Anorectal physiology.

Anorectal physiology, as assessed in an ARP laboratory, can provide helpful information in the management of patients with constipation and bowel incontinence. Beyond the uses described in this review, however, the ARP laboratory is most useful in the research setting. In this setting the laboratory can expand our understanding of function associated with other disease states, including anal fissure, fistula-in-ano, inflammatory bowel disease, and postoperative states. The lab can also provide improved understanding of the complex interactions of the enteric nervous and gut hormone systems with the smooth and skeletal muscle systems. A part of the failure of the ARP laboratory to enjoy more clinical usefulness lies in a lack of standardization of test protocols for many of the tests. Secondarily, there is a lack of normative data from large numbers of normal patients [1]. Finally, there is the difficulty in reproducing tests in situations where the patient has significant potential to compensate for deficits through the recruitment of adjacent muscle groups and other maneuvers. There is also some reluctance on the part of clinicians to make use of the ARP laboratory if the testing is not readily available in their community. Although the tests themselves are not difficult to learn to administer, lack of familiarity with the testing process can act as a barrier to acceptance. This is particularly true for clinicians that are used to making clinical decisions without the added benefit of physiologic testing. Despite these obstacles, the role of the ARP laboratory in the management of complex anorectal disease is likely to grow in the years ahead.