Un­cer­tainty in med­i­cal prac­tice can throw House rules into dis­ar­ray

The Weekend Australian - Travel - - Health -

IN med­i­cal TV dra­mas, pa­tients fre­quently present with baf­fling symp­toms. As the hour pro­gresses, so the pa­tient de­clines while lesser doc­tors strive in vain for a di­ag­no­sis. Then, when all seems lost and the case com­pletely in­ex­pli­ca­ble, Dr Hero MD fur­rows his brow one last time and dis­cov­ers the vi­tal clue oth­ers have missed. Amid gasps of won­der and grat­i­tude, the vil­lain’s true iden­tity is fi­nally re­vealed. The mis­cre­ant is usu­ally some mag­nif­i­cently rare but em­i­nently treat­able con­di­tion, al­low­ing for a suit­ably up­beat clos­ing scene.

Does this com­pare to my surgery? Would re­al­ity GP-TV pro­vide sim­i­lar ex­cite­ment?

Un­ex­plained or un­usual symp­toms are cer­tainly com­mon in gen­eral prac­tice, but they rarely play out in a way that would make for great telly — de­spite most GPs be­ing bet­ter-look­ing than Dr House.

While text­books com­monly set out algo- rithms that pro­vide log­i­cal path­ways from pre­sen­ta­tion to di­ag­no­sis, in re­al­ity doc­tors of­ten rely on pat­tern recog­ni­tion, a skill most hu­mans are very good at. Quite of­ten while tak­ing a his­tory or con­duct­ing an ex­am­i­na­tion the bits just fall into place, and the di­ag­no­sis sim­ply presents it­self.

When this doesn’t hap­pen, get­ting a re­ally thor­ough his­tory is usu­ally help­ful. Ev­ery ill­ness has a nar­ra­tive, and get­ting the story will tell at least what genre of ill­ness you’re deal­ing with. A good ex­am­i­na­tion and some tests will of­ten then re­veal the pre­cise ti­tle.

Not in­fre­quently, how­ever, even af­ter a thor­ough his­tory, ex­am­i­na­tion and ini­tial tests we are un­able to make a de­fin­i­tive di­ag­no­sis. Un­cer­tainty is part and par­cel of medicine, par­tic­u­larly gen­eral prac­tice. Why is this? Is it just be­cause most of us are Con­sta­ble Plod, baf­fled by cases that med­i­cal su­per sleuths would crack in an in­stant? And what do we do in the face of di­ag­nos­tic un­cer­tainty?

Of course, some doc­tors are bet­ter di­ag­nos­ti­cians than oth­ers, but GPs are in a dif­fi­cult po­si­tion. Most pa­tients with com­plex and con­fus­ing symp­toms, scant phys­i­cal signs and in­con­clu­sive test re­sults will not turn out to have a rare or life-threat­en­ing dis­ease.

This is not to say noth­ing is wrong with them — many will have very real ill­nesses such as fi­bromyal­gia, ir­ri­ta­ble bowel, re­gional pain syn­drome or so­mato­form dis­or­der, where psy­cho­log­i­cal dis­tress is be­ing ex­pressed as bod­ily symp­toms. None­the­less, rare dis­eases will oc­ca­sion­ally turn up.

By def­i­ni­tion they are not things we see reg­u­larly, so we are un­likely to recog­nise their par­tic­u­lar pat­tern. On the one hand we don’t like to over-in­ves­ti­gate. I’ve lost count of the times I’ve tested for por­phyria with­out ever get­ting a pos­i­tive re­sult. On the other, fail­ing to make a sig­nif­i­cant rare di­ag­no­sis leaves both doc­tor and pa­tient feel­ing pretty aw­ful.

So what guides us in the zone of un­cer­tainty? Gen­er­ally we try and keep in mind likely com­mon causes and pos­si­ble se­ri­ous ones. We also re­mem­ber that un­usual pre­sen­ta­tions of com­mon ill­ness are more com­mon in gen­eral prac­tice than typ­i­cal pre­sen­ta­tions of rare dis­eases. The pa­tient with headache, for in­stance, com­monly has ten­sion headache or mi­graine. Typ­i­cal pre­sen­ta­tions re­quire no fur­ther in­ves­ti­ga­tion.

Most of those with atyp­i­cal fea­tures will still have a be­nign cause, but once a slight pos­si­bil­ity of tem­po­ral ar­teri­tis, cere­bral in­fec­tion, hae­m­or­rhage or tu­mour has been raised we feel obliged to ex­clude it. When ex­actly we reach the thresh­old for con­duct­ing fur­ther tests or re­fer­ral is a mat­ter of judg­ment and ex­pe­ri­ence.

So even in this high-tech age, un­cer­tainty re­mains very much a part of medicine and even the best di­ag­nos­ti­cians need to know how to cope with it.

We all hope to pro­vide our pa­tients with a prompt, de­fin­i­tive di­ag­no­sis, or if not, at least ex­clude ma­jor pathol­ogy. It’s al­ways in­ter­est­ing, and some­times a truly fas­ci­nat­ing process. But you’d need a lot of edit­ing to make GP-TV com­pet­i­tive in the rat­ings. Si­mon Cowap is a GP in New­town, Syd­ney

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