Also, Doppler can detect abnormal blood flow within the heart, which can indicate a problem with one or more of the heart's four valves. Color Doppler. Color Doppler is an enhanced form of Doppler echocardiography. With color Doppler, different colors are used to designate the direction of blood flow.
Earlier Puberty: Age 9 or 10 for Average U.S. Boy. Oct. 20, 2012 -- American boys are starting puberty up to two years earlier than decades ago, new data show. Boys are entering puberty at an average age of 10 among whites and Hispanics, and at an average age of 9 among African-Americans. About a third of boys start to mature sexually up to two years earlier than average.
How Long Does Puberty Last For Boys. When there is an increase in the size of the testicles, it is the first sign of puberty for boys. In the puberty early stage, you can see light hair growth on the genitals and under the arms. A boy starts to gain height and have facial hair during this time period.