The periodic medical examination is one of the most effective methods of detecting and diagnosing illness. Physicians in ancient times knew to listen to heart sounds, examine urine, and observe the pulse. Real advances on these techniques were not made for many centuries. PercussionÑthe tapping of the chest or abdomen to elucidate fluid levels and the size of organsÑwas introduced in 1761; it was enhanced by the invention of the stethoscope in 1819. Inspection of the eye, throat, larynx, stomach, bladder, and other organs by means of mirrors and lenses began in the mid-19th century, following the development of endoscopes. Another basic diagnostic tool was added at the beginning of the 20th century with the development of medical X rays, and modern physicians can make use of a wide range of instrumentation.
Depending on its purpose, a medical examination may include any of several procedures. Every examination begins with a thorough recording of the patient's medical history. The physician then attempts to elucidate the state of the patient's health and the nature of any symptoms, such as pain or sudden and prolonged weight loss. In evaluating the origin of symptoms, the doctor may ask about the patient's workplace and home environment, any medicines the patient may be taking, and the occurrence of certain diseases in the patient's family.
Physical examination follows the oral history. This includes listening to the rate and regularity of heartbeats, measuring blood pressure, percussing the abdomen and back, and testing simple reflexes. An inspection of the skin can reveal alterations such as extreme dryness, growth, ulcers, and discoloration. The breasts, prostate, and genitals are palpated to detect tumors, and endoscopic examination of the rectum and colon may be appropriate in older persons.
Blood and urine samples are routinely taken for laboratory testing. Trained technologists count blood cells to determine whether any one component is present in excessive or diminished amounts. A high number of white blood cells, for example, could be an indication of bacterial infection; a sample of blood can be placed in a nutrient medium to search for infectious agents. The doctor may also order a measurement of the ability of the patient's blood to clot.
The blood cholesterol levels should be measured. In addition, the presence of certain enzymes in the blood can confirm a suspected diagnosis of heart attack or viral angina. The urine is examined for such things as sugar, found in diabetes; proteins, present in some kinds of kidney damage; and acid levels.
Radiographic investigations may take place when other findings suggest certain conditions (see radiology). Perhaps the most common is the X ray for detecting broken bones. The CAT scan and magnetic resonance imaging techniques can help diagnose illnesses and injuries such as brain tumors or joint injuries. Specialized radiologic examinations are available for patients who may have kidney stones or gallstones, and for inspection of the large intestine. An electroencephalograph can be taken if the doctor wants to see the patient's brain waves. An electrocardiograph can record the activity of the heart. One of the newer diagnostic techniques is the sleep examination, in which the patient spends one or more nights sleeping in a controlled environment while being electronically monitored.
As the number and expense of special tests have increased, doctors and health planners have attempted to determine the most efficient way to use them. In the 1980s several organizations reassessed the need for the so-called yearly physical examination. The American Medical Association instead recommended a checkup every five years for persons less than 40 years old, with increasing frequency thereafter; persons of age 65 or older were still recommended to have yearly examinations. A task force created by the U.S. Department ofh and Human Services later issued a controversial report that recommended various programs of periodic health examinations for different age groups.