Severe Persistent Constipation

Constipation is a common complaint, all of us having suffered short-lived symptoms at some point. Fewer people have symptoms sufficient to prompt a visit to a physician, but it is still remarkably common with up to 2.5 million physician visits annually, corresponding to a prevalence of 1.2% (1). Even fewer people, however, have severe persistent constipation that has a lifestyle-altering impact. Mertz in the present issue of The American Journal of Gastroenterology (2) assessed 131 such patients. Assessment of patients has been aided by two advances: clarified, widely accepted definitions and improved diagnostic techniques. Criteria established by an international workshop (3) have allowed for comparison of patients of equivalent severity, but also highlight the different symptoms that are encompassed by the diagnosis of constipation. A patient’s view of constipation may not be limited to or even include infrequent bowel movements, but be defined by straining or hard stools. The symptoms themselves may be suggestive of the underlying mechanism, for example infrequent bowel movements in slow transit constipation, or straining at defecation in pelvic floor dysfunction. Diagnostic techniques such as anorectal manometry, defecography, and electromyography have added to the description and classification of different types of constipation, but do not always add to the elucidation of underlying mechanisms. The authors have employed accepted, well-standardized methods of assessing colonic and pelvic-floor function and their results have generated a challenge to one accepted classification of constipation. The current system is described as incorporating three distinct pathophysiologic groups: 1) slow-transit constipation (STC); 2) pelvic-floor dysfunction (PFD); and 3) irritable bowel syndrome (IBS). In its most useful form, however, the system also describes a fourth group (4), that of STC plus PFD, thus not attempting to delineate distinct pathophysiologic groups. The usefulness of this approach has been both in guiding therapy and, as importantly, predicting results of therapy. Identification of IBS allows initiation of aggressive pharmacologic1/2 behavioral protocols to alleviate symptoms. Patients with pelvic floor dysfunction may experience marked improvements in symptomatology with intensive pelvic floor retraining (5). Both of these groups have poor results after surgical intervention, which is now contraindicated for these diagnoses. Slow transit constipation, however, in the absence of PFD, responds very well to surgical intervention, in the form of subtotal colectomy with anastomosis of the terminal ileum to the proximal rectum. This group of patients reports 97% satisfaction with the procedure (6) compared with only 50% satisfaction in series where current strict preoperative criteria based on physiologic testing are not fulfilled. The importance of the fourth group in this classification is considerable: lack of recognition of PFD in patients undergoing operation for STC will almost inevitably doom the procedure to failure with symptoms of difficult evacuation remaining unchanged (7); recognition and treatment of the PFD component, however, prior to subtotal colectomy for STC (or even after), produces levels of satisfaction equivalent to results in STC alone (6). This study delineates four groups based on the presence or absence of STC and visceral hypersensitivity (used to define the presence of IBS). PFD is not a separate classification. One of the surprises of this study is the prevalence of PFD, approximately 50% in each of the groups. Given this prevalence in both the author’s own study, and the studies quoted of PFD in both abused and healthy women, we agree with the author in questioning the physiologic relevance of PFD as defined by manometric assessment. This is further supported by the documented lack of correlation between defecography and manometrically-defined PFD. We, however, disagree with the author’s conclusion that PFD may be over emphasized as a factor in constipation, primarily because of the consequences of ignoring its presence in patients undergoing subtotal colectomy, as described above. Different tests of PFD, particularly balloon expulsion as an indicator of ability to coordinate pelvic floor actions, may be more clinically relevant (8). It would be interesting to assess correlation between the author’s tests of PFD (increased EMG activity and increased pressure with defecation effort) and balloon expulsion. The overlap of STC and visceral hypersensitivity is a useful observation. Of the 49% of patients with STC, almost two thirds also exhibited visceral hypersensitivity. Does this finding explain why some patients with an apparently satisfactory result after subtotal colectomy for STC, with daily bowel movements, still complain of abdominal cramping? Additionally, the earlier classification system made the assumption that absence of STC and absence of PFD defined the group of IBS patients. This study shows that 24% of patients had no evidence of STC nor visceral hypersensitivity (IBS). Even with 50% of this group having PFD, that leaves approximately 12% of patients with no abnormality identifiable by current standards of testing. What a fascinating group! In conclusion, each approach has its advantages and disadvantages and, in the first synthesis, this article does not so much challenge the current classification as enhance it, and illustrates that there is much we must still learn.