Normal Values and Associated Factors in Highresolution Anorectal Manometry in Healthy Vietnamese Adults

Introduction The present study aims to identify normal high-resolution anorectal manometry (HRAM) values and related factors in healthy Vietnamese adults. Methods The present cross-sectional study was conducted at the Viet Duc hospital, Hanoi, Vietnam, during April and May 2019. Healthy volunteers were recruited to participate in the study. Anorectal measurement values from the digestive tract, including pressure, were recorded. Results A total of 76 healthy volunteers were recruited. The mean functional anal canal length was 4.2 ± 0.5 cm, while the mean anal high-pressure zone length was 3.4 ± 0.5 cm. Themean defecation index was 1.4 ± 0.8, with values ranging from 0.3 to 5.0. The mean threshold volume to elicit the rectoanal inhibitory reflex (RAIR) was 18.1 mL. The mean rectal sensation values were 32.4mL, 81.6mL, and 159 mL for first sensation, desire to defecate, and urge to defecate, respectively. Dyssynergic patterns occurred in ~ 50% of the study participants and included mainly types I (27.6%) and III (14.6%). There were significant differences between male and female patients in terms of 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 The present study establishes normal HRAM values in healthy Vietnamese adults, particularly regarding normal values of anorectal pressure and rectal sensation. Further studies that include larger sample sizes should be conducted to further confirm the constants and their relationships.