Treatment of illness

The treatment of illness begins with the investigation of a patient’s symptoms and the diagnosis of their cause. Treatment then aims to eradicate the cause, by means of drug treatment, surgery, modifications to lifestyle or, increasingly, where conventional methods seem inappropriate, by recourse to those alternative therapies that have been approved by scientists.

In all medicine, however, investigation and diagnosis must be the starting point. Laboratory tests, X-ray and exploratory techniques are now aided by computers, which speed up the rate at which diagnoses can be made and treatment started. Ten years ago, the fastest autoanalyzer could investigate the blood chemistry of several patients simultaneously and produce hundreds of results within an hour. Nowadays, medically computed analyzers are many times faster.

Antibiotic drugs are tested on a culture plate containing a jellylike medium (right) with a colony of bacteria. Different drugs or different concentrations of drugs inhibit bacterial growth to varying extents, leaving a clear area in the culture. Similar techniques (below) are used in pathology laboratories to analyze samples as part of medical investigation and diagnosis.

Physical examination

No machine, however advanced, is ever likely to replace the physical examination of the patient by the physician. An easy patient-physician relationship has an important effect on the patient’s mental state, which in turn may influence the healing process. At a more complex level, the physician may be able to make judgments more subtle than any machine can. Ideally, physician and machine complement each other in diagnosis.

Complete physical examinations are usually carried out in a clinic or a physician’s office. The patient’s case history generally indicates which body system requires more detailed attention.
When the heart and major blood vessels are examined, the pulse is felt, the heart is listened to with a stethoscope (auscultation), and the blood pressure is measured. Air entry into both lungs is checked, and the chest tapped (percussed) to define air-containing areas. The abdomen is felt (palpated) with the flat of the hand to test for swelling, tenderness, or other abnormality. Internal examination, rectal or vaginal, explores the contours of the rectum and vagina, respectively.
Eyes are examined with a small flashlight for pupil size and reaction; each retina is studied with an ophthalmoscope that focuses on the light-sensitive membranes at the back of the eye. The eardrum is examined with the otoscope, and the mouth and throat with a flashlight and tongue depressor.

Cranial and spinal nerves are tested by the muscular power and surface sensation of the parts they supply. Spinal reflexes are gauged with the patellar hammer, used to elicit a series of reflexes, best-known of which is the knee jerk.

Laboratory analysis

Requests by a doctor for “culture and sensitivity” tests to be made on a particular specimen usually refer to urine samples. A drop is studied microscopically, by the laboratory analyst or pathologist, then “plated out” onto the surface of a culture medium (jelly) in special disposable plates, before being incubated for 24 hours.

Growths (cultures) of bacteria appear as small white or colored “colonies.” Their sensitivity to antibiotics is tested by their reactions to paper spots in the jelly, each spot being impregnated with a different antibiotic. Those to which the bacteria are sensitive inhibit the growth of the bacteria colonies in their vicinity.

Sputum (phlegm) is treated similarly, and for whooping cough special “cough plates” are available to catch the droplets of infected sputum from suspected patients.

Urine and blood are also tested chemically for abnormal constituents, or abnormally high or low levels of substances that are usually present in known proportions. A raised level of urea in urine, for instance, suggests kidney disease, while a low level of thyroid hormone in the blood characterizes malfunction of the thyroid gland.

Blood samples are tested for clotting ability. They may also be given a “blood count,” in which the red cells per cubic millimeter are counted and examined for shape, size, and hemoglobin content. White cells are also counted and the various types identified.

Feces are examined for blood, which indicates bleeding in the gastrointestinal tract, and for signs of infection or parasitic infestation.

Magnetic resonance imaging (MRI) techniques can be used instead of X rays to examine the interior of the body. MRI can reveal more detail than X rays and has no known side effects. One MRI image (far left) shows a cross section of a normal chest. The other (left) indicates the presence of a tumor in the patient’s lung.

Other techniques

The interior of the body can be examined visually by endoscopy, using a flexible fiberoptic tube that can be introduced either through natural openings or through a small surgical incision.

Endoscopes are usually named for the part of the body they examine. A bronchoscope allows the physician to examine the windpipe (trachea) and the bronchi of both lungs. Cancerous growths can be detected in this way. A gastroscope shows the lining of the esophagus and the stomach. Similarly, a colonoscope, sigmoidoscope, and cystoscope view the interiors of the descending colon, sigmoid colon, and bladder, respectively.

Patients are given either a sedative or a general anesthetic before endoscopic procedures. During the examination, the physician can remove a tiny piece of tissue for a biopsy. Then the pathologist examines it for the presence of abnormal cells that might indicate an infection, cancer, or changes due to a disorder, such as ulcerative colitis (which affects the lower gastrointestinal tract).

As well as being used to diagnose skeletal problems, X rays can be used to investigate abnormalities of the soft tissues and internal organs. Tomography produces X rays of structures in a selected plane of the body, by computer-aided interpretation of a sequence of X-ray scans.