title: Rectosigmoid Localization of Radiopaque Markers Does Not Correlate with Prolonged Balloon Expulsion in Chronic Constipation: Results from a Multicenter Cohort.
abstract: OBJECTIVE
  Ingestion of radiopaque markers (ROMs) is a common means of assessing colonic transit time in chronic constipation. Because anorectal manometry (ARM) testing for pelvic floor dysfunction is mostly limited to academic centers, clinicians frequently use rectosigmoid accumulation of markers as a surrogate for pelvic floor dysfunction. We sought to determine whether rectosigmoid localization of markers on a ROM study correlated with measures of pelvic floor dysfunction by ARM and balloon expulsion testing.
  
  
  METHODS
  We assembled a multicenter, retrospective cohort of patients diagnosed with chronic constipation who underwent both transit testing by ROM transit testing and ARM with balloon expulsion testing. We compared the proportion of patients with outlet obstruction by rectoanal pressure gradient or prolonged balloon expulsion stratified by marker location.
  
  
  RESULTS
  There were 610 patients with both ROM testing and ARM with balloon expulsion testing. The mean age was 44 years and 526 were women (86%). Eighty-one (13%) patients had markers confined to the rectosigmoid area alone and were compared with 529 patients with markers elsewhere (51%) or no retained markers (49%). Of those with markers confined to the rectosigmoid colon, 48 (59%) had a prolonged balloon expulsion compared with 276 (52%) who did not have rectosigmoid markers (P=0.28). The mean rectoanal gradient for patients with markers in the rectosigmoid colon was -29±46 mm Hg compared with -34±59 mm Hg for all others (P=0.59).
  
  
  CONCLUSIONS
  Among patients with chronic constipation undergoing ROM transit testing, there is no association between rectosigmoid location of markers and rectoanal gradient or prolonged balloon expulsion.
authors.affiliation: Division of Gastroenterology, Massachusetts General Hospital and Harvard Medical School Boston, Boston, Massachusetts, USA.
authors.forename: Kyle
authors.initials: K
authors.lastname: Staller
authors.affiliation: Pritzker School of Medicine, University of Chicago, Chicago, Illinois, USA.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Barshop
authors.affiliation: Division of Gastroenterology, Massachusetts General Hospital and Harvard Medical School Boston, Boston, Massachusetts, USA.
authors.forename: Ashwin N
authors.initials: AN
authors.lastname: Ananthakrishnan
authors.affiliation: Division of Gastroenterology, Massachusetts General Hospital and Harvard Medical School Boston, Boston, Massachusetts, USA.
authors.forename: Braden
authors.initials: B
authors.lastname: Kuo
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000368:Aged; D001003:Anal Canal / Q000503:physiopathology; D002908:Chronic Disease; D012809:Colon, Sigmoid / Q000000981:diagnostic imaging*; D003248:Constipation / Q000503:physiopathology*; D005260:Female; D005772:Gastrointestinal Transit; D006801:Humans; D008297:Male; D008365:Manometry; D008875:Middle Aged; D017773:Pelvic Floor / Q000503:physiopathology*; D011312:Pressure; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000008:administration & dosage / Q000032:analysis / Q000378:metabolism*; D012007:Rectum / Q000000981:diagnostic imaging* / Q000503:physiopathology; D012189:Retrospective Studies; D013997:Time Factors
chemical_list: D019275:Radiopharmaceuticals