Association Between Health-Related Quality of Life and Ultrasound-Based Transverse Rectal Diameter in Pediatric Functional Constipation

Background: Pediatric functional constipation (PFC) significantly impairs children’s daily functioning and health-related quality of life (HRQoL). Assessing baseline severity and ensuring treatment progression are key to successful management. Pocket-sized ultrasound (PsUS) offers an accessible, dynamic, quantitative assessment of rectal morphology, but it is unclear whether PsUS-derived transverse rectal diameter (TRD) may reflect patient-relevant functional burden. This study examined the associations between PsUS-derived TRD, constipation severity, and parent-reported HRQoL in children with PFC. Methods: This cross-sectional study included 47 children (mean age 7.22 ± 2.04 years; 62% boys) with Rome IV-defined PFC. TRD was measured using PsUS, constipation severity using the Wexner Constipation Scoring System (WCSS), and parent-reported outcomes using the PedsQL™ Generic Core Scales, Gastrointestinal Symptoms Module, and Family Impact Module. Associations were analyzed using Spearman correlations. Results: The cohort had a mean age of 7.22 ± 2.04 years. Mean PsUS-derived TRD was 36.5 ± 6.6 mm, consistent with rectal diameters reported in children with functional constipation. Mean constipation severity (WCSS) was 21.5 ± 2.8 (0–30 scale; higher scores indicating greater severity), and mean PedsQL scores were 28.7 ± 17.1 for the Gastrointestinal Symptoms Module, 21.8 ± 16.7 for the Family Impact Module, and 21.1 ± 16.7 for the Generic Core Scale (0–100 scale, higher indicating better HRQoL). Larger TRD values were strongly associated with poorer HRQoL across the PedsQL™ 4.0 Generic Core Scales, Gastrointestinal Symptoms Module, and Family Impact Module (ρ = −0.67 to −0.87, all p < 0.001). TRD also showed a very strong positive association with constipation severity (WCSS; ρ = 0.91, p < 0.001). Conclusions: Larger PsUS-derived TRD values were associated with greater constipation severity and poorer parent-reported HRQoL in children with PFC. These findings suggest that PsUS-derived TRD may provide objective information related to both constipation severity and parent-reported quality-of-life outcomes.