Internal Anal Sphincter Thickness Research Articles

Systemic sclerosis and anorectal dysfunction: The Leeds experience.

Systemic sclerosis is an autoimmune disorder which frequently affects the gastrointestinal tract. Anorectal dysfunction is common in systemic sclerosis and is manifested mainly by atrophy of internal anal sphincter. Faecal incontinence is the result of internal anal sphincter atrophy secondary to systemic sclerosis. In this study, we aimed to assess the internal anal sphincter in 17 patients with faecal incontinence and systemic sclerosis using anorectal manometry and endoanal ultrasound and compare them with an age and gender-matched control group without systemic sclerosis. Most patients have limited cutaneous systemic sclerosis. Majority of the patients with systemic sclerosis and faecal incontinence presented with symptoms of faecal leakage and urgency. Systemic sclerosis patients had low basal sphincter pressures. The mean thickness of internal anal sphincter in systemic sclerosis group was significantly lower than the control group (p < 0.001). Rectal sensation is preserved in systemic sclerosis. There was no difference in the mean thickness of the external anal sphincter between the two groups. To conclude internal anal sphincter is atrophic in systemic sclerosis resulting in decreased resting sphincter pressures and passive faecal leakage. Further investigations and studies are needed to determine the natural course of faecal incontinence in systemic sclerosis, associated risk factors and efficacy of therapeutic interventions.

Role of 3D high resolution anorectal manometry compared to conventional technique in management of constipation and fecal incontinence in children

BackgroundAnorectal manometry is a valuable tool for objective assessment of motility motor and sensory function of the anorectum. The aim of this study was to investigate role of water-perfused (WP) three dimensional high-resolution anorectal manometry (3D-HRARM) compared to WP conventional manometry (CM) in the management of chronic idiopathic constipation (CIC) and faecal incontinence (FI) in children. MethodsThis was a retrospective review of 122 consecutive children, who had WP 8-channel CM or 24 channel 3D-HRARM and endosonography under ketamine anaesthesia from September 2012 to February 2019. All patients had a validated symptom severity score questionnaire ranging from 0 (best) to 65 (worst). Mann-Whitney-U test and Spearman rank test were used and p<0.05 was considered significant. ResultsSubjects were divided according to investigation: CM group (n = 75) and 3D-HRAM (n = 47), who were otherwise comparable. Median anal resting pressure was 50 mmHg and rectoanal inhibitory reflex (RAIR) threshold volume was 10mls across the entire cohort. There were no significant differences in resting pressure or RAIR threshold when using conventional or 3D-HRARM. Rectal capacity was significantly higher in the CM group (p = 0.002). Rectal capacity and internal anal sphincter (IAS) thickness positively correlated with symptom severity, duration and patient age. 3D-HRARM provided a more detailed depiction of the anorectal pressure profile. Botulinum toxin was injected into the external anal sphincter (EAS) muscle (n = 75, 61%) and an anterograde colonic enema (ACE) stoma was needed subsequently in 19 (16%) to treat recurrent constipation and soiling symptoms. Rectal biopsy was done in 43(35%) patients, if RAIR was absent or inconclusive. ConclusionCM and 3D-HRARM are comparable in terms of resting pressure and RAIR threshold. 3D-HRAM is safe and provides detailed functional morphology of anal sphincters and it is useful to understand underlying pathophysiology of constipation and faecal incontinence in children and plan further treatment. Level of EvidenceLevel I

Morphological characteristic of anal canal in patients with dyssynergic defecation and its correlation with anorectal manometry

Objective: To evaluate the diagnostic value of three-dimensional endoanal ultrasound (3D-EAUS) for dyssynergic defecation (DD). Methods: A case-control study was performed to retrospectively collectclinical data of 46 DD patients, including 16 males and 30 females with median age of 51 (20 to 70) years, at Nanjing Hospital of Chinese Medicine from February 2012 to April 2015.All the patients met the diagnostic criteria of functional constipation of Rome III. The paradoxical contraction of puborectalis (PR) muscle was found by both rectal examination and anorectal manometry. In the same period,45 healthy volunteers, including 22 males and 23 females with median age of 48 (21 to 72) years, without pelvic operation history, and with normal defecation in recent 6 months, were enrolled as the control group. No significant differences were observed in age and gender between two groups (both P>0.05). Cleveland constipation score of DD group was higher than that of control group [15(8-24) vs. 5(1-9), t=15.720, P<0.001]. 3D-EAUS examination was performed in all the subjects. Thickness and length of internal anal sphincter (IAS) (anterior side and posterior side), thickness of PR muscle, length of external anal sphincter (EAS) plus PR muscle, and puborectalis angle were measured and compared by using student t test between two groups. Correlation between these ultrasound parameters and anorectal manometry was examined by Pearson correlation analysis. Results: Both male and female in the DD group had the greater thickness of IAS, as compared to those in the control group [male: (1.7±0.5) mm vs.(1.5±0.2) mm, t=2.516, P=0.016; female: (1.9±0.4) mm vs.(1.6±0.5) mm, t=2.034,P=0.047]. No significant differences between the two groups were observed with respect to the posterior length of IAS, length of EAS plus PR muscle, and thickness of PR muscle (all P>0.05). Compared to the control group, male in the DD group had smaller puborectalis angle during straining [(87.0±3.6)° vs. (90.5±1.8)°,t=3.502,P=0.002];female in the DD group had smaller puborectalis angle both in resting and straining [resting:(86.5±3.8)° vs. (90.1±2.1)°,t=4.047, P<0.001;straining: (84.1±4.5)° vs. (90.2±2.3)°, t=5.938, P<0.001]. Correlation analysis showed that anterior length of IAS was positively correlated with anal resting pressure (r=0.321, P=0.030); the length of EAS plus PR muscle was positively correlated with anal squeeze pressure (r=0.415, P=0.004). There were no correlations between the thickness and the posterior length of IAS and the anal resting pressure, or between the thickness of PR muscle and the anal squeeze pressure (all P>0.05). Conclusions: The 3D-EAUS can accurately assess the morphological features of anal canal in DD patients. There is a certain positive correlation between 3D-EAUS and anorectal manometry.

Normal Values of Anal Sphincter Biometry by 4-Dimensional Translabial Ultrasound: A Retrospective Study of Pregnant Women in Their Third Trimester.

Exoanal 4-dimensional translabial ultrasound (TLUS) is increasingly used to image the anal sphincter. The aim of this study was to define the limits of normality for assessment of external and internal anal sphincters with TLUS. This study was a retrospective analysis using data sets of nulliparous women seen antenatally. All women had a 4-dimensional TLUS examination at a mean gestational age ± SD of 36 ± 0.7 (range, 32.9-37.3) weeks. Anal sphincter biometry, including external anal sphincter (EAS) length and thickness, EAS proximal rotational asymmetry, and internal anal sphincter thickness, was assessed blinded against other data. A test-retest series showed good repeatability (intraclass correlation coefficients, 0.619-0.849) of all parameters. The mean age of the women (n = 111) was 30.9 (range, 18.8-40.5) years. None reported anal incontinence. On tomographic imaging, none showed anal sphincter defects. The mean EAS length was 17.5 (range, 8.4-34.8) mm, being shorter dorsally at 16.4 (range, 7.0-32.7) mm versus 18.7 (range, 7.5-36.9) mm ventrally (P < .001). The ventral EAS reached farther cranially by 0.8 ± 2.5 (range, -4.8-5.1) mm on average. The mean EAS thickness was 3.4 (range, 2.0-5.8) mm, being thicker dorsally than ventrally (P < .001). Anal sphincter biometry can be assessed with good repeatability by TLUS. The EAS seems longer ventrally. Asymmetry of the EAS could result in a false-positive diagnosis of defects in women in whom the ventral EAS terminates more caudally than its dorsal aspect, which seems uncommon. Hence, the likelihood of a false-positive diagnosis of substantial defects of the EAS using the published method seems low.

Role of three-dimensional endoanal ultrasound in assessing the anal sphincter morphology of female patients with chronic proctalgia.

AIMTo assess the role of three-dimensional endoanal ultrasound (3D-EAUS) for morphological assessment of the anal sphincter of female patients with chronic proctalgia (CP).METHODSIn this unmatched case control study, 30 consecutive female patients with CP and 25 normal women (control group) were enrolled. 3D-EAUS was performed in all subjects. Thickness and length of internal anal sphincter (IAS), thickness of puborectalis muscle (PR), length of the external anal sphincter (EAS) plus PR, and puborectalis angle were measured and compared between the two groups.RESULTSPatients with CP had significantly shorter IAS length and greater PR thickness, as compared to those in normal individuals (26.28 ± 3.59 mm vs 28.87 ± 4.84 mm, P < 0.05 and 9.67 ± 1.57 mm vs 8.85 ± 0.97 mm, P < 0.05, respectively). No significant between-group differences were observed with respect to IAS thickness and the EAS plus PR length (P > 0.05). Puborectalis angle in the CP group was significantly decreased, both in resting (88.23° ± 1.81° vs 89.94° ± 2.07° in control group, P < 0.05) and straining (88.47° ± 3.32° vs 90.72° ± 1.87° in control group, P < 0.05) phases, which suggest the presence of paradoxical contraction of PR in patients with CP. In the CP group, no significant difference in puborectalis angle was observed between the resting and straining phases (88.23° ± 1.81° vs 88.47° ± 3.32° respectively, P > 0.05).CONCLUSIONThe association of greater PR thickness and paradoxical contraction of PR with CP suggest their potential value as markers of CP.

The immediate effect of vaginal and caesarean delivery on anal sphincter measurements.

ObjectiveThis study evaluated the effects of vaginal and caesarean delivery on internal and external anal sphincter muscle thickness using translabial ultrasonography (TL-US).MethodsThis prospective cohort study enrolled nulliparous women who either had vaginal or caesarean deliveries. The thickness of the hypoechoic internal anal sphincter (IAS) and hyperechoic external anal sphincter (EAS) at the 12, 3, 6, and 9 o’clock positions at the distal level were measured before delivery and within 24–48 h after delivery.ResultsA total 105 consecutive women were enrolled in the study: 60 in the vaginal delivery group and 45 in the caesarean delivery group. The IAS muscle thickness at the 12 o’clock position in the vaginal delivery group was significantly thicker before compared with after delivery (mean ± SD: 2.31 ± 0.74 mm versus 1.81 ± 0.64 mm, respectively). The EAS muscle thickness at the 12 o’clock position in the vaginal delivery group was significantly thicker before compared with after delivery (mean ± SD: 2.42 ± 0.64 mm versus 1.97 ± 0.85, respectively).ConclusionsThere was significant muscle thinning of both the IAS and EAS at the 12 o’clock position after vaginal delivery, but not after caesarean delivery.

Influence of neoadjuvant chemoradiotherapy on the anal sphincter: ultrastructural damage may be critical.

Neoadjuvant chemoradiotherapy (nCRT) in addition to the curative surgery has been the first of treatment for local advanced rectal cancer because of its benefits in local recurrence and sphincter-saving. However, its side effects on anorectal function have been recognized. The histopathological changes on internal anal sphincter (IAS) have been reported, but ultrastructure changes of external anal sphincter (EAS) are unknown. The aim of this study is to detect the alterations on the gross morphology of IAS and ultrastructure of EAS after nCRT. We collected 34 anal canal specimens of patients undergoing abdominoperineal resection (APR) prospectively. The length and thickness of IAS were measured with vernier caliper. The EAS was dissected for observation with transmission electron microscope (TEM). Ten patients received nCRT (nCRT group) before surgery and 24 underwent APR directly (control group). The length and thickness of IAS in nCRT group were 22.68±3.56 and 5.39±0.74mm, respectively. These parameters were 21.28±3.62 and 5.35±1.12mm in control group, respectively. There were no significant differences in the length and thickness of IAS between the two groups (P>0.05). In nCRT group, the sarcomere and myofibril were arranged disorderly and parts of them that were filled with collagenous fiber, triads, and mitochondria were destroyed severely and the glycogenosome also distributed disorderly. Such alterations of EAS did not occur in control group. The nCRT cannot change the gross morphology of IAS, while it induces serious damages to the ultrastructures of EAS which may adversely affect the anorectal function.

Alteration of anal sphincter function in patients with levator avulsion: observational study.

The prevalence of levator avulsion after vaginal delivery ranges from 10 to 30 %. To our knowledge, no previous studies have used anorectal manometry (AM) to assess this injury's impact on the functionality of the anal sphincter complex. We hypothesized that women with levator avulsion have lower manometric pressures. A prospective observational study was conducted on 83 women, 61 in the birth group and 22 in the control group. Patients in the deliveries group were recruited in the period immediately postpartum. The control group was recruited through hospital announcements. All patients underwent 3D transperineal (3D TPUS) and 2D endoanal ultrasound (2D EAUS), as well as AM at 6 months postpartum. Median maximum resting and squeeze pressures were measured, and the presence or absence of levator ani muscle (LAM) avulsion and/or occult sphincter injury was evaluated. Hiatal area at rest was significantly higher in women with vaginal birth compared with controls (p = 0.02) and there was a trend toward statistical significance compared with the cesarean section group (p = 0058). No statistical differences were observed for the hiatal area regarding Valsalva, external anal sphincter thickness, and internal anal sphincter thickness among groups. There was a significantly higher prevalence of levator avulsion in the vaginal birth group (32.43 %) compared with the controls (0 %) and the cesarean section group (5.8 %; p < 0001). There were 5 occult sphincter injuries detected at ultrasound, all of them in the vaginal birth group. Lower squeeze pressure was observed in patients with levator injury compared with control group patients and patients without avulsion (112.2 mmHg vs 128.2 mmHg and 121.2mmH; p = 0.032). Finally, there was no difference in resting pressure (p = 0.541) or squeeze pressure (p = 0.449) between patients with and those without occult anal sphincter injuries. Levator avulsion is associated with lower manometric squeeze pressure (p = 0.032).

Thickened internal anal sphincter has been reported to be a typical finding in solitary rectal ulcer syndrome.

tion disorder among patients with solitary rectal ulcer syndrome (SRUS). The study showed that SRUS patients with abnormal balloon expulsion test had thicker internal anal sphincter (IAS), compared to those with normal tests. In fact, thickened IAS has been reported to be a typical endoanal sonographic finding in SRUS. 2,3 This finding could be associated with hypertrophy, possibly resulting from chronically increased work demand. A thickened IAS in patients with SRUS also is reported to be highly predictive of high-grade rectal intussusception. 4 Therefore, the result of Sharma et al’s study is not a novel finding but adds to the body of evidence demonstrating thickened anal sphincter as a typical endoanal feature in SRUS. As far as we know, several measuring points are required for the assessment of IAS thickness, since the thickness of IAS is not uniform. However, we could not find detailed methods for the measurement of IAS thickness in their article. We present typical endoscopic and sonographic findings of SRUS in a 59-year-old woman. She was referred to our constipation clinic for refractory constipation. Colonoscopy showed large ulcer with fold convergence (Figure A). The thickness of the IAS was measured at 4 different circumferential points. Endoanal sonography demonstrated thickened IAS irrespective of the level of anal canal (Figures B and C). Pathology showed fibrous obliteration and extension of smooth muscle fibers into the lamina propria. The confirmatory diagnosis of SRUS was made based on clinical presentation, endoscopic appearance and characteristic histologic features.

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

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. 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). 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. 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.

OP14.05: Internal anal sphincter thickness as a predictor of obstructed defecation

<scp>OP</scp>14.05: Internal anal sphincter thickness as a predictor of obstructed defecation

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

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

Preoperative MRI sphincter morphology and anal manometry: can they be markers of functional outcome following anterior resection for rectal cancer?

Good functional outcome following anterior resection (AR) for rectal cancer is an important clinical goal, but its prediction has proven difficult. Assessments such as anal manometry have been advocated as a potential tool but functional anatomy as depicted on MRI has not been investigated. This study looked at whether sphincter complex measurements recorded from preoperative staging MRIs and preoperative anal manometry have any correlation with functional outcome. Consecutive patients with rectal adenocarcinoma underwent preoperative manometric assessment and MRI staging. MRIs were assessed with regard to anorectal angle, puborectalis thickness, canal length and external and internal anal sphincter thickness. Functional outcome was categorized into three groups according to the number of adverse postoperative symptoms (frequency, urgency, leakage, diarrhoea, use of pads, use of antidiarrhoeal medication): 0, 1 and ≥ 2. This was evaluated 1 year following surgery and 6 months following stoma reversal where applicable. Univariate analysis of an ordinal regression model was performed with significance at the 5% level. Thirty patients were assessed. No single preoperative manometric parameter proved significant (P > 0.05). Only puborectalis thickness showed a significant (P = 0.01) relationship with the number of adverse symptoms suffered postoperatively. On receiver operating characteristics analysis, a cut-off value of 3.5 mm gave an optimal sensitivity of 0.5 (95% CI, 0.17-0.83) and specificity of 0.86 (95% CI, 0.64-0.96). Measurements of the puborectalis thickness on preoperative staging MRIs for rectal cancer may help predict functional outcome following AR. Prospective assessment of larger numbers with a fully validated continence score are required to evaluate these findings further.

Anterior and posterior compartment 3D endovaginal ultrasound anatomy based on direct histologic comparison

We used direct histologic comparison to validate the use of 3D endovaginal ultrasound (EVUS) as a novel and emerging technology for evaluating the structures found in the anterior and posterior pelvic floor compartments. A young nulliparous female pelvis specimen was dissected and histologic slides were prepared by making 8-Micron-thick sagittal cuts. The slides were stained with Mallory trichrome and arranged to form large sections encompassing each anterior and posterior sagittal plane. Healthy nulliparous women underwent 3D EVUS to obtain 3D cubes of the anterior and posterior compartments. Two investigators independently evaluated the anterior and posterior midsagittal structures. The investigators mutually viewed the images and calculated urethral and anal sphincter measurements. Thirty-one nulliparous women underwent 3D EVUS; 77% of the participants were Caucasian, with mean age 31.8 [standard deviation (SD) 5.8] and mean body mass index (BMI) of 28.5 (SD 7.9). The following mean (SD) measurements were obtained: urethral length 36 mm (± 5); striated urogenital sphincter area 0.6 cm(2) (± 0.16); longitudinal and circular smooth muscle area 1.1 cm(2) (± 0.4); urethral complex width 14 mm (± 2); urethral complex area 1.3 cm(2) (± 0.4); internal anal sphincter length 26 mm (± 4); internal anal sphincter thickness 3.2 mm (± 0.8); and rectovaginal septum length 31 mm (± 5). The agreement for visualization of structures was as follows: vesical trigone 96% (κ = 0.65), trigonal ring 94% (κ = 0.8), trigonal plate 84% (κ = 0.6); longitudinal and circular smooth muscle 100%; compressor urethra 97% (κ = 0.85); striated urogenital sphincter 97% (κ = 0.85); rectovaginal septum 100%; internal anal sphincter 100%; external anal sphincter subdivisions 100%. Three-dimensional EVUS can be used to visualize structures of the anterior and posterior compartments in nullipara.

Patient Characteristics and Treatment Outcome in Functional Anorectal Pain

Functional anorectal pain occurs in the absence of any clinical abnormality. It is common and disabling; it has previously been reported in only a few studies involving small patient numbers. This study aimed to report the clinical characteristics and treatment outcomes for patients with functional anorectal pain. Patient demographics, clinical history, and tests results for all referrals for anorectal physiological testing between 1997 and 2009 were prospectively recorded. For patients with functional anorectal pain, further information was gained from clinical notes. Clinical history, anorectal physiology, and radiological imaging data were recorded for all patients; treatment outcome was noted for patients treated and followed up at the present unit. One hundred seventy patients, 99 female, with a median age of 48 years (range, 18-86), were studied. Patients were classified as having chronic proctalgia (pain duration ≥20 min, 158 patients) or proctalgia fugax (pain duration <20 min, 12 patients). The pain was most commonly located in the anal canal (90%) and aggravated by defecation or sitting (66%). A third of patients had a history of psychological disturbance. Internal anal sphincter thickness correlated with resting anal pressures. Patients with proctalgia fugax had a higher internal anal sphincter thickness and resting pressure than patients with chronic proctalgia, whereas patients with a family history of similar symptoms were more likely to have proctalgia fugax and higher resting pressures and internal anal sphincter thickness compared with those without a family history of these symptoms. Patients referred for treatment underwent a range of interventions including biofeedback (29 patients, 17 improved), tricyclic antidepressants (26 patients, 10 improved), Botox injection (9 patients, 5 improved), and sacral nerve stimulation (3 patients, 2 improved). Biofeedback had the greatest treatment effect, especially in patients with defecatory dysfunction. Biofeedback is beneficial in the subset of patients with functional anorectal pain and difficulty with defecation. Tricyclic antidepressants, Botox, and sacral nerve stimulation may also have a role.

Internal anal sphincter atrophy in patients with systemic sclerosis

SSc is a connective tissue, multisystem disorder of unknown aetiology. The gastrointestinal tract (GIT) is affected in up to 90% of patients. The exact pathophysiology of GIT involvement is not known, but it is related to both neurogenic and myogenic abnormalities as well as possible vascular and ischaemic changes. Thinning of the internal anal sphincter (IAS) has been demonstrated in SSc with faecal incontinence. We aimed to investigate anal sphincter structure in patients with SSc. Forty-four SSc patients [24 symptomatic (Sx) and 20 asymptomatic (ASx)] and 20 incontinent controls (ICs) were studied. Patients underwent anorectal manometry and endoanal US. In the ICs, external anal sphincter defects were more common, but the IAS was less atrophic, evident by both atrophy scores and IAS thickness. There was no significant difference in atrophy scores [Sx: 2 (1.5-3) vs ASx: 2 (1-2)] or IAS thickness [Sx: 1.85 (1.5-2.3) vs ASx: 1.8 (1.7-2.25)] between the Sx and ASx SSc patients. Patients with SSc (both Sx and ASx) have thin and atrophic IAS, suggesting that IAS atrophy develops even in ASx patients and this may be amenable to treatment with sacral neuromodulation.

Endosonography of the Anal Canal

The aim of this study was to determine the endosonographic anatomy in children to define normal age-related differences in sphincter morphology and measurements. One hundred ten consecutive children (76 males and 34 females; mean age, 3.94 years; range, 1.10-15.09) with endoanal ultrasonography were studied. The thickness of the anal canal of the internal and external anal sphincter of each child was registered and correlated with the age. At the high level, the puborectalis muscles were clearly visualized, with a median thickness of 4.73 mm, and the internal anal sphincters were observed, with a mean thickness of 1.21 mm. At the mid level, both the internal and external anal sphincters were visualized, as well. The mean internal anal sphincter thickness was 1.23 mm and the median thickness of the external anal sphincter was 4.47 mm. At the lower level, the median external anal sphincter thickness was 5.39 mm. There was no significant correlation between the thickness of the internal and external sphincters and sex. The puborectalis and the external anal sphincter thickness showed a highly significant positive correlation with age. There was no significant correlation between the internal sphincter thickness and age. The endosonographic morphology of children is similar to that of adults, although the structures in children less than 5 years of age are difficult to differentiate. We detected a significant increase in the thickness of the external anal sphincter as patients grow older, but not in the internal anal sphincter.

The Internal Anal Sphincter in Systemic Sclerosis

Fecal incontinence in systemic sclerosis can occur secondary to fibrous replacement of the internal sphincter or ischemic myopathy of internal anal sphincter from vasculitis. Both lead to morphologic changes of the internal anal sphincter on endoanal ultrasound. This study documents the morphologic changes that can occur. A retrospective study of consecutive patients with systemic sclerosis and fecal incontinence was performed. Endoanal ultrasound was performed by using a 10 MHz Bruel and Kjaer endoprobe. Internal anal sphincter thickness and echogenecity were assessed at mid anal canal using prospectively collected images. Sphincter thicknesses were measured at 3, 6, 9, and 12 o'clock positions and averaged. Sphincter quality was assessed as homogeneous or heterogeneous and hyperechoic or hypoechoic by an experienced colorectal surgeon. Sphincter thickness was compared with sex- and age-matched controls by using Wilcoxon's signed-rank test. There were 11 patients (all women). Two distinct morphologic changes were observed where patients had a thickened, homogeneous, and hypoechoic internal anal sphincter, or a thinned, difficult to discern, and hyperechoic internal anal sphincter. Average sphincter thickness was 1.6 (range, 0.8-4) mm, which was significantly different from control subjects (P = 0.028). Available literature suggest that internal anal sphincter in systemic sclerosis is invariably thinned and hyperechoic. This series suggests that two distinct morphologic changes are possible.

481 Cytokinesis Blocked Micronucleus (Cbmn) Assay Is Predictive of Gastrointestinal (GI) Sequeale 2 Years Following Radiation Therapy (RT) for Prostate Carcinoma (CAP) Whilst Micronutrients Reduce Their Severity

RT for CaP is associated with GI sequelae including anorectal dysfunction up to 5 years after RT(1). Patients receive the same radiation dose despite variations in normal tissue tolerance(2). The CBMN assay quantifies spontaneous and radiation-induced DNA damage in peripheral blood lymphocytes(3) and has been correlated with GI sequelae after RT for CaP(2,4). The molecular basis of radiation sensitivity and role of dietary micronutrients on GI sequelae is unknown. This prospective study aims to develop biomarkers predictive for GI sequelae after RT for CaP, identifying modifying dietary and genetic factors.Methods:Before RT, venous blood of 21 patients 69(55-79)yrs with CaP, was assayed for (i)CBMN, (ii)plasma homocysteine, B12, folate, Zn, Se, lutein, retinol, α-tocopherol, lycopene and α-carotene and (iii)genotyping. LENT-SOMA GI symptoms(1), anorectal manometry and endoanal ultrasound were evaluated before RT, 1mth, 1 and 2yrs after RT(3). Data analyzed by ANOVA. Relationships among the anorectal function parameters and rectal volumes, CBMN and micronutrient data were examined by linear regression. Results:GI symptoms increased after RT and persisted at 2yrs. This was associated with reductions in (i)basal pressures, (ii)pressures in response to increased intra-abdominal pressure, (iii)rectal compliance, (iv)threshold volumes and (v)internal anal sphincter thickness. Spontaneous CBMN data were directly related to (a) 1 yr total GI symptom scores (r=0.52, p<0.05) and inversely related to squeeze pressures at 1 (r=-0.54, p<0.05) and 2 (r=-0.47, p<0.05) yrs. 1 mth desire to defecate volumes were also inversely related to radiation-induced (3Gy ex-vivo) CBMN index (r=-0.56, p<0.05). Plasma lycopene(r=-0.46, p<0.05) and α-carotene(r=-0.48, p<0.05) were inversely related to 1 yr diarrheal scores. Plasma α-carotene was also directly related to 1 yr threshold volumes (r=0.60, p<0.01). There were direct relationships between (a) plasma homocysteine and 1 yr diarrheal scores (r=0.62, p<0.01), (b) plasma zn and 1 yr basal pressures (r=0.45, p<0.05), (c) plasma retinol and 1 yr threshold volumes (r=0.59, p<0.01). Rectal bleeding scores at 1 mth were directly related to rectal volumes (r=0.48, p<0.05). Conclusion:The CBMN assay predicts GI sequelae 2 yrs after RT for CaP. Diets that include higher intake of foods rich in lycopene, α-carotene, zinc and retinol and which produce a lower homocysteine concentration in plasma, are likely to reduce the late adverse effects of RT for CaP. (1)Yeoh et al Am J Gastroenterol 2004, 2:361-369,(2)Lee et al Int J Radiat Oncol Biol Phys 2003,57:222-229,(3)Fenech, Mut Res 2000,455:81-95,(4)Yeoh et al,Gastroenterol 2007,132:A590

Effect of Aging and Gender on Internal Anal Sphincter Thickness

The prevalence of fecal incontinence (FI) in the general population increases with age in male and female. The internal anal sphincter (IAS) plays a key role in maintaining continence, providing a large part of the maximum resting pressure (MRP). Increasing age is associated with a weakening of the MRP. The IAS thickness was measured using an ultrasound scanner with a 10 MHz rotating endoprobe in 774 subjects (382 female and 392 male). There was a positive correlation between the thickness of IAS and age in both sexes. In female, the thickness of IAS did not change from 20’s (1.89±0.41) to 40’s (2.06±0.52), but increased after 50’s (2.32±0.47) with age. In male, after 50’s (2.14±0.54) was significantly thicker than to 40’s (1.86±0.54). The thickness of IAS was thicker in female than in male (2.30±0.60 and 2.05±0.53, p < 0.001). It is known that the MRP decreases with age, therefore an increase of IAS thickness in the elderly may be an attempt at compensation, which ultimately fails because of a loss of tone.