Penile Doppler is an ultrasound test that scans the male sexual organ and levaluates blood flow in the penile arteries to diagnose erectile dysfunction or vascular abnormalities. If the blood flow is low, drugs like viagra can help. But if someone have Hormonal problems , Diabetes, vitamin B or B12 deficiency, thyroid deficiency - it results normal , as blood flow is not directly effected. So it's necessary to take the penile Doppler, when your Doctor recommends you !! Follow for more informatio

Erectile dysfunction - Diagnosis and treatment - Mayo Clinic