Dyssynergic defecation in adolescents with constipation: Anorectal manometry findings

OBJECTIVES: To describe and compare anorectal manometry findings in constipated adolescents with and without dyssynergic defecation (DD). METHODS: We retrospectively reviewed adolescents ≤18 years who underwent anorectal manometry (ARM) and/or balloon expulsion testing (BET) between 2015 and 2022. Patients with prior pelvic floor therapy, inflammatory bowel disease, or colon surgery were excluded. DD was defined by abnormal ARM (paradoxical anal contraction or inadequate anal relaxation ≤20% during simulated evacuation) and/or abnormal BET (>60 s). Manometric parameters were compared between patients with and without DD and between those with abnormal versus normal BET. Diagnostic performance of rectoanal pressure gradient cutoffs were assessed. RESULTS: A total of 170 adolescents were included; 69 (40.6%) met criteria for DD. Median age was 17 years (interquartile range [IQR] 16-18), and 80.7% were female. Gastrointestinal symptoms did not differ between groups. Patients with DD demonstrated significantly more negative rectoanal pressure gradients compared with those without DD (median [IQR]: -49.0 mmHg [-73.9 to -31.4] vs. -25.2 mmHg [-40.2 to -9.8]; p < 0.001). Rectal sensory thresholds did not differ significantly between groups. A rectoanal pressure gradient cutoff of -45 mmHg demonstrated the best balance of sensitivity (58%) and specificity (86%) for identifying DD. Depression was more prevalent among adolescents with DD (p = 0.007). CONCLUSIONS: Rectoanal pressure gradient is a useful manometric parameter for identifying DD in constipated adolescents, particularly when BET is unavailable. Psychological factors such as depression may be more prevalent in this population.