Value of transabdominal ultrasonography for diagnosing functional constipation in children: a systematic review and meta-analysis.

Transabdominal ultrasonography is increasingly used as a novel modality for detecting pediatric functional constipation (FC). This systematic review and meta-analysis aimed to assess the diagnostic parameters of FC including rectal diameter (RD) and anterior rectal wall thickness. A systematic search was conducted of the Ovid MEDLINE, EMBASE, Scopus, and PubMed databases through September 29, 2023, to identify studies comparing RD and anterior wall thickness using transabdominal ultrasonography in children with versus without FC. Meta-analyses were performed using random-effects models to calculate the weighted mean differences in RD and anterior wall thickness. Comprehensive Meta-Analysis ver. 3, R, and Review Manager ver. 5.4.1 software were used to assess the optimal cutoff, sensitivity, specificity, and area under the curve (AUC). Fourteen studies involving 1,255 children (mean age, 6.21  2.3 years) were included. The mean RD was significantly larger in constipated children versus controls (mean difference [MD] = 10.35 mm; 95% confidence interval [CI], 6.97-13.74; P < 0.001; I2 = 94%). A meta-regression showed no significant effects of age, weight, or height on RD. An optimal RD cutoff point of 31 mm was suggested by a pooled analysis with an AUC of 0.86 (95% CI, 0.8-0.91; P < 0.001), sensitivity of 0.75 (95% CI, 0.59-0.86), and specificity of 0.84 (95% CI, 0.68-0.93). The mean anterior rectal wall thickness was greater among constipated children than among controls (MD = 0.44; 95% CI, -0.26 to 1.13; P = 0.22), but this difference was not statistically significant. RD measured using transabdominal ultrasonography with a cutoff point of 31 mm exhibited good diagnostic accuracy for diagnosing FC in children.