MIDTERM LAB: STOOL ARTIFACTS AND CONFUSERS

Question 1

• Suspicious forms that visually resemble parasite in terms of size & morphology
• can result from disease processes, medications, and dietary habits.
• may be caused by contact with water, sewage, or soil.
• AKA PSEUDOPARASITES

Answer 1

ARTIFACTS AND CONFUSERS

Question 2

Polymorphonuclear white blood cells (2-4 lobes) (WBCs) with an average size of 15 µm can be mistaken for

Answer 2

Entamoeba histolytica cysts

Question 3

Mononuclear WBCs (macrophages/monocytes) range from 28 to 62 µm and resemble

Answer 3

E. histolytica trophozoites

Question 4

POLLEN GRAINS
Thick-walled pollen grains resemble the eggs of _______
- but are smaller, have no notable interior structure (hooklets)
- may also resemble Ascaris (nematodes) eggs but pollen grains have spiky surface

Answer 4

Taenia spp. (cestodes)

Question 5

Vegetable cells (via dietary intake) may easily be confused with ______
- may be large & roundish oval to irregularly round in shape
- may have thick walls
- interior portion is unorganized and often consist appears to consist primarily of LARGE VACUOLES

Answer 5

helminth eggs

Question 6

Vegetable spirals often resemble _________ in their shape and size.
-DO NOT HAVE A HEAD OR TAIL REGION.
- Vegetable spirals are readily distinguished from parasitic forms by their ladder-like appearance
- adder consists of a series of RUNGS that are spaced closely together
- NO INTERNALSTRUCTURES

Answer 6

helminth larvae

Question 7

• have the most clinical significance.
• The presence of these diamond-shaped crystals, which develop from eosinophil breakdown products, indicates that an immune response of unknown origin
  has taken place.

Answer 7

CHARCOT-LEYDEN CRYSTALS

Question 8

YEAST CELLS
The round to oval yeast cells measures
4 to 8 μm in size and may be confused
with ________
- show no definite internal structures.
- Yeast may be easily distinguished from parasites when seen in their BUDDING STAGE

Answer 8

protozoan cysts (E. hartmanni, E.nana, E.hominis)

Question 9

Plant hair may resemble _______ in size and shape.
- does not have diagnostic structures, such as a buccal cavity, esophagus, intestine, or genital primordium.
- no head or tail region.

Answer 9

helminth larvae

Question 10

PLANT MATERIAL
May range in diameter from 12 to 150 μm and resemble HELMINTH EGGS, particularly an __________ (38 to 45 μm), in size and
shape.
-

Answer 10

Unfertilized Ascaris lumbricoides

Question 11

EPITHELIAL CELLS
➢ Often show a striking resemblance to ______ in size and shape
- lacks typical amebic trophozoite interior structures (cytoplasm is usually smooth and has no inclusions)
- its large nucleus consists of large karyosomes

Answer 11

amebic trophozoites

Question 12

May be similar to the size and shape of
PROTOZOAN CYSTS
-lack typical amebic interior structures

Answer 12

FUNGAL ELEMENTS

Question 13

STARCH CELLS
- Also referred to as starch granules, measure less than 10 μm and may appear at first glance to be _______ particularly those of _________ ___________ (both measure 5 to 12 μm)

Answer 13

protozoan cysts; E. hartmanni and E. nana

Question 14

Often appear on Giemsa-stained blood film smears and may be mistaken for MALARIAL PARASITES, especially the young trophozoite form.
- appear in various shades of purple.

Answer 14

CLUMPED OR FUSED PLATELETS

Question 15

STAIN PRECIPITATE
➢ May be visible on blood smears and
may be mistaken for?

Answer 15

MALARIAL PARASITES

Question 16

RED CELL ABNORMALITIES
➢ Such as ________ or ________ may be present on Giemsa- stained blood smears.
➢ May be easily distinguished from MALARIAL PARASITES by their different staining characteristics

Answer 16

Howell-Jolly bodies; Cabot’s rings