How to use a plain abdominal radiograph in children with functional defecation disorders

Defecation-related functional gastrointestinal disorders (FGIDs), such as infant dyschezia, functional constipation and functional non-retentive faecal incontinence, as defined by the Rome IV criteria, are common problems in childhood. The symptomatology varies from relatively mild, such as crying before passage of soft stools or infrequent defecation to severe problems with faecal impaction and the daily involuntary loss of faeces in the underwear. Conventional radiography is widely available, relatively cheap and is non-invasive. The drawback however, is radiation exposure. This review describes and evaluates the value of different existing scoring methods to assess faecal loading on an abdominal radiograph with or without the use of radio-opaque markers, to measure colonic transit time, in the diagnosis of these defecation-related FGIDs. Insufficient evidence exists for a diagnostic association between clinical symptoms of functional constipation or functional nonretentive faecal incontinence and faecal loading on an abdominal radiograph. Furthermore, evidence does not support the routine use of colonic transit studies to diagnose functional constipation. Colonic transit time measurement may be considered in discriminating between functional constipation and functional non-retentive faecal incontinence and in patients in which the diagnosis is not clear such as having an unreliable medical history. In children with the suspicion of defecation-related FGIDs, the diagnosis should be made based on the Rome IV criteria.