Wednesday, 9 July 2008

Thinking

Ms Medic recently said she appreciated me talking about the way I think when making decisions about patients. I suspect that GPs are more reluctant than hospital doctors to talk about this. Firstly because their diagnoses are often a bit “woolly”; partly due to diseases being at an early stage of development, partly because we are not as expert in a given disease as the specialists who are dealing with it all the time, and partly because we often take into consideration “soft” data such as the sort of person the patient is. And secondly because our management decisions are often swayed by social and psychological factors which we fear may be difficult to justify in the cold light of day.

As far as making diagnoses is concerned, medical students start off with the inductive method: where they collect all the facts they can and then sit down to induce the correct diagnosis in true Sherlock Holmes fashion. Pipes are optional nowadays. But most doctors use the hypotheco-deductive model, in which they think of the most likely diagnosis fairly early in the consultation and then seek evidence to confirm or exclude this first guess. If further evidence confirms the initial hypothesis they are home and dry, but if it makes it seem unlikely they consider the next most likely diagnosis and seek evidence to confirm or exclude that. There are some dangers with this process, such as where the doctor thinks he has confirmed a diagnosis and then ignores later evidence which clashes with that diagnosis. As a perceptive patient once said to me, “once the doctor has made his mind up, the patient has no chance”. What makes diagnosis so difficult is that there is often so much information that it is hard to tell what is relevant and what is not. And diseases often present with unusual symptoms, particularly in the early stages. But no-one said medicine was going to be easy.

The other day I saw a woman in her early thirties who complained of “piles” causing pain and bleeding. Now there are three basic anal symptoms, pain lumps and bleeding, and it is usually fairly easy to hone down the diagnostic possibilities. Fresh bleeding may be piles (in which case there may be lumps) or an anal fissure (in which case there will be sharp pain on defecation). An uncomfortable lump which appears suddenly and doesn't go back in is probably a perianal haematoma; it will not bleed unless it bursts. Bleeding associated with a change of bowel habit, particularly if the blood is “altered” (gone brown with age) is a worrying sign suggesting cancer but might also be inflammatory bowel disease. Bearing in mind the patient's age (early thirties makes cancer unlikely but inflammatory bowel disease more likely), I am usually pretty confident of my diagnosis before I examine them. This time however I couldn't make the story fit any of these patterns. When this happens I find it helps to go back and start again.

It turned out that she had two sets of symptoms. The first was intermittent fresh bleeding with the stool which had been going on for years and was not particularly troublesome at present, with no change in bowel habit and no weight loss. In a woman in her early thirties this does not suggest cancer. The second was anal pain over the past six months, fairly constant, of variable intensity and like “razor blades” when severe, not made worse by opening her bowels, and better at night. She can tolerate it, but it is a nuisance. Examination was completely normal apart from a lot of spasm of the levator ani muscle while inserting a finger.

Whenever possible we try to find one diagnosis to explain all the symptoms (the famous Occam's razor) but sometimes you can have two conditions at the same time. The patient thought she had just one condition which she called “piles”. But I think her bleeding is coming from internal haemorrhoids and the pain she has felt over the past six months is an odd condition called chronic proctalgia. Unfortunately there is little effective treatment.

When it came to management I came across further difficulty. Normally I would have referred her to a surgeon. Firstly to get her haemorrhoids treated to get rid of the bleeding, and secondly to confirm my diagnosis of chronic proctalgia as there are a few other conditions that can mimic it. Unfortunately she is going abroad for a prolonged period very shortly and I will not be able to arrange an outpatient appointment before she leaves. I can't justify referring her under the “two week wait” scheme because I don't think she has cancer. And yet I feel uncomfortable about leaving things for a long time. My advice was that she should seek medical advice while abroad if she gets further bleeding. This was not strictly logical, but it was the best I could come up with.

Incidentally, there is another sort of anal pain called proctalgia fugax where the pain is intermittent, nocturnal, and quite severe. I am quite familiar with it because I suffer from it myself. Normally I wouldn't burden you with my medical problems, but while looking up these conditions on GP Notebook I learned that “psychological testing has revealed that many patients [with proctalgia fugax] are perfectionistic, anxious, and/or hypochondriacal”. And there was I thinking I was normal!

(Everyone starts off by assuming that they are normal, because we use ourselves as a reference point when observing others. Some of us gain a little insight along the way and realise that we are a bit quirky. But I'm quite pleasant really, when you get to know me!)

7 comments:

Anonymous said...

So when we talk about someone being "anal" there is a medical basis for the description!!!!!! You couldn't make it up, could you. I wonder who applied the term first.

Anonymous said...

anon 14:45 - I always thought "anal" was short for "anally retentive" ie full of shit...

Dr Andrew Brown said...

"Anal retentive" derives from Freud's psychological theories and refers, according to my good friend Mr Wikipedia, to someone who demonstrates "orderliness, stubbornness and a compulsion for control, as well as a generalized interest in collecting, possessing, and retaining objects".

Some of these traits are useful to a doctor in small doses, which is just as well since the description applies to me to a certain extent. But not too much, obviously. :-)

Anonymous said...

I'm glad that you considered IBD as a posibility (as opposed to IBS!) as so many GPs ignore it as a possible diagnosis. I was lucky, mine said IBD as soon as I went to see him with my symptoms. But then he had just finished his GP registrar training so I think he was just a bit more on the ball, and less inclined to dismiss it as IBS.

I can't develop piles anymore seeing as I have no rectum now (no colon either)!!

The Shrink said...

Diagnosis has to be the most complex task we undertake that we make look easy.

One of my CPNs a few week weeks ago looked at me quizically, tilted her head to one side and said, "You really are mad as a sack of rats, aren't you?"
Normal is hard to find :-)

Ms Medic said...

I still appreciate an insight into the methods, I really do! If I change my mind back to GP from surgery I hope I am a GP like you. I'll let you know how my own efforts go in 2 weeks time...

Petra said...

“Psychological testing has revealed that many patients [with proctalgia fugax] are perfectionistic, anxious, and/or hypochondriacal”.

I would ignore that "fact". Wouldn't really believe it.
Psychological testing also showed that mothers of autistic children were cold and loveless; and that people suffering from a heart attack had type A personality (or was it B?) and that people suffering from cancer had type B (or was it A?).
It was all proven very wrong.

Maybe pain in your butt (sorry) does make you a little bit anxious and hypochondriacal? Can't explain the perfectionistic part though, although almost every other person on this planet thinks he/she is too perfectionistic and should loosen up...