Can three-dimensional endoanal ultrasonography detect external anal sphincter atrophy? A comparison with endoanal magnetic resonance imaging

PURPOSE: Anal sphincter atrophy is associated with a poor clinical outcome of sphincter repair in patients with faecal incontinence. Preoperative assessment of the sphincters is therefore relevant. External anal sphincter (EAS) atrophy can be detected by endoanal magnetic resonance imaging (MRI), but not by conventional endoanal ultrasonography (EUS). Three-dimensional EUS allows multiplanar imaging of the anal sphincters and thus enables more reliable anal sphincter measurements. The aim of the present study was to establish whether 3D EUS measurements can be used to detect EAS atrophy. For this purpose 3D EUS measurements were compared with endoanal MRI measurements. METHODS: Patients with symptoms of faecal incontinence underwent 3D EUS and endoanal MRI. Internal anal sphincter (IAS) and EAS defects were assessed on 3D EUS and endoanal MRI. EAS atrophy was determined on endoanal MRI. The following measurements were performed: EAS length, thickness and area. Furthermore, EAS volume was determined on 3D EUS and compared with EAS thickness and area measured on endoanal MRI. RESULTS: Eighteen parous women (median age 56 years, range 32-80) with symptoms of faecal incontinence were included. Agreement between 3D EUS and endoanal MRI was 61% for IAS defects and 88% for EAS defects. EAS atrophy was seen in all patients on endoanal MRI. Correlation between the two methods for EAS thickness, length and area was poor. In addition, correlation was also poor for EAS volume determined on 3D EUS, and EAS thickness and area measured on endoanal MRI. CONCLUSION: Three-dimensional EUS and endoanal MRI are comparable for detecting EAS defects. However, correlation between the two methods for EAS thickness, length and area is poor. This is also the case for EAS volume determined on 3D EUS and EAS thickness and area measured on endoanal MRI. Three-dimensional EUS can be used for detecting EAS defects, but no 3D EUS measurements are suitable parameters for assessing EAS atrophy.     

Relationship Between External Anal Sphincter Atrophy at Endoanal Magnetic Resonance Imaging and Clinical, Functional, and Anatomic Characteristics in Patients With Fecal Incontinence

Purpose External anal sphincter atrophy at endoanal magnetic resonance imaging has been associated with poor outcome of anal sphincter repair. We studied the relationship between external anal sphincter atrophy on endoanal magnetic resonance imaging and clinical, functional, and anatomic characteristics in patients with fecal incontinence. Methods In 200 patients (mean Vaizey score, 18 (±2.9 standard deviation)) magnetic resonance images were evaluated for external anal sphincter atrophy (none, mild, or severe) by radiologists blinded to anorectal functional test results and details from medical history. Subgroups of patients with and without atrophy were compared for medical history, anal manometry, pudendal nerve latency testing, anal sensitivity testing, external anal sphincter thickness, and external anal sphincter defects. Whenever significant differences were detected, we tested for differences between patients with mild and severe atrophy. Results External anal sphincter atrophy was demonstrated in 123 patients (62 percent): graded as mild in 79 (40 percent), and severe in 44 patients (22 percent). Patients with atrophy were more often female (P < 0.001) and older (P = 0.003). They had a lower maximal squeeze (P = 0.01) and squeeze increment pressure (P < 0.001). Patients with severe atrophy had a lower maximal squeeze (P = 0.003) and squeeze increment pressure (P < 0.001) than patients with mild atrophy. These effects were not attenuated by potential confounding variables. Patients with atrophy could not be identified a priori by other characteristics. Conclusions External anal sphincter atrophy at endoanal magnetic resonance imaging was depicted in 62 percent of patients, varying from mild to severe. Because increasing levels of atrophy were associated with impaired squeeze function, further studies are needed to evaluate whether grading atrophy is clinically valuable in selecting patients for anal sphincter repair. Supported by grant 945-01-013 of the Netherlands Organization for Health Research and Development. Presented in part at the scientific assembly and meeting of the Radiologic Society of North America, Chicago, Illinois, November 27 to December 2, 2005. Reprints are not available.     

Endosonographic Anatomy of the Normal Anal Canal Compared with Endocoil Magnetic Resonance Imaging

PURPOSE: This study was designed to clarify the sonographic anatomy of the normal anal canal by comparison with endoanal magnetic resonance imaging, to determine agreement between these imaging modalities and interobserver error in measuring layer thickness. METHODS: Three-dimensional endosonographic and endocoil magnetic resonance images of the anal canal were obtained in four males and five nulliparous females aged 22 to 34 years. Images were analyzed at similar levels throughout the canal using a graphics-overlay technique to compare sonographic with magnetic resonance images. Measurements were taken at one level for agreement analysis between modalities and for interobserver variability in the measurement of the thickness of the main anal canal layers. RESULTS: The muscularis submucosae ani, muscle bundles in the longitudinal muscle layer, and puboanalis were identified on sonography. The outer border of the external sphincter was demarcated by an interface reflection with ischioanal fat. Clarification of the external sphincter anatomy allowed excellent correlation (Ri = 0.96) for the assessment of thickness. There was excellent correlation for the interobserver measurement of the external and internal sphincters and the submucosal width on endosonography, but there was poor correlation for the longitudinal muscle (0.12). CONCLUSION: The overlay technique has improved endosonographic interpretation, and measurement of external sphincter thickness has been validated both by comparison with magnetic resonance and on interobserver agreement.     

Endoanal ultrasonography in fecal incontinence: Current and future perspectives

Fecal incontinence has a profound impact in a patient’s life, impairing quality of life and carrying a substantial economic burden due to health costs. It is an underdiagnosed condition because many affected patients are reluctant to report it and also clinicians are usually not alert to it. Patient evaluation with a detailed clinical history and examination is very important to indicate the type of injury that is present. Endoanal ultrasonography is currently the gold standard for sphincter evaluation in fecal incontinence and is a simple, well-tolerated and non-expensive technique. Most studies revealed 100% sensitivity in identifying sphincter defect. It is better than endoanal magnetic resonance imaging for internal anal sphincter defects, equivalent for the diagnosis of external anal sphincter defects, but with a lower capacity for assessment of atrophy of this sphincter. The most common cause of fecal incontinence is anal sphincter injury related to obstetric trauma. Only a small percentage of women are diagnosed with sphincter tears immediately after vaginal delivery, but endoanal ultrasonography shows that one third of these women have occult sphincter defects. Furthermore, in patients submitted to primary repair of these tears, ultrasound revealed a high frequency of persistent sphincter defects after surgery. Three-dimensional endoanal ultrasonography is currently largely used and accepted for sphincter evaluation in fecal incontinence, improving diagnostic accuracy and our knowledge of physiologic and pathological sphincters alterations. Conversely, there is currently no evidence to support the use of elastography in fecal incontinence evaluation.     

Relationship between sphincter morphology on endoanal MRI and histopathological aspects of the external anal sphincter

Atrophy of the external anal sphincter can be shown only on endoanal magnetic resonance imaging (MRI). Until now no study has compared the morphological endoanal MRI findings with histopathological aspects of the external anal sphincter. The aim of this study was to validate the MRI interpretation of the external anal sphincter using histology as a ”gold standard.” In this prospective study 25 consecutive unselected women (median age 48 years, range 27–72) with fecal incontinence due to obstetric trauma were assessed preoperatively with endoanal MRI. All patients underwent anterior sphincteroplasty within 6 months of the preoperative assessment. During sphincter repair, a biopsy specimen was taken both from the left and right lateral parts of the external anal sphincter. Interpretation of MRI was performed by one of the radiologists (J.S.), and biopsy specimens were evaluated by the pathologist (W.J.M.). Both were blinded to the interpretation of the other. MRI revealed external anal sphincter atrophy in 9 of the 25 patients (36%). Histopathological investigation confirmed these findings in all but one. In one additional patient atrophy was detected on histological investigation while the morphology of the external anal sphincter was classified as normal on MRI. In detecting sphincter atrophy endoanal MRI showed 89% sensitivity, 94% specificity, 89% positive predictive value, and 94% negative predictive value. MRI correctly identified sphincter morphology in 23 of 25 cases (92%). This study demonstrates that endoanal MRI accurately identifies normal and abnormal external anal sphincter morphology. Endoanal MRI is therefore a valuable preoperative diagnostic tool. Accepted: 29 December 1999     

Integrity of the Anal Sphincters After Pouch-Anal Anastomosis: Evaluation With Three-Dimensional Endoanal Ultrasonography

PURPOSE The aim of the present study was to assess the integrity of the anal sphincters after handsewn pouch-anal anastomosis performed with the help of a Scott retractor. For this purpose the anal sphincters were visualized with three-dimensional endoanal ultrasonography.METHODS Patients undergoing a colonic pouch-anal anastomosis or an ileal pouch-anal anastomosis were included. Before and six months after the procedure, the length and volume of both sphincters were assessed with three-dimensional endoanal ultrasonography, and anal manometry was performed. Continence scores were determined using the Fecal Incontinence Severity Index (FISI).RESULTS Fifteen patients with a colonic pouch and 13 patients with an ileal pouch were examined. Six months after the procedure, three-dimensional endoanal ultrasonography showed significant alterations of the internal anal sphincter in eight patients with a colonic pouch-anal anastomosis (53 percent) and in eight patients with an ileal pouch-anal anastomosis (62 percent). These alterations were characterized by asymmetry or thinning. No defects were seen in the colonic pouch group, but, in two patients with an ileal pouch, a small defect in the internal anal sphincter was found. A decrease in internal anal sphincter volume was seen only in patients with a colonic pouch-anal anastomosis (P = 0.009). In both groups the length of the internal anal sphincter and the length, thickness, and volume of the external anal sphincter remained the same. After the procedure a reduction of maximum anal resting pressure was found in both groups (colonic pouch: P < 0.001, ileal pouch: P = 0.001). Maximum anal squeeze pressure was reduced in only patients with an ileal pouch-anal anastomosis (P = 0.006). The observed alterations of the internal anal sphincter and the manometric findings showed no correlation with the postoperative Fecal Incontinence Severity Index scores.CONCLUSION Handsewn pouch-anal anastomosis, performed with the help of a Scott retractor, only rarely leads to internal anal sphincter defects, but three-dimensional endoanal ultrasonography shows alterations of the internal anal sphincter in 57 percent of the patients. No correlation was observed between these alterations and the functional outcome.Read at the meeting of the Netherlands Association of Gastroenterology (NVGE), Veldhoven, The Netherlands, October 7 and 8, 2004.Reprints are not available.     

Volume Measurements of the Anal Sphincter Complex in Healthy Controls and Fecal-Incontinent Patients With a Three-Dimensional Reconstruction of Endoanal Ultrasonography Images

OBJECTIVES The aim of this study was to determine sphincter volume, length, and external anal sphincter thickness in healthy controls and fecal incontinent patients by use of a three-dimensional reconstruction of endoanal ultrasonography images.METHODS Forty-four controls (15 males, 15 females, and 14 parous females) and 28 incontinent parous females (with and without a sphincter defect) were studied. Internal anal sphincter, external anal sphincter and puborectalis volume, sphincter length, and external anal sphincter thickness were measured. Intraobserver and interobserver variability were assessed. Anal pressure profile was also determined.RESULTS Internal anal sphincter and external anal sphincter volumes were larger in males than in females (P = 0.001 and P = 0.04), and external anal sphincter volume was smaller in parous females but this was not significant (P = 0.084). Anterior sphincter length was longer in males (P = 0.004) and shorter in parous females (P = 0.06). Males had a larger anterior external anal sphincter thickness (P = 0.018); parity made no difference. Sphincter volumes were not smaller in incontinent females. Incontinent females with a sphincter defect had a shorter anterior sphincter length than that of continent (P = 0.001) and incontinent females without a sphincter defect (P < 0.001). Anterior external anal sphincter thickness was smaller in incontinent females with a sphincter defect (P = 0.006), and posterior and right external anal sphincter thickness was smaller in incontinent females without a sphincter defect (P = 0.02 and P = 0.03). Intraobserver variability was seen for internal anal sphincter volume and sphincter length, but there was no interobserver variability. Correlation between anal pressures and endoanal ultrasonography measurements was poor.CONCLUSIONS Differences in anal sphincter volumes are seen for gender but not for parity. Fecal incontinence is not associated with loss of sphincter volume. However, anterior sphincter length and external anal sphincter thickness are smaller.Presented at the meeting of the Netherlands Society of Gastroenterology, Veldhoven, The Netherlands, March 20 to 21, 2003 and October 2 to 3, 2003, and at the Digestive Disease Week, New Orleans, Louisiana, May 15 to 20, 2004.R. L. West was supported by a grant from Janssen-Cilag B.V., The Netherlands.Reprints are not available.     

Endoanal ultrasound assessment of sphincter defects and thinning – Correlation with anal manometry

Background and study aimsThis study aims to determine if anal sphincter defects/thinning observed at endoanal ultrasound correlates with anal pressures recorded at anal manometry.Patients and methodsA total of 30 consecutive patients with history suggestive of anal sphincter pathology underwent anal endosonography with documentation of internal and external sphincter defects/thinning. The same patients underwent anal manometry with documentation of maximum resting and maximum squeeze pressures. Patients with a sphincter defect (SD) were compared to patients without a sphincter defect (NSD) and both groups were compared with respect to findings in manometry. The Mann–Whitney U test was used for statistical analysis. This study was approved by the Institutional Ethics Committee.ResultsA statistically significant correlation was found between decreased maximal resting pressure and decreased internal anal sphincter (IAS) thickness or an IAS defect. The correlation between MSP and external sphincter pathology was significantly less consistent in our study.ConclusionOur study showed a statistically significant correlation between maximum resting pressure and observation of internal sphincter defects at endoanal ultrasound. The patients with documented internal sphincter defects have significantly reduced maximum resting pressures. There was however, no correlation between external sphincter defects and decrease in maximum squeeze pressure as has been observed in other studies. Until a manometry cut-off can be set to discriminate between the absence and presence of defects, both manometry and ultrasound should be offered to patients with history suggesting anal sphincter pathology.     

Normal Female Anal Sphincter

PURPOSE: Our aims were to quantify the nature, characteristics, and frequency of variations in female anal sphincter anatomy. METHODS: Nulliparous patients from the antenatal clinic and healthy volunteers of both genders were studied. Sphincter length was determined by the position of the puborectalis sling. Defects in the external anal sphincter were defined at each level and recorded in degrees. Cylindric longitudinal images of the endoanal scans were created by a three-dimensional-representation software package. Manometry was performed by a pull-through technique. RESULTS: Fifty-seven nulliparous patients and 18 healthy volunteers were included in the study. The mean age was 39 years for males and 28.35 years for females. There was no significant difference in overall sphincter length or in the internal anal sphincter length as a percentage of overall sphincter length between genders. All nine males had a complete ring of external anal sphincter along the full sphincter length. In the external anal sphincter below the level of the puborectalis sling, a natural gap occurred in 43 nulliparous (75 percent) and all 9 female volunteers. The greater the size of the defect, the greater its extent (mean 1.33 cm for >90° and 1.16 cm for <90°; chi-squared P = 0.008, eight degrees of freedom). Manometry provided confirmatory evidence of the gaps seen. Anal manometry was analyzed by Mann-Whitney U test for continuous nonparametric data and t-test for comparison between genders. CONCLUSION: The female sphincter has a variable natural defect occurring along its anterior length. This makes interpretation of the isolated endoanal ultrasound difficult and explains previous overreporting of obstetric sphincter defects.     

Anal Sphincter Complex

PURPOSE: Recent clinical studies on the anal sphincter complex have criticized the lack of reliable morphologic concepts. The purpose of this study was to determine the anatomy and histology of the anal sphincter complex with the help of undisturbed anatomic preparations. METHODS: The anal sphincter complex was studied in axial, sagittal, and coronal sections of human fetal, newborn, and adult pelves. RESULTS: The anal canal was surrounded by the internal sphincter, the longitudinal muscle layer, and an external sphincter that turned in to become continuous with the internal sphincter and with it to enclose the longitudinal muscle bundles. The classical tripartite subdivision of the external sphincter was not confirmed. The external sphincter seems not to be a complete circle in certain planes, neither in the male nor in the female. Sexual differences of the ventral part of the external sphincter were already present in fetuses. Large lamellated corpuscles were embedded within the interlacing smooth and striated muscles. Branches of the pudendal nerve innervated them. CONCLUSION: Our anatomic and histologic findings highly correlate with the results of magnetic resonance imaging and endosonography as well as with the physiologic findings. Furthermore, they are of great clinical importance for the understanding of sphincter defects during vaginal delivery and for anorectal operations in the adult as well as in the child.     

Importance of the tridimensional ultrasound in the anorectal evaluation

BACKGROUND: Anorectal endosonography is actually the main image exam to evaluate some anorectal diseases. AIM: To show the three-dimensional endosonography importance in the anal canal anatomic evaluation and the anorectal diseases diagnosis. METHODS: Seventy four anorectal ultrasound were performed, 23 normal individuals (13 women) and 51 patients (33 women) with benign and malignant diseases. All the patients were examined with a 3-D equipment with 360 degrees transducer. Normal individuals were evaluated in midline sagittal plane concerning to the length of the anal canal, the internal anal sphincter, the external anal sphincter and the anatomic defect in the anterior quadrant. RESULTS: There were no differences in the anal canal and the internal anal sphincter length between men and women. Otherwise, the external anal sphincter length is longer in men and the anatomic defect is longer in women. In those with anorectal diseases, 11 sphincter injuries, 8 anal fistulas, 7 abscess, 1 perirectal endometriosis, 1 pre-sacral cyst, 3 anal canal and 10 rectal malignant neoplasias were diagnosed. The surgical findings confirmed the ultrasound diagnosis in all the patients. CONCLUSION: Three-dimensional endosonography demonstrated the anatomic differences between male and female anal canal, justifying the larger incidence of pelvic floor disorders in female patients. It was possible to diagnose the anorectal diseases, in multi-plane, with high spatial resolution, adding also important informations about the therapeutic decision. Such characteristics become it similar to nuclear magnetic resonance with intra-rectal coil, with the advantages to be easier, quicker, low cost and better tolerated.     

Anal endosonography: Relationship with anal manometry and neurophysiologic tests

Thirty-seven patients were referred for evaluation of anal function; their clinical diagnoses were traumatic fecal incontinence (13), idiopathic (pudendal neuropathy) fecal incontinence (7), fecal soiling (9), and other (8). In all patients, anal endosonography (sphincter defects and internal sphincter thickness [IST]) and anal manometry (maximal basal pressure [MBP] and maximal squeeze pressure [MSP]) were performed. In 18 patients, neurophysiologic tests (EMG-maximal contraction pattern [MCP], single-fiber EMG [fiber density; FD], and pudendal nerve terminal motor latency [PNTML]) were also performed. Endosonography demonstrated in seven patients both an internal and external sphincter defect (Group 1), in seven patients an internal sphincter defect and in one patient an external sphincter defect (Group 2), and in 22 patients no sphincter defect (Group 3). There was a significant difference among these three groups for MBP and MCP, the lowest being in Group 1. Between the patients with traumatic fecal incontinence and idiopathic fecal incontinence, no differences in IST, MBP, MSP, MCP, FD, and PNTML were found. In two patients with a suspected obstetric trauma, there was an unexpected additional severe pudendal neuropathy. In one patient with a suspected obstetric trauma, no damage of the anal sphincters could be demonstrated. In one patient with suspected idiopathic fecal incontinence, there was an additional, unsuspected defect of the internal sphincter. There was concordance between endosonography and EMG in the mapping of the external sphincter. Clinical diagnoses can be misleading in differentiating between traumatic and idiopathic fecal incontinence; anal endosonography provides unsuspected and additional information about the sphincters; PNTML can reveal unsuspected neuropathy in traumatic fecal incontinence. Therefore, the combination of endosonography and PNTML is promising in selecting patients for surgery.     

Diagnostic precision of endoanal MRI in the detection of anal sphincter pathology—a meta-analysis

Objective This study aims to evaluate the diagnostic precision of endoanal magnetic resonance imaging in identifying anal sphincter injury and/or atrophy when compared with either endoanal ultrasound or surgical diagnosis. Materials and methods Quantitative meta-analysis was performed on nine studies, comparing endoanal MRI with endoanal ultrasound or surgical diagnosis in 157 patients. Sensitivity, specificity, and diagnostic odds ratio were calculated for each study. Summary receiver operating characteristic curves (SROC) and subgroup analysis were undertaken. Results The overall sensitivity and specificity of endoanal MRI for external sphincter injury was 0.78 (95%CI: 0.66–0.84) and 0.66 (95%CI: 0.51–0.79), respectively. For internal sphincter injury detection, this was 0.63 (95%CI: 0.50–0.74) and 0.71 (95%CI: 0.60–0.81), respectively. For detection of atrophy, this was 0.86 (95%CI: 0.71–0.95) and 0.82 (95%CI: 0.65–0.93), respectively. The area under the SROC curve and diagnostic odds ratio were 0.84 (SE = 0.07) and 6.14 (95%CI: 2.17–17.4) for external sphincter injury, 0.79 (SE = 0.07) and 4.60 (95%CI: 1.75–12.15) for internal sphincter injury, and 0.92 (SE = 0.08) and 21.49 (95%CI: 2.87–160.64) for sphincter atrophy. Conclusion Endoanal MRI was sensitive and specific for the detection of external sphincter injury and especially sphincter atrophy. It may be useful as an alternative to endoanal ultrasound in patients presenting with fecal incontinence, although further clinical studies are needed to identify its best application in clinical practice.     

A New Method of Assessing Anal Sphincter Integrity Using Inverted Vectormanometry

Purpose Vectorgraphy as an integrated mapping of radial pressure profiles of the anal canal has been used to attempt identification of pressure-related defects with doubtful reliability since vectorgraphs bear no resemblance to endoanal ultrasound scans at similar levels in the anal canal. This study aimed to devise a technique to enable vectorgraphy to be more representative of sphincter function and integrity. Methods Vectormanometry was performed in 50 patients with anorectal disorders using an Arndorfer pneumohydraulic system. “Normal” three-dimensional manometric images of each 0.5 cm of the anal sphincter were computer-generated by plotting anal pressures at rest and during squeeze radially around a central zero axis. The graphs were replotted with zero at the periphery and maximal anal pressure at the center. Both this (“inverted”) and “normal” vectorgraphs were compared with endoanal ultrasound images at similar levels, assessing both internal and external anal sphincters. Results Standard vectormanometry produced excellent pictures of pressures throughout the anal canal; the anatomy however bore no resemblance to the pictures produced by endoanal ultrasound. The inverted vectographs showed a much better correlation with endoanal ultrasound at each 0.5-mm level of the anal canal, for both squeeze pressure graphs and external sphincter correlations and for resting pressure graphs and internal sphincter correlations. Conclusions Accurate assessment of sphincter integrity is not possible when interpreting the vectormanometry graphs in the current format; however, inverted vectorgraphy gives good correlations with endoanal ultrasound and provides combined functional (pressure measurement) and anatomic (three-dimensional profile) information regarding the anal canal. Presented at the Congress of the International Society of University Colon and Rectal Surgeons, Osaka, Japan, April 14 to 18, 2002.     

Vaginal endosonography

PURPOSE: Although anal endosonography provides clear images of anal sphincters, the probe in the anal canal may distort epithelial structures and sphincter muscles may be compressed, producing inaccurate muscle thickness measurements. The aim of this study is to describe a new approach using vaginal endosonography to image the anal canal undistorted. METHODS: Twenty females (10 healthy volunteers and 10 with fecal incontinence) had both anal and vaginal endosonography performed. RESULTS: The undisturbed anorectum, submucosa, anal cushions, and anal sphincter muscles were clearly visualized by vaginal endosonography, and anatomy was described. Although anal and vaginal endosonographic measurements of internal sphincter muscle thickness correlated (r=0.83;P=0.01), anal endosonography consistently underestimated the thickness (2.3±0.5 vs. 3.2±1.2 mm; mean ± standard deviation). Anterior internal and external anal sphincter defects were identified accurately with both techniques. CONCLUSIONS: Vaginal endosonography is a new technique that enables accurate imaging of anal sphincters and epithelial structures at rest. In addition to making the diagnosis of anal sphincter defects, it has potential applications in the imaging of anovaginal sepsis and malignancy and possibly in understanding the pathogenesis of anal fissure and hemorrhoids.Read at The Annual Scientific Congress of the Royal Australasian College of Surgeons, Adelaide, Australia, May 10 to 14, 1993.Dr. Sultan was supported by the Joint Research Board and the Directorate of Obstetrics and Gynaecology, St. Bartholomew's Hospital.Dr. Kamm was supported by The Research Foundation, St. Mark's Hospital, London, United Kingdom.     

Use of vector volume manometry and endoanal magnetic resonance imaging in the adult female for assessment of anal sphincter dysfunction

PURPOSE: This study compared conventional water-perfused and vector volume anal manometry in female patients with neurogenic fecal incontinence and chronic anal fissure and in healthy female volunteers. We used endoanal magnetic resonance (MR) imaging to measure internal and external sphincter lengths and thicknesses and contrasted these with the manometric findings in the different anorectal conditions. METHODS: One hundred thirty-three female subjects were studied over an eight-month period, including 33 control volunteers, 83 patients with neurogenic fecal incontinence, and 17 patients with chronic anal fissure. Conventional manometry was contrasted with automated vector volume-derived parameters. Endoanal magnetic resonance images were obtained using a previously described internal coil with a 0.5 T Asset scanner measuring quadrantal internal sphincter thickness and averaged coronal internal and external sphincter lengths. RESULTS: There was a statistically significant relationship between parameters measured by conventional manometry and those variables derived from vector volume manometry at rest and squeeze. There was no difference in sectorial vector-derived pressures within any anorectal condition and no correlation between quadrantal internal sphincter thickness measurements and sectorial pressures at rest. Patients with chronic anal fissure and neurogenic fecal incontinence had constitutionally shorter superficial and subcutaneous external sphincters than healthy control subjects (P<0.001). CONCLUSIONS: There is no association between manometric findings and morphologic sphincter measurement; however, the shorter distal external sphincter in patients with fissure might render the lower anal canal relatively unsupported after internal sphincterotomy in the female patient.Poster presentation at the meeting of the Association of Coloproctology of Great Britain and Ireland, Jersey, United Kingdom, June 29 to July 1, 1998.     

Anal Sphincter Damage After Vaginal Delivery

PURPOSE: This study was designed to assess the relationship of anal endosonography and manometry to anorectal complaints in the evaluation of females a long time after vaginal delivery complicated by anal sphincter damage. METHODS: Thirty-four patients with anal sphincter damage after delivery, 22 with and 12 without anorectal complaints, and 12 controls without anorectal complaints underwent anal endosonography, manometry, and rectal sensitivity testing. Complaints were assessed by questionnaire, with a median follow-up of 19 years. RESULTS: Median maximum anal resting pressures were significantly lower in patients with anal sphincter damage with complaints (31 mmHg) than in controls (52 mmHg; P < 0.001). Median maximum anal squeeze pressures were significantly lower in patients with (55 mmHg) and without (69 mmHg) complaints than in controls (112 mmHg; P < 0.001 for both). Maximum anal resting pressures were significantly lower in patients with anorectal complaints after anal sphincter damage than in patients without complaints (P = 0.02). Results of anal manometry showed a large overlap between all groups. Rectal sensitivity showed no significant differences between the three groups. Persisting sphincter defects, shown by anal endosonography, were significantly more present in patients with anal sphincter damage after delivery with (86 percent) and without (67 percent) complaints than in controls (8 percent; P < 0.001 and P < 0.01, respectively). No differences in the number of echocardiographically proven sphincter defects were found between patients with or without anorectal complaints after anal sphincter damage CONCLUSIONS: Echographically proven sphincter defects are strongly associated with a history of anal sphincter damage during delivery. Sphincter defects are present in the majority of patients with anorectal complaints. Anal manometry provides little additional therapeutic information when performed after anal endosonography in patients with anorectal complaints after anal sphincter damage during delivery.     

Anal inspection and digital rectal examination compared to anorectal physiology tests and endoanal ultrasonography in evaluating fecal incontinence

Background Anal inspection and digital rectal examination are routinely performed in fecal incontinent patients but it is not clear to what extent they contribute to the diagnostic work-up. We examined if and how findings of anal inspection and rectal examination are associated with anorectal function tests and endoanal ultrasonography. Methods A cohort of fecal incontinent patients (n=312, 90% females; mean age 59) prospectively underwent anal inspection and rectal examination. Findings were compared with results of anorectal function tests and endoanal ultrasonography. Results Absent, decreased and normal resting and squeeze pressures at rectal examination correlated to some extent with mean (±SD) manometric findings: mean resting pressure 41.3 (±20), 43.8 (±20) and 61.6 (±23) Hg (p<0.001); incremental squeeze pressure 20.6 (±20), 38.4 (±31) and 62.4 (±34) Hg (p<0.001). External anal sphincter defects at rectal examination were confirmed with endoanal ultrasonography for defects <90 degrees in 36% (37/103); for defects between 90-150 degrees in 61% (20/33); for defects between 150-270 degrees in 100% (6/6). Patients with anal scar tissue at anal inspection had lower incremental squeeze pressures (p=0.04); patients with a gaping anus had lower resting pressures (p=0.013) at anorectal manometry. All other findings were not related to any anorectal function test or endoanal ultrasonography. Conclusions Anal inspection and digital rectal examination can give accurate information about internal and external anal sphincter function but are inaccurate for determining external anal sphincter defects <90 degrees. Therefore, a sufficient diagnostic work-up should comprise at least rectal examination, anal inspection and endoanal ultrasonography.     

Anal sphincter repair improves anorectal function and endosonographic image

PURPOSE: This study investigated the effect of anal sphincter repair on fecal continence in relation to anal endosonography and anal manometry. METHODS: Eighteen patients (7 male, 11 female) with anal sphincter defects and complaints of fecal incontinence (5), soiling (= liquid discharge; 3), or both (10) were studied before and after sphincter repair with endosonography and anal manometry. Complaints were the result of obstetric trauma (7), surgical trauma (7), both (3), and other trauma (1). Five patients had previous surgery. Preoperative endosonography showed a defect of both sphincters in nine patients, a defect of the external anal sphincter in five patients, and a defect of the internal anal sphincter in four patients. An overlapping sphincter repair was performed. RESULTS: Postoperatively and subjectively (S; patient's view), 13 (72 percent) patients became continent or improved; in 5 (28 percent) patients the complaints were unaltered. Objectively (O) (incontinence or soiling frequency), these figures were 12 (67 percent) and 6 (33 percent). Postoperative endosonographic images improved in 14 (78 percent) patients; defects of the sphincters (almost) disappeared (4) or were smaller (10). In the other four patients, images were unchanged. In two patients, overlapping of the muscle was clearly visible with anal endosonography. Clinical result (subjective (S) and objective (O)) of sphincter repair correlated with changes in anal endosonography (S,r=0.64,P <0.004; O,r=0.51,P=0.03) and anal manometry (S,r=0.54,P=0.038; O,r=0.44,P=0.09 (not significant)) and not with pudendal nerve latency. CONCLUSION: In 78 percent of our patients, endosonographic sphincter defect had diminished or disappeared after sphincter repair. There was a good correlation between clinical effect of sphincter repair and changes with anal endosonography and anal manometry. Postoperative persistent incontinence is attributable to remaining sphincter defects. Anal endosonography should be performed as a routine procedure in patients with fecal incontinence or soiling, also after failed surgery.Presented at the meeting of the American Gastroenterology Association, New Orleans, Louisiana, May 15 to 18, 1994.     

Correlation of endoanal sonography with cross-sectional anatomy of the anal sphincter

BACKGROUND: Anal endosonography has become an important imaging method in the diagnosis of anorectal disorders. However, little information exists as to whether anal endosonography reliably defines pelvic floor structures. The aim of this study was to correlate endoanal sonography with cross-sectional anatomy and histology. METHODS: Endosonographic tomograms were obtained from 9 human cadavers before fixation and cross-sectioning at identical levels. Muscular layers were defined by visual inspection, histology, immunohistology, and morphometry using three-dimensional sphincter reconstructions. RESULTS: Endosonography visualized only two muscular layers, whereas anatomic sections always revealed three. Comparisons revealed identical findings with regard to internal sphincter volumes and asymmetries. However, due to its failure to identify the longitudinal muscle, endosonography largely overestimated external sphincter volumes. In contrast to current beliefs, anatomic studies failed to detect striated muscle fibers within the longitudinal muscle and did not show an intersphincteric space. However, anatomic cross sections demonstrated "anterior bands" as newly described anchoring mechanisms for the anal sphincters. CONCLUSIONS: Anal endosonography supplies accurate information with regard to internal anal sphincter dimensions, but does not reliably outline deeper muscular layers. However, despite these drawbacks, comparisons of modern imaging techniques with cross-sectional anatomy may enhance our understanding of pelvic floor anatomy.