Can Monocyte Distribution Width (MDW) Distinguish Infection from Ulcerative Colitis Flares?

Review by Prof. Angela Carbajal (Peru)

Study Summary 

Distinguishing bacterial enterocolitis from acute severe ulcerative colitis (ASUC) is a common—and clinically critical—challenge in emergency settings, where delays in diagnosis can directly impact treatment decisions. In this retrospective cohort study of 176 patients from a tertiary care center, researchers evaluated whether monocyte distribution width (MDW), a novel parameter obtained from routine blood counts, could help solve this problem. Patients with bacterial enterocolitis had significantly higher MDW levels than those with ASUC, with good discriminatory performance (AUC 0.78). Beyond diagnosis, MDW also correlated with inflammatory markers and predicted response to infliximab as well as biochemical remission. A simple blood parameter may offer more clinical insight than we previously recognized.

Commentary 

At first glance, these results may seem expected—but they carry important clinical implications. While clinicians have traditionally depended on markers like CRP or stool studies to distinguish infection from inflammation, this study highlights that a routinely available blood parameter (MDW) could provide faster and potentially more actionable information. What makes these findings compelling is the versatility of MDW: it not only aids in early diagnosis in the emergency setting but also reflects disease activity and helps predict response to advanced therapies.

Still, translating this into practice has challenges. MDW is not yet widely accessible, and the evidence comes from a single-center retrospective cohort. Although the biological rationale is strong, external validation in diverse populations is needed. The next step is clear: incorporate MDW into prospective studies and clinical decision-making pathways.

Citation

Li Wai Suen CFD, Kaul S, Tan EXZ, Con D, Taylor M, Wiid J, Hogan C, Choy MC, Visvanathan K, De Cruz P. Monocyte Distribution Width Differentiates Bacterial Enterocolitis from Acute Severe Ulcerative Colitis in the Emergency Department. Dig Dis Sci. 2026 Mar 2. doi: 10.1007/s10620-026-09786-w. Epub ahead of print. PMID: 41772239.

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