Endoluminal ultrasound defines anatomy of the anal canal and pelvic floor

Endoanal ultrasound in perianal fistulae and abscesses

Endoanal ultrasound is a technique that provides imaging of the anal sphincters and its surrounding structures as well as the pelvic floor. However, endoanal magnetic resonance imaging (MRI) is preferred by most physicians, although costs are higher and demand easily outgrows availability. Endoanal ultrasound is an accurate imaging modality delineating anatomy of both cryptoglandular as well as Crohn perianal fistula and abscess. Endoanal ultrasound is comparable with examination under anesthesia and equally sensitive as endoanal MRI in fistula detection. When fistula tracts or abscesses are located above the puborectal muscle, an additional endoanal MRI should be performed. Preoperative imaging is advocated in recurrent cryptoglandular fistula because a more complex pattern can be expected. Endoanal ultrasound can help avoid missing tracts during surgery, lowering the chance for the fistula to persist or recur. It can easily be performed in an outpatient setting and endosonographic skills are quickly incremented. Costs are low and endoanal ultrasound has the potential to improve outcome of patients with both cryptoglandular and fistulizing Crohn disease; therefore, it values more attention.

Anorectal anatomy and imaging techniques

The rectum and anus are two anatomically complex organs with diverse pathologies. This article reviews the basic anatomy of the rectum and anus. In addition, it addresses the current radiographic techniques used to evaluate these structures, specifically ultrasound, magnetic resonance imaging, and defecography.

Anorectal physiology and testing

A good understanding of anorectal physiology is essential for the diagnosis and appropriate treatment of various anorectal disorders, such as fecal incontinence, constipation, and pain. This article reviews the physiology of the anorectum and details the various investigations used to diagnose anorectal physiology disorders. These anatomic and functional tests include anal manometry, endoanal ultrasound, defecography, balloon expulsion test, magnetic resonance imaging, pudendal nerve terminal motor latency, electromyography, and colonic transit studies. Indications for investigations, steps in performing the tests, and interpretation of results are discussed.

MRI anatomy of the anal region

PURPOSE

The aim of this study was to identify the normal anatomy of the anal region on magnetic resonance images.

METHODS

T1-weighted turbo spin-echo images of anal sagittal sections, anal coronal sections, and oblique anal transverse planes were obtained with a body coil in 60 normal volunteers (30 women and 30 men, aged 19-25 years) at rest in the supine position.

RESULTS

T1-weighted images showed fat spaces and muscles simultaneously, allowing visualization of 7 image layers, including the mucosa, submucosa, anal smooth muscle, inner (intersphincteric) space, vertical levator, outer (intersphincteric) space, and external anal sphincter. The anal smooth muscle was derived from the rectal smooth muscle, and the inner space originated from the perirectal space. The outer space lay between the vertical levator and the external sphincters. The puborectalis did not have a longitudinal portion. The deep, superficial, and SC sphincters were 3 separate muscle bundles. The perianal spaces had a complex interconnection.

CONCLUSIONS

Multiplanar body-coil MRI studies can show anorectal fat spaces and musculature simultaneously, allowing fat spaces and musculature to serve as mutual referents. The results of imaging of the anal region with this method are different from previous imaging descriptions and may provide a more accurate and systemic description of the anal region structures than was previously available.

Predictive factors for faecal incontinence after third or fourth degree obstetric tears: a clinico-physiologic study

OBJECTIVE

This is a prospective study to review the natural history of anorectal dysfunction after primary repair for third or fourth degree obstetric tear and to identify the predictive factors for significant faecal incontinence.

METHOD

From January 2003 to December 2005, 121 consecutive women (mean age 29.9 +/- 4.7) who sustained third or fourth degree obstetric tears were assessed. All had primary repair by obstetricians. They were assessed using anorectal physiology testing and endoanal ultrasound. Short-term (3-month postpartum) and medium-term (mean 18.8 +/- 7.7 months) Wexner's continence scores were obtained.

RESULTS

Among the 121 women, seven were excluded because of incomplete follow-up. At short-term assessment, 25 out of 114 women were incontinent. One of them underwent another sphincter repair for significant faecal incontinence. Twenty-one and three patients respectively, had mild (Wexner's score 1-4) and moderate (Wexner's score 5-8) symptoms. At medium-term assessment, 24 patients remained incontinent; of these, 20 had mild symptoms (Wexner's score 1-4) and four had moderate incontinence (Wexner's score 5-8). The parity (P = 0.04), degree of obstetric tear (P = 0.036) and short-term Wexner's scores at 3 months postpartum (P < 0.0001) were significantly related to the change in Wexner's scores at medium-term assessment. However, the short-term Wexner's score was the only identifiable predictive factor for significant faecal incontinence.

CONCLUSION

Most women suffering from third or fourth degree obstetric tear were continent or mildly incontinent. Poor Wexner's score at short-term assessment at 3 months postpartum was predictive of faecal incontinence in the medium-term.

Endoanal ultrasound in benign anorectal disorders: clinical relevance and possibilities

Endoanal ultrasound is a well-established technique used to evaluate benign anorectal disorders. The technique is easy to perform, has a short learning curve and causes very little discomfort. Reconstruction of 3D images is possible. The clinical indications for endoanal ultrasound in benign anorectal diseases are fecal incontinence and peri-anal fistula. Sphincter defects can be depicted with precision and correlate perfectly with surgical findings. Furthermore, an impression of sphincter atrophy can be established. With perianal fistula the tracts can be visualized. Introducing hydrogen peroxide via the external fistula opening improves imaging. Endoanal ultrasound and MRI have comparable results in diagnosing anorectal disorders.

Translabial ultrasound assessment of the anal sphincter complex: normal measurements of the internal and external anal sphincters at the proximal, mid-, and distal levels

The purpose of this study was to measure the internal and external anal sphincters using translabial ultrasound (TLU) at the proximal, mid, and distal levels of the anal sphincter complex. The human review committee approval was obtained and all women gave written informed consent. Sixty women presenting for gynecologic ultrasound for symptoms other than pelvic organ prolapse or urinary or anal incontinence underwent TLU. Thirty-six (60%) were asymptomatic and intact, 13 symptomatic and intact, and 11 disrupted. Anterior-posterior diameters of the internal anal sphincter at all levels and the external anal sphincter at the distal level were measured in four quadrants. Mean sphincter measurements are given for symptomatic and asymptomatic intact women and are comparable to previously reported endoanal MRI and ultrasound measurements.

Endosonography in anorectal disease: an overview

Anorectal endosonography (AE), which was introduced 20 years ago, derives from the study of urology. It was first used to evaluate rectal tumours and later also to investigate benign disorders of the anal sphincters and pelvic floor. The technique is easy to perform, it has a short learning curve and causes no more discomfort than a routine digital examination. A rotating probe with a 360 degrees radius and a frequency between 5 and 16 MHz is introduced to the rectum and then slowly withdrawn so that the pelvic floor and subsequently the sphincter complex are seen. Recently, it has become possible to reconstruct three-dimensional images. AE has been used for almost every possible disorder in the anal region and has increased our insight into anal pathology. The clinical indications for AE are: 1. Faecal incontinence in patients when surgery is an option. AE can show sphincter defects with excellent precision. There is a perfect correlation with surgical findings. Studies comparing AE with endoanal magnetic resonance imaging (MRI) have shown that both methods are equally good for demonstrating defects in the external anal sphincter; the internal anal sphincter is better visualized with AE. After sphincter repair, the effect is directly related to the decrease in the sphincter defect. 2. Perianal fistulae. AE has been shown to be accurate in staging perianal cryptoglandular fistulae and fistulae in Crohn's disease. When there is an external fistula opening, H2O2 can be introduced with a plastic infusion catheter. The tract then becomes visible as a hyperechoic lesion ("white"). It has been shown that this corresponds well with surgical findings. It is equally sensitive as endoanal MRI. Since recurrent cryptoglandular fistulae are complex in 50% and Crohn's fistula in 75%, it is mandatory to perform AE preoperatively in these patients to avoid missed tracts during surgery and subsequent recurrences. 3. Rectal tumors. In low tubulovillous adenomas or malignant polyps considered removable locally, confirming the local resectability (T0 or T1) is mandatory. Although larger rectal and more advanced tumours can be evaluated with AE, MRI is more sensitive in staging nodal involvement. 4. Anal carcinoma for staging. AE has been shown to stage better than the classical TNM classification for both local extension and prognosis. In conclusion, AE images the internal and external anal sphincter with high accuracy. It is easy to perform and is of particular value in the diagnosis of anal incontinence and perianal fistulae. It is excellent in staging anal carcinoma and can also be used in staging rectal carcinoma, especially very low large malignant polyps.

Valor actual de la ecografía endoanal en el diagnóstico de la enfermedad proctológica benigna

Endoanal ultrasound is undoubtedly one of the major advances that has taken place in the evaluation of anorectal disease and pelvic floor disorders in the last decade. The main indications for endoanal ultrasound are evaluation of the morphology of the sphincteric apparatus in patients with fecal incontinence, the localization of perianal abscesses and fistulas, the staging of anal cancer and follow-up of squamous cell carcinoma after conservative treatment, and the study and morphological confirmation of lateral internal sphincterotomy in patients with fissure-in-ano, amongst others. In this article we review the main indications and use of endoanal ultrasound in the diagnosis of benign proctological disease.

Sacral nerve stimulation: an emerging treatment for faecal incontinence

Faecal incontinence is common, distressing to the patient and socially incapacitating. The treatment options depend on the severity and aetiology of incontinence. For mild cases of faecal incontinence, medical management and pelvic floor physiotherapy may be adequate. For more severe cases, surgery is often required. Patients who have a distinct sphincter defect are amenable to surgical repair. In many cases, there is a combination of diffuse structural damage of the anal sphincters with pudendal neuropathy. Conventional surgical repairs have a modest degree of success and the results tend to deteriorate with time. Neosphincter procedures such as artificial bowel sphincter and dynamic graciloplasty are potentially morbid and technically complex. Sacral nerve stimulation is innovative and has had a medium-term success with improvement of quality of life in over 80% of patients treated for faecal incontinence. These results are superior to other techniques in treating patients with severe refractory faecal incontinence, where current maximal therapy has failed. The technique is unique because there is a screening phase, which has a high predictive value. It is also associated with minimal complications that are usually minor. However, most published reports of sacral nerve stimulation for treatment of faecal incontinence were case studies and methods of assessing outcome were variable. Criteria for patient selection are evolving and are yet to be defined. The present paper critically reviews the publications to date on sacral nerve stimulation for treatment of faecal incontinence. This will form the basis for future evaluation of this emerging treatment of severe, intractable faecal incontinence. Randomized clinical trials like that of the Melbourne trial will further clarify the role and indications of sacral nerve stimulation for faecal incontinence.

Endosonography of the anal sphincter in women of different ages and parity

OBJECTIVES

To obtain reference data representative of normal findings at anal endosonography in pregnant and non-pregnant women. To determine intraobserver and interobserver agreement in the detection of endosonographic anal sphincter defects in asymptomatic women.

METHODS

Twenty-five non-pregnant nulliparous women and 25 non-pregnant parous women (age range, 20-67 years) and 47 pregnant women (age range, 21-39 years) underwent anal manometry and anal endosonography. The endosonographic internal and external sphincter thickness and sphincter length were measured online. Endosonographic sphincter defects were measured and classified offline from videotapes by two independent examiners using an endosonographic defect score ranging from 0 (no defect) to 16 (maximal defect), the score taking into account the location and the longitudinal and circumferential extension of the defect.

RESULTS

Endosonographic sphincter thickness and length did not differ between non-pregnant nulliparous and parous women and did not change substantially with age. The anal sphincter was thicker and the anal resting pressure area and manometric sphincter length were greater in pregnant than in non-pregnant women of the same age (20-39 years). There was good intra- and interobserver agreement with regard to detection of endosonographic anal sphincter defects (kappa > or = 0.70). Eighteen (19%) women had endosonographic sphincter defects but in only four (4%; 4/97) cases were they moderate or large (defect score, 7-10). Ten (20%) of the non-pregnant women reported minor gas incontinence and one reported minor incontinence for both gas and liquid stool. The frequency of incontinence did not differ between women with and without sphincter defects.

CONCLUSIONS

Reference data representative of normal findings at anal endosonography have been established for non-pregnant women and for nulliparous women in the third trimester of pregnancy. Small endosonographic sphincter defects and minor gas incontinence are common in women without known sphincter trauma. They seem to be unrelated to each other and may be regarded as normal variants.

Thickening of the internal anal sphincter in idiopathic constipation in children

Thickening of the internal anal sphincter (IAS) is observed in chronic idiopathic constipation (IC) and solitary rectal ulcer syndrome (SRUS), where it has been correlated with the presence and severity of rectal intussusception. Alternatively, thickened IAS may be a feature of the obstructed megarectum in a similar way to the hypertrophy of bladder neck seen in dyssynergic bladders. The aim of this study was to investigate the significance of thickening of the IAS in children with chronic IC and to determine any association between the thickened IAS and anorectal manometry findings and patient's symptoms. A total of 144 children were admitted for investigations and treatment of chronic IC and evaluated prospectively between April 2001 and April 2003. IAS thickness was measured by endosonography using B&K axial endosonic probe type 1850 with a 10-MHz rotating transducer. The thickness of IAS was measured at 3, 6, and 9 o'clock, and the mean value of the three measurements was used for analysis. Functional assessment was done by anorectal manometry pressure studies under ketamine anaesthesia. A validated symptom score (SS) was used to assess the severity of symptoms. The sum of SS ranged between 0 and 65. Spearman's rho two-tailed test was used to correlate the thickness of IAS with patients' symptoms and anorectal manometry findings. Results were expressed as median and range and p-value of less than 0.05 was considered significant. Of 144 children, 84 were boys, median age 8.1 years (range 3.1-15). Soiling was present in 137 (94%) patients, delay in defecation in 132 (91%), and a palpable megarectum on abdominal examination in 117 (80%). The median duration of symptoms and duration of laxative treatment were 4 years (range 0.3-14.5) and 3.3 years (0.2-13.5), respectively. The average severity score for soiling, delay in defecation, palpable megarectum, and the total SS were 8 (range 0-10), 5 (0-10), 2 (0-12), and 33 (11-51), respectively. The median thickness of IAS was 0.9 mm (range 0.3-2.8) and the median resting anal sphincter pressure was 54 mmHg (19-107). The median amplitudes of rectal and anal sphincter contraction were 3 mmHg (1-25) and 9 mmHg (1-35), respectively. The thickness of IAS correlated significantly with total symptom severity score (r=0.31, p=0.0001), soiling score (r=0.28, p=0.001), megarectum score on abdominal palpation (r=0.29, p=0.001), size of megarectum on manometry (r=0.36, p=0.0001), amplitude of rectal contraction (r=0.23, p=0.007), and age of patient (r=0.55, p=0.0001). There was also a significant correlation between the amplitude of rectal and anal sphincter contraction (r=0.32, p=0.0001). There was no correlation between thickness of IAS and resting anal sphincter pressure and amplitude of anal sphincter contraction on anorectal manometry study. A total of 24 children had myectomy of thickened and overactive IAS in addition to the medical treatment of their chronic IC. The histology examination of myectomy specimen with eosin and haematoxylin staining and histochemical acetylcholine esterase staining showed smooth muscle fibres and ganglion cells. Thickening of IAS correlates significantly with duration and severity of symptoms, size of megarectum, and amplitude of rectal contraction. The pathogenesis is secondary to the continuous presence of faeces in the rectum, resulting in chronic abnormal stimulus to the IAS, which leads to hypertrophic changes in the rectum wall and IAS.

Endoanal sonography in assessment of fecal incontinence following obstetric trauma

OBJECTIVES

Fecal incontinence is a common, incapacitating and largely unrecognized medical problem and can be caused by various factors. Obstetric trauma is the most common cause of fecal incontinence secondary to trauma. We aimed to analyze the role of endoanal ultrasound in assessment of this type of fecal incontinence, and report the functional results of surgical treatment.

METHODS

We reviewed the records of all 22 patients with fecal incontinence secondary to obstetric trauma who were evaluated by endoanal ultrasound and underwent surgical management in our department from April to 1997 to April 2002. Pre- and postoperative evaluation of the degree of incontinence was done using the incontinence score of Jorge and Wexner.

RESULTS

The patients had a median age of 43 (range, 29-68) years. All had vaginal deliveries, five of which (22.7%) were instrumental. Most of the patients had total fecal incontinence (solids) with preoperative incontinence score values of 15-20 (median, 18). Endoanal ultrasound confirmed structural defects in the anterior external anal sphincter alone in 16 (72.7%) patients, and both anterior external and internal sphincter defects in six (27.3%) patients. A thinned perineal body was present in all patients. All patients received surgical treatment with overlapping sphincteroplasty and there was improvement of continence in 19 (86.4%) patients with postoperative incontinence score values between 4 and 0 (median, 2).

CONCLUSIONS

Endoanal sonography is an accurate method for assessing sphincter anatomy, delineating both internal and external anal sphincters. Surgical treatment of sphincter defects is associated with good outcome.

Digital examination compared to trans-perineal ultrasound for the evaluation of anal sphincter repair

OBJECTIVE

To assess the adequacy of a third- or a fourth-degree laceration repair by comparing digital and trans-perineal ultrasound measurements.

METHOD

During a 4-year period, 34 subjects without prior history of anal sphincter injury or fecal incontinence underwent ultrasound measurements of external anal sphincter muscle diameter and perineal length, which were compared to measurements obtained by digital examination.

RESULTS

Pearson's correlation coefficients for comparing the digital external sphincter examination to trans-perineal ultrasonography, and the digital perineal examination to trans-perineal ultrasonography were 0.88 and 0.40, respectively. Patients (n=4/34) whose external sphincter was identified as less than 1 cm by digital examination were found to have an external sphincter diameter of less than 1 cm by trans-perineal ultrasound.

CONCLUSION

The digital perineum examination is a reliable method of measuring the external sphincter thickness and perineal body length immediately after primary repair.

Modelling the biomechanics and control of sphincters

This paper reviews current mathematical models of sphincters and compares them with a new spatial neuromuscular control model based on known physiological properties. Almost all the sphincter models reviewed were constructed as a component of a more extensive model designed to mirror the overall behaviour of a larger system such as the lower urinary tract. This implied less detailed modelling of the sphincter component. It is concluded that current sphincter models are not suitable for mimicking detailed interactions between a neural controller and a sphincter. We therefore outline a new integrated model of the biomechanics and neural control of a sphincter. The muscle is represented as a lumped-mass model, providing the possibility of applying two- or three-dimensional modelling strategies. The neural network is a multi-compartment model that provides neural control signals at the level of action potentials.The integrated model was used to simulate a uniformly activated sphincter and a partially deficient innervation of the sphincter, resulting in a non-uniformly activated sphincter muscle. During the simulation, the pressure in the sphincter lumen was prescribed to increase sinusoidally to a value of 60 kPa. In the uniformly activated situation, the sphincter muscle remains closed, whereas the partially denervated sphincter is stretched open, although the muscle is intact.

Faecal incontinence after lateral internal sphincterotomy is often associated with coexisting occult sphincter defects: a study using endoanal ultrasonography

BACKGROUND

Troublesome faecal incontinence following a lateral internal sphincterotomy (LIS) is often attributed to faulty surgical techniques: division of excessive amount of internal sphincter or inadvertent injury to the external sphincter. The aim of the present paper was to assess the anatomic and physiological factors that may contribute to faecal incontinence following a technically satisfactory lateral internal sphincterotomy by a group of colorectal specialists.

METHODS

Fourteen patients (nine women, five men; median age: 38 years; range: 23-52 years) who developed troublesome postoperative faecal incontinence were evaluated by clinical assessment, endoanal ultrasonography and anorectal physiological studies (manometry, pudendal nerve terminal motor latency) by two independent observers. The Cleveland Clinic continence score (0-20; 0, perfect continence; 20, complete incontinence) was used to quantify the severity of faecal incontinence. Fourteen continent subjects after a LIS (nine female patients, five male patients; median age: 36 years; range: 20-44 years) were also evaluated as 'continent' controls (continence score </= 4).

RESULTS

In the incontinent group, the median postoperative Cleveland Clinic continence score was 9 (range: 6-13) compared with a preoperative score of 1 (range: 0-3). On assessment by endoanal ultrasonography the site of the internal sphincterotomy was clearly identified. There were additional coexisting defects, on endoanal ultrasonography, of the external anal sphincter in seven female patients, of the internal sphincter in two female and two male patients; and a defect of both the external and internal sphincters in a male patient who had had a prior fistulotomy. The pudendal nerve terminal motor latency (PNTML) was prolonged in two female patients on the side contralateral to the lateral internal sphincterotomy. In two of five male patients there was no evidence of any occult sphincter injuries. In the continent controls a defect of the distal portion of the external sphincter was noted in one female patient. None of the patients had a prolonged PNTML. The maximum voluntary contraction was significantly lower in the female subjects than in the female continent controls (92 mmHg vs 140 mmHg; P < 0.05), while the resting anal canal pressures and length of the high pressure zone were similar between the study subjects and the continent controls.

CONCLUSION

Troublesome faecal incontinence after a satisfactorily performed lateral internal sphincterotomy is often associated with coexisting occult sphincter defects.

Multiplanar anal endosonography--normal anal canal anatomy

INTRODUCTION

Volume acquisition during anal ultrasound enables multiplanar imaging of the anal canal. The normal ultrasonic multiplanar appearance of the anal canal is described and gender differences in canal anatomy are highlighted.

METHODS

Ten male and 12 female normal volunteers (mean ages 31.5 years (s.d. 5.9) and 31.2 (s.d. 6.7)) had three-dimensional anal endosonography (3-D AES). Each volume dataset was seeded in the axial plane facilitating multiplanar identification of known anatomical structures.

RESULTS

The anterior external anal sphincter (EAS) was significantly longer in men than women 30.1 mm (3.9) vs 16.9 mm (7.4) (P < 0.001). There was no difference in the length of the puborectalis 24.7 mm (6.4) vs 24 mm (5) (P=0.78) in men compared with women. The cranial extent of the anterior EAS was tilted forward in both sexes. The angle formed by the anterior EAS and the longitudinal axis of the anal canal was more acute in men than in women (11.1 degrees vs 18.6 degrees; P=0.007). Dataset volume seeding of familiar structures in the axial plane allowed the multiplanar endosonographic anatomy to be described.

CONCLUSIONS

Multiplanar AES has enabled detailed longitudinal measurement of the components of the anal canal and has revealed important gender differences. The multiplanar ultrasonic appearance of the normal anal canal has been described for the first time.

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.

Endosonography in benign anorectal disease: an overview

BACKGROUND

Endosonography may be used for diagnosing various anorectal disorders. This review addresses its technique and clinical use in benign anorectal disease.

METHODS

The English literature available on anal endosonography was reviewed. The different modalities, the endosonography technique itself and its value in benign anorectal disease were described.

RESULTS

Anal endosonography is easy to perform, has a short learning curve and causes less discomfort than routine digital examination. Anal sphincters can be clearly visualized and distinction is possible between the internal (hypoechoic) and external (hyperechoic) anal sphincters. Other pelvic floor structures, like the puborectalis muscle, can also be visualized. Endosonography is mostly used in the assessment of faecal incontinence; it has brought new insight into the pathophysiological mechanisms of this disorder and can select patients with traumatic incontinence for sphincter repair. It has replaced electromyographical sphincter mapping, which is a painful and time-consuming procedure. In perianal sepsis, endosonography assists in defining fistula tract anatomy. The use of contrast agents has significantly increased the accuracy of endosonography in the assessment of perianal fistulae. In addition, endosonography is an excellent alternative to expensive MRI. Besides its use in incontinence and perianal sepsis, with anal endosonography surgical possibilities can be evaluated in individual patients, for example, to decide whether a sphincter repair or a lateral sphincterectomy is preferable. Finally, endosonography may occasionally identify internal sphincter myopathy in patients with intractable constipation or proctalgia.

CONCLUSION

Anal endosonography images the internal and external sphincters with high accuracy. It is easy to perform and is especially valuable in the diagnosis of anal incontinence and perianal sepsis.

Endosonographic criteria for an internal opening of fistula-in-ano

PURPOSE

The aim of the present study was to define endosonographic criteria for an internal opening of fistula-in-ano.

METHODS

118 patients with a diagnosis of fistula-in-ano and a control group of 201 cases underwent endosonography in an outpatient setting. Confirmation of an internal opening was performed by intraoperative procedures.

RESULTS

Of the 139 cases of fistula-in-ano, the internal opening of 130 cases was confirmed. Analysis of endosonographic findings of the confirmed cases revealed that 122 cases showed positive findings for predictive location of an internal opening, and 8 cases demonstrated negative findings. Fifty-seven cases showed an appearance of a root-like budding formed by the intersphincteric tract that contacts the internal sphincter, classified as Criterion I. Fifty cases demonstrated the appearance of a root-like budding with an internal sphincteric defect, classified as Criterion II. Fifteen cases showed a subepithelial breach connecting to the intersphincteric tract through an internal sphincteric defect, classified as Criterion III. Using the combination of these three criteria, the accuracy was as follows: sensitivity, 94 percent; specificity, 87 percent; positive predictive value, 81 percent; negative predictive value, 96 percent.

CONCLUSION

These combined criteria would be of particular help in performing preoperative location of an internal opening with endosonography.

Accuracy and reliability of transanal ultrasound for anterior anal sphincter injury

INTRODUCTION

Although transanal ultrasound has rapidly become the test of choice for the diagnosis of anal sphincter injury, the accuracy and reliability of this technique are unknown. This study evaluates the accuracy and reliability of transanal ultrasound for anterior (obstetric-related) anal sphincter injury.

METHODS

Sixty-two women underwent transanal ultrasound with hard-copy images obtained at 0.5-cm intervals from the anal verge to 2.5 cm into the anal canal. All transanal ultrasound procedures were also recorded on videotape. Two experienced ultrasonographers blinded as to the patients' clinical history and examination independently reviewed the images and videotape recordings for the presence or absence of anal sphincter injury.

RESULTS

The accuracy of transanal ultrasound in 22 incontinent women with known anal sphincter injury was 100 percent. The accuracy of transanal ultrasound in 20 nulliparous women with intact anal sphincters was only 35 percent but improved to 50 percent after the "real time" videotape was reviewed (P = 0.16) and further improved to 85 percent when interpretation was limited to the distal 1.5 cm of the anal canal (P = 0.004). In these nulliparous women, intact internal sphincters were more accurately predicted than intact external sphincters (95 vs. 85 percent; P = 0.24). Measurement agreement between the two ultrasonographers was 68 percent (fair; kappa, 0.26) but significantly improved to 78 percent (moderate; kappa, 0.48; P = 0.0001) when interpretation was limited to the distal 1.5 cm of the anal canal. Overall clinical agreement (final scan interpretation) was good (81 percent agreement; kappa, 0.61). Agreement was better for the internal sphincter (74 percent; fair; kappa, 0.36) than the external sphincter (61 percent; poor; kappa, 0.17; P = 0.0002).

CONCLUSIONS

Although transanal ultrasound can accurately identify anterior anal sphincter injury when present, transanal ultrasound falsely identifies sphincter injury in at least 5 to 25 percent of normal anal sphincters. Only fair agreement in the interpretation of transanal ultrasound exists between experienced ultrasonographers. Both the accuracy and reliability of transanal ultrasound are significantly improved by limiting transanal ultrasound to the distal 1.5 cm of the anal canal.

Successful overlapping anal sphincter repair: relationship to patient age, neuropathy, and colostomy formation

BACKGROUND

Fecal incontinence from single anal sphincter defects are surgically remedial and commonly the result of obstetric injuries. Overlapping anal sphincter repair has previously been associated in small series with good results in 69 to 97 percent of patients.

OBJECTIVES

The aims of this study were to assess the results of overlapping anal sphincter repair in one institution and to assess the effects of age, presence of a neuropathy, and addition of a temporary colostomy on the success of surgery.

METHODS

A study of 57 overlapping anal sphincter repairs in 56 (54 females) patients at the Royal Prince Alfred Hospital during a six-year period was performed. All patients were investigated preoperatively with endoanal ultrasound and concentric needle electromyography. Patients have been assessed prospectively since 1994 with a questionnaire, including a four-point Likert scale of continence level, the St. Mark's incontinence scoring system (range, 0-13), the Pescatori incontinence scoring system (range, 0-6), and patient assessment of success or failure of the overlapping anal sphincter repair. A colostomy was selectively formed in conjunction with an overlapping anal sphincter repair in 21 patients (8 preoperatively, 13 simultaneously), and 18 patients had a concomitant neuropathy (3 unilateral, 15 bilateral).

RESULTS

After a median follow-up of 18 months, median continence scores overall had improved from St. Mark's incontinence scoring 13 to 3 (P < 0.0001) and Pescatori incontinence scoring 6 to 2 (P < 0.0001). Forty-nine of 57 (86 percent) repairs have been successful, and 8 are considered to be failures. Twenty-one of 27 (78 percent) repairs in patients younger than 40 years of age were successful, as were 28 of 30 (93 percent) repairs in patients older than 40 years of age (P = 0.10). Four of 18 (22 percent) repairs associated with a neuropathy failed compared with 4 of 39 (10 percent) without a neuropathy (P = 0.21). Improved or normal continence was achieved in 17 of 21 (81 percent) patients with a stoma and overlapping anal sphincter repair and in 32 of 36 (89 percent) patients with an overlapping anal sphincter repair alone (P = 0.32). The presence of a stoma did not improve the rate of wound healing by primary intention (62 percent for stoma vs. 64 percent for overlapping anal sphincter repair alone; P = 0.55).

CONCLUSIONS

Single anal sphincter defects can be successfully treated with an overlapping anal sphincter repair. There is no improvement in primary healing with selective stoma formation. Age of the patient and presence of a neuropathy should not detract from proceeding with overlapping anal sphincter repair when singular anal sphincter defects are detected on endoanal ultrasound in muscle that is still active.

Exoanal ultrasound of the anal sphincter: normal anatomy and sphincter defects

OBJECTIVE

To describe the sonographic appearance of normal anal sphincter anatomy and sphincter defects evaluated with a conventional 5 MHz convex transducer placed on the perineum.

DESIGN

Prospective, single-blind study.

SETTING

Department of Obstetrics and Gynecology, University of Michigan Medical Center, USA.

POPULATION

Twenty-five women with symptoms of faecal incontinence, 11 asymptomatic nulliparous women, and 32 asymptomatic parous women.

METHODS

A convex scanner was placed on the perineum with the woman in lithotomy position. Images were taken at three levels of the sphincter canal. Pictures were evaluated by two examiners who were blinded to the case history of the women and to the results of each other for the presence or absence of sphincter defects.

MAIN OUTCOME MEASURES

Description of anal sphincter appearance on endoanal ultrasound. Reproducibility of the evaluation of sphincter defects.

RESULTS

The internal anal sphincter is visible as a hypoechoic circle; the external anal sphincter shows a hyperechoic pattern. Proximally the sling of the puborectalis muscle is visible. Sphincter defects were detected in 20 women. In all five women who subsequently underwent surgery, the presence and location of the defect was confirmed at the time of surgery. Examiners were in agreement 100% of the time on the presence or absence of internal defects. They disagreed in one patient on the presence of an external defect.

CONCLUSION

Exoanal ultrasound provides information on normal anatomy and on defects of the anal sphincter.

Anal endosonography in faecal incontinence

Images

Endoanal ultrasonography in the follow-up of anal carcinoma

As the modern treatment for anal carcinoma is either radiotherapy alone or combined radiochemotherapy, an exact histological staging is impossible. Therefore we have to depend on an accurate preoperative staging method. Endoanal ultrasonography enables imaging of the normal anal canal and its pathologies. In a prospective investigation we were able to confirm the histological proven diagnosis of an anal epidermoid carcinoma in 12 patients with a 10-MHz transducer covered with a sonolucent plastic cone. The depth of infiltration can be determined in relation to the normal layers of the anal canal. Six patients treated with radiotherapy alone or combined radiochemotherapy were followed and the success or failure of the treatment was documented. Endosonography of the anal canal allows an exact staging of a primary anal carcinoma and the follow-up in irradiated carcinomas. Besides digital palpation and proctoscopy with biopsy, endosonography complements the preoperative staging of anal carcinomas.

Magnetic resonance imaging facilitates assessment of perianal Crohn's disease

Three illustrative cases of magnetic resonance imaging (MRI) in patients with perianal Crohn's disease are presented. Modern MRI techniques provided excellent visualization of perineal anatomy, inflammatory tissues and an anorectal stricture. It also allowed detailed delineation of the patho-anatomy of fistulous abscess and any communication to more proximal bowel. This report illustrates the potential of modern MRI as an important investigative adjunct in evaluating the anorectal manifestations of Crohn's disease.

Anorectal physiological testing in defecatory disorders: a prospective study

A prospective study of anorectal physiological testing in 26 patients with obstructed defecation and 20 patients with faecal incontinence was performed. There were overlaps in individual test parameters between the two groups of patients. However, patients with severely blunted rectal sensation (maximum tolerated volume > 300 mL) and anismus were more likely to have obstructed defecation. Patients with very low anal canal pressures, a short (< 2.0 cm) anal canal, bilaterally prolonged (> 2.1 ms) pudendal nerve terminal motor latency and a grossly distorted and canal (vector symmetry index < or = to 0.75) were more likely to have faecal incontinence. Thus, patterns of anorectal physiological test results together with clinical evaluation, rather than individual test measurements, are more valuable in defining the underlying defecatory disorders and providing guidance on therapy.

Anorectal motor physiology and pathophysiology

Disorders of anorectal function are complex. A clear definition of the underlying pathophysiologic process is possible only with the use of the anal physiology laboratory. A reasonable treatment plan is then possible.

Leiomyosarcoma of the rectum and anal canal

Leiomyosarcoma of the rectum and anal canal is rare and the optimal treatment is not clear. Eight patients with isolated anorectal leiomyosarcoma treated surgically were reviewed. The age ranged from 44 to 76 years (median 63 years) and the follow up ranged from 6 months to 4.5 years (median 2 years). All patients were symptomatic at presentation. All tumours involved the muscularis propria of the low and/or mid-rectum with three tumours also involving the anal sphincters. The tumour size ranged from 1.2 to 10 cm (median 4 cm). Mucosal involvement occurred in only three patients and there was no lymph node involvement. All showed microscopic infiltration at the advancing border, despite macroscopic circumscription. Only one patient was thought to have a tumour sufficiently small (3 cm) and localized on clinical and intrarectal ultrasound examinations (UST2N0) to be suitable for wide local excision. That patient remained tumour-free after 2 years. The remaining patients (88%) were treated by abdomino-perineal resection. The disease free interval in this latter group ranged from 3 months to 4.5 years. All recurrences were detected within 15 months of surgery and the mean interval from detection of recurrence to death was 9 months. Using a histological grading system that included tumour differentiation, mitotic count and amount of necrosis, high grade sarcomas were associated with a worse prognosis. Other factors associated with a poor outcome included large tumour size (> 6-7 cm) and prior incomplete local excision.

Anorectal malignant melanoma has a poor prognosis

Clinicopathologic features and surgical treatment of 15 patients with primary anorectal malignant melanoma were studied retrospectively. There was a female preponderance (2:1). The median age was 66 years. Common initial symptoms were rectal bleeding (87%) and/or anal pain (33%); 25% of the melanomas were amelanotic. The maximum tumor size ranged between 0.8 and 8.4 cm (median 3.0 cm). Of the tumors evaluated histologically (n = 12), tumor thickness ranged from 0.9 to 11.3 mm (median 6.1 mm). All melanomas invaded at least into the subepithelial tissue (n = 8) and/or the submucosa of the distal rectum (n = 4), with extension into the internal anal sphincter (n = 5) and lamina propria (n = 3). Endoluminal ultrasound accurately demonstrated depth of invasion in 3 of 3 patients. Three (20%) patients with distant metastases at initial presentation had a mean survival of 8 mo; one of these primary melanomas measured 0.8 cm. Of 12 patients undergoing "curative" treatments--4 by abdominoperineal resection (APR) and 8 by local excision (LE), the incidence of loco-regional recurrence was similar (2/4 and 5/8). All these 7 patients with loco-regional recurrence developed distant metastases within 3 months. The mean survival was similar between APR and LE in the total group (25 mo vs 20 mo), in the decreased (27 mo vs 24 mo) and in those treated with a curative intent (29 mo vs 22 mo). There was no long-term survivor but four patients remained tumor-free up to 19 mo after APR (n = 1) or LE (n = 3).(ABSTRACT TRUNCATED AT 250 WORDS)

Endoluminal ultrasound is preferable to electromyography in mapping anal sphincteric defects

Assessment of complex sphincteric defects in patients with fecal incontinence by digital rectal examination and intraoperative dissection can be difficult in the presence of excessive scarring. Adjunctive investigation such as endoluminal ultrasound (ELUS) and needle electromyography (EMG) may provide objective evidence of the nature and extent of the sphincteric defects. In a series of 11 patients, ELUS of the anal canal with a 10-MHz transducer (focal zone of 1-4 cm) accurately detected defects in the external anal sphincter (EAS) in seven of seven patients, defects in the internal anal sphincter (IAS) in eight of eight patients, and integrity of both sphincters in two patients. These findings were confirmed by needle EMG of the EAS alone in five patients, by operative findings at a perineal sphincteroplasty operation in six patients, and by both in two patients. ELUS was associated with less pain than was needle EMG (pain score 4 vs. 10, 10 being most painful) and provided high-resolution radial images of both the EAS and the IAS. Thus, ELUS seems preferable to EMG in mapping anal sphincteric defects and can be a useful anatomic adjunct to physiologic studies of anorectal function in patients with fecal incontinence.