Travel in the Saada region of northern Yemen is strongly discouraged because of the risk of violent civil unrest. Travel to the eastern parts of the country (Ma'rib, Shabwah, Hadramawt) and the south (Aden, Abyan, Al-Bayda') is also inadvisable because Al-Qaeda is active in some of these areas.
Your doctor will not test for illegal drugs unless you ask him to. A CBC stands for complete blood count which has to do with your blood cells not drugs.
A complete blood count (CBC) test measures the following: 1  The number of red blood cells (RBC count) 2  The number of white blood cells (WBC count) 3  The total amount of hemoglobin in the blood.  The fraction of the blood composed of red blood cells (hematocrit)