Mucosal Healing - How Deep Is Enough?

Mucosal healing has emerged as an important outcome measure of treatment in inflammatory bowel disease (IBD). It is increasingly incorporated in the outcome measures of clinical trials along with patient reported outcomes and used in clinical practice as a therapeutic target or goal. The exact definition of mucosal healing continues to evolve and several scoring systems have been developed, some of which require further validation. Considerable inter-observer variation may also exist in interpretation of mucosal appearance in IBD. Novel endoscopic techniques demonstrate that even in patients who have achieved mucosal healing by conventional criteria, subtle inflammation may continue to persist. Whether mucosal healing needs to incorporate or reflect histological healing is a topic of intense debate and further studies. In addition, surrogate markers of mucosal healing, such as fecal calprotectin, may serve as a therapeutic target, but there is debate about whether normalization of fecal calprotectin always reflects mucosal healing. Patients with mucosal healing may also continue to have clinical symptoms reflecting visceral hypersensitivity.