Urine collection bag with integral anti-reflux valve

A urine collection bag is disclosed. The collection bag includes at least one sheet of flexible material defining a fluid reservoir and an anti-reflux valve (120). The anti-reflux valve includes a valve housing defining a fluid receptacle positioned externally to the fluid reservoir. The valve housing includes a peripheral rim which is secured to the sheet of flexible material adjacent an inlet opening formed in the sheet of flexible material. The inlet opening in the sheet of flexible material forms a flap in the sheet of flexible material, the flap being positioned to abut the peripheral rim of the housing and substantially seal the inlet opening when fluid flows from the fluid reservoir toward the fluid receptacle. The peripheral rim includes at least one protrusion positioned to engage the flap to prevent the flap from sealing the peripheral rim.