The practice of emergency medicine always evolves with new data, reconsidered concepts, and the translation of medical evidence and shared experience to bedside decision-making. With a shrinking world and vibrant educational process, we continually see a narrowing of the gap between academic literature and clinical practice. Some stalwart holdouts persist against bevies of observations, trials, and guidelines, however. Few anachronisms better represent this than the pediatric pedagogy of abdominal radiography.
Despite near-eradication in adult emergency medicine (aside from narrow, niche applications), abdominal radiographs (AXRs) seemingly remain a staple of evaluating children presenting to the ED with abdominal pain. It is, frankly put, a bizarre practice—the use of ionizing radiation equating to 35 chest x-rays—to confirm a benign diagnosis, despite overwhelming evidence of the test's complete inability to do so. (Medicine [Baltimore] 2017;96:e5907; http://bit.ly/2Im4ECy.)
Perhaps you're as bamboozled as I am by this practice, and have yet to use your radiology suite to take a picture of pediatric poop. It would seem, unfortunately, that we're in the minority. A study published just last year found that 63 percent of children diagnosed with constipation in a pediatric emergency department received an AXR, echoing previous investigations consistently demonstrating rates of abdominal radiography between 50 percent and 75 percent. (Pediatrics 2017;140; doi: 10.1542/peds.2016-2290.)
Champions of this practice argue that the benefit of identifying a benign diagnosis is to avoid further evaluation and resource use in pursuit of more serious causes of abdominal pain. But AXRs are well-demonstrated to lack any validity or reliability when employed for pediatric constipation and abdominal pain. Studies have shown sensitivity and specificity as low as 60 percent and 43 percent, respectively, and inter-rater reliability little better than a coin flip. (J Pediatr 2012;161:44; http://bit.ly/2KhHx0Y.)
What's more, the use of AXR likely causes outright harm. Putting aside the radiation exposure that should give anyone pause, there is little question that this test serves only as confirmation bias. Fifty percent of AXRs are interpreted as normal (which speaks independently toward poor test application), but obtaining abdominal radiography was associated with a higher rate of misdiagnosis (29%). The most commonly missed diagnoses were appendicitis (!), intussusception (!!), and bowel obstruction (!!!). (J Pediatr 2014;164:83; http://bit.ly/2tukWnv.) Less concerning but nonetheless notable was that AXR independently predicted a higher likelihood of ED bounceback, even when the diagnosis of constipation was accurate. (J Pediatr Gastroenterol Nutr 2014;59:32.)
The United Kingdom's National Institute for Health and Care Excellence (NICE) workgroup released guidelines in 2010 recommending against AXRs for diagnosing pediatric constipation. (Clinical Guideline 99; updated July 2017; http://bit.ly/2KhiDi7.) Some may attempt to argue that British baby bellies differ from American ones, but this condemnation of abdominal radiography was echoed in a 2014 clinical guideline from the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition.
Publications from the American Academy of Pediatrics and the American Academy of Family Physicians all offer similar sentiments. (JPGN 2014;58:258; http://bit.ly/2KczXox.) Abdominal radiography adds nothing beyond history and physical exam in evaluating for constipation, and is more likely to lead to misdiagnosis when utilized for serious underlying pathology.
Ultrasound's availability is growing and emergency physicians are increasingly comfortable with it, so either point-of-care at the bedside or performed by the radiology department offers a better alternative to poorly sensitive and nonspecific abdominal radiography, when imaging is needed at all. Ultrasound consistently demonstrates excellent sensitivity (nearing 100% in some studies) and specificity (nearly always 97% or greater) when evaluating serious abdominal etiologies of abdominal pain, such as appendicitis, bowel obstruction, intussusception, or volvulus, though, of course, it is limited by sonographer experience and skill. Even in the ridiculous and unnecessary application of imaging for constipation, US outperforms abdominal radiography without the harm of ionizing radiation. (J Pediatr Surg 2010; 45:1849; http://bit.ly/2tuAlV6.)
Why, then, does this practice persist? Perhaps we've waited for more rigorous investigations or abundant data before changing ingrained practice in recognition of the unique considerations and fundamental differences of the pediatric population. Our desire to shield our most vulnerable has led us to ignore the harm borne from the dogma.
We emergency physicians stand at the forefront of knowledge translation to clinical practice, yet the persistence of AXRs in evaluating pediatric abdominal pain and constipation flies in stark contrast to the evidence-based practice and nonmaleficence we pioneer. The identification of benign poop causing a patient's complaint at first seems reasonable. In our search, though, we need not have ever looked beyond the test itself.