The Most Indispensable Medical Device

I also vote for the steth from the physician's angle. The walking stick or spectacles from the user angle.

Stethoscope

Endoscope

I am a type 1 diabetic so my vote goes for the syringe. Look at all the medicines we would not be able to take without it. Just a thought.

Sphygmomanometer

Even before the development of the stethoscope a physician could hear the heart beat. The stethoscope did make it easier.

But the patients blood pressure?

Sphygmomanometer.
That's easy for you to say.

Needle and blood transfusion...
Pacemaker.
Autoclave.
Scalpel.
Placebos! They're great, the big orange ones work a treat.
Del

The objects named so far are things that can be done with more common things, even an ear to a chest, for example. Sure, they are used everywhere and are a big convenience. But how about seeing INSIDE the human body with X-rays or MRI? Those would be my choice.

My vote goes to the hypodermic needle. Vaccinations, blood transfusions, test samples, etc are all made possible because of this device.

Vaccinations

May best be accomplished either by ingestion, sub-lingual or via sinus spray.

test samples, etc

Yes within these parameters currently the hypodermic needle is efficient when especially paired with endoscopic devices.

I would say there is no one device that is the most important. Stethoscope, Syringe, X-ray machine are all important and are used in partnership with one another.

A bar of soap.