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xxx Introduction and User’s Guide
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neurologic examination (Chapter 14), and the psychiatric and social evaluations (Chapter 15).
Parts 3 and 4 provide supplemental information. Chapter 16 discusses
the preoperative examination. The intent is to give the reader a framework for
evaluating the medical risks in the perioperative period and an approach to
communicating those risks to the patient and surgeon. Chapter 17 introduces
the principles of laboratory testing and imaging critical to an efcient use of
the laboratory and radiology. Chapter 18 lists many common (not “routine”)
laboratory tests that provide important information about the patient’s condition not accessible from the history or physical examination. More specialized
tests used to evaluate specic diagnostic hypotheses are not discussed.
Chapters 6 thru 14 have a uniform organization: (A) each chapter begins
with a brief overview of the major organ systems to be considered; (B) next
is a discussion of the supercial and deep anatomy of the body region; (C)
the physical examination of the region or system is described in detail in the
usual order of performance; (D) the symptoms particularly relevant to the
body region and systems are presented; (E) the physical signs in the region
or system examinations are listed (some ndings can be both symptoms and
signs; discussion of a nding is in the section where it is most likely to be
encountered, then cross-referenced in the other section); and (F) discusses
diseases and syndromes commonly in the differential diagnosis of symptoms
and signs in the body region and systems under discussion. To avoid duplication, the text is heavily cross-referenced.
Brief discussions of many diseases and clinical syndromes are included
so the reader can appreciate the patterns of symptoms and signs they commonly manifest. This will help the clinician determine whether that disease
or syndrome should be included in the differential diagnosis of the symptoms
and signs in their specic patient. Particularly useful points of differentiation
are listed after the DDX symbol.
DeGowin’s Diagnostic Examination is not a textbook of medicine. The
reader must use this with a comprehensive textbook of medicine to fully
understand the diseases and syndromes. We strongly recommend Harrison’s
Principles of Internal Medicine as a companion text.
We emphasize the characteristics of diseases because a clinician who
knows the manifestations of many diseases will ask the right questions,
obtain the key history, and elicit the pertinent signs distinguishing one disease from another. Instructions on how to elicit the specic signs are included
in the physical examination section for each region; if the maneuver is not
part of the usual examination, it is discussed with the sign itself. Following
the descriptions of many symptoms and signs is a highlighted
OCCURRENCE
tom or sign. The organization of the Clinical Occurrence section is based upon
the approach to the differential diagnosis of the symptom or sign felt to be
most clinically useful.
Where a broad differential exists, we have introduced an organizational
scheme for the
mechanisms of disease. The clinician can often narrow their differential diagnosis to one or a few basic mechanisms of disease: congenital, endocrine,
degenerative/idiopathic, infectious, inammatory/immune, mechanical/
traumatic, metabolic/toxic, neoplastic, neurologic, psychosocial, or vascular.
This facilitates the creation of a limited yet reasonable differential diagnosis.
section. This is a list of diseases often associated with the symp-
CLINICAL OCCURRENCE based upon the pathophysiologic
CLINICAL
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The categories in this scheme are not mutually exclusive; a congenital syndrome may be metabolic, infections are usually accompanied by inammation, and a neoplastic process may cause mechanical obstruction. Although
not rigid, this is a useful conceptual construct for thinking about the patient’s
problems.
Symptoms, signs, syndromes, and diseases that may indicate an emergent condition requiring immediate and complete evaluation are noted by
the • marginal symbol.
Use your understanding of normal and abnormal anatomy and physiology as the basis for thinking within clinical medicine, you can avoid the
trap of “word-space.” This is the term one of us (RFL) has given to the common practice of using lists and word association as an approach to diagnosis: associating a word (for instance, cough) with a memorized list of
other words (pneumonia, bronchitis, asthma, postnasal drip, gastroesophageal reux, etc.). The inherent emphasis on memorization in this scheme
is the bane of all medical students; fortunately, it is not only unnecessary,
it is counterproductive. Cough is a protective reex arising from sensory
phenomena in the upper airway, bronchi, lungs, and esophagus mediated
through peripheral and central nervous system pathways and executed by
coordinated contraction of the diaphragm, chest wall, and laryngeal muscles. With this physiologic context, and our understanding of the mechanisms of disease, we can hypothesize the irritants most likely to be relevant
in each specic patient.
New diseases are being encountered with surprising frequency. They
present not with new symptoms and signs, but with new combinations of the
old symptoms and signs. It is our hope that the reader will learn to recognize
the patterns of known diseases and to be alert for patterns that are unfamiliar (those not yet in their knowledge base) or previously unrecognized (the
new diseases). HIV/AIDS was recognized as an unprecedented clinical syndrome with a new pattern of familiar symptoms (weight loss, fever, fatigue,
dyspnea, cough) and signs (wasting, generalized lymphadenopathy, mucocutaneous lesions, Kaposi’s sarcoma, opportunistic infections) in a unique
population (homosexual males and IV drug users). Continuous expansion of
our personal knowledge of the known while welcoming the unfamiliar and
unknown is the excitement of clinical practice.
The testing of specic diagnostic hypotheses is beyond the scope of this
book. It is subject to constant change as new tests are developed and their usefulness evaluated in clinical trials. Part 4 discusses the principles of laboratory testing (Chapter 17) and some common laboratory tests (Chapter 18). The
reader should consult Harrison’s Principles of Internal Medicine and the current
literature when selecting specic tests to evaluate their diagnostic hypotheses
[Guyatt G, Rennie D, eds. Users’ Guides to the Medical Literature: A Manual for
Evidence-Based Clinical Practice. Chicago, IL: AMA Press; 2002; Guyatt G, Rennie
D, Meade MO, Cook DJ, eds. Users’ Guides to the Medical Literature: A Manual
for Evidence-Based Clinical Practice. 2nd ed. New York, NY: McGraw-Hill; 2008].
User’s Guide
DeGowin’s Diagnostic Examination can be read cover-to-cover with benet to
the student or practitioner; however, most will not, and should not, choose
this strategy. As Osler said, read to understand your patients and to answer
your questions.
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We strongly suggest that all readers start with Chapters 1, 2, 3, and 17,
which outline the conceptual basis for the diagnostic examination, including
the approach to laboratory testing and imaging. This context is critical to efciently using time and resources.
If you have questions about the systems being examined consult part A
of the relevant chapter and Harrison’s Principles of Internal Medicine. If your
question concerns anatomy, consult part B and an anatomy textbook. If you
are uncertain of the techniques of the physical examination, see Chapter 3
and part C of the body region chapters. If you are uncertain what to make of
a symptom, see part D of the relevant chapter. If you are wondering how to
elicit or interpret a sign, see part E of the relevant chapter. To nd out more
about the diseases mentioned in the section, consult part F of that chapter or
look in the index for the page where it is discussed. Remember, the disease
and syndrome discussions in this book are brief and must be complemented
with reading in a textbook of medicine, for example, Harrison’s Principles of
Internal Medicine.
The Table of Contents should be scanned to familiarize yourself with
the structure and general content of the text. The index locates all the subject
matter in the text.
There is no right way to use a book. The key is to use the information to
inform your thinking about patients and the problems they present. No text is
denitive, and the reader is encouraged to consult other texts and the current
and historic literature to develop a full understanding of your patients and
their illnesses. The acquisition of clinical skills is a journey without end; this
is an intimidating thought for the student but is the source of lifelong stimulation for the practitioner.
After all, what we call truth is only the hypothesis which is found to work best.
——S J G F
DeGowin’s
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Diagnostic Examination
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PART 1
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The Diagnostic Framework
To carefully observe the phenomena of life in all its phases,
normal and perverted, to make perfect that most difcult
of all arts, the art of observation, to call to aid the science of
experimentation, to cultivate the reasoning faculty, so as to be
able to know the true from the false—these are our methods.
– S W O
Don’t strain for arrangement. Look and put down and let your
sensibility be the sieve.
– T R
“Poetry and Craft”
. . . the framing of hypotheses is the most difcultpartof
scientic work, and the part where great abilityisindispensable.
So far, no method has been found which would make it
possible to invent hypotheses by rule. Usually some hypothesis
is a necessary preliminary to the collection of facts, since the
selection of facts demands some way of determining relevance.
Without something of this kind, the multiplicity of facts is
bafing.
– B R
“A History of Western Philosophy”
1
CHAPTER 1
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Diagnosis
Accurate Diagnosis Is Imperative: An ill person has three fundamental ques-
tions: (1) What is happening to me and why? (2) What does this mean for my
future? (3) What can be done about it? Providing answers to these questions
are the three timeless tasks of the healing professions: explanation, prognostication, and treatment. This has been true across time and cultures, regardless of the belief system underpinning the culture: magic, faith, rationalism,
or science. Accurate explanation, prognostication, and appropriate treatment
require precise diagnosis. The history and physical exam are the basis for
diagnostic hypothesis generation, the rst step in the diagnostic process.
Knowledge, an understanding of clinical epidemiology, and experience
are necessary to determine when pursuit of specic symptoms and signs is
warranted. For common minor complaints in healthy people without alarm
symptoms, a good prognosis can be assumed without knowing the exact
cause, as, for instance, an upper respiratory infection (URI). The patient can
be reassured that further testing will not change prognosis or treatment.
When the diagnosis is not self-evident from the initial symptoms, or the
course deviates from what is expected, a more exacting diagnostic evaluation
becomes necessary.
Diagnostic Process: In the process of making a diagnosis, the clinician makes
a series of inferences about the nature of bodily dysfunction. When making
these inferences from clinical data, clinicians use many strategies to combine,
integrate, and interpret the data. After collating the data, the next step in the
diagnostic process is generation of one or more diagnostic hypotheses. A hypothesis is sometimes generated merely from a patient’s age, sex, race, appearance, and presenting complaint. On the other hand, hypotheses may emerge
exclusively from a physical nding or laboratory data. New hypotheses are
triggered as new ndings emerge. Diagnostic hypotheses can be general
(infection or inammation) or quite specic (acute right ventricular myocardial infarction). Diagnostic reasoning proceeds by progressively modifying
and rening the hypotheses. This inferential reasoning process continues until
the clinician arrives at a working diagnosis, a diagnostic hypothesis sufcient
to establish a prognosis and direct therapeutic intervention. The hypothesis
should yield accurate predictions of test results and the patient’s future clinical course.
Diseases and Syndromes: A diagnostic hypothesis provides entry to the
medical literature for current information about etiology, diagnostic ndings,
prognosis, and treatment. Recurring patterns of disordered bodily structure,
function, and mentation suggest a common cause. When a shared pathophysiology and etiology are conrmed, the condition is a disease. Combinations
2
The Diagnostic Process 3
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of features not clearly related to a single cause are syndromes. Diseases and
syndromes are intellectual constructs that do not exist independently of the
patients who manifest them. These constructs allow aggregation of patients
with relatively homogeneous physiologic disorders for study to promote
understanding of disease and to evaluate potential treatments. Accurate diagnosis is indispensable for initiating treatment.
THE DIAGNOSTIC PROCESS
An accurate diagnosis requires the clinician to catalog each anatomic, physiologic, and cognitive abnormality. Each disease and syndrome has a temporal sequence of clinical and laboratory features distinguishing it from similar
conditions. During the diagnostic examination, the clinician performs two
parallel tasks: (1) develops a problem list of the symptoms and signs requiring
explanation; and (2) generates physiologic, anatomic, and etiologic hypotheses regarding the diagnoses. A recursive process is used to work toward a
diagnosis.
Stories: The patient tells us a story of their illness. The clinician creates an
anatomic and pathophysiologic story congruent with the illness narrative. A
good medical story has the same elements as a good newspaper story: who,
what, when, where, how, and why. The rst three items come directly from
the patient narrative:
WHO: This is a description of this person, including their social history (reli-
gion, beliefs, priorities, education, sexual preferences, habits, demographics, employment, and leisure activities), family history, past medical and
surgical history, and current medications.
WHAT: The patient relates the story of their illness experience describing
their symptoms and signs, diagnostic efforts and studies, treatments,
and concerns. Encourage a free narrative ow by not interrupting or
expecting premature clarity. Ascertain their thoughts about what might
be wrong and why. Estimate illness severity by how it has affected their
life. Ask why they sought evaluation at this time. No symptom is irrelevant. Often patients dismiss the symptoms that they think are irrelevant,
which, in fact, may be a key diagnostic clue. Determine when each symptom began, how long it lasts, how often it occurs, what makes it better or
worse, its course over time, and any other associated symptoms.
WHEN: Timing is everything. The sequence, pattern, and duration of symp-
toms are critical for identifying the etiology of a unique combination of
symptoms each common to many diseases. Understanding the timeline
(intermittent, relapsing, acute, subacute or chronic, etc.) for each symptom is vital as it reects the dynamic pathophysiologic disease process
and is one of the most important clues to diagnosis.
The last three story elements are constructed from the history and physi-
cal exam:
WHERE: All disease processes take place somewhere. Your job is to precisely
envision the anatomy of the problem (anatomic hypothesis). Envision
the precise location of the pathophysiologic processes producing the
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disease: which systems, organ(s), tissues, and cells. The process can be
localized or diffuse. If diffuse, look for a pattern of involved tissues.
HOW: This is the testable pathophysiologic hypothesis. How, by what
physiologic mechanism(s), did this illness come about? There are only a
limited number of ways people become ill. A useful way of parsing patho-
physiology is used in this text. Ask which one or more of the following
mechanisms are most likely: congenital, degenerative/idiopathic, endo-
crine, infectious, inammatory/immune, mechanical/traumatic, meta-
bolic/toxic, neoplastic, neurological, psychosocial, and/or vascular. The
pathophysiologic explanation must precede search for a specic etiology.
WHY: This is the etiologic hypothesis. Strive for an exact diagnosis that explains
the illness narrative and each abnormality. An accurate prognosis also
requires understanding why the disease is affecting the patient now.
The ability to reproduce a story verbatim is a rare gift, but our brains
effortlessly capture and recall the gist and ow of stories even if we retain
only a few specic phrases. Similarly, we easily recall visual images and the
sensation of what we hear. As the patient tells their story, listen actively. Try to
avoid analysis until you have captured the whole story. Just listen, translating
the words into a mental recording of your shared experience, as you would
for any other story. During the exam, mentally record what is seen, felt, and
heard. Do not translate the observations into words until the experience of
the exam has been captured. Later it may be a struggle to nd the best words,
but the words will be trying to describe the remembered experience. By performing the screening physical exam in a structured and relatively stereotypic sequence, each patient is observed in a comparable manner. When the
process becomes routine little or no thought is required, so the mind is free to
observe. If attention is too sharply focused, as is often the case with beginners,
one thing may be seen, whereas much is missed.
Gathering and Processing Information:
Clues to the diagnosis. The diagnostic examination has four components:
(1) history taking, where the patient’s perceptions are symptoms; (2) physical
exam, where the examiner observes physical signs; (3) laboratory examinations; and (4) special anatomic and physiologic examinations, e.g., imaging
studies. DeGowin’s diagnostic examination focuses on generating hypotheses from the history and physical exam. Most diagnoses are suggested by
the history and to a lesser extent the physical exam. Laboratory testing is for
evaluating hypothesis, not hypothesis generation.
The diagnostic examination begins with rst patient contact. The
patient’s age and sex are surrogates for diseases common in that demographic. Ethnicity is important for suggesting genetic diseases like sickle
cell anemia. X-linked diseases such as hemophilia are rarely encountered in
females. Males do not get pregnant. Although seemingly obvious, it is important to make explicit each categorical probability decision. The correct diagnosis can be unconsciously passed over by such a heuristic.
Each symptom and sign is analyzed for consistency. Assess the level
of concern attached to each symptom. Symptoms are only as reliable as the
patient’s memory and description. Whenever possible, obtain collateral history
from family and friends to corroborate the patient’s history. Ascertain if each
sign was present previously, and, if so, has it changed from previous exams.
The Diagnostic Process 5
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The problem list. List every problem identied by history, physical exam,
and initial laboratory studies. This is a frequently omitted step in the diagnostic algorithm. Grouping problems into clusters likely to have a common
pathophysiology assists hypothesis generation. Only chunk problems when
it is certain they are closely linked. Common examples are nausea and vomiting, and fever and chills. Avoid lumping if uncertain.
Problem representation. A problem representation is a brief summary of
the patient encounter translating the patient’s story into medical terminology. A well-formed problem representation facilitates clinical reasoning and
serves as the backbone for how clinicians communicate with one another. By
summarizing the most salient features and minimizing distractors, effective
problem representations reduce cognitive load and facilitate clinical problemsolving. Problem representation generally includes semantic qualiers which
are paired opposing descriptors that can be used systematically to compare
and contrast diagnostic considerations: sharp/dull, acute/chronic, tender/
nontender, productive/nonproductive, insidious/abrupt, proximal/distal.
A problem representation is iteratively updated as further data is gathered.
Translating lay language into abstractions (problem representation with
semantic qualiers) using medical terminology enables easier access and
retrieval of knowledge stored as illness scripts, mental representations of potential diagnoses within the clinician’s memory (see below). The clinician develops a prioritized differential diagnosis based on the degree of match between
the patient’s problem representation and previous illness scripts and disease
prototypes.
A thorough problem representation answers three questions:
1. Who is the patient, including pertinent demographics and risk factors?
2. What is the temporal pattern of illness, including acuity (hyperacute,
acute, subacute, chronic) and tempo (stable, progressive, resolving,
intermittent, waxing, and waning)?
3. What is the clinical syndrome integrating key signs and symptoms?
It is easy to get lost in the problems and miss a unifying synthesis, missing the forest for the trees. Avoid this error by creating an explicit problem
statement that, in one or two sentences, reassembles the problems into a concise summary of the big picture.
Illness scripts. An illness script is a narrative structure for recalling the key
attributes of a typical case presentation of a condition or diagnosis. These
are packets of stored knowledge that are retrieved by specic presentations.
Classically, the components of a thorough illness script fall into three main
categories: the predisposing conditions, the pathophysiological insult, and
the clinical consequences. Within these categories, illness scripts often include
a disease’s pathophysiology, epidemiology, time course, salient symptoms
and signs, diagnostics, and treatment.
Differential Diagnosis:
Hypothesis generation. The process by which skilled clinicians form hypotheses has attracted the attention of physicians, mathematicians, and psychologists. As the Bertrand Russell quote at the beginning of this section indicates,
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