In patients with irritable bowel syndrome with constipation (IBS-C, Rome II) we determined if pelvic floor function correlates with rectal sensitivity and tone, and if the pelvic and rectal measurements correlate with symptoms.
Sensory thresholds and tone in fasting and postprandial states were evaluated with an electronic barostat in 34 patients and 10 normal controls. The pelvic floor was assessed by defaecography.
Pain threshold to rectal distension was lower in IBS-C patients (P = 0.007). Postprandially, IBS-C patients showed lower values for sensation of gas, perception of urge, and pain threshold compared with controls. In IBS-C the anorectal angle widened less and showed less perineal mobility during defecation; the rectal tone in fasting IBS-C patients correlated with the angle at rest (P = 0.04) and with the perineal descent at rest (P = 0.01). The severity of abdominal discomfort or pain, and abdominal fullness correlated with the anorectal angle. The duration of symptoms and frequency of bowel movements correlated with perineal descent. Straining, mucus expulsion, and the feeling of incomplete evacuation correlated with rectal sensitivity variables.
Patients with IBS-C have lowered sensory thresholds for noxious and non-noxious stimuli, increased visceral sensitivity after food, less perineal mobility during defecation, and symptoms that correlate with rectal sensitivity and pelvic floor parameters.