To determine the proportion of children diagnosed with constipation assigned a significant alternative diagnosis within 7 days (misdiagnosis), if there is an association between abdominal radiograph (AXR) performance and misdiagnosis, and features that might identify children with misdiagnoses.

We conducted a retrospective cohort study of consecutive children <18 years who presented to a pediatric emergency department in Toronto, between 2008 and 2010. Children assigned an International Statistical Classification of Diseases and Related Health Problems 10th Revision code consistent with constipation were eligible. Misdiagnosis was defined as an alternative diagnosis during the subsequent 7 days that resulted in hospitalization or an outpatient procedure that included a surgical or radiologic intervention. Constipation severity was classified employing text word categorization and the Leech score.

3685 eligible visits were identified. Mean age was 6.6 ± 4.4 years. AXR was performed in 46% (1693/3685). Twenty misdiagnoses (0.5%; 95% CI 0.4, 0.8) were identified (appendicitis [7%], intussusception [2%, bowel obstruction [2%], other [9%]). AXR was performed more frequently in misdiagnosed children (75% vs 46%; P = .01). These children more often had abdominal pain (70% vs 49%; P = .04) and tenderness (60% vs 32%; P =.01). Children in both groups had similar amounts of stool on AXR (P = .38) and mean Leech scores (misdiagnosed = 7.9 ± 3.4; not misdiagnosed = 7.7 ± 2.9; P = .85).

Misdiagnoses in children with constipation are more frequent in those in whom an AXR was performed and those with abdominal pain and tenderness. The performance of an AXR may indicate diagnostic uncertainty; in such cases, the presence of stool on AXR does not rule out an alternative diagnosis.