[Comparative analysis of the characteristics of high-resolution anorectal manometry in children with outlet obstructive constipation of different age groups].

Objective: To compare the characteristics of high-resolution anorectal manometry (HR-ARM) in children with outlet obstructive constipation (OOC) in different age groups. Methods: Retrospective inclusion of clinical data of functional constipation (FC) patients who underwent HR-ARM examination in the Department of Gastroenterology of Children's Hospital Affiliated of Zhengzhou University from January 2019 to September 2023 was conducted. The patients were divided into low age group (4 years old≤age<6 years) and high age group (6 years old≤age≤15 years old) according to age. They were divided into OOC group (the pediatric patients with uncoordinated pelvic floor muscle contractions, insufficient rectal thrust during defecation, or insufficient relaxation of anal sphincter muscles during contraction) and non-OOC group based on HR-ARM results. The rectal motility [rectal resting pressure, maximum squeeze pressure (MSP), rectal pressure during force delivery, residual anal pressure, rectal anal pressure gradient], rectal sensory function (initial rectal sensory capacity threshold, initial fecal sensory capacity threshold, defecation distress capacity threshold, and maximum tolerance capacity threshold) and other indicators were compared between OOC group and non-OOC group in 2 age groups, respectively. Results: A total of 228 children with FC were included, including 146 males and 82 females, with an age [M (Q₁, Q₃)] of 7.5 (6.0, 9.7) years, including 54 in the low age group and 174 in the high age group. There were 131 cases in the OOC group and 97 cases in the non-OOC group. Compared with non OOC children (24 cases), there were no statistically significant differences in rectal resting pressure, anal sphincter resting pressure, MSP, rectal pressure during force delivery, initial rectal sensory capacity threshold, initial fecal sensory capacity threshold, defecation distress capacity threshold, and maximum tolerance capacity threshold among OOC children (30 cases) in the low age group (all P>0.05). In the high age group, the residual anal pressure of the OOC children (101 cases) was higher than that of the non-OOC children (73 cases) [102 (70, 113) vs 41 (24, 58) mmHg (1 mmHg=0.133 kPa), P<0.001], and the rectal anal pressure gradient was lower than that of the non-OOC children [-43 (-55, -23) vs 16 (9, 29) mmHg, P<0.001];The initial fecal sensory capacity threshold of the OOC children was higher than that of the non-OOC children [90 (54, 110) vs 60 (50, 91) ml, P=0.024]. Conclusions: Compared with non-OOC children in the same age group, OOC children aged 6 years and above have higher residual anal pressure and initial fecal sensory capacity threshold, and lower rectal anal pressure gradient. There is no statistically significant differences in the rectal sensory function in children under 6 years old with OOC.