Also known (of course) as TMTs, triple-meaning TLAs are a potential source of ambiguity and miscommunication in many fields, and may become particularly troublesome in the world of medicine, where time pressure (and maybe an element of laziness) necessitates their use in patient records. For example:
(More as I think of them...)
A sample entry
Mrs AB—83F→A&E p/w SOB, bg 6/12 ↓ET, PND. Hx ht, chol++, AMI '93. Rx CCB, β-bl, ACEi. FHx dad † CVA 72, mum † AMI 70. PSHx EtOH++, °act'y. O/E hr 70AF, JVP++, HSD+PSM, bibas crep, ank oed. Imp CCF±MR. Ix UA, FBC, EUC, CXR, TTE/TOE.
Mrs AB is an 83 year old woman who presents to Accident and Emergency with shortness of breath on a background of six months' decreased exercise tolerance and paroxysmal nocturnal dyspnoea. She has hypertension and hypercholesterolaemia, and suffered an acute myocardial infarction in 1993. She takes a calcium-channel blocker, a beta-adrenoceptor antagonist, and an angiotensin converting enzyme inhibitor. Her father died with a cerebrovascular accident at age 72, and her mother died of an acute myocardial infarction at age 70. Mrs AB drinks much alcohol and is minimally physically active. Physical examination revealed a heart rate of 70 beats per minute in an irregularly irregular rhythm consistent with atrial fibrillation, a markedly elevated jugular venous pressure, dual heart sounds with a pansystolic murmur, fine crackles on auscultation of both lung bases, and ankle oedema. My impression is that she has congestive cardiac failure and possible mitral regurgitation. She should be investigated with urinalysis, full blood count, measurement of electrolytes, urea and creatinine, a chest x-ray, and trans-thoracic or trans-oesophageal echocardiography.
(Will try to come up with a situation where ambiguity would be consequential. Disclaimer: my records are much clearer and more comprehensive!)