- Email: [email protected]
Can High-Resolution Anorectal Manometry Shed New Light on Defecatory Disorders?
Editorials 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54
Can High-Resolution Anorectal Manometry Shed New Light on Defecatory Disorders?
AQ: 1
See “Phenotypic identification and classification of functional defecatory disorders using high resolution anorectal manometry,” by Ratuapli S, Bharucha AE, Noelting J, et al, on page 000.
D
isorders of defecation comprise a spectrum of conditions, including dyssynergic defecation (DD), rectal prolapse, descending perineum syndrome, rectocele, rectal hyposensitivity, rectal hypersensitivity, and others.1 From a patient’s’ perspective, difficulty with defecation and/or satisfactorily completing evacuation are the predominant complaints, which are described in numerous ways that are often hard to tease out because of the overlapping and subjective nature of self-reported symptoms. Although symptoms tell a descriptive story of any given patient’s problem, they are notoriously unpredictable for defining the underlying mechanistic disorder.2 A welldefined pathophysiologic basis for the patient’s symptoms is essential not only to aid in the diagnosis, but to develop an optimal treatment plan. Consequently, over the last decade most clinicians and investigators have increasingly relied on objective tests such as anorectal manometry, the balloon expulsion test (BET), defecography, and magnetic resonance defecography to help identify underlying mechanisms, and use this knowledge to guide treatment.2–7 However, the phenotypic heterogeneity of anorectal conditions and the often inexplicable findings on physiologic or morphologic tests have been perceived by many clinicians and academicians as a significant weakness and as a reason to either not conduct testing or move toward empirical treatment options. Regrettably, such approaches have only stifled the field and have promoted significant patient dissatisfaction. In this issue of GASTROENTEROLOGY, Ratuapli et al8 embarked on a bold search to help better define the manometric phenotypes among patients with chronic constipation presenting to a tertiary care center. They combined the recently adopted tool of high-resolution anorectal topography and manometry (HRM) with BET in a large cohort of constipated women with symptoms of difficult defecation. These functional data were compared with those from a group of healthy women. Standard manometric maneuvers were performed, including measurement of anorectal pressure (at rest, during maximal squeeze including squeeze duration, and with simulated defecation) and assessment of responses to rectal balloon distention (rectoanal inhibitory reflex, sensation). Their
aims were 3-fold: (1) To examine the utility of HRM in diagnosing DD, (2) to assess whether HRM can identify phenotypes of DD and facilitate further classification, and (3) to characterize the utility of symptom profiles for predicting abnormal BET results. A complex statistical protocol was applied using principal components logistical modeling (PC) to identify the major DD phenotypes. The 7 variables defined by HRM were assessed alongside age, body mass index, and BET findings using various combinations of this PC methodology. Given the extraordinary volume of data generated and the large number of variables examined, it is certainly reasonable and expected that complex statistical analyses were required to help sort out and identify which, if any, variable or group of variables could best discriminate and identify DD phenotypes. To the investigators’ surprise, their analyses revealed 7 distinct composite scores or PCs rather than a single factor. Of these 7 PCs, 3 (high anal, low rectal, and a hybrid group of high anal–low rectal) were correlated with BET findings with r values ranging from 0.43 to 0.88. These PCs with high correlations for balloon expulsion were proposed to represent distinct underlying pathophysiologic mechanisms in patients with DD. Furthermore at a predefined specificity of 75%, anorectal manometric variables were approximately 50% sensitive for discriminating healthy persons and patients with normal BET and 75% sensitive for distinguishing healthy subjects and constipated patients with abnormal BET. Thus, HRM was able to characterize DD subtypes similar to those previously described.2 Additionally, the authors observed that symptoms were poor predictors of underlying pathophysiology. The findings of this investigation underscore the heterogeneity of disorders of defecation. They further emphasize that the correlation of HRM and BET findings is far from perfect and that a single test by itself cannot fully characterize the neuromuscular complexities of these prevalent conditions.2,5,7,9 The important findings of this painstaking study employing a novel anorectal physiologic testing protocol in a large cohort of constipated patients should not be negated. However, the limitations of the tools that are currently available, the conditions under which these studies are performed (sitting on a commode for BET versus lying down for HRM), and the ability of an individual to perform defecatory maneuvers in a motility laboratory as opposed to their usual habit of doing the act in privacy must be acknowledged. Importantly, findings of this study identifying distinct DD subtypes are analogous to those previously described using a 6-sensor, solid-state manometry technology.2 The auGASTROENTEROLOGY 2012;xx:xxx
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54
Editorials, continued 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109
thors’ approach further enabled the identification and confirmation of high anal resting pressures as another important variable that could play a significant role in the pathogenesis of DD, a finding also described in a recent study that compared digital rectal examination with anorectal manometry.9 The authors acknowledged several limitations of their analyses, including (1) fewer than one third of their patients had colonic transit assessments, (2) a rigorous characterization of rectal sensory dysfunction was not a component of their PC analyses, and (3) the potential influence of hysterectomy in the pathogenesis of symptoms and/or abnormal physiology in their cohort of patients was not delineated. However, as described in this paper, some of these same authors have recently reported only limited effects of hysterectomy on anorectal sensorimotor function.10 Also, the parity of women in either the control or patient groups if these subjects had a previous history of obstetric or back injury or pelvic surgery were not described; these factors may have confounded their results and may have contributed to the lower resting pressures in the patient cohort. In addition, because the study was only conducted in women and in a prominent tertiary care center, their findings cannot be generalized to all comers with constipation or to the general population. However, it should be recognized that most anorectal testing is conducted in specialized referral settings. The rationale for performance of anorectal physiologic testing in individuals with refractory constipation is to define functional sensorimotor abnormalities responsive to nonlaxative treatments.3–5 Detection of characteristic motor findings on conventional anorectal manometry is included among the requisite criteria for diagnosing DD.3 Other supportive tests including BET, defecography, and magnetic resonance defecography are sensitive for DD diagnosis but afford specificities of only 23%–50%.6,7 One drawback of current diagnostic modalities is the significant discordance in abnormal test results in patients with difficult defecation. In 1 investigation, 22% of those with normal BET results exhibited conventional manometric findings consistent with DD.5 Conversely, 12% with prolonged BET results exhibited completely normal conventional manometry profiles. Furthermore, in 1 systematic review, manometric methods detected dyssynergic patterns in only about half of those with fecal evacuation problems.4 Very little research has been performed comparing the clinical utility of HRM to conventional methods. In 1 prior published investigation, HRM findings correlated closely with those of low-resolution techniques although HRM provided greater temporospatial discrimination of pressures in the anus and rectum.11 Based on these performance advantages, it has been postulated that HRM may enhance detection of DD—a speculation that must be confirmed in prospective comparison studies.4 2
Over the past several decades, many prominent investigators have detailed therapeutic benefits of biofeedback in approximately two thirds to three quarters of patients with DD.11–13 Components of such a biofeedback program for DD include instruction in pelvic floor muscle relaxation, in expelling rectal balloons, and in controlling straining.12–14 It remains to be determined whether stratifying patients into distinct DD subtypes based on manometric findings as in the current study will influence treatment decisions or modify components of biofeedback protocols.12–14 Specifically in the present investigation, it is not clear if the definition of 3 primary PCs which were to some extent weighted on the findings of abnormal BET, a test with only 50% sensitivity, facilitates important characterization to identify patients who are more likely to respond to medical therapy or to biofeedback therapy. One can hypothesize that biofeedback training designed to promote pelvic or anal relaxation might be more effective in those with a high anal pattern rather than a low rectal pattern; however, this must be confirmed by controlled investigation. Indeed, stratifying DD into different subtypes based on conventional manometric profiles as in prior studies has yet to translate into distinct management protocols.2 Finally, it is not certain if these elaborate PC analysis can be routinely adopted into clinical diagnostic protocols. Conventional diagnostic anorectal manometric methods provide both qualitative and quantitative parameters that are derived from visual and relatively simple computer interpretations of pressure recordings. The phenotypes identified in the article by Ratuapli et al8 were generated by more complex scrutiny of manometric data; clinicians who evaluate patients with disordered defecation may find such analyses to be conceptually more difficult to embrace. Several strides forward have been taken with the evolution of novel HRM technologies that provide improved manometric and topographic display and analysis both in real time and in static displays.4,15 In addition, they provide a more complete characterization of the pressure changes simultaneously in the rectum and anal canal, as elegantly illustrated by this study. However, we have a ways to go before either the hardware or sophisticated software analysis can provide complete understanding of the heterogeneity of these disorders or offer information that can promote more accurate diagnosis and direct optimal therapy. The analyses of Ratuapli et al8 serve as an important foundation for future prospective investigations to clarify the clinical relevance of DD phenotypes.
SATISH S. C. RAO Department of Medicine, Section of Gastroenterology & Hepatology, Medical College of Georgia, Georgia Health Sciences University, Augusta, Georgia
55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109
Editorials, continued 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164
WILLIAM L. HASLER Department of Medicine, Division of Gastroenterology, University of Michigan Health System, Ann Arbor, Michigan References
AQ: 2
1. Schey R, Cromwell J, Rao SS. Medical and surgical management of pelvic floor disorders affecting defecation. Am J Gastroenterol 2012;107:1624 –1633. 2. Rao SS, Mudipalli RS, Stessman M, et al. Investigation of the utility of colorectal function tests and Rome II criteria in dyssynergic defecation (Anismus). Neurogastroenterol Motil 2004;16: 589 –596. 3. Bharucha AE, Wald A, Enck P, et al. Functional anorectal disorders. Gastroenterology 2006;130:1510 –1518. 4. Rao SS. Advances in diagnostic assessment of fecal incontinence and dyssynergic defecation. Clin Gastroenterol Hepatol 2010;8: 910 –919. 5. Raza N, Bielefeldt K. Discriminative value of anorectal manometry in clinical practice. Dig Dis Sci 2009;54:2503–2511. 6. Minguez M, Herreros B, Sanchiz V, et al. Predictive value of the balloon expulsion test for excluding the diagnosis of pelvic floor dyssynergia in constipation. Gastroenterology 2004;126:57– 62. 7. Reiner CS, Tutuian R, Solopova AE, et al. MR defecography in patients with dyssynergic defecation: spectrum of imaging findings and diagnostic value. Br J Radiol 2011;84:136 –144. 8. Ratuapli S, Bharucha AE, Noelting J, et al. Phenotypic identification and classification of functional defecatory disorders using high resolution anorectal manometry. Gastroenterology 2013;143:000 – 000. 9. Tantiphlachiva K, Rao P, Attaluri A, Rao SS. Digital rectal examination is a useful tool for identifying patients with dyssynergia. Clin Gastroenterol Hepatol 2010;8:955–960.
10. Bharucha AE, Klingele CJ, Seide BM, et al. Effects of vaginal hysterectomy on anorectal sensorimotor functions—a prospective study. Neurogastroenterol Motil 2012;24:235–241. 11. Jones MP, Post J, Crowell MD. High-resolution manometry in the evaluation of anorectal disorders: a simultaneous comparison with water perfused manometry. Am J Gastroenterol 2007;102: 850 – 855. 12. Rao SS, Seaton K, Miller M, et al. Randomized controlled trial of biofeedback, sham feedback, and standard therapy for dyssynergic defecation. Clin Gastroenterol Hepatol 2007;5:331–338. 13. Chiarioni G, Whitehead WE, Pezza V, et al. Biofeedback is superior to laxatives for normal transit constipation due to pelvic floor dyssynergia. Gastroenterology 2006;130:657– 664. 14. Rao SS, Valestin J, Brown CK, et al. Long-term efficacy of biofeedback therapy for dyssynergic defecation: randomized controlled trial. Am J Gastroenterol 2010;105:890 – 896. 15. Noelting J, Ratuapli SK, Bharucha AE, et al. Normal values of HRM in healthy women: effects of age and significance of rectoanal gradient. Am J Gastroenterol 2012;107:1530 –1536.
Reprint requests Address requests for reprints to: Satish S. C. Rao, MD, PhD, FRCP, FACG, AGAF, Georgia Health Sciences University, 1120 15th Street - BBR2538, Augusta, Georgia 30912-3120. e-mail: srao@ georgiahealth.edu. Conflicts of interest The authors disclose no conflicts. © 2012 by the AGA Institute 0016-5085/$36.00 http://dx.doi.org/10.1053/j.gastro.2012.12.011
3
110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164
Can High-Resolution Anorectal Manometry Shed New Light on Defecatory Disorders?
AQ: 1
See “Phenotypic identification and classification of functional defecatory disorders using high resolution anorectal manometry,” by Ratuapli S, Bharucha AE, Noelting J, et al, on page 000.
D
isorders of defecation comprise a spectrum of conditions, including dyssynergic defecation (DD), rectal prolapse, descending perineum syndrome, rectocele, rectal hyposensitivity, rectal hypersensitivity, and others.1 From a patient’s’ perspective, difficulty with defecation and/or satisfactorily completing evacuation are the predominant complaints, which are described in numerous ways that are often hard to tease out because of the overlapping and subjective nature of self-reported symptoms. Although symptoms tell a descriptive story of any given patient’s problem, they are notoriously unpredictable for defining the underlying mechanistic disorder.2 A welldefined pathophysiologic basis for the patient’s symptoms is essential not only to aid in the diagnosis, but to develop an optimal treatment plan. Consequently, over the last decade most clinicians and investigators have increasingly relied on objective tests such as anorectal manometry, the balloon expulsion test (BET), defecography, and magnetic resonance defecography to help identify underlying mechanisms, and use this knowledge to guide treatment.2–7 However, the phenotypic heterogeneity of anorectal conditions and the often inexplicable findings on physiologic or morphologic tests have been perceived by many clinicians and academicians as a significant weakness and as a reason to either not conduct testing or move toward empirical treatment options. Regrettably, such approaches have only stifled the field and have promoted significant patient dissatisfaction. In this issue of GASTROENTEROLOGY, Ratuapli et al8 embarked on a bold search to help better define the manometric phenotypes among patients with chronic constipation presenting to a tertiary care center. They combined the recently adopted tool of high-resolution anorectal topography and manometry (HRM) with BET in a large cohort of constipated women with symptoms of difficult defecation. These functional data were compared with those from a group of healthy women. Standard manometric maneuvers were performed, including measurement of anorectal pressure (at rest, during maximal squeeze including squeeze duration, and with simulated defecation) and assessment of responses to rectal balloon distention (rectoanal inhibitory reflex, sensation). Their
aims were 3-fold: (1) To examine the utility of HRM in diagnosing DD, (2) to assess whether HRM can identify phenotypes of DD and facilitate further classification, and (3) to characterize the utility of symptom profiles for predicting abnormal BET results. A complex statistical protocol was applied using principal components logistical modeling (PC) to identify the major DD phenotypes. The 7 variables defined by HRM were assessed alongside age, body mass index, and BET findings using various combinations of this PC methodology. Given the extraordinary volume of data generated and the large number of variables examined, it is certainly reasonable and expected that complex statistical analyses were required to help sort out and identify which, if any, variable or group of variables could best discriminate and identify DD phenotypes. To the investigators’ surprise, their analyses revealed 7 distinct composite scores or PCs rather than a single factor. Of these 7 PCs, 3 (high anal, low rectal, and a hybrid group of high anal–low rectal) were correlated with BET findings with r values ranging from 0.43 to 0.88. These PCs with high correlations for balloon expulsion were proposed to represent distinct underlying pathophysiologic mechanisms in patients with DD. Furthermore at a predefined specificity of 75%, anorectal manometric variables were approximately 50% sensitive for discriminating healthy persons and patients with normal BET and 75% sensitive for distinguishing healthy subjects and constipated patients with abnormal BET. Thus, HRM was able to characterize DD subtypes similar to those previously described.2 Additionally, the authors observed that symptoms were poor predictors of underlying pathophysiology. The findings of this investigation underscore the heterogeneity of disorders of defecation. They further emphasize that the correlation of HRM and BET findings is far from perfect and that a single test by itself cannot fully characterize the neuromuscular complexities of these prevalent conditions.2,5,7,9 The important findings of this painstaking study employing a novel anorectal physiologic testing protocol in a large cohort of constipated patients should not be negated. However, the limitations of the tools that are currently available, the conditions under which these studies are performed (sitting on a commode for BET versus lying down for HRM), and the ability of an individual to perform defecatory maneuvers in a motility laboratory as opposed to their usual habit of doing the act in privacy must be acknowledged. Importantly, findings of this study identifying distinct DD subtypes are analogous to those previously described using a 6-sensor, solid-state manometry technology.2 The auGASTROENTEROLOGY 2012;xx:xxx
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54
Editorials, continued 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109
thors’ approach further enabled the identification and confirmation of high anal resting pressures as another important variable that could play a significant role in the pathogenesis of DD, a finding also described in a recent study that compared digital rectal examination with anorectal manometry.9 The authors acknowledged several limitations of their analyses, including (1) fewer than one third of their patients had colonic transit assessments, (2) a rigorous characterization of rectal sensory dysfunction was not a component of their PC analyses, and (3) the potential influence of hysterectomy in the pathogenesis of symptoms and/or abnormal physiology in their cohort of patients was not delineated. However, as described in this paper, some of these same authors have recently reported only limited effects of hysterectomy on anorectal sensorimotor function.10 Also, the parity of women in either the control or patient groups if these subjects had a previous history of obstetric or back injury or pelvic surgery were not described; these factors may have confounded their results and may have contributed to the lower resting pressures in the patient cohort. In addition, because the study was only conducted in women and in a prominent tertiary care center, their findings cannot be generalized to all comers with constipation or to the general population. However, it should be recognized that most anorectal testing is conducted in specialized referral settings. The rationale for performance of anorectal physiologic testing in individuals with refractory constipation is to define functional sensorimotor abnormalities responsive to nonlaxative treatments.3–5 Detection of characteristic motor findings on conventional anorectal manometry is included among the requisite criteria for diagnosing DD.3 Other supportive tests including BET, defecography, and magnetic resonance defecography are sensitive for DD diagnosis but afford specificities of only 23%–50%.6,7 One drawback of current diagnostic modalities is the significant discordance in abnormal test results in patients with difficult defecation. In 1 investigation, 22% of those with normal BET results exhibited conventional manometric findings consistent with DD.5 Conversely, 12% with prolonged BET results exhibited completely normal conventional manometry profiles. Furthermore, in 1 systematic review, manometric methods detected dyssynergic patterns in only about half of those with fecal evacuation problems.4 Very little research has been performed comparing the clinical utility of HRM to conventional methods. In 1 prior published investigation, HRM findings correlated closely with those of low-resolution techniques although HRM provided greater temporospatial discrimination of pressures in the anus and rectum.11 Based on these performance advantages, it has been postulated that HRM may enhance detection of DD—a speculation that must be confirmed in prospective comparison studies.4 2
Over the past several decades, many prominent investigators have detailed therapeutic benefits of biofeedback in approximately two thirds to three quarters of patients with DD.11–13 Components of such a biofeedback program for DD include instruction in pelvic floor muscle relaxation, in expelling rectal balloons, and in controlling straining.12–14 It remains to be determined whether stratifying patients into distinct DD subtypes based on manometric findings as in the current study will influence treatment decisions or modify components of biofeedback protocols.12–14 Specifically in the present investigation, it is not clear if the definition of 3 primary PCs which were to some extent weighted on the findings of abnormal BET, a test with only 50% sensitivity, facilitates important characterization to identify patients who are more likely to respond to medical therapy or to biofeedback therapy. One can hypothesize that biofeedback training designed to promote pelvic or anal relaxation might be more effective in those with a high anal pattern rather than a low rectal pattern; however, this must be confirmed by controlled investigation. Indeed, stratifying DD into different subtypes based on conventional manometric profiles as in prior studies has yet to translate into distinct management protocols.2 Finally, it is not certain if these elaborate PC analysis can be routinely adopted into clinical diagnostic protocols. Conventional diagnostic anorectal manometric methods provide both qualitative and quantitative parameters that are derived from visual and relatively simple computer interpretations of pressure recordings. The phenotypes identified in the article by Ratuapli et al8 were generated by more complex scrutiny of manometric data; clinicians who evaluate patients with disordered defecation may find such analyses to be conceptually more difficult to embrace. Several strides forward have been taken with the evolution of novel HRM technologies that provide improved manometric and topographic display and analysis both in real time and in static displays.4,15 In addition, they provide a more complete characterization of the pressure changes simultaneously in the rectum and anal canal, as elegantly illustrated by this study. However, we have a ways to go before either the hardware or sophisticated software analysis can provide complete understanding of the heterogeneity of these disorders or offer information that can promote more accurate diagnosis and direct optimal therapy. The analyses of Ratuapli et al8 serve as an important foundation for future prospective investigations to clarify the clinical relevance of DD phenotypes.
SATISH S. C. RAO Department of Medicine, Section of Gastroenterology & Hepatology, Medical College of Georgia, Georgia Health Sciences University, Augusta, Georgia
55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109
Editorials, continued 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164
WILLIAM L. HASLER Department of Medicine, Division of Gastroenterology, University of Michigan Health System, Ann Arbor, Michigan References
AQ: 2
1. Schey R, Cromwell J, Rao SS. Medical and surgical management of pelvic floor disorders affecting defecation. Am J Gastroenterol 2012;107:1624 –1633. 2. Rao SS, Mudipalli RS, Stessman M, et al. Investigation of the utility of colorectal function tests and Rome II criteria in dyssynergic defecation (Anismus). Neurogastroenterol Motil 2004;16: 589 –596. 3. Bharucha AE, Wald A, Enck P, et al. Functional anorectal disorders. Gastroenterology 2006;130:1510 –1518. 4. Rao SS. Advances in diagnostic assessment of fecal incontinence and dyssynergic defecation. Clin Gastroenterol Hepatol 2010;8: 910 –919. 5. Raza N, Bielefeldt K. Discriminative value of anorectal manometry in clinical practice. Dig Dis Sci 2009;54:2503–2511. 6. Minguez M, Herreros B, Sanchiz V, et al. Predictive value of the balloon expulsion test for excluding the diagnosis of pelvic floor dyssynergia in constipation. Gastroenterology 2004;126:57– 62. 7. Reiner CS, Tutuian R, Solopova AE, et al. MR defecography in patients with dyssynergic defecation: spectrum of imaging findings and diagnostic value. Br J Radiol 2011;84:136 –144. 8. Ratuapli S, Bharucha AE, Noelting J, et al. Phenotypic identification and classification of functional defecatory disorders using high resolution anorectal manometry. Gastroenterology 2013;143:000 – 000. 9. Tantiphlachiva K, Rao P, Attaluri A, Rao SS. Digital rectal examination is a useful tool for identifying patients with dyssynergia. Clin Gastroenterol Hepatol 2010;8:955–960.
10. Bharucha AE, Klingele CJ, Seide BM, et al. Effects of vaginal hysterectomy on anorectal sensorimotor functions—a prospective study. Neurogastroenterol Motil 2012;24:235–241. 11. Jones MP, Post J, Crowell MD. High-resolution manometry in the evaluation of anorectal disorders: a simultaneous comparison with water perfused manometry. Am J Gastroenterol 2007;102: 850 – 855. 12. Rao SS, Seaton K, Miller M, et al. Randomized controlled trial of biofeedback, sham feedback, and standard therapy for dyssynergic defecation. Clin Gastroenterol Hepatol 2007;5:331–338. 13. Chiarioni G, Whitehead WE, Pezza V, et al. Biofeedback is superior to laxatives for normal transit constipation due to pelvic floor dyssynergia. Gastroenterology 2006;130:657– 664. 14. Rao SS, Valestin J, Brown CK, et al. Long-term efficacy of biofeedback therapy for dyssynergic defecation: randomized controlled trial. Am J Gastroenterol 2010;105:890 – 896. 15. Noelting J, Ratuapli SK, Bharucha AE, et al. Normal values of HRM in healthy women: effects of age and significance of rectoanal gradient. Am J Gastroenterol 2012;107:1530 –1536.
Reprint requests Address requests for reprints to: Satish S. C. Rao, MD, PhD, FRCP, FACG, AGAF, Georgia Health Sciences University, 1120 15th Street - BBR2538, Augusta, Georgia 30912-3120. e-mail: srao@ georgiahealth.edu. Conflicts of interest The authors disclose no conflicts. © 2012 by the AGA Institute 0016-5085/$36.00 http://dx.doi.org/10.1053/j.gastro.2012.12.011
3
110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164