High-resolution anorectal manometry and barium defecography in suspected functional defecation disorders: agreement and impact of structural findings

Purpose Functional defecation disorders (FDD) affect approximately one-third of patients with functional constipation. No single diagnostic test reliably identifies FDD, and guidelines recommend that pathological results from two investigations are required for diagnosis. Commonly used tests include high-resolution anorectal manometry (HRAM), barium defecography (BD), and the balloon expulsion test (BET). Their agreement is uncertain, and structural abnormalities may influence HRAM metrics. We assessed diagnostic agreement between HRAM and BD in patients with suspected FDD and explored relationships between key variables and the influence of structural findings on HRAM parameters. Methods We included 80 patients with constipation and suspected FDD who underwent HRAM and BD. HRAM recordings were reinterpreted using pattern-based and threshold-based approaches. Radiologists evaluated BD for puborectalis relaxation and structural abnormalities, and in a subsequent assessment, we quantified rectal barium evacuation and anorectal angles. We used Cohen’s kappa (κ) to assess agreement, Spearman's rho to assess correlations, and the Mann-Whitney U test to compare distributions. Results Rectoceles were present in 71% of women. Agreement between HRAM and BD was only fair and similar across interpretation methods (κ = 0.27–0.31). Continuous HRAM and BD measures were not correlated. Rectocele was associated with higher anal resting pressure and greater anal relaxation (p = 0.005 and 0.023). Among patients with normal barium evacuation (N = 56), 41% had both a non-relaxing puborectalis and an abnormal HRAM pattern, with moderate agreement (κ ≈ 0.44–0.45). Conclusion Overall agreement between HRAM and BD is limited, indicating that they assess complementary aspects of anorectal function. Different HRAM interpretation approaches perform similarly. Rectoceles influence HRAM metrics. In patients with normal barium evacuation, puborectalis assessment on BD may support the interpretation of abnormal HRAM and identify a relevant patient group.