Definition of reliable, objective criteria by abdominal radiography to identify occult constipation in children with lower urinary tract symptoms.
OBJECTIVE
Treating constipation in children with voiding dysfunction may improve or resolve urinary symptoms. A clinical diagnosis of constipation may not identify all patients. Abdominal radiographs (plain x-ray of the kidneys, ureters and bladder) are often used to assess constipation but no objective definition of constipation based on abdominal radiographs exists. Most abdominal radiograph rating scales use subjective criteria and our previous series showed that these scales have poor reliability. We identified reliable, objective parameters on abdominal radiograph to predict constipation.


METHODS
The abdominal radiographs of 80 children 4 to 12 years old, including 40 with constipation and 40 successfully treated for constipation, were assessed for several measurable parameters. Logistic regression was used to construct a model to predict constipation status based on these abdominal radiograph parameters. Model accuracy was assessed using AUC analysis of ROC curves.


RESULTS
The most predictive model included cecal diameter, total length of stool measured, stool length in the rectum, and patient age and gender. As measured by the area under the ROC curve, accuracy was excellent at 0.87. We calculated cutoffs for individual parameters on abdominal radiograph, including total stool length greater than 33.4 cm, cecal diameter greater than 3.7 cm and stool length in the rectum greater than 5.9 cm.


CONCLUSIONS
We identified accurate, reliable criteria based on objective measurements on abdominal radiograph to differentiate patients with and without constipation. These criteria may be applied to objectively assess constipation status in children with urinary symptoms without a history of constipation. Further study will determine whether these criteria predict the response to treatment.
Division of Pediatric Urology and Department of Medical Imaging, Lurie Children's Hospital, Chicago and Department of Urology, Loyola University Stritch School of Medicine, Maywood, Illinois, USA.
Andrew
A
Marks
Evalynn
E
Vasquez
Susan
S
Moylan
Dawn
D
Diaz-Saldano
Jennifer
J
Schreiber
Martha
M
Saker
Bruce W
BW
Lindgren
D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D003248:Constipation / Q000150:complications / Q000000981:diagnostic imaging*; D006801:Humans; D059411:Lower Urinary Tract Symptoms / Q000150:complications; D011237:Predictive Value of Tests; D011860:Radiography, Abdominal; D015203:Reproducibility of Results; D012189:Retrospective Studies