Influence of Body Position on Anorectal Manometric
Assessment in Functional Constipation
Seksit Osatakul MD*,**, Sopa Boonviriya RN**,
Sulee Saengnil RN**, Bancha Ovartlarnporn MD**
Affiliation :
* Department of Pediatrics, Faculty of Medicine, Prince of Songkla University, Hat Yai, Songkhla, Thailand
** NKC Institute of Gastroenterology, Faculty of Medicine, Prince of Songkla University, Hat Yai, Songkhla, Thailand
Objective : To date, there have been no studies to evaluate the influence of posture on anorectal manometric measurements
in patients with functional constipation. The present study aimed to compare differences in anorectal manometric
measurements in constipated patients when performing the test in the lying and sitting positions.
Material and Method: Anorectal manometry with a conventional solid state manometric catheter was performed in
30 constipated patients in both the lying and sitting positions. Anorectal manometric variables at rest and during attempted
defecation with empty rectum were assessed in both positions. A colonic transit study using Sitzmarks radiopaque markers
and a 50-mL water-filled balloon expulsion test was also performed in all patients. Patients exhibiting an abnormal
manometric pattern of defecation in either the sitting or lying position proceeded to a simulated defecation test. The anorectal
pressure parameters of resting and during attempted defecation of the both positions were compared.
Results : The resting rectal pressure, maximum rectal straining pressure, and defecation index during attempted defecation
were significantly higher in the sitting position than the lying position. A dyssynergic manometric pattern during attempted
defecation with empty rectum was seen in 46% of the patients in the lying position, not significantly different from the 56%
in the seated position (p = 0.58). Most patients (71%) who exhibited manometric dyssynergia with an empty rectum could
relax their anal sphincter during the simulated defecation test. Only six (20%) constipated patients had abnormal dyssynergic
anal sphincter contraction confirmed by a simulated defecation test.
Conclusion : Body position affects the results of manometric measurements related to the defecation mechanism.
Keywords : Anorectal manometry, Functional constipation, Body position
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