A cap for a container is described that is configured to retain a gynecological sample collected with a sampling device. The cap includes a peripheral wall extending between a base and a flange opposite the base, and a diaphragm extending from the base of the peripheral wall. The flange projects beyond the peripheral wall and is configured to seat against a rim of the container. The diaphragm defines a first open area communicating with a second open area that is smaller than the first open area and includes a boundary spaced from the peripheral wall that is configured to detach the distally located sampler from the sampling device.