title: Diagnostic accuracy study of anorectal manometry for diagnosis of dyssynergic defecation.
abstract: OBJECTIVE
  The diagnostic accuracy of anorectal manometry (AM), which is necessary to diagnose functional defecatory disorders (FDD), is unknown. Using blinded analysis and standardised reporting of diagnostic accuracy, we evaluated whether AM could discriminate between asymptomatic controls and patients with functional constipation (FC).
  
  
  METHODS
  Derived line plots of anorectal pressure profiles during simulated defecation were independently analysed in random order by three expert observers blinded to health status in 85 women with FC and 85 age-matched asymptomatic healthy volunteers (HV). Using accepted criteria, these pressure profiles were characterised as normal (ie, increased rectal pressure coordinated with anal relaxation) or types I-IV dyssynergia. Interobserver agreement and diagnostic accuracy were determined.
  
  
  RESULTS
  Blinded consensus-based assessment disclosed a normal pattern in 16/170 (9%) of all participants and only 11/85 (13%) HV. The combined frequency of dyssynergic patterns (I-IV) was very similar in FC (80/85 (94%)) and HV (74/85 (87%)). Type I dyssynergia ('paradoxical' contraction) was less prevalent in FC (17/85 (20%) than in HV (31/85 (36.5%), p=0.03). After statistical correction, only type IV dyssynergia was moderately useful for discriminating between FC (39/85 (46%)) and HV (17/85 (20%)) (p=0.001, positive predictive value=70.0%, positive likelihood ratio=2.3). Interobserver agreement was substantial or moderate for identifying a normal pattern, dyssynergia types I and IV, and FDD, and fair for types II and III.
  
  
  CONCLUSIONS
  While the interpretation of AM patterns is reproducible, nearly 90% of HV have a pattern that is currently regarded as 'abnormal' by AM. Hence, AM is of limited utility for distinguishing between FC and HV.
authors.affiliation: National Centre for Bowel Research and Surgical Innovation and GI Physiology Unit, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
authors.forename: Ugo
authors.initials: U
authors.lastname: Grossi
authors.affiliation: National Centre for Bowel Research and Surgical Innovation and GI Physiology Unit, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
authors.forename: Emma V
authors.initials: EV
authors.lastname: Carrington
authors.affiliation: Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Adil E
authors.initials: AE
authors.lastname: Bharucha
authors.affiliation: National Centre for Bowel Research and Surgical Innovation and GI Physiology Unit, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
authors.forename: Emma J
authors.initials: EJ
authors.lastname: Horrocks
authors.affiliation: National Centre for Bowel Research and Surgical Innovation and GI Physiology Unit, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
authors.forename: S Mark
authors.initials: SM
authors.lastname: Scott
authors.affiliation: National Centre for Bowel Research and Surgical Innovation and GI Physiology Unit, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
authors.forename: Charles H
authors.initials: CH
authors.lastname: Knowles
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001003:Anal Canal / Q000503:physiopathology*; D016022:Case-Control Studies; D003248:Constipation / Q000175:diagnosis* / Q000503:physiopathology; D003672:Defecation / Q000502:physiology*; D005260:Female; D006801:Humans; D008365:Manometry; D008875:Middle Aged; D015588:Observer Variation; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D016037:Single-Blind Method; D055815:Young Adult
keywords: ANAL SPHINCTER; ANORECTAL DISORDERS; ANORECTAL FUNCTION; ANORECTAL PHYSIOLOGY; COLORECTAL MOTILITY