Vaginal endosonography of the anal sphincter complex is important in the assessment of faecal incontinence and perianal sepsis

Immediate postpartum assessment of the anal sphincter by endovaginal ultrasound: An experimental study

INTRODUCTION AND HYPOTHESIS

Obstetric anal sphincter injuries are frequently missed and carry a significant risk for the development of anal incontinence. Immediate postpartum endoanal ultrasound increases identification of these injuries but is rarely employed. We hypothesize that endovaginal ultrasound could be a feasible and easily available alternative sonographic tool to improve early diagnosis of anal sphincter tears.

METHODS

We conducted a prospective experimental study including 160 primiparous women. Shortly after vaginal delivery, patients underwent clinical and sonographic perineal examinations. We analyzed the feasibility of anal sphincter assessment by endovaginal ultrasound and its potential contribution in the early diagnosis of anal sphincter injuries.

RESULTS

Sonographic assessment of the anal sphincter was analyzable for 136 patients (85.0%). Causes of non-analyzability included air artifacts (6.9%), lack of distinction between the external anal sphincter and surrounding tissues (9.4%) and distortion artifacts (9.4%). Patients in the non-analyzable ultrasound subgroup were less likely to have delivered in a dorsal lithotomy position (62.5% vs. 85.3 %) and more likely to have had an episiotomy (33.3% vs. 14.0%), and their risk of sphincter injury was more frequently classified as "improbable" on clinical examination (91.7% vs. 61.0%). Ultrasounds were analyzable for 96.4% of patients clinically reported as having "possible" or "certain" sphincter injuries. The incidence of anal sphincter injury was 16.9% for clinical observation and 20.0% with associated sonographic examination.

CONCLUSIONS

Endovaginal ultrasound could be used as a complementary tool in assessment of the anal sphincter in high-risk patients. Its feasibility and easy availability make this technique a promising tool for improving the management of anal sphincter tears.

Internal anal sphincter: Clinical perspective

OBJECTIVE

To summarise current knowledge of Internal anal sphincter.

BACKGROUND

The internal anal sphincter (IAS) is the involuntary ring of smooth muscle in the anal canal and is the major contributor to the resting pressure in the anus. Structural injury or functional weakness of the muscle results in passive incontinence of faeces and flatus. With advent of new assessment and treatment modalities IAS has become an important topic for surgeons. This review was undertaken to summarise our current knowledge of internal anal sphincter and highlight the areas that need further research.

METHOD

The PubMed database was used to identify relevant studies relating to internal anal sphincter.

RESULTS

The available evidence has been summarised and advantages and limitations highlighted for the different diagnostic and therapeutic techniques.

CONCLUSION

Our understanding of the physiology and pharmacology of IAS has increased greatly in the last three decades. Additionally, there has been a rise in diagnostic and therapeutic techniques specifically targeting the IAS. Although these are promising, future research is required before these can be incorporated into the management algorithm.

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.

Ultrasound imaging of the anal sphincter complex: a review

Endoanal ultrasound is now regarded as the gold standard for evaluating anal sphincter pathology in the investigation of anal incontinence. The advent of three-dimensional ultrasound has further improved our understanding of the two-dimensional technique. Endoanal ultrasound requires specialised equipment and its relative invasiveness has prompted clinicians to explore alternative imaging techniques. Transvaginal and transperineal ultrasound have been recently evaluated as alternative imaging modalities. However, the need for technique standardisation, validation and reporting is of paramount importance. We conducted a MEDLINE search (1950 to February 2010) and critically reviewed studies using the three imaging techniques in evaluating anal sphincter integrity.

The diagnostic accuracy of endovaginal and transperineal ultrasound for detecting anal sphincter defects: The PREDICT study

AIM

To determine the accuracy and predictive value of transperineal (TPU) and endovaginal ultrasound (EVU) in the detection of anal sphincter defects in women with obstetric anal sphincter injuries and/or postpartum symptoms of faecal incontinence.

MATERIALS AND METHODS

One hundred and sixty-five women were recruited, four women were excluded as they were seen years after their last delivery. TPU and EVU, followed by endonanal ultrasound (EAU), were performed using the B&K Viking 2400 scanner. Sensitivity and specificity, as well as predictive values with 95% confidence intervals, for detecting anal sphincter defects were calculated for EVU and TPU, using EAU as the reference standard.

RESULTS

On EAU a defect was found in 42 (26%) women: 39 (93%) had an external (EAS) and 23 (55%) an internal anal sphincter (IAS) defect. Analysable images of one level of the EAS combined with an analysable IAS were available in 140 (87%) women for EVU and in 131 (81%) for TPU. The sensitivity and specificity for the detection of any defect was 48% (30-67%) and 85% (77-91%) for EVU and 64% (44-81%) and 85% (77-91%) for TPU, respectively.

CONCLUSION

Although EAU using a rotating endoprobe is the validated reference standard in the identification of anal sphincter defects, it is not universally available. However while TPU and/or EVU with conventional ultrasound probes can be useful in identifying normality, for clinical purposes they are not sensitive enough to identify an underlying sphincter defect.

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.

Posterior pelvic floor disorders: a prospective comparison using introital ultrasound and colpocystodefecography

OBJECTIVE

To compare introital ultrasound with colpocystodefecography (CCD) in quantifying the anorectal angle and in the diagnosis of posterior pelvic floor disorders.

METHODS

Forty-three consecutive women with functional impairment of the posterior pelvic floor were enrolled after a clinical evaluation. Using both CCD and introital ultrasound examination, the anorectal angle was measured during squeezing to evaluate the strength of voluntary muscle contraction and during straining to assess pelvic floor relaxation. Rectocele depth and the presence of intussusception were assessed. The performance of CCD and that of introital ultrasound were compared.

RESULTS

Good concordance was obtained between introital ultrasound and CCD. The intraclass correlation coefficient was 0.82 (95% CI, 0.69-0.89) for measurement of the anorectal angle during squeezing and 0.67 (95% CI, 0.47-0.81) during straining. Rectoceles > 4 cm on CCD were detected by introital ultrasound in 100% of cases, and there was 91% agreement for rectal intussusception. Cohen's kappa index was moderate for rectocele assessment (0.41, P < 0.01) and excellent for intussusception (0.91, P < 0.001). It was also noted that introital ultrasound could be used to detect pelvic floor dyssynergia.

CONCLUSIONS

Introital ultrasound is a simple, accurate, non-invasive method with which to assess anorectal dynamics.

Measurement of the anal cushions by transvaginal ultrasonography

PURPOSE

The anal cushions are believed to contribute to the anal continence mechanism. Transvaginal ultrasound previously has been used to visualize the anal sphincters. Using this method, visualization of the anal cushions has been described but no quantitation of the cushions has been undertaken. Because impairment of the anal cushion function may lead to anal incontinence, this study was designed to evaluate the use of transvaginal ultrasound to measure the anal cushions.

METHODS

Patients attending a gynecologic ultrasound list were recruited into the study. By measuring cross-sectional areas, a cushion:canal ratio was calculated.

RESULTS

Fifty females were studied. Results showed that the area enclosed within the internal anal sphincter had a median of 2.37 cm(2) (interquartile range, 1.76-2.61). The cushion:canal ratio was 0.66 (interquartile range, 0.57-0.7). Interobserver error was 0.98 and intraobserver error 0.99.

CONCLUSIONS

In this pilot study, we conclude that transvaginal ultrasonography is a reliable method of measuring the anal cushions in healthy control subjects. A narrow normal range can be established. This may be compared later with anal cushion size in patients who have symptoms of incontinence and may be used to assess changes in the size of the cushions in response to recently described anal cushion bulking agents.

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.

Endoanal and endorectal ultrasound: applications in colorectal surgery

Endoanal and endorectal ultrasound have an important role in colorectal surgery. They can be applied in the management of faecal incontinence, rectal tumours and inflammatory perianal conditions. In faecal incontinence, anal ultrasound will confirm the presence or absence of sphincter defects. This will direct any operative intervention such as direct sphincter repair. Ultrasound in rectal cancer allows staging of the tumour by assessing the depth of invasion through the bowel wall and involvement of mesenteric nodes. Such staging might influence the choice of operation and determine which patients might benefit from preoperative chemotherapy and radiotherapy. Ultrasound has a particular role in recurrent and complex anal fistula and perianal sepsis. Preoperative and perioperative planning with accurate delineation of fistula tracts, extensions and sphincter involvement might help prevent recurrence and impaired continence from sphincter damage after surgery. Correct interpretation of ultrasound images requires training and experience so that the results can be properly correlated with the clinical situation.

Perianal Crohn's disease

BACKGROUND

The management of perianal Crohn's disease is difficult. A wide variety of treatment options exist although few are evidence based.

METHODS

A search was conducted using the National Library of Medicine for articles on perianal Crohn's disease and its incidence, classification, assessment and management.

RESULTS AND CONCLUSION

Perianal Crohn's disease can manifest as skin tags, ulcers, fissures, abscesses, fistulas or stenoses. Improved radiological imaging with endoanal anal ultrasonography and magnetic resonance imaging has improved its assessment and may be used to predict outcome after surgery. Many treatment options exist. During acute complications they are generally aimed at resolving the immediate problem and limiting damage to anal and perianal tissues; this may be a 'bridge' to definitive treatment. The likelihood of success of definitive treatment must be weighed against the risk of complications, especially faecal incontinence.

Trans-perineal versus endo-anal ultrasound in the detection of anal sphincter tears

OBJECTIVE

To compare endo-anal and trans-perineal ultrasonography in the detection of anal sphincter lesions.

STUDY DESIGN

Sixty-four patients sent for a uro-gynaecological consultation were given tests by two ultrasound methods using the same apparatus (Aloka) with different probes. The endo-anal ultrasound (EAUS) was carried out in a supine position using a rotary circular probe at 7.5 MHz. The trans-perineal ultrasound (TPUS) was carried out using a curved linear probe at 5 MHz, applied to the perineum in the transverse direction, allowing a proximal view of the sphincter. For each image the thicknesses of the two components of the sphincter (internal and external) were noted, as well as the presence of any ultrasonographic tear, its position, and its width on the sphincterian circumference.

RESULTS

The average of the internal and external thickness of the sphincters was of 2.8 and 5.6 mm, respectively for the TPUS, and 2.1 and 6.2 mm for the EAUS. Among the 64 patients, 15 external lesions of the anal sphincter were found with the TPUS, and 14 with the EAUS. The kappa correlation coefficient was 48%, with a confidence interval of 95%.

CONCLUSION

The endo-anal technique, which provides a staged analysis of the anal sphincter muscle, remains the benchmark of sphincterian imaging. TPUS is a useful method, in that it gives good visualisation of anatomical structures, but its sensitivity in detecting sphincter lesions remain to be demonstrated.

Anovaginal and rectovaginal fistulas: endoluminal sonography versus endoluminal MR imaging

OBJECTIVE

The exact location of anovaginal and rectovaginal fistulas cannot be determined by physical examination and conventional techniques. The objective of our study was to compare the accuracy of endoluminal sonography and endoluminal MR imaging in revealing the location of anovaginal and rectovaginal fistulas.

MATERIALS AND METHODS

Nineteen consecutive patients (age range, 28-56 years; median age, 39 years) with clinical indications of an anovaginal or rectovaginal fistula were included in our retrospective study. Endoluminal sonography was performed using a 7.5-MHz transducer. Endoluminal MR imaging was performed at 0.5 T for 10 patients and 1.5 T for nine patients; axial T2-weighted gradient-echo, coronal and sagittal T2-weighted turbo spin-echo (0.5 T), or axial and radial T2-weighted turbo spin-echo and axial T2-weighted fat saturated turbo spin-echo (1.5 T) images were obtained. For a variety of reasons, surgery of the fistula was not attempted in six of these 19 patients. The imaging findings were compared with the findings obtained during surgery in the remaining 13 patients.

RESULTS

In 12 of the 13 patients, the fistula was found during surgery: seven of the fistulas were anovaginal, and five were rectovaginal. Findings of endoluminal sonography were true-positive in 11 patients, true-negative in one, and false-negative in one. Findings of endoluminal MR imaging were true-positive in 11 patients, false-negative in one, and false-positive in one. Positive predictive value for endoluminal sonography and endoluminal MR imaging were 100% and 92%, respectively. Imaging findings for anal sphincter defects were comparable.

CONCLUSION

Endoluminal sonography and endoluminal MR imaging have comparable positive predictive values in revealing the location of anovaginal and rectovaginal fistulas.

Constipation and fecal incontinence in the elderly

Although constipation and fecal incontinence are common symptoms in the elderly, relatively little research has been done to differentiate physiologic changes in rectoanal function resulting from aging and pathologic changes resulting from diseases occurring as patients age. Certain physiologic changes occur in many older patients and may predispose them to the development of constipation or fecal incontinence. These symptoms need the same thoughtful evaluation and management in the elderly as in younger patients. Results of therapy often can be good, leading to alleviation of suffering and the ability to lead a fuller life.

Anal sphincters defects--verification of the anal ultrasound diagnosis in 'bimanual' examination

The aim of this is to evaluate the diagnostic value of anal endosonography performed during pressing anterior wall of anal canal with a finger introduced into the lumen of vagina for the identification of anal sphincter defects. Anal ultrasound (AUS) with a finger introduced into the lumen of vagina was performed in a group of 55 women with anal sphincter defects recognized initially in standard AUS. This technique prevented false positive diagnoses of sphincter defects in 12 out of a group of 55 women (21.8%).

Imaging of anorectal disease

BACKGROUND

Over the past two decades developments in imaging have changed the assessment of patients with anorectal disease.

METHODS

The literature on imaging techniques for anorectal diseases was reviewed over the period 1980-1999.

RESULTS

For the staging of primary rectal tumours, phased array magnetic resonance imaging (MRI) may be regarded as the most appropriate single technique. The combination of endosonography or endoluminal MRI with ultrasonography or spiral computed tomography yields similar results. All techniques have limitations both for local staging and in the assessment of distant metastases. MRI or positron emission tomography is preferable for tumour recurrence. For perianal fistula, high-resolution MRI (phased array or endoluminal) is the technique of choice. For constipation, defaecography is the preferred technique, nowadays with emphasis on functional information. The role of magnetic resonance defaecography is currently being evaluated. For faecal incontinence, endosonography and endoluminal MRI give similar results in detecting sphincter defects; endoluminal MRI has the advantage of detecting external sphincter atrophy.

CONCLUSION

High-resolution MRI, endosonography and defaecography are currently the optimal imaging techniques for anorectal disease.

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.

Third-degree obstetric perineal tear: long-term clinical and functional results after primary repair

BACKGROUND

This study was designed to investigate the long-term clinical and anorectal functional results after primary repair of a third-degree obstetrical perineal rupture.

METHODS

One hundred and fifty-six consecutive women who had a primary repair of a third-degree perineal rupture were sent a questionnaire and asked to undergo anorectal function testing (anal manometry, anorectal sensitivity, anal endosonography and pudendal nerve terminal motor latency (PNTML)) RESULTS: Some 117 women (75 per cent) responded. Anal incontinence was present in 47 women (40 per cent); however, in most cases only mild symptoms were present. In 40 women additional anorectal function tests were performed and compared with findings in normal controls. Mean(s.d.) maximum squeeze pressure (31(15) versus 63(17) mmHg, P< 0.001) was decreased and first sensation to filling of the rectum (88(47) versus 66(33) ml, P=0.03) and anal mucosal electrosensitivity (4.7(1.7) versus 2.5(0.8) mA, P=0.003) were increased compared with values in normal controls. In 35 women (88 per cent) a sphincter defect was found with anal endosonography. Factors related to anal incontinence were the presence of a combined anal sphincter defect (relative risk (RR) 1.7 (95 per cent confidence interval (c.i.) 1.1-2.8)) or subsequent vaginal delivery (RR 1.6 (95 per cent c.i. 1.1-2.5)).

CONCLUSION

Anal incontinence prevails in 40 per cent of women 5 years after primary repair of a third-degree perineal rupture. The presence of a combined sphincter defect or subsequent vaginal delivery increase the risk of anal incontinence.