark in the surgery of the sigmoid colon due to its deep structural relationship with the left ureter and external iliac artery.

[Anatomical study of pelvic colon]. / Étude anatomique du côlon pelvien.

OBJECTIVES: Identifying the different kinds of anatomical sigmoid colon in our environment and determine what exposes the most to the occurrence of pelvic colon volvulus. MATERIALS AND METHODS: This is a transverse prospective study from 1 January 2007 to 31 December 2012 on a series of 63 patients (33 men and 30 women) who underwent laparotomy for non-colonic pathologies. For all patients, the following parameters were recorded: C1: total length of the pelvic colon; C2: the length of the root of the meso-sigmoid; C3: the height of the meso-sigmoid; C4: maximum width of the meso-sigmoid. RESULTS: C1 through the entire series was 61,3cm. C2 average was 5.5cm. C3 height and maximum width C4 were on average 14,6cm and 7.6cm, respectively. Comparison of parameters in men and women showed no significant difference. CONCLUSION: This study allows us to know the different types of pelvic colons among the population of our operated patients. The measurements performed on the pelvic colon of patients presenting volvulus will help to attribute objectively the true authorship of this surgical emergency to an anatomical type of pelvic colon.

Segmental colonic length and mobility.

INTRODUCTION: Locoregional variation in the human colon is important in surgical practice; the length and mobility of different colonic regions impacts on laparoscopic and endoscopic colorectal procedures. The aim of this study was to refine anatomical understanding of the colon in terms of segmental length and mobility. METHODS: The colons of 35 cadavers were examined to determine lengths of caecum as well as ascending, transverse, descending and rectosigmoid colon, and to characterise colonic mobility at each location in terms of the mesenteric attachments. The presence of Jackson's membrane (a congenital peritoneal band of the right colon) was also documented. RESULTS: The mean total colonic length was 131.2cm (standard deviation [SD]: 13.4cm). There was no correlation with height, age or sex; the best predictor of total colonic length was the length of the rectosigmoid segment. The mean height of the transverse mesocolon was 7.4cm (SD: 3.6cm) and that of the sigmoid mesocolon was 6.3cm (SD: 2.6cm). Two-thirds of the subjects had a mobile portion of the ascending colon and nearly one-third had a mobile descending colon. A mobile ascending colon was significantly more common in females. Jackson's membrane was present in 66% of the subjects. CONCLUSIONS: This cadaveric study suggests that rectosigmoid length accounts for most of the variability in total colonic length. The significant proportion of colons with mobility of the ascending and descending segments prompts revision of the traditional anatomical teaching of these segments as fixed and retroperitoneal. Mobility of the ascending colon may account for the anecdotal finding that colonoscopy is more challenging in female patients. Jackson's membrane was identified in most colons.

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.

Image-Based Brachytherapy for the Treatment of Cervical Cancer.

Cervical cancer is a disease that requires considerable multidisciplinary coordination of care and labor in order to maximize tumor control and survival while minimizing treatment-related toxicity. As with external beam radiation therapy, the use of advanced imaging and 3-dimensional treatment planning has generated a paradigm shift in the delivery of brachytherapy for the treatment of cervical cancer. The use of image-based brachytherapy, most commonly with magnetic resonance imaging (MRI), requires additional attention and effort by the treating physician to prescribe dose to the proper volume and account for adjacent organs at risk. This represents a dramatic change from the classic Manchester approach of orthogonal radiographic images and prescribing dose to point A. We reviewed the history and currently evolving data and recommendations for the clinical use of image-based brachytherapy with an emphasis on MRI-based brachytherapy.

The morphology of the foetal sigmoid colon in the African population: a possible predisposition to sigmoid volvulus.

AIM: This study aimed to determine the morphological types of the foetal sigmoid colon and establish if the anatomical predisposition to sigmoid volvulus is present in Black African foetuses. Sigmoid volvulus affects Black Africans in our province more frequently than other ethnic groups, and males more than females. Its aetiology remains speculative, with factors being proposed that do not suggest the pathogenetic mechanisms or the gender bias. Previous anatomical studies have suggested that Black Africans have a predisposition to sigmoid volvulus due to an elongated sigmoid colon. We investigated whether this phenomenon occurred during foetal development. METHOD: Foetuses were donated from local hospitals. Population groups were defined as Black African and non-African. After dissection, the anatomy of the sigmoid colon was described according to level of origin, classic or elongated type and shape (broad or narrow). RESULTS: A total of 296 Black African foetuses and 37 non-African foetuses were donated. The sigmoid colon in the majority of foetuses in all gestational age groups had a low level of origin. An elongated colon was seen in 68% of Black African and 17% of non-African foetuses (P < 0.0001). Among Black Africans there was a higher proportion of elongated sigmoid colon among male (73%) than female foetuses (62%) (P = 0.044). In foetuses with an elongated sigmoid colon the broad shape was more common in females than males and the long-narrow shape was more common in males (P = 0.038). CONCLUSION: The elongated sigmoid colon seen in Black Africans is present in utero and occurs more frequently in Black African males. A narrow shape is more common in male foetuses and the broad shape is more common in female foetuses. These anatomical features may be the cause of the predisposition to sigmoid volvulus in Black African adults.