Low rectal volumes in patients suffering from fecal incontinence: what does it mean?


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Sirs, This study explores rectal sensorimotor function in faecal incontinence (FI),1 reporting a relationship between rectal compliance, sensitivity and perception in those with reduced maximal tolerable volume to isobaric distension. However, the authors have failed to acknowledge significant contributions already published in this field.

Traditionally, the focus of attention in FI has been abnormal anal sphincter function, but a multifactorial basis is emerging.2, 3 For example, Bharucha et al., have recently shown that FI is associated with puborectalis atrophy and rectal hypersensitivity (lowered rectal sensory volumes).4 Studies from our institution have also shown rectal sensory mechanisms to be important in FI.5 We examined the relationship between sensation and symptoms in patients with urge FI, and confirmed6 that up to half have rectal hypersensitivity, which is associated with increased stool frequency and urgency, compared to those patients with normal rectal sensation.5 In addition, the influence of rectal hyposensitivity (increased rectal sensory volumes) on FI has been studied, with two pathophysiologies identified: increased rectal compliance and truly disordered afferent function.7, 8

We have also reported the relationship between rectal sensation and motor function in patients with urge FI using prolonged rectosigmoid manometry,9 and shown that in the group with rectal hypersensitivity, symptoms were more prevalent and were more often temporally associated with contractile events. Furthermore, in patients with rectal hypersensitivity, an increase in frequency of high-amplitude contractions, and alteration in variables of the rectal motor complex were demonstrated, in comparison to control subjects and patients with normal rectal sensation. For individual patients, rectal hypocompliance and exaggerated rectal motor complex activity were only found in those with rectal hypersensitivity.9

With regard to the authors’ concluding statement: ‘…a better recognition of physiological impairment may enlarge the fields of rectal surgery in selected patients, suffering from incontinence with low compliant rectum, thus bringing it into a similar perspective than bladder surgery’, it is disappointing that the rectal augmentation procedure, developed in our institution for these reasons, has not been discussed.10 In patients with urge FI, secondary to a deficient sphincter mechanism and rectal hypocompliance/hypersensitivity, standard management is problematic, as correction of the sphincter defect may not abolish faecal urgency, which may be incapacitating. This has been achieved by rectal augmentation with a distal ileal segment, and is associated with normalization of rectal sensory thresholds and frequency of high-amplitude rectal contractions.10

We accept with time a greater understanding of the pathophysiological mechanisms associated with incontinence may unveil further targets for symptomatic relief, but feel that recently published work has already revealed exciting avenues for investigation.