It has previously been shown that the menstrual cycle has no effect on rectal sensitivity of normal healthy women, despite the fact that they have looser stools at the time of menses.
In patients with irritable bowel syndrome (IBS) however, the menstrual cycle may have a greater role, as such patients often report a significant worsening of their IBS symptoms with menses.
In order to test whether this is the case, a balloon catheter was inserted into the rectum of 29 women aged between 21 and 44, who had been diagnosed with IBS according to the Rome I criteria.
|Rectal sensitivity - increased during menses in IBS patients|
Rectal responses to distention of the balloon during Days 1-4 (menses), 8-10 (follicular phase), 18-20 (luteal phase), and 24-28 (premenstrual phase) were assessed to detect changes in sensitivity and other sensations, such as urge.
A general symptom diary was kept by the women during the course of the study, to evaluate abdominal pain and bloating (using a visual analogue scale), and frequency and consistency of bowel habits.
Throughout the study the levels of anxiety and depression of the subjects were also assessed using the hospital anxiety and depression questionnaire.
The researchers found the women reported abdominal pain and bloating as being significantly worse during menses compared with most other phases of the cycle.
Bowel habits became more frequent, and patients tended to have a lower general well-being - although there was no evidence that they were more depressed or anxious at this time.
Their rectal sensitivity was also significantly increased at the time of their period, more so than during any other phase of their cycle.
However, there was no difference in resting anal pressure or the distension volumes required to relax the internal anal sphincter compared to other times during the menstrual cycle.
There was also no associated change in rectal compliance, wall tension, or motility index, suggesting that the increased rectal sensitivity was independent of any other bowel changes.
Dr LA Houghton, from the University Hospital of South Manchester, England, where the study was carried out, said that the research confirms that IBS symptomatology is exacerbated at menses.
Speaking on behalf of her fellow colleagues, she added that the study had shown, for the first time, that in contrast to healthy women, rectal sensitivity changes with the menstrual cycle in IBS patients.
The authors suggest that other triggers, such as hormones, may further sensitize the guts of women with IBS, which are already acutely sensitive.
Dr Houghton concluded, "These cyclical changes in sensitivity suggest that women with IBS respond differently to fluctuations in their sex hormonal environment or its consequences, compared with healthy females."