Rectal diameter measured by transabdominal ultrasonography for monitoring treatment response in children with functional constipation

doi:10.5409/wjcp.119251

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World Journal of Clinical Pediatrics

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2219-2808

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Baishideng Publishing Group Inc, 7041 Koll Center Parkway, Suite 160, Pleasanton, CA 94566, USA

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Copyright: ©Author(s) 2026. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution-NonCommercial (CC BY-NC 4.0) license. No commercial re-use. See permissions. Published by Baishideng Publishing Group Inc.

World J Clin Pediatr. Dec 9, 2026; 15(4): 119251
Published online Dec 9, 2026. doi: 10.5409/wjcp.119251

Rectal diameter measured by transabdominal ultrasonography for monitoring treatment response in children with functional constipation

Duc Long Tran, Nitikarn Pinyoying, Palittiya Sintusek

Duc Long Tran, Nitikarn Pinyoying, Palittiya Sintusek, Center of Excellence in Thai Pediatric Gastroenterology, Hepatology and Immunology, Division of Gastroenterology, Department of Pediatrics, Faculty of Medicine, King Chulalongkorn Memorial Hospital, Chulalongkorn University, Bangkok 10330, Thailand

Duc Long Tran, Faculty of Medicine, Can Tho University of Medicine and Pharmacy, Can Tho 90000, Viet Nam

Author contributions: Tran DL and Sintusek P conceptualized, designed the methodology, and performed the research; Tran DL, Pinyoying N and Sintusek P collected data; Tran DL analyzed the data and wrote the original draft; Sintusek P validated the results and made critical revisions; all authors have read and approved the final manuscript.

Supported by Chulalongkorn University, the Second Century Fund, No. C2F; and Thailand Science research and Innovation Fund Chulalongkorn University, No. HEA_FF_69_225_3000_031.

Institutional review board statement: This study was approved by the Institutional Review Board of Chulalongkorn University (No. 0093/67).

Clinical trial registration statement: This study is registered at ClinicalTrials.gov. The registration identification number is NCT06357897.

Informed consent statement: All study participants provided informed written consent prior to study enrollment.

Conflict-of-interest statement: The authors declare no conflict of interest regarding this study.

CONSORT 2010 statement: The authors have read the CONSORT Statement—checklist of items, and the manuscript was prepared and revised according to the CONSORT Statement—checklist of items.

Data sharing statement: Technical appendix, statistical code, and data set available from the corresponding author at palittiya.s@chula.ac.th. Participants gave informed consent for data sharing.

Corresponding author: Palittiya Sintusek, MD, PhD, Associate Professor, Center of Excellence in Thai Pediatric Gastroenterology, Hepatology and Immunology, Division of Gastroenterology, Department of Pediatrics, Faculty of Medicine, King Chulalongkorn Memorial Hospital, Chulalongkorn University, 1873 Rama IV, Pathumwan, Bangkok 10330, Thailand. palittiya.s@chula.ac.th

Received: January 26, 2026
Revised: February 6, 2026
Accepted: March 6, 2026
Published online: December 9, 2026
Processing time: 242 Days and 9.8 Hours

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.

Keywords: Constipation; Rectal diameter; Ultrasonography; Children; Anterior wall thickness

Core Tip: Although transabdominal ultrasonography (USG) has been increasingly employed to assess fecal impaction in children with functional constipation (FC), evidence supporting its role in monitoring treatment responses remains limited. In this prospective substudy of a randomized controlled trial evaluating the efficacy of commercial polyethylene glycol (PEG) and PEG-Chula, USG-measured rectal diameter (RD) exhibited a significant decrease after 8 weeks of treatment, paralleling clinical improvement. In contrast, anterior rectal wall thickness did not change significantly during treatment. These findings indicate that USG-measured RD may be a practical, noninvasive parameter for monitoring treatment response in children with FC.