Echinocytes are abnormally shaped red blood cells. They are crenated (notched) and resemble a hedgehog or sea urchin rather than the pale-centered biconcave disks that are characteristic of normal red blood cells.
A check for abnormal red blood cells is performed systematically when irregularities are found in an automated complete blood count or when a blood smear (examination of the blood under the microscope) is specifically prescribed by the doctor. While all possible varieties of abnormal red blood cells are checked for (unless a specific request is made), the test results report mentions only the abnormal varieties found in the specimen.
Echinocytes are found in various diseases such as kidney failure (uremia), hemorrhagic ulcers and stomach cancers, and certain liver diseases. Echinocytes sometimes appear when microscope slides are improperly prepared (artifacts are present).