Rectal diameter measured by transabdominal ultrasonography for monitoring treatment response in children with functional constipation
In brief
Rectal ultrasound diameter falls 14% after eight weeks of constipation treatment
In 44 children who completed follow-up, rectal diameter on ultrasound fell from 2.70 cm to 2.33 cm after eight weeks of polyethylene glycol, alongside improved stool frequency and consistency. Rectal wall thickness did not change, and the time since the last bowel movement affected diameter, so larger studies are needed to establish how reliably the measurement tracks treatment response.
- Journal
- World journal of clinical pediatrics (Q1)
- Published
- 9 December 2026
- Study design
- Randomized controlled trial
- Evidence level
- Level 1, High (CEBM 1b)
- Authors
- Duc Long Tran, Nitikarn Pinyoying, Palittiya Sintusek
- PMID
- 42964424
- DOI
- 10.5409/wjcp.119251
Why clinicians should know about it
- Picked for Radiology, Radiation Oncology, Nuclear Medicine, Medical Physics and Imaging (top studies of the week, 8 November 2026): Ultrasound measurements assess treatment response in children
Abstract
BACKGROUND: Transabdominal ultrasonography (USG) is a noninvasive tool for detecting fecal impaction in children with functional constipation (FC) and may predict treatment response. However, supporting evidence remains limited and controversial. AIM: To evaluate changes in rectal diameter (RD) and anterior rectal wall thickness (AWT) measured by USG in children with FC after treatment with polyethylene glycol (PEG) for 8 weeks. METHODS: This substudy of a randomized controlled trial included children aged 6 months to 18 years diagnosed with FC according to the Rome IV criteria at King Chulalongkorn Memorial Hospital (May 2024-February 2025). Participants received either commercial PEG or PEG-Chula as laxatives for FC. USG was performed at baseline and at 1, 4, and 8 weeks by the primary investigator. RD and AWT were measured following Klijn's technique. RESULTS: Of the 52 enrolled children, 44 completed all four visits. The median age was 50.5 [interquartile range (IQR): 28-92.5] months, and 65.9% were female. The median FC duration was 19.5 (IQR: 12-36) months. Stool frequency and consistency improved significantly over 8 weeks, with no difference between the commercial PEG and PEG-Chula groups. The mean RD decreased significantly from 2.70 cm (95%CI: 2.51-2.88) at baseline to 2.46 cm (95%CI: 2.30-2.62) at week 1, 2.45 cm (95%CI: 2.30-2.60) at week 4, and 2.33 cm (95%CI: 2.18-2.48) at week 8. AWT remained 0.29 cm (95%CI: 0.27-0.32) at baseline and 0.29 cm (95%CI: 0.26-0.30) at week 8 (P = 0.997). The time since the last defecation to USG significantly influenced RD (P = 0.030) but not AWT (P = 0.382). CONCLUSION: USG-measured RD decreases significantly with effective PEG treatment and may serve as a useful noninvasive marker for monitoring treatment response in children with FC.
Abstract as published, via PubMed.
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