Hi! Great question. Visceral fat is the most dangerous- just imaging- having your organs coated in unhealthy white fat. It is difficult to get rid of and cannot be measured by the traditional skinfolds system (which we do with skinfold calipers). Visceral fat is dangerous compared to subcutaneus fat (fat just under the skin) becuase it has a different cell structure and properties. They grow larger in size, and produce hormones which increase inflammation. They are also linked to tumor growth, rapid aging, oxidation, hypertension, and cardiovascular disease.
Though we cannot find out how much the percent of the visceral fat is, alone, there are machines which determine overall body fat. The more expensive the machine, the more accurate. The test is called a "bioelectric impedence analysis". The one to look for which is more accurate to take into account stomach fat is the 4 point reader. Some gyms may have these, or very good weightloss clinics. You are looking for a mchine which measures from both the hands and feet at the same time. It records several check-points and can report how much fat from each quadrant of the body exists. These machines are usually within 1.5% correct. To find access to a machine, you'll have to do some research in your area.