Objectives: Dyssynergic defecation is a common disorder in children with functional constipation (FC) because of relaxation disorders of the sphincter apparatus and intra-rectal pressure during defecation. The aim of the study was to determine frequency and type of dyssynergic defecation and to assess pressure in the anal canal poles during simulated evacuation and function of puborectalis muscle in defecation in children with FC.
Methods: Three-dimensional (3D) high-resolution anorectal manometries (3D HRAM) were performed in 131 children with FC. In the manometric test, resting pressure measurements were assessed in 4 measuring poles of the anal canal.
Results: One hundred thirty-one children ages 5 to 17 years (mean age 10.2; SD ± 3.8; median 10) were involved in the study (69 girls and 62 boys). Dyssynergic defecation was shown in 106/131 (80.9%) examined children. A statistically significant difference between the age of examined children (P < 0.02) and intrarectal pressures at the anal canal measuring points (left P < 0.009, right P < 0.005, anterior P < 0.01) was found. Correlation between the residual pressure values in lateral anal canal measurement poles and intrarectal pressure was demonstrated in all types of dyssynergy (left: r = 0.69, P < 0.0005; right: r = 0.74, P < 0.0005). In a group of 53/131 (40.5%) children, 3D HRAM showed a rectal pressure increase during simulated defecation, because of the dysfunction of the puborectalis muscle.
Conclusion: The increase in sphincter pressure in lateral and posterior poles in I and II types of dyssynergia and in lateral poles in other types of dyssynergia may depend on relaxation disorders of the puborectalis muscle during defecation.