People associate doctors with many things, but by far and away the most commonly associated objects with doctors are...
Small needles. Fat needles. Long needles. Short needles. It doesn't really matter. No one likes them.
Needles have lots of uses from (1) removing fluid or small bits of tissue from locations within the body or beneath the skin, (2) injecting medicines or fluids beneath the skin or directly into the vascular system, or (3) poking holes in things to permit passage of slightly larger plastic tubes over them. They are sized by "gauge" sizes - usually larger numbers mean smaller diameters.
But what many don't know is the relationship between doctors' specialties is directly correlated to the type and size of needle they use.
The Dermatologist - Even though they work on the largest organ of the body, it seems everything's smaller in dermatology: warts, skin tags, basal cells. And they don't like scars. Resecting these takes a little local anesthetic delivered by, you guessed it, tiny 25-gauge needles, shown here:
The Pediatrician or Oncologist - These guys have a knack for flare, but they're still dealing with tiny veins, so they've devised the cutest of the needles called the "butterfly" needle:
The Internist - Nothing can be simple for internists, so the "Angiocath IV" was invented. It's a smaller needle with a thin plastic tapered tube over it that follows the needle into the vein, provided, of course, this doctor was trained earlier by a really good nurse. Otherwise, the plastic tube will rest outside the vein and permit intravenous (IV) fluids to be poured into the space beneath the skin, swelling the hand to the size of a small softball. So placing intravenous catheters ("IVs") takes a moderate amount of skill and a steady hand:
The Orthopedist - All it takes is a strong arm, a heavy hand, and just about any orifice in the body can be reached by an orthopod with this thicker, sturdy, 18 gauge needle:
The Cardiologist - By far and away, the workhorse needle is the Cook or Seldinger needle. It's also 18 gauge, but it's longer length helps reach the femoral artery in the upper leg region. (Yes, the othopedist could reach this with his shorter needle, but cardiologists don't like to push so hard). This needle's thinner wall and larger diameter permits passage of a thin wire within the lumen of the needle into the artery. The needle is then removed and a short plastic straw-like structure (called a "sheath") can be passed over the wire into the artery. For such a novel task, it has a strong, commanding look:
The Emergency Room Physician - Not to be outdone by the meager Cardiologist, Emergency Room physicians' trademark needle is the spinal needle. It's a bit longer than the Cardiologist's needle and handy to puncture the lower back to enter the spinal canal (getting lightheaded yet?):
The Cardiac Electrophysiologist - But ER doctors have nothing on the Electrophysiologist. Poking a hole in the heart by passing it from the upper leg area takes a very special needle. And with atrial fibrillation ablation procedures performed in the left atrium, this is the workhorse of today's electrophysiologist. Pioneered by E.C. Brockenbrough to puncture from the right atrium to the left atrium, this needle is the granddaddy of them all.
And what can I say, except...
Yes, ladies and gentlemen, size does matter.