Three-dimensional high-resolution anorectal manometry: cut-off values for diagnosis of dyssynergic defecation in children

OBJECTIVE: Dyssynergic defecation (DD) may be one of the most important causes of constipation, but its diagnostic criteria have not been formally validated in children. This study aims to evaluate constipated children with 3DHRAM (three-dimensional high-resolution anorectal manometry) and determine a new pediatric cut-off for DD variables. PATIENTS AND METHODS: 205 patients diagnosed with functional constipation (FC) based on Rome III criteria were prospectively enrolled. Data were compared to a historical control group (C). Initially, the diagnosis of DD was based on adult criteria and divided into 4 types. A new cutoff value for percent anal relaxation was determined based on ROC curve analysis. RESULTS: The FC group presented significantly lower values of percent anal relaxation during straining compared to the C group (9.5% vs. 20%, respectively, p=0.03). Based on adult criteria, DD was found in 53% of the FC group and 46% of the C group (p= 0.3), with type II occurring most frequently (35.8%). New cut-off value of 31% for percent anal relaxation in children was derived based on the ROC curve analysis. Based on this new cut-off value, DD was diagnosed in 69.3% of constipated children, with type IV occurring most frequently (28.9%). The analysis of segmental pressure showed significant influence of segments at the locations of the puborectalis muscle and external anal sphincter. CONCLUSIONS: We found that during bear down maneuver the percent anal relaxation variable significantly differed between patients and controls. The higher cut-off value should be used when 3DHRAM and the standard four-type classification are used to diagnose DD in children.