A patient support surface, such as a mattress, includes one or more sensors to sense movement of at least a portion of the mattress caused by extension or retraction of an associated mattress support section of a bed frame. The apparatus has a substantially horizontal bottom wall and a support structure which together provide a storage region adapted to store substantially upright the absorbent articles. In one form, the chevrons have a uniform height relative to the upper and lower sealing surfaces. The anchor rack thus formed can also prevent electromagnetic interference.