Normal values and associated factors in high-resolution anorectal manometry in healthy Vietnamese adults

Abstract

Background This study aims to identify normal HRAM values and related factors in healthy Vietnamese adults. Methods This cross-sectional study was conducted at Viet Duc hospital, Hanoi, Vietnam, during April and May, 2019. Healthy volunteers were recruited to participate in the study. Anorectal measurement values including pressure and an electromyographical signal from the digestive tract were recorded. Differences between groups were analyzed using paired t-tests, and linear regression models was used to compare anorectal values between men and women. Results A total of the 76 healthy volunteers was recruited. The mean functional anal canal length was 4.2 ± 0.5 cm while the mean anal high-pressure zone (HPZ) length was 3.4 ± 0.5 cm. The mean defecation index was 1.4 ± 0.8, with values ranging from 0.3 to 5.0. The mean threshold volume to elicit RAIR was 18.1 mL. Mean rectal sensation values were 32.4 mL, 81.6 mL, and 159 mL at the first sensation, the desire to defecate, and the urge to defecate, respectively. Dyssynergic patterns occurred in approximately 50% of study participants and included mainly types I (27.6%) and III (14.6%). There were significant differences between males and females in maximum anal squeeze pressure, maximum anal cough pressure, maximum anal strain pressure, maximum rectal cough pressure, and maximum rectal strain pressure (all p < 0.01). Conclusions This study establishes normal HRAM values in healthy Vietnamese adults, particularly with regards to normal values of anorectal pressure and rectal sensation. Further studies that include larger sample sizes should be conducted in order to further confirm the constants and their relationships.