Most people hate the standard medical routines. We don't like lying semi-naked on a slab, or having blood taken, or the prospect of the insertion of mechanical devices into veins, sinuses, bronchial tubes, urethras, and other personal apertures.

Not long ago I had to go for a CAT scan of my abdomen. It was nothing special, more a loss of dignity than anything else. Still it was uncomfortable and invasive (I had to swallow a barium milk shake that tasted like glue). It was not pleasant and I did not like it.

How might we improve all this?

Before we get to that, let's recall the past - and things far worse than anything that will happen to us now.

Until a hundred years ago, a doctor had few tools to examine a patient's interior. A stethoscope to listen to body processes, a thermometer to measure body temperature, a spatula to examine tongue and throat, and that was about it. The rest of the diagnosis relied on palpation (feeling you), tapping, external symptoms such as ulcers and rashes, and the appearance of various waste products. If all those failed, the dreaded next step could be "exploratory surgery," with or without anesthetics.

And then, as though by magic, in the last decade of the nineteenth century a device came along that could actually see inside a human body. True, the X-ray was better at viewing bones and hard tissue than organs and soft tissue, but it was an enormous step forward.

The X-ray was the first "modern" tool of diagnosis. Since then we have developed a variety of other methods for taking an inside look: the CAT scan, the MRI, and ultrasonic imaging. They permit three-dimensional images, of both hard and soft tissues. Used in combination with the injection of special materials, they allow the operation of particular organs or the flow of substances through the body to be studied as they happen. The radioactive tracers used for this purpose are one undeniably positive fallout of the nuclear age.

Hand in hand with the images goes chemical diagnosis. Today, blood samples can provide a doctor with information about everything from liver function to diabetes to urinary infection to rheumatoid arthritis to AIDS to the presence of the particular bacterium (Helicobacter pylori) responsible for most stomach ulcers. Any tiny skin sample is sufficient to permit a DNA analysis, which can in turn warn of the presence of certain hereditary diseases and tendencies.

We have come a long way in a hundred years. What about the next hundred?

Completely non-invasive diagnosis, with superior imaging tools and with chemical tests that can operate without drawing blood, will become available in the next generation. The chemical tests will use saliva and urine samples, or work through the skin without puncturing it. For the digestive system, we may swallow a pill-sized object, which will quietly and unobtrusively observe and report on the whole alimentary canal as it passes along it.

No more upper GI exams, no more sigmoidoscopies. Our grandchildren will regard today's invasions (drawing blood, taking bone marrow samples, or inserting objects into the body) the way we think of operations without anesthetics: part of the barbarous past.

Or even my recent uncomfortable indignity.

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