Irritable Bowel Syndrome Message Boards | Abdominal Bloating: Relation to Rectal Hypersensitivity and Menstrual Cycle

Abdominal Bloating: Relation to Rectal Hypersensitivity and Menstrual Cycle

Lin Chang, MD

Abdominal bloating and visible abdominal distension are commonly reported by patients with IBS.[17] Despite the introduction of tegaserod, which has been shown to relieve symptoms of bloating in female patients with IBS-C,[18] bloating can still be challenging to treat because of the lack of understanding of the pathophysiologic mechanisms underlying these common symptoms.[19] While some patients with bloating have associated abdominal distension, others do not. Although patients with IBS with abdominal bloating, with and without associated visible abdominal distension, are quite similar in the majority of parameters, eg, those with both bloating and distension are more likely to be female, are more likely to report a greater perceived symptom severity, and are more likely to have less diurnal variation in symptoms.[20] In addition, abdominal bloating is reportedly worse in women during the late luteal and early menses phases of the menstrual cycle.[21]

Lea and colleagues[22] performed several studies to further evaluate the impact of these associated factors (ie, diurnal variation, abdominal distension, and menstrual cycle) in patients with IBS with bloating. In one study, they evaluated the diurnal variation of abdominal girth in 16 patients with IBS-C, 21 with IBS-D, and in 20 healthy control subjects. Abdominal distension was measured using a recently validated objective technique of Ambulatory Abdominal Inductance Plethysmography.[23] Abdominal girth was greatest in the early evening in approximately 60% of both IBS-C and IBS-D patients, but only correlated with worsening bloating symptoms in the IBS-C patients.

In a second study,[24] these investigators assessed whether rectal sensitivity differed between female patients with IBS with abdominal bloating, with and without increased abdominal distension (total n = 37). Those patients who did not exhibit physical abdominal distension (compared with healthy controls) had significantly lower rectal pain thresholds than both patients with IBS who were distended and healthy controls. The investigators concluded that the symptom of bloating in the absence of visible abdominal distension may be due to increased visceral sensitivity to gastrointestinal events.

In their third study, Lea and colleagues[25] sought to determine whether perimenstrual bloating is associated with abdominal distension. Abdominal girth was recorded for 24 hours in 12 women with IBS and in 10 healthy female volunteers during the various menstrual cycle phases. Both women with IBS and control females reported more bloating during menses and the premenstrual phase, although bloating was rated as more severe in the patients than in the controls. However, abdominal girth was not different between the different phases of the menstrual cycle in IBS patients or in controls. Taken in conjunction with the results from the first study and with the previous finding that rectal perception is increased during menses compared with the other menstrual cycle phases in women with IBS,[26] these results lend support to the hypothesis that abdominal bloating is related to visceral hypersensitivity in IBS.

Summary. Abdominal bloating is a common symptom reported by patients with IBS, although its pathophysiology is not well understood. Several findings suggest that abdominal bloating may be related to visceral hypersensitivity: (1) bloating without distension is associated with lowered rectal pain thresholds; (2) bloating is reported as worse in the premenstrual and early menses phases of the menstrual cycle; and (3) rectal sensitivity is increased during menses compared with the other phases in women with IBS. If abdominal bloating is related to visceral hypersensitivity, it is not clear whether this is due primarily to visceral hyperalgesia (ie, increased pain perception to noxious visceral events) or to a hypervigilance towards expected aversive events arising from the viscera.

http://www.medscape.com/viewarticle/480232

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Heather is the Administrator of the IBS Message Boards. She is the author of Eating for IBS and The First Year: IBS, and the CEO of Heather's Tummy Care. Join her IBS Newsletter. Meet Heather on Facebook!

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