The
Clinical Approach to the Acutely Ill Patient
Diagnosis
The
Use of Guidelines and Algorithms
The
Emergency Setting
History
Physical
Examination
Primary
Survey
Secondary
Survey
Laboratory
Testing
Imaging
Sonography
Plain
Abdominal Films
Intravenous
Pyelography
Computed
Tomography
Magnetic
Resonance Imaging
Chest
X-Ray
Laboratory
Testing
In
all cases, laboratory values that appear erroneous or do not make sense should be
quickly rechecked before irrevocable لا رجعة فيه steps are taken in the patient’s care. Blood drawn from a vein above an intravenous infusion,
for example, may show a very low hematocrit level indicating massive blood
loss, but if the patient appears well and has normal vital signs the value
might best be rechecked rapidly before acting. In the management of
emergencies, the time required for a particular test to return a result is a
relevant issue. Diagnostic tools that are faster but less accurate may be
substituted. For example, a patient with a suspected pulmonary embolus and a
positive d-dimer blood test in the emergency room (fast but not 100% accurate)
may be started on heparin while awaiting a more definitive spiral CT of the
chest or angiogram.
This
provides the soonest effective therapy.
A
peculiarity in urologic laboratory testing is found in the analysis of dipstick
versus microscopic versus microbiological (culture) urine analysis. Culture results,
particularly, will not be available for 48–72 h. It is imperative,
however, to have collected a sample before starting empiric antibiotic
treatment. The safest plan is to consider a complete urinalysis to consist not
only of a dipstick test but also microscopic analysis and, if there are any
nitrates or white blood cells present, an automatic Gram-positive and
Gram-negative microbiologic culture. Dipstick tests are quick but give both
false-positive and false-negative results in the presence of some physicochemical
urine properties as well as certain drugs. Blood detection might be hindered by
captopril or vitamin
C
intake and leukocyte esterase by elevated specific gravity, glycosuria,
proteinuria, and oxidating drugs, including some cephalosporins, tetracycline,
and gentamicin
.
The
sensitivity of dipstick urinalysis ranges from91% to 96% for microscopic
hematuria, 72% to 97% for abnormal leukocyte esterase, and 19% to 48% for
nitrites; specificity ranges from 65% to 99%, 41% to 86%, and 92% to 100%,
respectively.
Many
with severe or recurrent UTI, the practice of obtaining microscopy in addition
to dipstick urinalysis is warranted.
