Emily Embasciani, age 16, of Casper, Wyo., for her question:
HOW IS A MEDICAL DIAGNOSIS MADE?
Diagnosis is the art by which doctors determine which diseases are affecting their patients. There are many different types of diagnosis.
A clinical diagnosis is made by analyzing specific symptoms. A differential diagnosis is one that compares symptoms of several diseases to see which one is most likely to be causing the trouble. A biological diagnosis is made by performing tests on animals with a sample of the patient's body fluids.
X rays may be used to diagnose tuberculosis. A chemical analysis of the patient's urine is often taken to see if the patient has diabetes.
One way of deciding what is wrong with a patient is to decide what diseases he does not have. The doctor compares the sick person's symptoms with the known symptoms of various diseases. All the diseases are weeded out until it is fairly certain that the patient could have only one disease. This is called diagnosis by exclusion. Laboratory diagnosis is made by studying the blood, urine or other liquids of the body in a laboratory, as in the case of anemia and diabetes.
A physical diagnosis is made by looking at the patient for signs of disease apparent to the eye, such as rashes or broken bones, and examining the patient by touch.
A tentative diagnosis is sometimes made when the symptoms are not definite. The diagnosis is made, and the doctors give treatment for what they decide the disease to be, but they then watch the patient closely and carefully for new symptoms.
When a patient is first seen, the doctor usually checks a few basic things immediately. He may look into the mouth to see if the patient's tongue is coated, or if his throat shows signs of an infection. The doctor may also listen to the patient's heart and lungs with a stethoscope.
Often a doctor can make an accurate medical diagnosis with nothing more than a simple examination.
In the doctor's first examination, her simple diagnosis will be based in part on findings discovered after a close look at the patient's eyes and ears.
If the doctor hears something unusual in the heart action, she may make further heart diagnosis with an electrocardiograph machine. Terminals of wire conducting very small amounts of electricity are fastened to the patient's arms and legs to register the way the heart functions and record the movement on a graph. An irregular heart action will make an irregular line on the graph.
Modern methods of diagnosis have been aided by the invention of such devices as the electrocardiograph and the stethoscope, and by improvements in laboratory techniques. If cancer is suspected now, for instance, a small piece of tissue may be cut from the diseased part and examined in the laboratory to see if cancerous cells are present. Smears of body fluids can be examined underneath the microscope as part of a diagnosis to identify the germ of a disease.