Purpose: Assessment of anal sphincter tone is a critical part of anorectal examination, yet no standardized, quantifiable method for describing anal sphincter tone on digital rectal examination exists. We developed a novel scoring system for anal sphincter tone using a scale of 0 to 5 for both resting pressure and squeeze pressure. The score ranges from 0 = no discernable pressure to 5 = extremely tight and 3 = normal. We hypothesized that the digital rectal examination scoring system (DRESS) score would correlate with anorectal manometry pressures.
Methods: Three hundred three patients (mean age, 51 y; range, 28-86 y) who had a DRESS score and a concurrent manometry test (1998-2008) were identified from a prospective database. Means of 4 quadrant manometry at rest and with squeeze were compared with the resting pressure and squeeze pressure DRESS scores at each point from 0 to 5. Box plots for manometry results by DRESS score were graphed. ANOVA using a significance level of α = .05 tested whether each of the DRESS scores were different from one another. Spearman rank correlation coefficients assessed associations between manometry and DRESS results.
Results: Manometric pressures (mmHg; mean ± SEM) for DRESS resting pressure values 0 to 5 were 20.6 ± 2.1, 38.5 ± 2.0, 47.8 ± 1.6, 72.3 ± 1.5, 94.4 ± 2.9, and 128.0 ± 6.7, respectively. Pressures for DRESS squeeze pressure values 0 to 5 were 45.9 ± 5.6, 66.5 ± 3.2, 108.2 ± 4.9, 156.3 ± 4.5, 238.6 ± 9.8, and 368.2 ± 49.1. Box plots demonstrated clear differences between each DRESS score and positive progression from 0 to 5 for both resting pressure and squeeze pressure. ANOVA analysis showed a significant difference in mean manometry measurements at all levels of digital rectal examination, both for resting pressure and squeeze pressure (P < .001). Spearman rank correlations showed a strong positive correlation between the DRESS values and manometry pressures with coefficients of 0.82 for resting pressure and 0.81 for squeeze pressure.
Conclusions: The DRESS score correlated very well with manometry pressures for resting pressure and squeeze pressure. The DRESS system may be a useful description of anal sphincter resting pressure and squeeze pressure in the clinical setting. Further validation may support adoption of the DRESS system as part of the standard anorectal examination.