CEA test: Carcinoembryonic antigen test is to detect response to therapy in cancer patients, especially colon cancer, with normal range of less than 2.5 (less than 5 in heavy smokers). Note that a positive test may not always be indicative of cancer.
Os Trigonum Syndrome. An Os Trigonum is a small, extra bone found at the back of the ankle in approximately 5-10% of people. Often it goes completely unnoticed, not causing any problems.
External os (ostium uteri, external orifice of uterus) is the opening of the cervix into the vagina. It occupies a central position in the cervix and is round in the nulligravida and slit-like in the parous woman. Endocervix (cervical canal) is the cavity of the cervix and connects the external os with the internal os. It is fusiform in shape and has posterior and anterior oblique longitudinal ridges, the plicae palmatae. These are not exactly apposed but inter-lock like a zipper so that the canal is kept closed.