title: Phenotypic identification and classification of functional defecatory disorders using high-resolution anorectal manometry.
abstract: OBJECTIVE
  Disordered defecation is attributed to pelvic floor dyssynergia. However, clinical observations indicate a spectrum of anorectal dysfunctions. The extent to which these disorders are distinct or overlap is unclear; anorectal manometry might be used in diagnosis, but healthy persons also can have abnormal rectoanal pressure gradients during simulated evacuation. We aimed to characterize phenotypic variation in constipated patients through high-resolution anorectal manometry.
  
  
  METHODS
  We evaluated anorectal pressures, measured with high-resolution anorectal manometry, and rectal balloon expulsion time in 62 healthy women and 295 women with chronic constipation. Phenotypes were characterized by principal components analysis of high-resolution anorectal manometry.
  
  
  RESULTS
  Two healthy persons and 71 patients had prolonged (>180 s) rectal balloon expulsion time. A principal components logistic model discriminated healthy people from patients with prolonged balloon expulsion time with 75% sensitivity and a specificity of 75%. Four phenotypes discriminated healthy people from patients with abnormal balloon expulsion times; 2 phenotypes discriminated healthy people from those with constipation but normal balloon expulsion time. Phenotypes were characterized based on high anal pressure at rest and during evacuation (high anal), low rectal pressure alone (low rectal) or low rectal pressure with impaired anal relaxation during evacuation (hybrid), and a short anal high-pressure zone. Symptoms were not useful for predicting which patients had prolonged balloon expulsion times.
  
  
  CONCLUSIONS
  Principal components analysis of rectoanal pressures identified 3 phenotypes (high anal, low rectal, and hybrid) that can discriminate among patients with normal and abnormal balloon expulsion time. These phenotypes might be useful to classify patients and increase our understanding of the pathogenesis of defecatory disorders.
authors.affiliation: Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota; Clinical Enteric Neuroscience Translational and Epidemiological Research, Mayo Clinic, Rochester, Minnesota.
authors.forename: Shiva K
authors.initials: SK
authors.lastname: Ratuapli
authors.affiliation: Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota; Clinical Enteric Neuroscience Translational and Epidemiological Research, Mayo Clinic, Rochester, Minnesota. Electronic address: bharucha.adil@mayo.edu.
authors.forename: Adil E
authors.initials: AE
authors.lastname: Bharucha
authors.affiliation: Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota.
authors.forename: Jessica
authors.initials: J
authors.lastname: Noelting
authors.affiliation: Clinical Enteric Neuroscience Translational and Epidemiological Research, Mayo Clinic, Rochester, Minnesota; Department of Nursing, Mayo Clinic, Rochester, Minnesota.
authors.forename: Doris M
authors.initials: DM
authors.lastname: Harvey
authors.affiliation: Division of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, Minnesota.
authors.forename: Alan R
authors.initials: AR
authors.lastname: Zinsmeister
mesh_terms: D000328:Adult; D001003:Anal Canal / Q000503:physiopathology*; D003248:Constipation / Q000145:classification* / Q000235:genetics* / Q000503:physiopathology; D003672:Defecation / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008365:Manometry / Q000379:methods; D008875:Middle Aged; D059952:Pelvic Floor Disorders / Q000150:complications / Q000235:genetics / Q000503:physiopathology; D010641:Phenotype; D011312:Pressure; D012007:Rectum / Q000503:physiopathology*; D012189:Retrospective Studies