Objective To analyze the correlations of symptoms of functional constipation (FC) with anorectal motor and paresthesia diagnosed by high-resolution anorectal manometry (HR-ARM).

Methods Data of FC patients with HR-ARM in the First Hospital Affiliated to Soochow University from June 2020 to December 2021 were prospectively collected. Before examination, the occurrence of constipation symptoms was recorded and the total score of symptom scoring system (CSS) was filled in, and the correlations of symptoms with HR-ARM parameters and HR-ARM results were analyzed.

Results Patients with exertion in defecation had higher anal residual pressure (t=2.359, P=0.021), lower anal relaxation rate (t=-2.996, P=0.004), and higher rectal propulsive pressure (t=3.099, P=0.003) than those without exertion in defecation. Patients with hard stools had lower rectal propulsive pressure (t=-2.440, P=0.017). Patients who needed manual maneuvers to facilitate defecation had higher anal residual pressure (t=2.249, P=0.027) and lower threshold value of willingness in urgent defecation (U=451.000, P=0.013). The first sensitive volume of patients with abdominal bloating was lower than that of patients without abdominal bloating (U=532.500, P=0.016). HR-ARM results showed that patients with exertion in defecation had higher incidence of dyssynergic defecation compared with those without exertion in defecation (χ²=4.697, P=0.030). CSS score was positively correlated with anal residual pressure (r=0.263, P=0.019), and negatively correlated with anal relaxation rate (r=-0.386, P < 0.001).

Conclusion The symptoms of exertion in defecation in patients with FC are primarily associated with dyssynergic defecation rather than inadequate defecatory propulsion. High residual anal pressure and low anal relaxation rate in patients with FC have more severe symptoms. They could better assess the pathophysiological abnormalities of FC.