SGEM Xtra: RANThony #4 X-rays for Pediatric Constipation

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Date: June 26th, 2016

Guest Skeptic: Dr. Anthony Crocco is a Pediatric Emergency Physician and is the Medical Director & Division Head of the Division of Pediatric Emergency at McMaster’s Children’s Hospital.

He is known on YouTube for his RANThony‘s. These are short rants on pediatric topics. They were inspired by the rants done by the great Canadian comedian Rick Mercer. Previous topics have included Fever Fear, Cough Medication and Pain Control.

Anthony is also the creator of the evidence based medicine (EBM) education website SketchyEBM. These are white board videos that present EBM concepts in a creative and understandable formate. He covers topics like:

Relative risk (RR), relative risk reduction (RRR), absolute risk reduction (ARR)
What is bias?
Confidence intervals and “p” values
Number needed to treat (NNT)
Intention to treat (ITT) analysis

This fourth RANThony addresses the issue of x-rays for the diagnosis of pediatric constipation. Click on this LINK to watch the YouTube video and as Anthony says “always draw your own conclusions.”

X-rays for Pediatric Constipation

Introduction: Pediatric constipation is a common presentation to clinics, urgent care centers and emergency departments. The first step in management of pediatric constipation is making the appropriate diagnosis.

Diagnosis: The NASPGHAN and ESPGHAN concluded in a 2014 guideline that “the diagnosis of functional constipation is based on history and physical examination” and that we use “the Rome III criteria for the definition of functional constipation for all age groups”.

Radiography: A systematic review by Berger (2012) found that there was “insufficient evidence for a diagnostic association between clinical symptoms of constipation and fecal loading on abdominal radiographs”. The NASPGHAN and ESPGHAN guidelines state that “the routine use of an abdominal radiograph to diagnose functional constipation is not indicated”.

Adverse effects: Aside from the risks of radiation exposure concern had been raised about whether performing xrays in children to diagnose constipation can be misleading. A paper by Freedman (2014) found that “misdiagnoses in children with constipation are more frequent in those in whom an AXR was performed”, that “the presence of stool on AXR does not rule out an alternative diagnosis.” Missed diagnoses included appendicitis, bowel obstruction and intussusception.

Imagine Two Stories:

A three year-old presents with a history of infrequent stools that are large caliber, painful and plug the toilet. The child has fecal soiling in between bowel movements. Is this child constipated? Yes. Does the child need an abdominal xray to help with this diagnosis? No.
A four year-old presents with abdominal pain. Earlier in the day he was at a birthday party where he ate four hot-dogs and two pieces of cake. There is a history of regular bowel movements, which are soft and easy to pass. Is this child constipated? Unlikely. An xray may show fecal loading, which likely represents food digesting in the bowel. Alternative diagnoses should be sought.

Bottom Line: Constipation is a clinical diagnosis based on history and physical exam. Use the Rome III criteria. Abdominal x-rays are not indicated to diagnose constipation in children, are misleading and expose children to unnecessary radiation.

References:

Freedman SB et al. Pediatric abdominal radiograph use, constipation, and significant misdiagnoses. J Pediatr 2014; 164: 83-8.
Tabbers MM et. al. Evaluation and treatment of functional constipation in infants and children: Evidence-based recommendations from ESPGHAN and NASPGHAN. JPGN 2014; 58: 258-274.
Berger MY et. al. Value of abdominal radiography, colonic transit time, and rectal ultrasound scanning in the diagnosis of idiopathic constipation in children: A systematic review. J Pediatr 2012; 161: 44-50.