blumer's shelf blumer's shelf blumer's shelf, or the rectal shelf, is a finding palpable (felt) in rectal or vaginal examination that indicates that a tumor has metastasized to the pouch of douglas. it is usually a site of metastasis of cancers of the lung, pancreas and stomach, due to metastatic tumor cells gravitating from an abdominal cancer and growing in the rectovesical or rectouterine pouch.