Explain the following material in good way: CONSTRUCTING A DIFFERENTIAL DIAGNOSIS
Abdominal pain is the most common cause for hospital admission
in the United States. Diagnoses range from benign entities (eg, irritable bowel syndrome [IBS]) to life-threatening diseases (eg, ruptured abdominal aortic aneurysms [AAAs]). The first pivotal step in
diagnosing abdominal pain is to identify the location of the pain.
The differential diagnosis can then be narrowed to a subset of conditions that cause pain in that particular quadrant of the abdomen
(Figure 3–1 and Summary table of abdominal pain by location at
the end of the chapter). The character and acuity of the pain are
also pivotal features that help prioritize the differential diagnosis.
Other important historical points include factors that make the
pain better or worse (eg, eating), radiation of the pain, duration of
the pain, and associated symptoms (nausea, vomiting, anorexia,
inability to pass stool and flatus, melena, hematochezia, fever, chills,
weight loss, altered bowel habits, orthostatic symptoms, or urinary
symptoms). Pulmonary symptoms or a cardiac history can be clues
to pneumonia or myocardial infarction (MI) presenting as abdominal pain. In women, sexual and menstrual histories are important.
The patient should be asked about alcohol consumption.
A few points about the physical exam are worth emphasizing.
First, vital signs are just that, vital. Hypotension, fever, tachypnea,
and tachycardia are pivotal clinical clues that must not be overlooked. The HEENT exam should look for pallor or icterus. Careful heart and lung exams can suggest pneumonia or other extraabdominal causes of abdominal pain. 
The physical exam of a patient with abdominal
pain includes more than just the abdominal exam.
Of course, the abdominal exam is key. Inspection assesses for distention (often associated with bowel obstruction or ascites). Auscultation evaluates whether bowel sounds are present. Absent bowel
sounds may suggest an intra-abdominal catastrophe; high-pitched
tinkling sounds and rushes suggest an intestinal obstruction. Palpation should be done last. It is useful to distract the patient by continuing to talk with him or her during abdominal palpation. This allows
the examiner to get a better appreciation of the location and severity of maximal tenderness. The clinician should palpate the painful
area last. The rectal exam should be performed, and the stool tested
for occult blood. Finally, the pelvic exam should be performed in
adult women and the testicular exam in men.
1
Mr. C felt well until the onset of pain several hours ago.
He reports that the pain is a pressure-like sensation in
the mid-abdomen, which is not particularly severe. He
reports no fever, nausea, or vomiting. His appetite is
diminished, and he has not had a bowel movement since
the onset of pain. He reports no history of urinary symptoms such as frequency, dysuria, or hematuria. His past
medical history is unremarkable. On physical exam, his
vital signs are temperature 37.0°C, RR 16 breaths per
minute, BP 110/72 mm Hg, and pulse 85 bpm. His cardiac
and pulmonary exams are normal. Abdominal exam
reveals a flat abdomen with hypoactive but positive bowel
sounds. He has no rebound or guarding; although he has
some mild diffuse tenderness, he has no focal or marked
tenderness. There is no hepatosplenomegaly. Rectal
exam is nontender, and stool is guaiac negative.
At this point, what is the leading hypothesis,
what are the active alternatives, and is there
a must not miss diagnosis? Given this differential diagnosis, what tests should be
ordered?
PRIORITIZING THE DIFFERENTIAL DIAGNOSIS
The patient’s history is not particularly suggestive of any diagnosis.
Focus your attention on diseases associated with mid-abdominal
pain. Appendicitis should always be considered in young, otherwise
healthy patients with unexplained abdominal pain. Peptic ulcer disease (PUD) and pancreatitis may also present with epigastric or
mid-abdominal pain.