title: Prolonged balloon expulsion is predictive of abdominal distension in bloating.
abstract: OBJECTIVE
  Abdominal bloating and distension are common in patients with constipation. The precise mechanism of abdominal distension remains uncertain. We hypothesized that constipated patients with bloating plus distension exhibit a greater degree of anorectal dysfunction, potentially affecting gas evacuation, than those without distension. Therefore, our aim was to evaluate anorectal function and other clinical features in patients with constipation who exhibit bloating with and without distension.
  
  
  METHODS
  In all, 88 female patients with abdominal bloating and either non-diarrhea irritable bowel syndrome (IBS) or functional constipation were included in the study. The presence or absence of abdominal distension was assessed according to the Rome II questionnaire, and all patients underwent comprehensive clinical assessment and anorectal function studies.
  
  
  RESULTS
  Patients were divided into two groups: abdominal bloating with distension (D; n=53) and abdominal bloating without distension (ND; n=35). D featured a prolonged balloon expulsion time (P=0.005), a higher resting anal sphincter pressure (P=0.002), and a higher maximum anal sphincter squeeze pressure (P=0.015) than ND. They also experienced more bloating (P<0.001), more abdominal pain (P=0.004), harder stools (P=0.01), and more incomplete emptying (P=0.005). In logistic regression modeling, prolonged balloon expulsion time was a significant predictor of abdominal distension (P=0.018).
  
  
  CONCLUSIONS
  This is the first study to show that prolonged balloon expulsion time predicts abdominal distension in patients with bloating and constipation. Hence, ineffective evacuation of gas and stool associated with prolonged balloon expulsion may be an important mechanism underlying abdominal distension.
authors.affiliation: Department of Gastroenterology, Gastrointestinal Investigation Unit, Royal North Shore Hospital, University of Sydney, Sydney, New South Wales, Australia.
authors.forename: L
authors.initials: L
authors.lastname: Shim
authors.forename: G
authors.initials: G
authors.lastname: Prott
authors.forename: R D
authors.initials: RD
authors.lastname: Hansen
authors.forename: L E
authors.initials: LE
authors.lastname: Simmons
authors.forename: J E
authors.initials: JE
authors.lastname: Kellow
authors.forename: Allison
authors.initials: A
authors.lastname: Malcolm
mesh_terms: D000005:Abdomen / Q000503:physiopathology*; D001003:Anal Canal / Q000503:physiopathology*; D016009:Chi-Square Distribution; D003248:Constipation / Q000503:physiopathology*; D005260:Female; D005414:Flatulence / Q000503:physiopathology*; D005772:Gastrointestinal Transit; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000503:physiopathology*; D016015:Logistic Models; D008875:Middle Aged; D011237:Predictive Value of Tests; D012007:Rectum / Q000503:physiopathology*; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D011795:Surveys and Questionnaires