Download Oxford Cases in Medicine and Surgery pdf Easily In Format For Free
preface
Th e inspiration for this book comes from our time as medical students. Th e
problem we found with existing textbooks was twofold.
Firstly, most books are organized by pathology. For example, they may have chapters on ‘cardiology’ that then discuss specifi c conditions, like ‘myocardial infarction’,
in detail. But patients do not present with ready-made diagnoses like ‘myocardial
infarction’. Th ey present with symptoms, such as ‘chest pain’, which could be a myocardial infarction – but could also be anything from refl ux oesophagitis to aortic
dissection.
Secondly, there are also textbooks based around cases rather than pathologies.
Our experience is that these tend to skip over the diagnostic approach too quickly,
in order to move on to a discussion of the underlying disease. Many give the reader
so much information in the initial case presentation that the diagnosis is virtually
made for you. For example, a ‘62-year-old diabetic male with sudden onset, crushing chest pain; tachycardia on examination; ST elevation on his ECG, plus raised
troponins’ has a myocardial infarction. But by giving so much information upfront,
these books neglect to address what many students fi nd most challenging – how
do you decide what information to collect in order to make a diagnosis? Patients
present with symptoms such as ‘chest pain’ and it is your job to elicit the key clues
on history and examination, and to arrange the key investigations that will confi rm
that this is a myocardial infarction and rule out other diagnoses.
Knowing what to do when faced simply with ‘confusion’ or ‘abdominal pain’ can be
daunting and tricky – we know, and that is what motivated us to write this book.
We hope this book will help you start thinking like a diagnostician from your fi rst
day on the wards. Th us, we hope you will be able to work out why your patient is
short of breath or has abdominal pain in a way that is safe and effi cient, and avoids
you missing important diagnoses. Even with detailed knowledge of anatomy, physiology, biochemistry, pathology, history-taking, examination skills, and data interpretation, it can be diffi cult to integrate everything when faced with acutely ill
patients on the wards. We benefi ted greatly from case-based seminars that taught
us a hypothesis-driven, logical, step-by-step approach to diagnosis. Our hope is that
this book emulates the teaching that we found so benefi cial.
Finally, we wanted to write a workbook that students will enjoy using and where
even the simplest concepts are clearly explained.
The need for a logical diagnostic approach
Looks like an elephant. Sounds like an elephant. Smells like an elephant. Probably an elephant. Experienced clinicians often use pattern recognition to guide
diagnosis. As a student, you will begin to do this rapidly for conditions that you
will encounter frequently – chances are that, by now, you easily recognized that
the 62-year-old diabetic male mentioned above was having a myocardial infarction.
Pattern recognition is useful and effi cient, and we have tried to illustrate stereotypical
presentations of some diseases in our short cases.
Looks like a crocodile. Sounds like a crocodile. Smells like a crocodile . . .
but is actually an alligator.Pattern recognition is a problem when a disease presents
in a way that mimics another disease. For example, patients with oesophageal spasm
may describe the same pain as those with an acute coronary syndrome. Such diagnostic puzzles are the stuff that hospital grand rounds and television shows are made
of. But misdiagnosis due to (incorrect) pattern recognition can have disastrous consequences – you could inadvertently thrombolyse a patient you thought was having
a myocardial infarction but actually had an aortic dissection. Th is is one reason why
it is important to always follow a logical diagnostic approach.
Looks like an elephant. Sounds like a lion. Not sure what it smells like. Must be
a . . . ? You cannot recognize a pattern you have never seen before, an especially big
problem for the inexperienced medical student starting their clinical placements.
On other occasions, the symptoms may not fi t any known pattern, and even experienced clinicians may struggle initially with the diagnosis. Th is is another reason for
having a logical diagnostic approach.
A logical approach to diagnosis
Below is an outline of the diagnostic strategy we have used throughout this book. We
recognize that, over time, everyone develops their own diagnostic strategy and that
tutors may teach you diff ering approaches. Th is is simply one that has worked for us.
‘50-year-old male with chest pain’. It is tempting to assume that he is having a myocardial infarction, like the 62-year-old diabetic male mentioned above. However, . . .
• Step 1:Th ink of all the things that could cause this presentation. Use anatomy,
a surgical sieve (e.g. INVITED MD), etc. to come up with as long a list as
possible.
• Step 2: Highlight from your list the most common causes. For example, acute
coronary syndrome is a common cause of chest pain, viral costochondritis is
not. Mark the ones that you must exclude because they are lethal. In the case
of chest pain, Boerhaave’s perforation of the oesophagus is important as, if
untreated, it carries a 100% mortality.
• Step 3: Th ink of key clues in the patient history for each of the diagnoses. For
example, patients with Boerhaave’s perforation of the oesophagus invariably
give a history of vomiting immediately before onset of the pain. Now take a
history that deliberately tries to pick up these clues, rather than just going
through a set of ‘standard’ questions which may miss things. Also consider the
patient themselves (e.g. their age, occupation, etc.) and how this aff ects the
relative likelihoods of your diff erential diagnoses. Has the patient’s history or
epidemiological factors made any diagnoses more/less likely?
• Step 4: Th ink of key clues on examination for your diagnoses. For example,
patients with a pneumothorax will have an area of the chest that is hyperexpanded, hyper-resonant to percussion, with absent breath sounds. Perform a
thorough examination looking for these clues. Have your examination fi ndings made any diagnoses more/less likely?
