Hematology and Clinical Microscopy Glossary - College of American ...
Hematology and Clinical Microscopy Glossary - College of American ...
Hematology and Clinical Microscopy Glossary - College of American ...
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44<br />
Urine Sediment Cell Identification<br />
At Neutral to Alkaline pH<br />
Ammonium biurate crystals may be associated with<br />
phosphate crystals in alkaline urine. Biurates appear as<br />
crystalline yellow-brown smooth spheres, with radial or<br />
concentric striations. The “thorn apple” variety has<br />
projecting horns. These crystals should not be confused<br />
with sulfonamide crystals.<br />
Amorphous phosphate crystals form colorless or brown<br />
granular aggregates. They are similar in appearance<br />
to amorphous urates, but occur in alkaline, rather than<br />
acid, urine.<br />
Ammonium magnesium (triple) phosphate crystals are<br />
typically colorless, <strong>of</strong>ten large monoclinic crystals with<br />
a “c<strong>of</strong>fin-lid” appearance. Triple phosphate crystals<br />
assume a characteristic four-armed, feathery<br />
appearance as they dissolve. They are birefringent<br />
<strong>and</strong> are <strong>of</strong>ten accompanied by amorphous phosphates<br />
<strong>and</strong> bacteria.<br />
Organisms<br />
Bacteria<br />
Rod-shaped bacteria (bacilli), most commonly<br />
Gram-negative enteric organisms, are identified in wet<br />
mounts as rod-shaped organisms <strong>of</strong> medium size. Large,<br />
longer bacilli seen in urine are likely to be Gram-positive<br />
lactobacilli from vaginal or fecal contamination. Cocci<br />
are more difficult to identify in wet mounts <strong>and</strong> must be<br />
distinguished from amorphous phosphates <strong>and</strong><br />
amorphous urates.<br />
Abnormal elongated bacillary forms, about the size <strong>of</strong><br />
yeast cells with swollen centers, are occasionally seen<br />
in urine. Their appearance is due to bacterial cell wall<br />
damage induced by antibiotics, typically <strong>of</strong> the<br />
penicillin group, in patients being treated for urinary<br />
tract infections.<br />
Stained bacteria may be round or spherical (cocci),<br />
or rod-shaped (bacilli). They can appear singly or in<br />
groups, clusters, pairs, or chains <strong>of</strong> variable length <strong>and</strong><br />
may be seen in both intracellular <strong>and</strong> extracellular<br />
locations. They stain deeply basophilic with<br />
Wright-Giemsa. Gram stain may be helpful for further<br />
classification. If found within a cell, the more specific<br />
diagnosis <strong>of</strong> “neutrophil/macrophage with phagocytized<br />
bacteria, stained” should be used. The fact that<br />
bacteria are regular <strong>and</strong> uniform in appearance is<br />
helpful in distinguishing them from cellular constituents,<br />
especially granules <strong>and</strong> phagocytized debris, <strong>and</strong> from<br />
crystals such as amorphous urates.<br />
Yeast/Fungi<br />
C<strong>and</strong>ida albicans is characteristically a colorless ovoid<br />
form with a single bud. The 5 to 7 μm, thick-walled cells<br />
stain poorly with aqueous stains in wet preparations but<br />
are strongly positive with Gram staining. C<strong>and</strong>ida<br />
species form elongated cells (pseudohyphae) up<br />
to about 50 μm long, resembling mycelia. They are<br />
branched <strong>and</strong> may have terminal budding forms.<br />
These pseudomycelia may be found in urine from<br />
immunocompromised patients or those with serious<br />
underlying illnesses.<br />
Stained yeast <strong>and</strong> fungi may assume a variety <strong>of</strong> forms.<br />
They are regular in contour <strong>and</strong> usually basophilic on<br />
Wright-Giemsa stain. They may be within or outside <strong>of</strong><br />
cells, <strong>and</strong> may have a clear capsule surrounding them.<br />
The most commonly encountered yeast is C. albicans.<br />
The spores may form pseudohyphae, up to 50 μm in<br />
length, that branch <strong>and</strong> may have terminal budding.<br />
If found within a cell, the more specific diagnosis <strong>of</strong><br />
“neutrophil/macrophage with phagocytized fungi,<br />
stained” should be used.<br />
Protozoa<br />
Trichomonas vaginalis primarily causes vaginal infections,<br />
but is also capable <strong>of</strong> infecting the urethra,<br />
periurethral gl<strong>and</strong>s, bladder, <strong>and</strong> prostate. The normal<br />
habitat <strong>of</strong> T. vaginalis is the vagina in women <strong>and</strong> the<br />
prostate in men. This protozoan flagellate has only a<br />
trophozoite stage. It is pyriform, or pear-shaped, with<br />
a length <strong>of</strong> 7 to 23 μm. There is a single nucleus <strong>and</strong> a<br />
stout central axostyle protruding from the posterior end<br />
<strong>of</strong> the body. Additional morphologic features include<br />
four anterior flagella <strong>and</strong> an undulating membrane in<br />
the anterior half, from which projects a single posterior<br />
flagellum. In wet mounts, it demonstrates a jerky,<br />
rotating, nondirectional leaf-like motion. This is a required<br />
diagnostic feature that obviously cannot be illustrated in<br />
the photomicrographs used for pr<strong>of</strong>iciency surveys.<br />
Rippling <strong>of</strong> the undulating membrane can be seen<br />
for several hours after cessation <strong>of</strong> motility.<br />
Degenerating forms resemble large oval cells,<br />
without visible flagella, <strong>and</strong> may be easily confused<br />
with neutrophils or other leukocytes.<br />
Helminths<br />
Schistosoma haematobium is a trematode that inhabits<br />
the veins <strong>of</strong> the bladder, prostate, vagina, <strong>and</strong> uterus. It<br />
is most <strong>of</strong>ten present in the urine <strong>of</strong> patients from Africa<br />
<strong>and</strong> the Middle East who have schistosomiasis. Large<br />
oval eggs, about 150 μm long, with a distinct terminal<br />
spine, accumulate in the bladder wall. Eggs containing<br />
<strong>College</strong> <strong>of</strong> <strong>American</strong> Pathologists 2012 <strong>Hematology</strong>, <strong>Clinical</strong> <strong>Microscopy</strong>, <strong>and</strong> Body Fluids <strong>Glossary</strong>