Three-dimensional anal endosonography may improve diagnostic confidence of detecting damage to the anal sphincter complex

Baiona's Consensus Statement for Fecal Incontinence. Spanish Association of Coloproctology

Faecal incontinence (FI) is a major health problem, both for individuals and for health systems. It is obvious that, for all these reasons, there is widespread concern for healing it or, at least, reducing as far as possible its numerous undesirable effects, in addition to the high costs it entails. There are different criteria for the diagnostic tests to be carried out and the same applies to the most appropriate treatment, among the numerous options that have proliferated in recent years, not always based on rigorous scientific evidence. For this reason, the Spanish Association of Coloproctology (AECP) proposed to draw up a consensus to serve as a guide for all health professionals interested in the problem, aware, however, that the therapeutic decision must be taken on an individual basis: patient characteristics/experience of the care team. For its development it was adopted the Nominal Group Technique methodology. The Levels of Evidence and Grades of Recommendation were established according to the criteria of the Oxford Centre for Evidence-Based Medicine. In addition, expert recommendations were added briefly to each of the items analysed.

The relationships between the results of contemporary tests of anorectal structure and sensorimotor function and the severity of fecal incontinence

BACKGROUND

Diagnostic investigations for fecal incontinence (FI) assess the structure and sensorimotor function of the anorectum. Investigations include anorectal manometry, anorectal sensory testing, pudendal nerve terminal motor latencies (PNTML), and endoanal sonography. The severity of FI and results of investigations are often discordant and the rate of symptom resolution following treatment remains <40%. High-resolution anorectal manometry (HRAM) and three-dimensional endoanal ultrasound (3D-US) have been introduced during the last decade. This study aims to assess the strength of relationships between contemporary investigation results and FI severity.

METHODS

Adults presenting for investigation of FI were assessed using the St Mark's FI severity score (SMIS), HRAM, anorectal sensory testing, PNTML, and 3D-US.

KEY RESULTS

246 patients were included. There were significant relationships between the SMIS and HRAM (resting pressure r_s = -0.23, 95% CI = (-0.34, -0.11), P < .001; squeeze pressure (r_s  = -0.26, 95% CI = (-0.37, -0.14), P < .001) and 3D-US (anterior EAS length r_s = -0.22, 95% CI = (-0.34, -0.09), P = .001). The relationships between SMIS and HRAM had a greater effect size in those with urge-predominant symptoms (resting pressure: r_s = -0.40, 95% CI = (-0.57, -0.20), P < .001, squeeze pressure: r_s = -0.34, 95% CI = (-0.52, -0.12), P = .003). Overall, the variance in SMIS accounted for by anorectal investigations was 8.6% (R² = 0.098, adjusted R² = 0.086, P < .001).

CONCLUSIONS AND INFERENCES

Anorectal investigations are not strong predictors of FI severity. These findings may reflect the multifactorial, heterogeneous pathophysiology of FI, the limitations of the SMIS and anorectal investigations, and contributing factors extrinsic to the anorectum.

Three-Dimensional Endoanal Ultrasound Features of the Anal Sphincter in Asian Primigravidae

OBJECTIVES

The normal parameters of 3-dimensional endoanal ultrasound (3DEAUS) of the anal sphincter have not been reported for primigravidae or pregnant women at present. 3DEAUS parameters in Asian primigravidae were assessed in this study.

METHODS

We analyzed 3DEAUS data of 101 consecutives Asian primigravidae, assessed in the early third trimester. The assessment was performed with a rigid ultrasonic probe (Olympus^® RU 12M-R1 probe and EU-ME1 ultrasound system (Olympus Corp., Shinjuku, Japan). The Wilcoxon signed-rank test was used to detect the differences in pressure in different quadrants.

RESULTS

The participants had a mean age of 24.7 (standard deviation [SD], 5.1) years. The Cleveland Clinic Incontinence Score was normal in all participants. The anal sphincter complex had 3 characteristic segments that were identifiable: upper, middle and lower. The puborectalis muscle was identified as a striated "V"-shaped sling, and its mean thickness was 7.44 (SD, 1.41) mm. The mean thickness of internal (IAS) and external (EAS) sphincters at the mid-sphincter level were 1.78 (SD, 0.59) and 5.49 (SD, 1.21) mm, respectively. The EAS measured 6.02 (SD, 1.07) mm at the lower sphincter level. The statistically significant differences seen in the in quadrants were: the IAS was thicker anteriorly (Z = -2.642; P = .008), the EAS at both midsphincter level (Z = -3.70; P < .001) and lower sphincter level (Z = -7.712; P < .001) was thicker posteriorly, and the IAS was thicker at the 9 o'clock position (Z = -2.081; P = .037). Good symmetry at all 3 levels was seen in the EAS (including the puborectalis muscle).

CONCLUSIONS

Normal values of 3DEAUS for primigravidae have been identified and may serve as reference values for other laboratories.

Postpartum two- and three-dimensional ultrasound evaluation of anal sphincter complex in women with obstetric anal sphincter injury

OBJECTIVE

To compare the sensitivity and specificity of two- (2D) and three- (3D) dimensional transperineal ultrasound (TPUS) and 3D endovaginal ultrasound (EVUS) with the gold standard 3D endoanal ultrasound (EAUS) in detecting residual defects after primary repair of obstetric anal sphincter injuries (OASIS).

METHODS

External (EAS) and internal (IAS) anal sphincters were evaluated by the four ultrasound modalities in women with repaired OASIS. 2D-TPUS was evaluated in real-time, whereas 3D-TPUS, 3D-EVUS and 3D-EAUS volumes were evaluated offline by six blinded readers. The presence/absence of any tear in EAS or IAS was recorded and defects were scored according to the Starck system. Sensitivity, specificity and predictive values were calculated, using 3D-EAUS as reference standard. Inter- and intraobserver analyses were performed for all 3D imaging modalities. Association between patients' symptoms (Wexner score) and ultrasound findings (Starck score) was calculated.

RESULTS

Images from 55 patients were analyzed. Compared with findings on 3D-EAUS, the agreement for EAS evaluation was poor for 3D-EVUS (κ = 0.01), fair for 2D-TPUS (κ = 0.30) and good for 3D-TPUS (κ = 0.73). The agreement for IAS evaluation was moderate for both 3D-EVUS (κ = 0.41) and 2D-TPUS (κ = 0.52) and good for 3D-TPUS (κ = 0.66). Good intraobserver (3D-EAUS, κ = 0.73; 3D-TPUS, κ = 0.78) and interobserver (3D-EAUS, κ = 0.68; 3D-TPUS, κ = 0.60) agreement was reported. Significant association between Starck and Wexner scores was found only for 3D-EAUS (Spearman's rho = 0.277, P = 0.04).

CONCLUSIONS

2D-TPUS and 3D-EVUS are not accurate modalities for the assessment of anal sphincters after repair of OASIS. 3D-TPUS shows good agreement with the gold standard 3D-EAUS and a high sensitivity in detecting residual defects. It, thus, has potential as a screening tool after primary repair of OASIS. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Correlation of three dimensional anorectal manometry and three dimensional endoanal ultrasound findings in primi gravida: a cross sectional study

Background

3-dimensional anorectal manometry (3DARM) and 3-dimensional endoanal ultrasound (3DEAUS) have not been used to assess the anal sphincter complex (ASC) in primi gravida. This study was conducted to identify any correlation that may exist between 3DARM and 3DEAUS.

Methods

We analyzed 3DARM and 3DEAUS data of 101 consecutive primi mothers assessed in the late second trimester or early 3rd trimester. 3DARM was performed using the Given Imaging^® Manoscan system and 3DEAUS was performed with the Olympus^® RU 12M-R1 probe and EU-ME1 ultrasound system.

Results

The mean age was 24.7 (SD—5.1) years. All patients had a normal Cleveland Clinic Incontinence Score. The mean resting pressure (RP) was 87.02 (SD—18.43) mmHg and the maximum squeeze pressure (SP) was 179.21 (SD—52.96) mmHg. The mean length of the high pressure zone was 3.67 (SD—0.52) cm. On 3DEAUS, there were three characteristic segments of the ASC that were identified; upper, middle and lower. Mean thicknesses for both internal anal sphincter (IAS) and external anal sphincter (EAS) were identified for primi gravida. IAS was thicker anteriorly and at 9 o’ clock positions and EAS was thicker posteriorly. There was good correlation in the length of the ASC at each quadrant between 3DARM and 3DEAUS. There was no correlation between either RP or SP thickness of IAS or EAS at each level and quadrant.

Conclusion

Correlation is seen only in the length of ASC at each quadrant. No correlation exist between RP or SP and thickness of IAS and EAS.

Diagnosis and treatment of faecal incontinence: Consensus statement of the Italian Society of Colorectal Surgery and the Italian Association of Hospital Gastroenterologists

Faecal incontinence is a common and disturbing condition, which leads to impaired quality of life and huge social and economic costs. Although recent studies have identified novel diagnostic modalities and therapeutic options, the best diagnostic and therapeutic approach is not yet completely known and shared among experts in this field. The Italian Society of Colorectal Surgery and the Italian Association of Hospital Gastroenterologists selected a pool of experts to constitute a joint committee on the basis of their experience in treating pelvic floor disorders. The aim was to develop a position paper on the diagnostic and therapeutic aspects of faecal incontinence, to provide practical recommendations for a cost-effective diagnostic work-up and a tailored treatment strategy. The recommendations were defined and graded on the basis of levels of evidence in accordance with the criteria of the Oxford Centre for Evidence-Based Medicine, and were based on currently published scientific evidence. Each statement was drafted through constant communication and evaluation conducted both online and during face-to-face working meetings. A brief recommendation at the end of each paragraph allows clinicians to find concise responses to each diagnostic and therapeutic issue.

Obstetrics anal sphincter injury and repair technique: a review

The Urogynecology Committee of the Asia and Oceania Federation of Obstetrics and Gynaecology (AOFOG) has held seminars and workshops on various urogynecological problems in each country in the Asia-Oceania area in order to encourage young obstetricians and gynecologists. In 2013, we organized the operative seminar for obstetrical anal sphincter injuries (OASIS) in which we prepared porcine models to educate young physicians in a hands-on workshop at the 23rd Asian and Oceanic Congress of Obstetrics and Gynaecology in Bangkok, Thailand. Laceration of the anal sphincter mostly occurs during vaginal delivery and it can develop into anal sphincter deficiency, which causes fecal incontinence, if an appropriate suture is not performed. OASIS has become an important issue, especially in developing countries. The prevalence of OASIS of more than the third degree is around 5% in primary parous women and the frequency is higher when detected by ultrasonographic evaluation. Several risk factors, such as macrosomia, instrumental labor, perineal episiotomy and high maternal age, have been recognized. In a society where pregnant women are getting older, OASIS is becoming a more serious issue. An intrapartum primary appropriate stitch is important, but the 1-year outcome of a delayed operation after 2 weeks postpartum is similar. A randomized controlled study showed that overlapping suture of the external sphincter is better than that of end-to-end surgical repair. The Urogynecology Committee of the AOFOG would like to continue with educative programs about the appropriate therapy for OASIS.

Anal sphincter complex: 2D and 3D endoanal and translabial ultrasound measurement variation in normal postpartum measurements

INTRODUCTION AND HYPOTHESIS

Women may experience anal sphincter anatomy changes after vaginal birth (VB) or Cesarean delivery (CD). Therefore, accurate and acceptable imaging options to evaluate the anal sphincter complex (ASC) are needed. ASC measurements may differ between translabial (TLUS) and endoanal (EAUS) ultrasound imaging and between 2D and 3D US. The objective of this analysis was to describe measurement variation between these modalities.

METHODS

Primiparous women underwent 2D and 3D TLUS imaging of the ASC 6 months after VB or CD. A subset of women also underwent EAUS measurements. Measurements included internal anal sphincter (IAS) thickness at proximal, mid, and distal levels and the external anal sphincter (EAS) at 3, 6, 9, and 12 o'clock positions, as well as bilateral thickness of the pubovisceralis muscle (PVM).

RESULTS

There were 433 women presenting for US: 423 had TLUS and 64 had both TLUS and EAUS of the ASC. All IAS measurements were significantly thicker on TLUS than EAUS (all p < 0.01), while EAS measurements were significantly thicker on EAUS (p < 0.01). PVM measurements with 3D or 2D imaging were similar (p > 0.20). On both TLUS and EAUS, there were multiple sites where significant asymmetry existed in left versus right measurements.

CONCLUSIONS

US modality used to image the ASC introduces small but significant changes in measurements, and the direction of the bias depends on the muscle and location being imaged.

Detection of anal sphincter defects in female patients with fecal incontinence: a comparison of 3-dimensional transperineal ultrasound and 2-dimensional endoanal ultrasound

BACKGROUND

Endoanal ultrasound is widely used for the detection of external and internal anal sphincter defects in patients with fecal incontinence. Recently, 3-dimensional transperineal ultrasound has been introduced as a noninvasive imaging method for the detection of these sphincter defects.

OBJECTIVE

This study was designed to assess agreement between 3-dimensional transperineal ultrasound and 2-dimensional endoanal ultrasound regarding the detection of anal sphincter defects in women with fecal incontinence.

DESIGN

This study was designed as a prospective observational study.

SETTINGS

The study took place in a university hospital.

PATIENTS

Between October 2008 and June 2009, all women with concerns of fecal incontinence underwent 2-dimensional endoanal ultrasound as well as 3-dimensional transperineal ultrasound.

MAIN OUTCOME MEASURES

The main outcome measures are the presence of external and internal anal sphincter defects.

RESULTS

Fifty-five patients were included. External and internal anal sphincter defects were observed with 2-dimensional endoanal ultrasound in 27 (49%) and 15 (27%) patients. Three-dimensional transperineal ultrasound detected an external and internal sphincter defect in 19 (35%) and 16 (29%) patients. The Cohen κ coefficient for the detection of external (κ = 0.63) and internal (κ = 0.78) anal sphincter defects was good.

LIMITATIONS

This study's limitations include the absence of a surgical examination as the reference standard in the determination of sphincter defects.

CONCLUSION

This study shows good agreement between 3-dimensional transperineal ultrasound and 2-dimensional endoanal ultrasound regarding the detection of anal sphincter defects. Based on these data, 3-dimensional transperineal ultrasound might be considered as a valuable alternative noninvasive investigation method.

Endoanorectal ultrasonography

Endoanorectal ultrasonography (EARUS) may be used for diagnosing various anorectal disorders. EARUS is easy to perform, has a short learning curve, and causes less discomfort than routine digital examination. Anal sphincters can be clearly visualized, and one can easily distinguish between the internal (hypoechoic) and external (hyperechoic) anal sphincters. Other pelvic floor structures, like the puborectalis muscle, can also be visualized. The use of contrast agents can increase the accuracy of EARUS in the assessment of perianal fistulae. In addition, EARUS is an excellent alternative to expensive magnetic resonance imaging. Besides its use in incontinence and perianal sepsis, the presence of slight or massive submucosal invasion in early rectal cancer may be imaged in greater detail. With 3-dimensional EARUS, it is possible to diagnose the anorectal diseases, in multiplane, with high spatial resolution, adding important information about the therapeutic decision. The normal sonographic anatomy of the anorectum, sonographic findings of anorectal diseases, and indications and limitations of endosonography with complementary techniques such as transvaginal and transperineal ultrasound are reviewed in this article.

Three-dimensional endoanal ultrasonography in daily proctological practice

Three-dimensional endoanal ultrasonography (3D-EAUS) provides unequalled quality in terms of the anatomical image of the anal canal and sphincter complex. In less than one minute it produces a three-dimensional "cube" that can be manipulated in all spatial dimensions, then archived. In just a few years it has become a new gold standard exploration in proctology. In addition to image quality, 3D-EAUS has the advantage of being easily and rapidly performed, well-tolerated and moderate in cost. For anal incontinence, 3D-EAUS contributes to the identification of sphincter defects. The anatomy of the sphincters can be evaluated spatially. Simple scoring systems with good reproducibility and readily applicable in routine practice can be used to evaluate the "damaged" sphincter volume. For the management of anoperineal suppurations, 3D-EAUS provides information on the fistulous track(s) and on potential collections. These data are crucial as the choice of treatment and its efficacy depend on accurate topographic assessment of the suppuration and the state of the sphincter apparatus.

Three-dimensional endoanal ultrasonography: intraobserver and interobserver agreement using scoring systems for classification of anal sphincter defects

OBJECTIVES

To determine the degree of intraobserver and interobserver agreement for an experienced and an inexperienced sonologist using two scoring systems for ultrasonographic assessment of anal sphincter defects.

METHODS

The study sample comprised the datasets of all women aged between 20 and 40 years who had attended our outpatient clinic and undergone a complete three-dimensional (3D) endoanal ultrasound (EAUS) examination in the period from January 2003 to December 2005. The EAUS datasets were assessed twice independently by two sonologists: one with experience of > 400 3D EAUS assessments and one inexperienced sonologist who had performed approximately 50 assessments before the study. Cases with intraobserver disagreement were resolved by a third (final) assessment. The final assessment from each observer was used to determine the degree of interobserver agreement. Sphincter defects were classified according to our EAUS defect score and the Starck score.

RESULTS

EAUS datasets of 55 women were included. Based on first vs. second assessments, intraobserver agreement for the experienced sonologist was good for our EAUS defect score (weighted kappa, 0.75) and the Starck score (weighted kappa, 0.73). Intraobserver agreement for the inexperienced sonologist was moderate for our EAUS defect score (weighted kappa, 0.58) and good for the Starck score (weighted kappa, 0.62). Interobserver agreement was good for both our EAUS defect score (weighted kappa, 0.65) and the Starck score (weighted kappa, 0.74).

CONCLUSIONS

Intraobserver and interobserver agreement was acceptable for both scoring systems. The experienced sonologist obtained a higher degree of intraobserver agreement than did the inexperienced sonologist.

Effects of age and gender on three-dimensional endoanal ultrasonography measurements: development of normal ranges

BACKGROUND

Faecal incontinence is a common and morbid disorder that is often related to anal sphincter dysfunction. High-frequency, three-dimensional (3-D) endoanal ultrasonography (EAUS) allows greater spatial resolution and longitudinal appreciation of the anal canal than conventional 2-D assessment. A robust normal range of values allowing for age and sex is required for subsequent disease comparison.

METHODS

A group of 30 healthy male (n=12) and female (n=18) volunteers (median age, 49 years; range, 31-63 years) underwent 3-D EAUS using a high-frequency 10-MHz transducer. A reconstructed data cube was interrogated to measure anal canal structures in 2-D at high, middle and low levels, and in 3-D for longitudinal measurements.

RESULTS

Men had a significantly longer 3-D external anal sphincter (EAS) and internal anal sphincter (IAS) than women, especially the anterior EAS (mean in men 2.5 cm, mean in women 1.6 cm, p<0.0001). There were no significant differences between the sexes for anal canal length or by 2-D scanning for the thickness of the EAS and IAS. No significant differences were observed between parous and nulliparous women. Age had no significant effect on 3-D length measurements, but 2-D EAUS measurements of the thickness of both the IAS and EAS increased with age significantly (mid canal, p=0.004). On these bases, normal ranges were generated.

CONCLUSIONS

Sphincter measurements, enabled by 3-D reconstruction, vary with age and sex. A normal range incorporating these variations has been produced for future data comparison in disease states.

Radiologic evaluation of pelvic floor disorders

Several imaging modalities are available ranging from fluoroscopic techniques to ultrasonography and MRI for the evaluation of patients with pelvic floors disorders. High-resolution ultrasonography and MRI not only provide superior delineation of the pelvic floor anatomy but also reveal pathology and functional changes. This article focuses on standard imaging procedures including defecography, ultrasonography, and MRI and discusses its use in clinical practice by illustrating both normal and abnormal patterns.

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.

[Anal incontinence]

Anal incontinence today is more frequent than current estimates indicate. When a patient seeks care for this condition, its cause and severity are assessed by a careful history and clinical examination. Two essential atraumatic examinations are decision-support tools: transrectal ultrasound and anal manometry. Treatment should always be proposed. Surgery is necessary in some cases: obvious rupture of the external sphincter, if possible confirmed by transrectal ultrasound, should be directly repaired. Should this treatment fail, a repeated repair or a sphincter replacement (graciloplasty or artificial sphincter) is called for. Neuromodulation therapy is often indicated in the absence of obvious rupture, especially in cases of pudendal neuropathy.

Obstetric anal sphincter injury: incidence, risk factors, and management

BACKGROUND AND AIMS

Obstetric sphincter damage is the most common cause of fecal incontinence in women. This review aimed to survey the literature, and reach a consensus, on its incidence, risk factors, and management.

METHOD

This systematic review identified relevant studies from the following sources: Medline, Cochrane database, cross referencing from identified articles, conference abstracts and proceedings, and guidelines published by the National Institute of Clinical Excellence (United Kingdom), Royal College of Obstetricians and Gynaecologists (United Kingdom), and American College of Obstetricians and Gynecologists.

RESULTS

A total of 451 articles and abstracts were reviewed. There was a wide variation in the reported incidence of anal sphincter muscle injury from childbirth, with the true incidence likely to be approximately 11% of postpartum women. Risk factors for injury included instrumental delivery, prolonged second stage of labor, birth weight greater than 4 kg, fetal occipitoposterior presentation, and episiotomy. First vaginal delivery, induction of labor, epidural anesthesia, early pushing, and active restraint of the fetal head during delivery may be associated with an increased risk of sphincter trauma. The majority of sphincter tears can be identified clinically by a suitably trained clinician. In those with recognized tears at the time of delivery repair should be performed using long-term absorbable sutures. Patients presenting later with fecal incontinence may be managed successfully using antidiarrheal drugs and biofeedback. In those who fail conservative treatment, and who have a substantial sphincter disruption, elective repair may be attempted. The results of primary and elective repair may deteriorate with time. Sacral nerve stimulation may be an appropriate alternative treatment modality.

CONCLUSIONS

Obstetric anal sphincter damage, and related fecal incontinence, are common. Risk factors for such trauma are well recognized, and should allow for reduction of injury by proactive management. Improved classification, recognition, and follow-up of at-risk patients should facilitate improved outcome. Further studies are required to determine optimal long-term management.

Correlation between anal sphincter defects and anal incontinence following obstetric sphincter tears: assessment using scoring systems for sonographic classification of defects

OBJECTIVE

To determine if there is a correlation between the sonographic extent of anal sphincter defects revealed by three-dimensional endoanal sonography (EAUS) and the degree of anal incontinence following primary repair of obstetric sphincter tears.

METHODS

This was a follow-up study of women who had suffered anal sphincter tearing during vaginal delivery at Aalesund Hospital between January 2002 and July 2004. Incontinence was assessed by St Mark's score. The anal canal was assessed with three-dimensional endoanal sonography (EAUS). Sphincter defects were classified according to the Starck score and our new EAUS defect score. The EAUS images were interpreted by an observer blinded to other patient data.

RESULTS

Sixty-one women were included in this study. Incontinence was reported by 32 (52%) women at a median of 21 (range, 9-35) months after delivery. Three-dimensional EAUS datasets were obtained in 55 women. There was a significant correlation between St Mark's score and our EAUS defect score (P = 0.034), and correlation approached but did not reach significance between St Mark's score and the Starck score (P = 0.053). There was a strong correlation between our EAUS defect score and the Starck score (P < 0.001).

CONCLUSIONS

There is a positive correlation between the extent of sphincter defects and the degree of anal incontinence following primary repair of obstetric sphincter tears. Our findings highlight the importance of adequate reconstruction of the anal sphincters during primary repair.

Sonography of benign conditions of the anal canal: an update

OBJECTIVE

The objective of this article is to describe our experience with sonography for the study of benign conditions of the anal canal and perianal soft tissues.

CONCLUSION

Assessment of the anal sphincters in patients with fecal incontinence and documentation of perianal inflammatory masses and tracts in those with perianal inflammatory disease are the major indications for imaging the anal canal. We augment traditional transanal sonography with transperineal scanning in both sexes and transvaginal scanning in women to better show the anal canal in its quiet state to allow an accurate assessment of the integrity of the anal sphincters and of evidence of acute or chronic inflammatory involvement.

The advantages of volume rendering in three-dimensional endosonography of the anorectum

Anorectal diseases require imaging for proper case management. At present, endoanal ultrasonography and endorectal ultrasonography have become important parts of diagnostic workup of patients with fecal incontinence, perianal fistulas, and rectal cancer and provides sufficient information for clinical decision-making in many cases. However, with the currently available ultrasonographic equipment and techniques, a good deal of relevant information may remain hidden. The advent of high-resolution three-dimensional endoluminal ultrasound, constructed from a synthesis of standard two-dimensional cross-sectional images, and of "Volume Render Mode," a technique to analyze information inside a three-dimensional volume by digitally enhancing individual voxels, promises to revolutionize diagnosis of pelvic floor disorders. By use of the different postprocessing display parameters, the volume-rendered image provides better visualization performance when there are not large differences in the signal levels of pathologic structures compared with surrounding tissues. The anatomic structures in the pelvis, the axial and longitudinal extension of anal sphincter defects, the anatomy of the fistulous tract in complex perianal sepsis, and the presence of slight or massive submucosal invasion in early rectal cancer may be imaged in greater detail. This additional information will bring an improvement for both planning and conduct of surgical procedures.

External anal sphincter defects in patients with fecal incontinence: comparison of endoanal MR imaging and endoanal US

PURPOSE

To prospectively compare in a multicenter study the agreement between endoanal magnetic resonance (MR) imaging and endoanal ultrasonography (US) in depicting external anal sphincter (EAS) defects in patients with fecal incontinence.

MATERIALS AND METHODS

The study was approved by the medical ethics committee of all participating centers. A total of 237 consenting patients (214 women, 23 men; mean age, 58.6 years +/- 13 [standard deviation]) with fecal incontinence were examined from 13 different hospitals by using endoanal MR imaging and endoanal US. Patients with an anterior EAS defect depicted on endoanal MR images and/or endoanal US scans underwent anal sphincter repair. Surgical findings were used as the reference standard in the determination of anterior EAS defects. The Cohen kappa statistic and McNemar test were used to calculate agreement and differences between diagnostic techniques.

RESULTS

Agreement between endoanal MR imaging and endoanal US was fair for the depiction of sphincter defects (kappa = 0.24 [95% confidence interval: 0.12, 0.36]). At surgery, EAS defects were found in 31 (86%) of 36 patients. There was no significant difference between MR imaging and US in the depiction of sphincter defects (P = .23). Sensitivity and positive predictive value were 81% and 89%, respectively, for endoanal MR imaging and 90% and 85%, respectively, for endoanal US.

CONCLUSION

In the selection of patients for anal sphincter repair, both endoanal MR imaging and endoanal US are sensitive tools for preoperative assessment, and both techniques can be used to depict surgically repairable anterior EAS defects.

Computer-assisted evaluation of perianal fistula activity by means of anal ultrasound in patients with Crohn's disease

OBJECTIVES

Assessment of the activity of perianal fistulas may be of clinical relevance in patients with Crohn's disease. Fistula activity is currently evaluated by means of magnetic resonance imaging; anal ultrasound can also be used, but its diagnostic performance in this setting remains to be defined. Our aims were to evaluate the agreement between clinical examination, magnetic resonance imaging, and anal ultrasound in assessing perianal fistula activity, and to apply computerized analysis to improve the assessment of ultrasound images.

METHODS

Thirty-one consecutive patients with Crohn's perianal fistulas underwent clinical examination, and magnetic resonance and anal ultrasound imaging. Active fistulas were defined as the presence of active drainage or signs of local inflammation on clinical examination, and the definition was confirmed by surgical examination. Activity was assessed on the basis of T2 hyperintensity on magnetic resonance imaging and the degree of hypoechogenicity on anal ultrasound; the anal ultrasound images were also analyzed using dedicated computer image-analysis software.

RESULTS

Twenty-five patients had an active fistula at clinical examination. The agreement between clinical examination and magnetic resonance imaging was good (k-value = 0.739), whereas that with anal ultrasound was only fair (k-value = 0.266-0.294); computer-assisted analysis of the anal ultrasound images improved the agreement from fair to good (k-value = 0.608-0.670).

CONCLUSIONS

Anal ultrasound can be used to assess fistula track activity in patients with Crohn's disease. The diagnostic performance of the technique can be improved to values comparable with those of magnetic resonance imaging by using a computer-assisted evaluation of the anal ultrasound images.