There are some differences in the way functional constipation is diagnosed based on whether the patient is a child or an adult. In both cases, a diagnosis will involve an evaluation by a medical professional as well as ruling out other medical explanations (like irritable bowel syndrome), but the identifying symptoms are not entirely the same.
The Rome IV criteria for diagnosing (chronic) functional constipation in adults require three months of at least two of the following symptoms:
- Straining: more than 25% of defecations.
- Lumpy or hard stools: more than 25% of defecations.
- Sensation of incomplete evacuation: more than 25% of defecations.
- Sensation of anorectal obstruction/blockage: more than 25% of defecations.
- Manual maneuvers to facilitate: more than 25% of defecations.
- Fewer than three spontaneous bowel movements per week.
The Rome IV criteria for diagnosing functional constipation in infants and children up to four years old, meanwhile, require one month of either two or fewer defecations per week or at least two of the following:
- History of excessive stool retention
- History of painful or hard bowel movements
- History of large-diameter stools
- Presence of a large fecal mass in the rectum
- Minimum of one episode/week of incontinence after the acquisition of toileting skills (toilet-trained children only)
- History of large-diameter stools that may obstruct the toilet (toilet-trained children only)
Finally, The Rome IV criteria for diagnosing functional constipation in children older than four requires at least one month of two of the following occurring at once per week:
- Two or fewer defecations in the toilet per week (children of a developmental age of at least 4 years old only)
- One or more episode(s) of fecal incontinence per week
- History of retentive posturing or excessive volitional stool retention
- History of painful or hard bowel movements
- Presence of a large fecal mass in the rectum
- History of large diameter stools that can obstruct the toilet