People with an outward peristomal body profile can experience difficulties obtaining a secure seal with a flat baseplate to the peristomal skin. Baseplates with a concave contour have been designed to provide a better fit to curved body profiles and reduce the risk of leakage. In this 4-week product evaluation, 110 individuals with an outward peristomal body profile using flat one-piece pouching systems were enrolled to evaluate the impact of a concave one-piece pouching system on wear time, unplanned changes of pouching systems and use of accessories. The product evaluation consisted of two test periods of 2 weeks each. After the first screening period, study nurses evaluated whether the concave pouching system was suitable for the participants and, together with each participant, decided whether to proceed to the second evaluation period. Use of the concave pouching system did not significantly affect wear time but led to significantly fewer unplanned changes of pouching systems and less use of accessories, which may lead to cost savings for the healthcare system.