RESUMO
AIM: The study aimed primarily to compare the transverse rectal diameter in children with functional constipation (FC) and children without constipation in different age groups, and between cases of constipation at baseline and after treatment. Secondary aim was to determine factors that could affect the transverse rectal diameter. METHODS: A controlled prospective study, including a total of 100 children between the ages of 2 and 11 years, who were divided into 50 patients suffering from constipation according to Rome IV criteria and 50 age- and sex-matched controls. Transverse rectal diameter was measured at presentation, and after 3 months of laxative therapy and behavioural modification. RESULTS: Initial rectal diameter was significantly different between cases (3.55 cm (interquartile range, IQR), 3.2-4) and controls (2.3 cm (IQR, 1.8-2.5)), P value < 0.001, and it was also significantly different between those above and below 4 years, so a separate cut-off point for diagnosis of constipation was suggested being >3 cm for the former and >2.5 cm for the latter. After 3 months of follow-up, rectal diameter significantly reduced to become 2.6 (IQR, 2-2.8), P value < 0.001. Duration of symptoms positively correlated with rectal diameter. CONCLUSIONS: Ultrasound measurement of rectal diameter is an important tool to diagnose and follow-up functional constipation in children. Different values of rectal diameter are found between those above and below 4 years of age.