Anatomía segmentaria del recto. Nuevo enfoque / Anatomy segmentation of the rectal. New approach

RESUMEN Se actualizó la clasificación anatómica del tumor de recto, con la revisión de varios tratados sobre anatomía. El estudio de la morfología interna del recto reconoce la formación de anchos pliegues. La formación de anchos pliegues de mucosas transversales, denominadas válvulas: una válvula inferior a 7 cm del ano, otra a 2 cm. Más arriba con una forma de media luna y la tercera a 11 cm del ano. Como estas válvulas son pliegues mucosos sin localización precisa no pueden ser consideradas como puntos anatómicos para segmentación del recto. De esta manera, la segmentación rectal como el límite entre recto superior e inferior se sitúa en la reflexión peritoneal; en el diagnóstico de tumores rectales la definición de su situación anatómica es importante para la conducta terapéutica, ya que el recto inferior tiene su origen embriológico en el proctodeo (ectoblástica) y puede ser más sensible a las radiaciones y los tumores del recto superior son tumores que se originan de tejido de formación entoblástica, las radiaciones producen lesiones del peritoneo y de otros órganos de la cavidad pelviana. La segmentación rectal es importante para el estadio locorregional del tumor y para la definición de un esquema de tratamiento adecuado. En primer lugar, establece el concepto anatómico de localización de un tumor de recto inferior, se diagnóstica con un tacto rectal, si es tocable es del recto inferior. En segundo lugar, define cuáles son los estudios complementarios para saber el estadio de la enfermedad y establece los parámetros anatómicos necesarios para la indicación del tratamiento neoadyuvante (AU).

SUMMARY To present a recent an anatomic classification of rectal tumor localization. Review of many anatomy treaties. The rectal internal morphology studies recognize the formation of thick folds of transversal mucosa thick folds named valves: a low valve to 7 cm from anus. Another is to 2 cm upper with a half moon form, a third one to 11 cm from anus. As this valves are mucosal folds without a clear localization they can't be consider as anatomical points to the rectum segment. Therefore, the rectal segmentation as the limit between up and low rectum, is located in the peritoneal reflection. In the rectal tumors diagnosis definition of it's anatomic situation is important for the therapeutic behavior, because the low rectum has its embryologic origin in the Proctodeum (ectoblastic). It can be more sensitive to the radiation the up rectum tumors are originated from the formation entoblast tissue (endoblast) the radiations cause peritoneal injuries and other pelvic cavity organs. The rectal segmentation is important for the locate-regional tumor stadium and for the appropriate treatment definition. In first place, establish the anatomic concept of the low rectal tumor localization. In second place defines which are the complementary for the new adjuvant indication (AU).

Precise Three-Dimensional Morphology of the Male Anterior Anorectum Reconstructed From Large Serial Histologic Sections: A Cadaveric Study.

BACKGROUND: Deep anatomic knowledge of the male anterior anorectum is important to avoid urethral injury and rectal perforation in intersphincteric resection or abdominoperineal resection for very low rectal cancer. However, its structure is difficult to understand, because the anorectum, muscles, and urogenital organs are complicatedly and 3-dimensionally arranged. OBJECTIVE: The purpose of this study was to revisit the anatomic information of the male anterior anorectum for intersphincteric resection and abdominoperineal resection with a focus on the spatial muscular morphology. DESIGN: This was a descriptive cadaveric study. SETTINGS: The study was conducted at Ehime and Kyoto universities. PATIENTS: Tissue specimens from 9 male cadavers were included. MAIN OUTCOME MEASURES: Specimens around the anterior anorectum were serially sectioned in the horizontal, sagittal, or frontal plane; large semiserial histologic sections were created at 250-µm intervals. The series were stained with Elastica van Gieson, and some sections from the series were studied by immunohistochemistry to detect smooth and striated muscles. Two series were digitalized and reconstructed 3-dimensionally. RESULTS: Two regions without a clear anatomic border were elucidated: 1) the anterior region of the external anal sphincter, where the external anal sphincter, bulbospongiosus muscle, and superficial transverse perineal muscle were intertwined; and 2) the rectourethralis muscle, where the smooth muscle of the longitudinal muscle continuously extended to the posteroinferior area of the urethra, which became closest to the anorectum at the prostatic apex level. A tight connection between the striated and smooth muscles was identified at the anterior part of the upper external anal sphincter and anterolateral part of the puborectalis muscle level. LIMITATIONS: This study involved a small sample size of elderly cadavers. CONCLUSIONS: This study clarified the precise spatial relationship between smooth and striated muscles. The detailed anatomic findings will contribute more accurate step-by-step anterior dissection in intersphincteric resection and abdominoperineal resection, especially with the transanal approach, which can magnify the muscle fiber direction and contraction of striated muscle by electrostimulation. MORFOLOGÍA TRIDIMENSIONAL PRECISA DEL ANORRECTO ANTERIOR MASCULINO RECONSTRUIDO A TRAVÉS DE SECCIONES MAYORES HISTOLÓGICAS EN SERIE: UN ESTUDIO CADAVÉRICO: El conocimiento anatómico amplio del anorrecto anterior masculino es importante para evitar lesiones de uretra y perforación de recto en la resección interesfinterica o la resección abdominoperineal para cáncer de recto bajo. Sin embargo, su estructura es difícil de entender porque el anorrecto, los músculos y los órganos urogenitales están aliñados en forma complexa tridimensional. OBJETIVO: Revisar de nuevo el conocimiento anatómico del anorrecto anterior masculino relevante a la resección interesfinterica y la resección abdominoperineal con un enfoque en la morfología muscular espacial. DISEÑO:: Estudio descriptivo cadavérico. ENTORNO: Ehime y la Universidad de Kyoto. SUJETOS: Tejido especímenes de nueve cadáveres masculinos. PUNTOS FINALES DE VALORACIÓN:: Las muestras alrededor del anorrecto anterior se seccionaron en serie en planos horizontal, sagital y coronal. Se crearon mayores secciones histológicas en serie a intervalos de 250 µm. Los especímenes fueron teñidos con Elástica van Gieson, y algunas secciones de la serie se estudiaron mediante inmunohistoquímica para detectar músculos lisos y estriados. Dos series fueron digitalizadas y reconstruidas tridimensionalmente. RESULTADOS: Se demostraron dos regiones sin un borde anatómico definido: (i) la región anterior del esfínter anal externo, donde se entrelazaron el esfínter anal externo, el músculo bulbospongoso y el músculo perineal transverso superficial; y (ii) músculo rectouretral, donde el músculo liso del músculo longitudinal se extiende continuamente a la zona posteroinferior de la uretra, que se acerca más al anorrecto a nivel del ápice prostático. La conexión estrecha entre los músculos estriados y lisos se identificó en la parte anterior del esfínter anal externo superior y la parte anterolateral del nivel del músculo puborrectal. LIMITACIÓN:: Este estudio incluyó una muestra pequeña de cadáveres ancianos. CONCLUSIÓN:: Este estudio aclaró la relación espacial precisa entre los músculos lisos y estriados. Los hallazgos anatómicos detallados ayudarán para una disección anterior paso a paso más precisa en la resección interesfintérica y la resección abdominoperineal, especialmente con el abordaje transanal, que puede magnificar la dirección de las fibras musculares y la contracción del músculo estriado utilizando electroestimulación.

A systematic review: effectiveness of rectal emptying preparation in prostate cancer patients.

While the importance of a consistent rectal volume during radiation therapy planning and treatment for patients receiving radiation therapy to the prostate is recognized, there is no clear guidance as to the most effective method. This review examines the evidence for the efficacy of rectal preparations. Eighteen papers were found where the primary aim was to investigate a rectal emptying intervention and included 5 different strategies. These included evacuation techniques, dietary interventions, laxatives, and enemas and were either investigated alone or in combination. There is no robust evidence to recommend one rectal emptying strategy over another. Further investigation in adequately powered clinical trials is advised.

An update on anorectal disorders for gastroenterologists.

Gastroenterologists frequently encounter pelvic floor disorders, which affect 10% to 15% of the population. The anorectum is a complex organ that collaborates with the pelvic floor muscles to preserve fecal continence and enable defecation. A careful clinical assessment is critical for the diagnosis and management of defecatory disorders and fecal incontinence. Newer diagnostic tools (eg, high-resolution manometry and magnetic resonance defecography) provide a refined understanding of anorectal dysfunctions and identify phenotypes in defecatory disorders and fecal incontinence. Conservative approaches, including biofeedback therapy, are the mainstay for managing these disorders; new minimally invasive approaches may benefit a subset of patients with fecal incontinence, but more controlled studies are needed. This mini-review highlights advances, current concepts, and controversies in the area.

Imaging paradigms in assessment of rectal carcinoma: loco-regional and distant staging.

The role of imaging in the management of rectal malignancy has progressively evolved and undergone several paradigm shifts. Unlike a few decades ago when the role of a radiologist was restricted at defining the longitudinal extent of the tumour with barium enema, recent advances in imaging techniques permit highly accurate locoregional and distant staging of the disease as well as prognostication on those who are likely to have a postoperative recurrence. Computed tomography (CT) has always been the mainstay of imaging when evaluating for distant metastasis, with the advent of positron emission tomography/CT improving its specificity. In rectal malignancy, it is the local extent of the disease that often influences the surgical decision making and need for neoadjuvant therapy. Although endoscopic ultrasound has been the traditional technique for determining the depth of tumour invasion, over the last decade magnetic resonance imaging (MRI) has emerged as a very effective tool for accurate T-staging. This review intends to address the status of various imaging modalities and their advantages and limitations in detection, pretreatment staging, and assessment of therapeutic efficacy in rectal cancer, with emphasis on MRI of high spatial resolution.

Adaptive image-guided radiotherapy (IGRT) eliminates the risk of biochemical failure caused by the bias of rectal distension in prostate cancer treatment planning: clinical evidence.

PURPOSE: Rectal distension has been shown to decrease the probability of biochemical control. Adaptive image-guided radiotherapy (IGRT) corrects for target position and volume variations, reducing the risk of biochemical failure while yielding acceptable rates of gastrointestinal (GI)/genitourinary (GU) toxicities. METHODS AND MATERIALS: Between 1998 and 2006, 962 patients were treated with computed tomography (CT)-based offline adaptive IGRT. Patients were stratified into low (n = 400) vs. intermediate/high (n = 562) National Comprehensive Cancer Network (NCCN) risk groups. Target motion was assessed with daily CT during the first week. Electronic portal imaging device (EPID) was used to measure daily setup error. Patient-specific confidence-limited planning target volumes (cl-PTV) were then constructed, reducing the standard PTV and compensating for geometric variation of the target and setup errors. Rectal volume (RV), cross-sectional area (CSA), and rectal volume from the seminal vesicles to the inferior prostate (SVP) were assessed on the planning CT. The impact of these volumetric parameters on 5-year biochemical control (BC) and chronic Grades ≥2 and 3 GU and GI toxicity were examined. RESULTS: Median follow-up was 5.5 years. Median minimum dose covering cl-PTV was 75.6 Gy. Median values for RV, CSA, and SVP were 82.8 cm(3), 5.6 cm(2), and 53.3 cm(3), respectively. The 5-year BC was 89% for the entire group: 96% for low risk and 83% for intermediate/high risk (p < 0.001). No statistically significant differences in BC were seen with stratification by RV, CSA, and SVP in quartiles. Maximum chronic Grades ≥2 and 3 GI toxicities were 21.2% and 2.9%, respectively. Respective values for GU toxicities were 15.5% and 4.3%. No differences in GI or GU toxicities were noted when patients were stratified by RV. CONCLUSIONS: Incorporation of adaptive IGRT reduces the risk of geometric miss and results in excellent biochemical control that is independent of rectal volume/distension while maintaining very low rates of chronic GI toxicity.

The acute effect of dorsal genital nerve stimulation on rectal wall properties in patients with idiopathic faecal incontinence.

AIM: Faecal continence depends on several factors, including rectal wall properties. Stimulation of the dorsal genital nerve (DGN) can suppress bladder contraction and similar effects are anticipated for the rectum. In this study, the acute effect of DGN stimulation on the rectal cross-sectional area is investigated. METHOD: Ten female patients (median age 60 years) with idiopathic faecal incontinence were included in the study. Stimulation was applied via plaster electrodes with the maximum tolerable amplitude (pulse width was 200 µs at a pulse rate of 20 Hz). Three series of pressure-controlled phasic (10, 20 and 30 cm H(2) O) and stepwise (5-30 cm H(2) O in steps of 5 cm H(2) O) rectal distensions were conducted (unstimulated, stimulated, unstimulated), and the rectal cross-sectional area (CSA) was measured with impedance planimetry. RESULTS: All patients completed the investigation. The median stimulation amplitude was 21 (8.5-27) mA. Comparing stimulated with unstimulated phasic distension, there was no significant difference in the median rectal CSA. Comparing stimulated with unstimulated stepwise distension, there was no significant difference in the median rectal CSA. Neither the rectal pressure-CSA relationship (CSA/P(R) ) nor the rectal wall tension changed during stimulation. CONCLUSION: No acute effect on rectal CSA during pressure-controlled distension was demonstrated during DGN stimulation.

Segmenting the prostate and rectum in CT imagery using anatomical constraints.

The automatic segmentation of the prostate and rectum from 3D computed tomography (CT) images is still a challenging problem, and is critical for image-guided therapy applications. We present a new, automatic segmentation algorithm based on deformable organ models built from previously segmented training data. The major contributions of this work are a new segmentation cost function based on a Bayesian framework that incorporates anatomical constraints from surrounding bones and a new appearance model that learns a nonparametric distribution of the intensity histograms inside and outside organ contours. We report segmentation results on 185 datasets of the prostate site, demonstrating improved performance over previous models.

Manejo de los tumores retrorrectales del adulto / Management of the retrorectal tumors of the adult

Antecedentes: Los tumores que asientan en el espacio virtual entre el mesorrecto y el sacrocoxis comprenden un grupo heterogéneo y poco frecuente cuya incidencia se estima en 1/40.000 ingresos. Se clasifican en congénitos, neurogénicos, óseos y misceláneas. Por ser asintomáticos u ocasionar síntomas inespecíficos su diagnóstico suele ser tardío y muchas veces cuando han alcanzado un gran tamaño o comprometido las estructuras vecinas. El diagnóstico y tratamiento, que requiere un equipo multidisciplinario, han evolucionado en los últimos años por el aporte de la resonancia magnética nuclear (RMN), las nuevas terapias quimiorradiantes y un abordaje quirúrgico más agresivo. Objetivo: Comunicar nuestra experiencia y sugerir la estrategia de manejo de estos tumores basada en esta serie y la de los centros internacionales de referencia. Pacientes y Métodos: Se revisaron retrospectivamente las historias clínicas de los pacientes con tumores retrorrectales operados entre 1991 y 2006 en la División Cirugía del Hospital Juan A. Fernández. Se excluyeron procesos inflamatorios, tumores rectales localmente avanzados y metastásicos. Se registraron sexo, edad, síntomas/signos, tiempo de evolución, estudios preoperatorios, tamaño tumoral, compromiso sacro y/o de órganos vecinos, tratamiento quirúrgico, morbimortalidad inmediata, estadía postoperatoria, secuelas, histopatología, recurrencia y supervivencia. Además se evaluó la utilidad de la tomografía axial computada (Te) y la RMN para establecer la estirpe tumoral, la posible malignidad, la invasión de estructuras vecinas y la vía de abordaje. Resultados: Hubo 7 pacientes (5 mujeres), edad promedio 37,5 (23-54) años. Congénitos: 2 (cordoma 1, hamartoma quístico 1), neurogénicos: 2 (neurofibroma plexiforme 1, schwanoma maligno 1), óseos: 1 (tumor de células gigantes del sacro) y misceláneas: 2 (liposarcoma 1, fibroma extrapleural maligno 1)...

Background: Tumors occupying the virtual space between the mesorectum and sacro-coccyx are heterogeneous and infrequent, with an estimated incidence of 1/40.000 hospitalizations. They are classified as congenital, neurogenic, osseous, and miscellaneous. Because they are asymptomatic or cause non-specific symptoms diagnosis is usually delayed, and very often done when have reached a great dimension or involved adjacent structures. Diagnosis and treatment, that required a multidisciplinary team, has evolved in recent years due to the role of magnetic resonance imaging (MRI), new chemo-radiation therapies and a more aggressive surgical approach. Objective: Report on our experience, and suggest the management strategy for these tumors based on this series and that of international referral centers. Patients and Methods: Clinical records of patients with retrorectal tumors operated on, between 1991 and 2006 in the Division of Surgery of the Hospital Juan A. Fernández were retrospectively reviewed. Inflammatory processes, locally advanced rectal tumors and metastatic lesions were excluded. Registe red data included gender, age, symptom/signs, time of evolution, preoperative studies, size of tumors, involvement of sacrum and/or adjacent viscera, surgical treatment, 30-day morbidity and mortality, postoperative hospital stay, secuela, histopathology, recurrence and survival. Besides, the usefulness of computed tomography (CT) and MRI to establish the histologic tumor type, possible malignancy, invasion of adjacent structures, and operative approach was assessed. Results: Seven patients (5 women), mean age 37.5 (23-54) years, were treated. Congenital: 2 (chordoma 1, tailgut cyst 1), neurogenic: 2 (plexiform neurotibroma 1, malignant schwannoma 1), osseous: 1 (gigant cell tumor of the sacrum) and miscellaneous: 2 (liposarcoma 1, extrapleural malignant fibroma 1)...

[Reconstruction of a digital three-dimensional model of the rectum and the surrounding structures based on CT angiographic data].

OBJECTIVE: To reconstruct a digital three-dimensional model of the rectum and the surrounding structures based on CT angiographic (CTA) data. METHODS: Based on air pressure enema and CTA, the chest T12 level to upper portion of the femur of a healthy volunteer was scanned with 64-slice spiral CT in the arterial phase and venous phase. The rectum and the surrounding structures were reconstructed with Mimics software based on the two-dimensional images of 856 consecutive layers obtained by Dicom 3.0 standard CT. The model was validated using finite element analysis software. RESULTS AND CONCLUSION: The established three-dimensional digital model allowed clear visualization of such structures of the lumbar vertebrae, pelvis, femur, abdominal aorta, internal iliac artery, external iliac artery, branches of the external iliac artery, skin, rectum, the colons, part of the small intestines, and the urinary bladder and prostate. The application of thin-layer CT and Dicom 3.0 standard renders better accuracy of the established digital model, which can provide a platform for surgical skill training and teaching of anatomy.

Anorectal malformations.

Anorectal malformations comprise a wide spectrum of diseases, which can affect boys and girls, and involve the distal anus and rectum as well as the urinary and genital tracts. They occur in approximately 1 in 5000 live births. Defects range from the very minor and easily treated with an excellent functional prognosis, to those that are complex, difficult to manage, are often associated with other anomalies, and have a poor functional prognosis. The surgical approach to repairing these defects changed dramatically in 1980 with the introduction of the posterior sagittal approach, which allowed surgeons to view the anatomy of these defects clearly, to repair them under direct vision, and to learn about the complex anatomic arrangement of the junction of rectum and genitourinary tract. Better imaging techniques, and a better knowledge of the anatomy and physiology of the pelvic structures at birth have refined diagnosis and initial management, and the analysis of large series of patients allows better prediction of associated anomalies and functional prognosis. The main concerns for the surgeon in correcting these anomalies are bowel control, urinary control, and sexual function. With early diagnosis, management of associated anomalies and efficient meticulous surgical repair, patients have the best chance for a good functional outcome. Fecal and urinary incontinence can occur even with an excellent anatomic repair, due mainly to associated problems such as a poorly developed sacrum, deficient nerve supply, and spinal cord anomalies. For these patients, an effective bowel management program, including enema and dietary restrictions has been devised to improve their quality of life.

Macaca fascicularis vs. Macaca nemestrina as a model for topical microbicide safety studies.

Preclinical studies of topical microbicide products, using appropriate animal models for assessing the safety of repeated use are essential. The pig-tailed macaque (Macaca nemestrina) model has been used to assess the safety of vaginally and rectally applied topical microbicide products. The availability of sexually mature female pig-tailed macaques has become extremely restricted. Currently, M. fascicularis is more readily available, and was therefore evaluated as an alternative model for topical microbicide pre-clinical evaluation. Twenty sexually mature M. fascicularis were assessed for feasibility to mimic the established models. The rectal and cervicovaginal microenvironments of the M. fascicularis were determined to be similar to those of M. nemestrina and humans. The gross anatomy was significantly smaller than that of the pig-tailed macaque, such that colposcopic examinations and multiple biopsies would not be possible. Thus, the M. fascicularis may not be useful for vaginally applied topical microbicide safety studies yet adequate for assessing safety of rectally applied topical microbicide products.

Underlying anatomy for CTV contouring and lymphatic drainage in rectal cancer radiation therapy.

Despite the low local recurrence rate that can be achieved by adequate surgery (total mesorectal excision--TME), radiation therapy was shown to play a significant role in reducing this risk. The widespread use of TME in many European Centers has introduced a new terminology and the need to identify the area at major risk for local failure using this surgical procedure. In the surgical series where extended extra-mesorectal surgery was performed, the role of lymphatic spread was evidenced, especially for low rectal cancer, through the pelvic parietal fascia and lateral pelvic spaces. The aim of this study was to better define some anatomic concepts and the main risk factors which impact on CTV contouring and field conformation in rectal cancer treatment. This information helps formulating guidelines for CTV contouring in daily radiotherapy practice, in order to define the best therapy, according to the tumor stage and location.

Follow-up studies of anorectal malformations after posterior sagittal anorectoplasty.

BACKGROUND/PURPOSE: There are few follow-up studies comparing posterior sagittal anorectoplasty (PSARP) with conventional procedures for patients with anorectal malformations (ARM). The authors have examined retrospectively postoperative anorectal function of patients with ARM treated with PSARP compared with those treated with conventional methods. METHODS: Anorectal function in 23 patients with high and intermediate type anorectal malformations (PSARP group), who underwent PSARP more than 4 years previously, were assessed by Kelly's clinical scoring system and objective studies. These results were compared with those in 14 cases (5 high and 9 intermediate type cases; control group), who underwent other conventional surgical procedures. RESULTS: Using Kelly's clinical scoring system, scores of the PSARP group compared with the control group were good in 48% versus 21%, fair in 48% versus 58%, and poor in 4% versus 21%, respectively. Barium enema studies suggested better anorectal sphincteric function in patients with high anorectal malformation in the PSARP group. Magnetic resonance imaging (MRI) studies showed more correct placement of the rectum through the striated muscle complex in the PSARP group at the I-line level. Manometric studies showed no difference in maximum resting pressure, anal canal length, and the incidence of anorectal reflex between the two groups. CONCLUSIONS: The favorable results of MRI and barium enema studies can be explained by direct visualization of the striated muscle complex with the aid of electrical stimulation as well as no harmful effects of amputation of the sphincter muscle in PSARP. However, manometric studies suggest anorectal function in patients with high and intermediate anorectal malformations is limited even after PSARP. Long-term postoperative follow-up with adequate bowel management is required for all patients with high or intermediate anorectal malformation.

Electrophysiological study of the rectosigmoid canal: evidence of a rectosigmoid sphincter.

Previous studies strongly suggest the presence of a sphincter at the rectosigmoid junction, an area with a mean length of 2.8 cm in adults, called the rectosigmoid canal (RSC). To find supporting evidence of a sphincteric function for the RSC, two recording electrodes were applied to each of the sigmoid colon (SC), RSC and rectum (R) in 11 subjects during operative repair of huge incisional hernias. The RSC, SC and R were individually stimulated by a further electrode and their pressures monitored by a three-channel microtip catheter. The variables of the slow waves or pacesetter potentials, recorded at rest from the RSC and R, were significantly higher than those of the SC. While the frequency and conduction velocity of pacesetter potentials of the RSC and R were similar, the potential pacesetter amplitude of the RSC was significantly higher. The increase of the electrical activity and pressure upon electrostimulation was significantly greater in the RSC than that of the SC or R. Electrostimulation led to an increase in pressure of all three areas, the RSC increase being significantly the greatest. The greater increase of the electrical activity and pressure of the rectosigmoid canal upon electrostimulation, compared to that of the SC or R, strongly supports the presence of a rectosigmoid sphincter.

Transverse folds of rectum: anatomic study and clinical implications.

There are controversies with respect to the location, number, and function of the transverse folds of the rectum (TFR), probably because their physioanatomic aspects have not been fully investigated. The purpose of this communication was to study the anatomic and histologic structure of the TFR aiming at elucidation of their function in the light of their structure. The TFR were studied morphologically and histologically in 18 cadavers (10 male, 8 female) with a mean age of 36.6 +/- 10.4 (SD) years. Barium enema studies were also performed in 36 volunteers (20 male, 16 female; mean age 38.6 +/- 15.2 [SD] years). The number of TFR varied, the commonest findings being two and three. In a few cases, TFR were absent or exceeded three in number. Most folds extended beyond the middle of the rectal lumen; a few were narrow. They were thick at the base and tapered gradually. Microscopically, the TFR contained circular and longitudinal smooth muscle fibers; they were rarely purely mucosal. TFR varied in location dividing the rectum into compartments; an alternating side-to-side arrangement allows for a wavy movement of the stool in the rectum. The wavy movement, compartmental division, and the shelving action of the TFR are suggested to retard stool movement in the rectum so as to allow time for fecal sampling (stool or gas) and for impulses to reach the conscious level to decide whether or not to defecate. Further studies are needed to investigate the role of the TFR in clinical practice.

An increased rectal maximum tolerable volume and long anal canal are associated with poor short-term response to biofeedback therapy for patients with anismus with decreased bowel frequency and normal colonic transit time.

PURPOSE: Biofeedback is an effective therapy for a majority of patients with anismus. However, a significant proportion of patients still failed to respond to biofeedback, and little has been known about the factors that predict response to biofeedback. We evaluated the factors associated with poor response to biofeedback. METHODS: Biofeedback therapy was offered to 45 patients with anismus with decreased bowel frequency (less than three times per week) and normal colonic transit time. Any differences in demographics, symptoms, and parameters of anorectal physiologic tests were sought between responders (in whom bowel frequency increased up to three times or more per week after biofeedback) and nonresponders (in whom bowel frequency remained less than three times per week). RESULTS: Thirty-one patients (68.9 percent) responded to biofeedback and 14 patients (31.1 percent) did not. Anal canal length was longer in nonresponders than in responders (4.53 +/- 0.5 vs. 4.08 +/- 0.56 cm; P = 0.02), and rectal maximum tolerable volume was larger in nonresponders than in responders. (361 +/- 87 vs. 302 +/- 69 ml; P = 0.02). Anal canal length and rectal maximum tolerable volume showed significant differences between responders and nonresponders on multivariate analysis (P = 0.027 and P = 0.034, respectively). CONCLUSIONS: This study showed that a long anal canal and increased rectal maximum tolerable volume are associated with poor short-term response to biofeedback for patients with anismus with decreased bowel frequency and normal colonic transit time.

Rectosigmoid junction: anatomical, histological, and radiological studies with special reference to a sphincteric function.

The existence of a sphincter at the rectosigmoid junction (RSJ) is controversial. Recent studies have demonstrated a high-pressure zone within the RSJ which responds to sigmoid colon or rectal contractions by relaxation or contraction, respectively. These findings suggest the presence of a "physiological" sphincter at the RSJ. The current study investigated the anatomical and histological structure and the radiological picture of the RSJ in view of the possible existence of an anatomical sphincter at the RSJ and elucidating its function. The RSJ was studied in 28 cadavers (18 adults and 10 fully mature neonates) by dissection. A histological study of the RSJ was performed in 5 cadavers. Radiological examination using double-contrast barium enema was carried out in 50 healthy volunteers (mean age 44.2+/-14.4 years; 32 men, 18 women). The mucous membrane of the RSJ was found in folds forming a "mucosal rosette" of a mean length of 2.8+/-0.9 cm in adult specimens and 0.7+/-0.2 cm in neonates. The distal end of the mucosal rosette was sharply delineated and in some specimens protruded into the rectal lumen as a small nipple, which was surrounded by a "rectal fornix" on either side. The histological examination of the RSJ showed mucosal foldings with deep crypts surrounded by lymphocytic aggregates and marginated by muscularis mucosa. The circular muscle coat showed gradually increasing thickness towards the rectum. Nerve cells in the submucosa were located at three levels: in the vicinity of the muscularis mucosa, in the middle of the submucosa, and in the proximity of the circular muscle. Radiologically the opening of the sigmoid colon into the RSJ presented as a ring or crescent. Radiological striations representing the mucosal rosette were demonstrated. The RSJ appeared as a narrow contractile segment. The anatomical, histological, and radiological findings thus indicate that the RSJ is a segment which can be identified by its interior rather than outer aspect. The study suggests the presence of an anatomical sphincter at the RSJ which seems to regulate the passage of stools from the sigmoid colon to the rectum.

Evaluation of the colorectal wall in normal subjects and patients with ulcerative colitis using an ultrasonic catheter probe.

BACKGROUND: Ulcerative colitis is usually evaluated by barium enema and colonoscopy, methods of imaging that are limited to the mucosal surface. Endoscopic ultrasonography (EUS) is the best modality for the evaluation of transmural changes in the bowel wall. We therefore evaluated the colorectal wall in normal control subjects and patients with ulcerative colitis using an ultrasonic catheter probe. METHODS: Endoscopic ultrasound with a catheter probe was performed on 36 normal control subjects (36 examinations) and 72 patients (111 examinations) with documented ulcerative colitis. RESULTS: In normal control subjects, the total wall, mucosa, submucosa, and muscularis propria were significantly thicker in the rectum than in the colon. There was no significant difference in the thickness of the colon and rectum among different age groups or between men and women. In ulcerative colitis, we classified the boundary of each layer into three patterns (smooth, irregular, and blurred) and then classified the wall into six types. In Matts grade 2 and 3 ulcerative colitis lesions, the total wall and each layer were significantly thicker than lower grade lesions and normal control subjects. For grade 1 and most of the grade 2 lesions, the boundary of each layer was smooth. In some of the grade 3 lesions, the mucosa-submucosa and submucosa-muscularis propria layer borders were abnormal. In all grade 4 cases, the mucosa-submucosa boundary was blurred. There was some correlation between the Matts grade and EUS findings except for Matts grade 3 lesions which had various EUS patterns. CONCLUSION: Endoscopic ultrasound with a catheter probe is a useful modality for the transmural assessment of the colorectal wall and, when used in conjunction with the many clinical and endoscopic parameters currently available, may contribute to the diagnosis and treatment of ulcerative colitis.