A team from Montreal, Quebec, Canada, assessed the value of rectal distention testing in patients with irritable bowel syndrome (IBS).
Visceral hypersensitivity was detected in patients with functional gastrointestinal disorders and has been proposed as a biological marker of IBS.
Patients were diagnosed according to Rome II criteria.
Rectal sensory thresholds were determined in 164 patients (86 IBS patients, 26 painless constipation, 21 functional dyspepsia, and 31 miscellaneous conditions) and in 25 normal controls.
All individuals underwent a series of rectal isobaric distentions, using an electronic barostat.
The bag was progressively distended from 0 to 48 mm Hg. In response to the distention, subjects reported on discomfort or pain.
Mean pain thresholds were found to be lower in IBS patients (30 mm Hg) compared with controls (45), painless constipated (45), functional dyspepsia (39), and miscellaneous patients (43).
|Rectal barostat testing in IBS:|
| Gastroenterology |
The investigators used a level of 40 mm Hg for the rectal barostat, to identify IBS patients from normal subjects and non-IBS subjects.
They found that this had a sensitivity of 96% and a specificity of 72%.
The positive and negative predictive values were 85% and 90%, respectively.
Mickael Bouin, of the Saint-Luc Hospital, University of Montreal, concluded on behalf of the group, "Lowered rectal pain threshold is a hallmark of IBS patients.
"Rectal barostat testing is useful to confirm the diagnosis of IBS and to discriminate IBS from other causes of abdominal pain."
In an accompanying Editorial, Michel Delvaux comments, "Rectal distention tests remain, up to now, a very useful tool to investigate patients with IBS in pathophysiological studies or to assess the effect of drugs on visceral afferents in humans."
"However, their role in clinical practice has not yet been defined, as they mainly confirm the diagnosis based on clinical criteria and ultimately do not influence the work-up of the patient," he concludes.