Anorectal anatomy and physiology

Overlooked Long-Term Complications of Colorectal Surgery

While colorectal surgery has been documented to have some of the highest complication rates in the surgical field, some of the more common, functional complications are often overlooked in the literature and in discussion with patients. Urinary, sexual, and defecatory dysfunction are common after colorectal surgery, especially after pelvic dissections, and may severely impact the postoperative quality of life for patients. These complications include urinary retention, erectile dysfunction, retrograde ejaculation, dyspareunia, infertility, and low anterior resection syndrome. The majority is rooted in autonomic nerve damage, both sympathetic and parasympathetic, that occurs during mobilization and resection of the sigmoid colon and rectum. While not all of these postoperative complications are preventable, treatment strategies have been developed to ameliorate the impact on quality of life. Given the high incidence and direct effect on patients, clinicians should be familiar with the etiology, prevention, and treatment strategies of these complications to provide the highest quality of care.

Preservation of the colo-anal reflex in colonic transection and post-operative Hirschsprung's disease: Potential extrinsic neural pathway

BACKGROUND

The colo-anal reflex is a distinct reflex whereby the internal anal sphincter (IAS) relaxes in association with colonic high amplitude propagating contractions (HAPCs) in contrast to the recto-anal inhibitory reflex (RAIR), which is characterized by IAS relaxation upon rectal distension. The RAIR is mediated by the myenteric plexus and therefore absent in Hirschsprung disease. We retrospectively assessed the presence and the characteristics of the colo-anal reflex in children in whom large bowel continuity had been surgically disrupted to assess the role of the extrinsic nervous system in the reflex.

METHODS

High-resolution (HR) colonic manometry and HR-anorectal manometry were used to evaluate both colonic and anal motor activity in ten children with treatment-unresponsive slow transit constipation (STC), who had previously undergone left-sided colostomy formation with consequent disruption of the bowel continuity, and in two children with Hirschsprung's disease (HSCR), who had previously undergone distal colon resection followed by Duhamel pull-through. Eight children with STC, normal colonic motor activity, and preserved large bowel continuity served as a control group. The presence and characteristics of colo-anal reflex were analyzed.

KEY RESULTS

In the study group, all patients showed the presence of both normal HAPCs and the presence of the colo-anal reflex. In two cases of HSCR, RAIR was absent; however, both patients demonstrated a colo-anal reflex.

CONCLUSIONS

In children with disrupted continuity of the colon and/or abnormal anal reflex, the colo-anal reflex is still preserved suggesting that it is mediated by a different pathway from the RAIR, possibly an extrinsic neural pathway.

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.

Analysis of biomechanical parameters extracted from anorectal manometry of fecally-continent and incontinent patients

OBJECTIVE

to evaluate the average resulting area from the Pressure x Time curves resulting from the manometric anorectal exam and compare it with the support capacity of voluntary squeeze.

MATERIALS AND METHODS

the data set was represented by data from 11 exams from continent patients and eight exams from patients with grade III fecal incontinence. The manometric curves were delineated, and the areas and support capacity of voluntary squeeze calculated, by means of the R computer language and the algorithm developed.

RESULTS

the resulting averages for support capacity of voluntary squeeze in continent patients and patients with grade III fecal incontinence were 33.07 seconds and 30.76 seconds (p>0.05) and the averages for area were 2362.04 mmHg x second and 947.92 mmHg x second (p<0.05), respectively.

CONCLUSION

the average resulting area is able to differentiate continent patients from incontinent and is shown to be a possible parameter in the analysis of biomechanical behavior related to the mechanisms of anorectal continence.

Anorectal incontinence: a challenge in diagnostic and therapeutic approach

Anorectal incontinence is a symptom of a complex multifactorial disorder involving the pelvic floor and anorectum, which is a severe disability and a major social problem. Various causes may affect the anatomical and functional integrity of the pelvic floor and anorectum, leading to the anorectal continence disorder and incontinence. The most common cause of anorectal incontinence is injury of the sphincter muscles following delivery or anorectal surgeries. Although the exact incidence of anorectal incontinence is unknown, various studies suggest that it affects ~2.2-8.3% of adults, with a significant prevalence in the elderly (>50%). The successful treatment of anorectal incontinence depends on the accurate diagnosis of its cause. This can be achieved by a thorough assessment of patients. The management of incontinent patients involves conservative therapeutic procedures, surgical techniques, and minimally invasive approaches.

Influence of perineal prostatectomy on anal continence

OBJECTIVE

Perineal prostatectomy has been proposed as a less invasive and safe procedure, but the risk of anal incontinence has been studied. This study aimed to evaluate the effects of perineal access on anal continence mechanisms after perineal prostatectomy.

METHODS

From August 2008 to May 2009, twenty three patients underwent perineal prostatectomy. These patients were evaluated before surgery and eight months postoperatively using the Cleveland Clinic Anal Incontinence Score, the Fecal Incontinence Quality of Life Score, and anorectal manometry.

RESULTS

The mean age of the subjects was 65 (range, 54-72) years, and the mean prostate weight was 34.5 (range, 24-54) grams. Gleason scores ranged from 6-7, and the mean Cleveland Clinic Anal Incontinence Score (mean±standard deviation) values were 0.9±1.9 and 0.7±1.2 (p>0.05) before and after surgery, respectively. The Fecal Incontinence Quality of Life Score did not change significantly after surgery. The mean values for anal manometric parameters before and after surgery were, respectively: Resting Pressures of 64±23 mmHg and 65±17 mmHg (p = 0.763), Maximum Squeezing Pressures of 130±41 mmHg and 117±40 mmHg (p = 0.259), High Pressure Zones of 3.0±0.9 cm and 2.7±0.8 cm(p = 0.398), Rectal Sensory Thresholds of 76±25 ml and 71±35 ml (p = 0.539), Maximum Tolerated Rectal Volumes of 157±48 ml and 156±56ml (p = 0.836), and Sphincter Asymmetry Indexes 22.4±9% and 14.4±5% (p = 0.003).

CONCLUSION

There was a significant decrease in the sphincter symmetry index after perineal prostatectomy. With the exception of the sphincter asymmetry index, perineal prostatectomy did not affect anal continence parameters.

Effects of ovarian failure on submucosal collagen and blood vessels of the anal canal in postmenopausal women

BACKGROUND

Estrogen and progesterone receptors are expressed in the anal canal. Fecal control deteriorates after menopause. This phenomenon is related to decreased circulating levels of estrogen and progesterone due to ovarian failure at menopause.

AIM OF WORK

To study the effects of estrogen and progesterone on inflammatory cells, submucosal collagen fibers, and vascular plexus of the anal canal of postmenopausal women.

SUBJECTS AND METHODS

Experiments were performed on samples of anorectal tissue obtained from 40 women, 19 menstruating (group I), and 21 postmenopausal women (group II). Investigations included immunohistochemistry of estrogen and progesterone receptors and CD34.

RESULTS

In negative estrogen receptors (ER) and progesterone receptors (PR), inflammatory cells, submucosal blood vessels, collagen type I were nonsignificantly changed in postmenopausal women relative to menstruating women (P > 0.05) whereas, in positive ER and PR, inflammatory cells and collagen I were significantly increased and submucosal blood vessels were significantly decreased in postmenopausal women relative to menstruating women (P < 0.05).

CONCLUSION

Estrogen and progesterone, in menstruating women, produce beneficial effects by decreasing incidence of inflammation and increasing anal canal submucosal blood vessels number and collagen types I, thus both hormones have a positive effect on anal compliance and pressure.

Neuroanatomy and physiology of colorectal function and defaecation: from basic science to human clinical studies

Colorectal physiology is complex and involves programmed, coordinated interaction between muscular and neuronal elements. Whilst a detailed understanding remains elusive, novel information has emerged from recent basic science and human clinical studies concerning normal sensorimotor mechanisms and the organization and function of the key elements involved in the control of motility. This chapter summarizes these observations to provide a contemporary review of the neuroanatomy and physiology of colorectal function and defaecation.

Is simple mucosal resection really possible? Considerations about histological findings after stapled hemorrhoidopexy

INTRODUCTION

The common removal of smooth muscle during stapled hemorrhoidectomy had raised concerns about its effects on postoperative anorectal function. The purpose of the study is to confirm the high frequency of the involvement of smooth muscle fibers in stapled hemorrhoidectomy and to determine its association with postoperative findings.

METHODS

This retrospective study evaluated 241 cases of stapled hemorrhoidopexy treated from 2003 to 2006. Data include the most common postoperative complications such as bleeding, anal pain, and recurrence. Histological doughnuts were examined, and the presence of muscle fibers was evaluated.

RESULTS

Early complications occurred in 27/241 patients (11.2%) including bleeding (14), anal pain (eight), incontinence (two), abscess (two), hematoma (one). Recurrence was observed in 11 cases (4.5%). Muscularis propria fibers were identified in 217 of 241 (90%) pathologic specimens. Five complications occurred in the group in which muscle fibers were not identified (4/24). The frequency of complications in the group with and without smooth muscle tissue in the resected specimens was 9.6% and 25%, respectively.

CONCLUSIONS

The presence of muscle fibers is not an occasional finding in the histological specimens, even if the presence of smooth muscle does not seems to influence the outcome of stapled hemorrhoidopexy. The idea of a simple mucosal resection needs to be revised.

Posterior sagittal anorectoplasty in anorectal anomalies: clinical, manometric and profilometric evaluation

CONTEXT AND OBJECTIVE

Anorectal malformations comprise a spectrum of anomalies that continue to be difficult to treat, even today. The aim was to evaluate the fecal continence of children who underwent posterior sagittal anorectoplasty due to anorectal malformations, via computerized anorectal manometry and profilometry.

DESIGN AND SETTING

Prospective study at Universidade Federal de São Paulo.

METHOD

82 patients (56.1% boys; 43.9% girls) of mean age 85.5 months were evaluated. They were divided into continent, partially continent and incontinent groups. Age, sex, manometric variables and profilometric parameters were studied. The results were statistically analyzed.

RESULTS

Among the 82 patients, 37.8% were continent, 25.6% were partially continent and 36.6% were incontinent. The overall mean resting pressure was 22 mmHg, and the means for the continent, partially continent and incontinent groups were, respectively, 30.7 mmHg, 23 mmHg and 14.7 mmHg. The overall mean pressure response to voluntary contraction was 56 mmHg, and the means for the groups were 65.4 mmHg, 55.8 mmHg and 46.6 mmHg, respectively. The rectosphincteric reflex was absent in 82.9% of the cases. In the profilometry analysis for all patients together, blue (20 to 50 mmHg) and yellow (50 to 80 mmHg) were predominant, and there was a similar distribution for the continent and partially continent patients. However, among the incontinent patients, green (< 20 mmHg) and blue prevailed.

CONCLUSIONS

Manometric and computerized profilometric analyses were an excellent method for postoperative evaluations on patients with intermediate and high anorectal anomalies, and for therapeutic planning.

Transrectal sonography in prostate evaluation

Prostate cancer is the most prevalent newly diagnosed noncutaneous malignancy in men. With the continued use of prostate-specific antigen screening, there has been a dramatic rise in the number of prostate biopsied performed. Transrectal ultrasonography (TRUS) is an essential tool used for detecting prostate pathology and performing prostate biopsies. This article review the indications and principles of TRUS of the prostate, the technique of TRUS, and controversies pertaining to prostate core biopsy.

Anatomofisiología de la continencia y la defecación

Continence and defecation are two essential functions in humans. Any alteration resulting in anal incontinence and/or constipation can severely impair the patient's quality of life. This study analyzes the anatomical structures and physiologic mechanisms accepted as factors involved in the correct development of both functions, while recognizing that there are still many unclear issues within this complex and sometimes paradoxical structure/function of the human body.

Estrogen and ghrelin increase number of submucosal urethral and anal canal blood vessels in ovariectomized rats

OBJECTIVES

Urinary and fecal control deteriorates after menopause, but it is not clear whether this is age or hormone related. This study investigates whether administration of estrogen and/or the anti-aging growth hormone-releasing peptide, ghrelin, improves the adverse effects of menopause/aging on urethral and anal canal submucosal blood vessel counts in middle-age rats.

METHODS

Female Wistar rats (13 months old) underwent ovariectomy, followed 1 month later by intraperitoneal once-daily administration of 17-beta estradiol (10 microg/kg), ghrelin (2 microg/kg), both hormones, or vehicle (n = 6 in each of four groups) for 42 days. An age-matched sham group (n = 6) received no intervention. Submucosal blood vessels were counted by light microscopy in five randomly selected fields from five nonconsecutive sections (5 microm thick) per rat of formalin-fixed and paraffin-embedded tissue blocks of the urethra and anal canal stained with hematoxylin-eosin. The results are expressed as the mean vessel number per high power field (x400).

RESULTS

Ovariectomy significantly reduced submucosal urethral and anal vascular counts below the sham values (7.41 +/- 0.98 versus 5.46 +/- 0.82, P = 0.003 and 7.16 +/- 1.11 versus 4.92 +/- 0.65, P = 0.0009, respectively). Estrogen restored the urethral counts (7.76 +/- 0.88, P = 0.5) and ghrelin or combined estrogen and ghrelin administration significantly increased the counts to greater than the sham counts (8.68 +/- 0.99, P = 0.04 and 9.72 +/- 1.21, P = 0.004, respectively). Estrogen, ghrelin, and combined estrogen and ghrelin administration also restored the anal counts to sham levels (7.26 +/- 0.97, P = 0.8; 6.56 +/- 0.78, P = 0.3; and 7.76 +/- 0.88, P = 0.3, respectively).

CONCLUSIONS

Combined or individual replacement of estrogen and ghrelin produces a beneficial effect by reversing the ovariectomy-induced decrease in urethral and anal canal submucosal vessel numbers in middle-age rats.

Effects of ovariectomy and hormone replacement on submucosal collagen and blood vessels of the anal canal of rats

OBJECTIVE

To study the effects of oestrogen and progesterone on submucosal collagen fibres and vascular plexus of the anal canal.

MATERIALS AND METHODS

Experiments were performed on sections of the anal canal of ovariectomized rats following 28 daily subcutaneous injections of 17-beta oestradiol (n = 6, OVX + E, Group 1), medroxyprogesterone acetate (n = 6, OVX + P, Group 2), both drugs (n = 6, OVX + E + P, Group 3) or vehicle (n = 6, OVX) and after sham surgery without castration or injection (n = 6). Investigations included immunohistochemistry of oestrogen and progesterone receptors and collagen fibres, Western blot analysis of collagen types I and III and counting of perianal vessels by light microscopy.

RESULTS

There was positive immunostaining for oestrogen and progesterone receptors in the mucosa and for collagen types I and III in the submucosa in all samples. Type I collagen levels increased significantly with ovariectomy but were normalized with treatment with oestrogen and progesterone. Type III collagen levels decreased after ovariectomy. Administration of oestrogen and progesterone appeared to restore level to near sham values. Semi-quantitative measurement of Type I/III collagen ratios by signal intensity demonstrated a very high ratio after ovariectomy. This appeared to be restored by both oestrogen and progesterone administration either individually or in combination. Mean vessel count was significantly lower in sham animals compared to values in OVX animals (P = 0.006). However, while only oestrogen treatment increased significantly the number of vessels compared to sham animals (P = 0.04), replacement with progesterone did not affect and in combination with oestrogen reduced submucosal vessel number.

CONCLUSION

Oestrogen and progesterone have synergistic effects on collagen types I and III and probably antagonistic effects on the vascular plexus of the anal canal submucosa in adult female rats.

Review article: the management of pelvic floor disorders

Anorectal disorders, such as faecal incontinence, defecation difficulty and conditions associated with anorectal pain, are commonly encountered in the practices of gastroenterologists, urogynaecologists and colorectal surgeons. The evaluation of these disorders has been very much improved by the development and wider availability of diagnostic tests, such as manometry, endo-anal ultrasound, static and dynamic pelvic magnetic resonance imaging and electromyography. After briefly reviewing the normal anatomy and physiology of the anorectum, the pathophysiology and diagnostic approaches to faecal incontinence, defecation disorders and functional anorectal pain are discussed. Until recently, the management of these disorders has been largely anecdotal. However, our therapeutic armamentarium has been expanded by pharmacological agents, such as nitrates, calcium channel blockers and botulinum toxin, as well as the development of novel techniques, such as sacral nerve stimulation. These and other pharmacological, behavioural and surgical approaches are reviewed with respect to the robustness of evidence to support their efficacy in patients with these disorders.

Physiologic variables that predict the outcome of treatment for fecal incontinence

Identification of physiologic factors that predict response to fecal incontinence therapy would be helpful in choosing the optimal treatment and advising patients on the likelihood of a successful outcome. However, few physiologic parameters have been consistently identified as important in predicting response to either biofeedback or surgery. The process of isolating these factors has been hampered by heterogeneity in the definition of fecal incontinence, lack of consensus on what constitutes a successful outcome, lack of follow-up data, variations in the way "standard" treatments are implemented, and lack of properly powered randomized controlled trials. Among the physiologic variables that studies have generally found to be predictive of successful outcomes in biofeedback treatment are the threshold for external anal sphincter contraction after treatment, the inclusion of sensory training in treatment, and a reduction in volume for the first sensation after treatment. Factors that have not been found to be important in predicting outcome following biofeedback retraining include the duration of fecal incontinence, pudendal nerve damage, patient age, symptom severity, pretreatment anal canal pressures, and results of anal ultrasonography. The presence of some degree of anorectal sensation is the only preoperative assessment that has been found to be predictive of response to surgical therapy. It is recommended that outcome measures for fecal incontinence be more clearly defined, that future biofeedback studies elaborate the predictive value of pretreatment anorectal sensation and the response to sensory retraining, and that postsurgical measurements such as anal squeeze pressure and sphincter length be taken into account.