M1: Urine Sediments Part 4: Contaminants and Artifacts

Question 1

• May occur when cornstarch is the powder used in powdered gloves
• Granules are highly refractile spheres, usually with a dimpled center
• They resemble fat droplets
  when polarized, producing a Maltese cross formation
• Occasionally be confused with RBCs.

Answer 1

Starch granules

Question 2

• Seasonal contaminant
• Spheres with a cell wall and occasional concentric circles; look like leucine crystals
• Like many artifacts, their large size may cause them to be out of focus with true sediment constituents.

Answer 2

Pollen grain

Question 3

• Hair and fibers from clothing and diapers may initially be mistaken for casts, though they are usually much longer and more refractile
• Examination under polarized light can frequently differentiate between fibers and casts
• Often polarize and have thick edges, whereas casts, do not polarize (except fatty casts)

Answer 3

Fibers

Question 4

What are fibers commonly mistaken with? how is it differentiated?

Answer 4

casts; examin under polarized light

Question 5

T or F

casts often polarize and have thick edges, whereas fibers, do not polarize

Answer 5

F (oppsoite; Fibers often polarize and have thick edges, whereas casts, do not polarize)

Question 6

• irregular in size, highly refractile
  and may resemble RBCs to
  inexperienced laboratory personnel.
• may result from
  contamination by immersion oil or lotions and creams and maybe seen with fecal contamination

Answer 6

Oil droplets

Question 7

• irregular in size, highly refractile
  and may resemble RBCs to
  inexperienced laboratory personnel.
• occur when the specimen is placed under a cover slip.

Answer 7

Air bubbles

Question 8

What resembles starch granules? how are they differentiated?

Answer 8

fat droplets and rbc; examine under polarized light

Question 9

T or F

starch when polarized it produces maltese formation hence differentiates it from fat droplets and rbc

Answer 9

T