++
++
Amniotic Fluid Ferning Pattern. Ferning is the arborization pattern found when a drop of amniotic fluid is allowed to air dry on a microscope slide and helps distinguish rupture of the amniotic sac in pregnancy from normal vaginal secretions. (Photo contributor: Robert Buckley, MD.)
++
+
++
++
To evaluate for the presence of cells, casts, and crystals.
++
Freshly collected urine specimen, centrifuge, graduated centrifuge tubes, glass microscope slide, and coverslip.
++
Pour 10 mL of freshly collected urine into a graduated centrifuge tube.
Centrifuge at ×400 to ×450 gravity for 5 minutes.
Decant 9 mL of supernatant, leaving 1 mL in the tube.
Resuspend the centrifuged pellet in the remaining 1 mL of urine by stirring with a pipet.
Place one drop of resuspended urine on a glass microscope slide.
Overlay with a coverslip.
Examine initially using scanning ×10 power, emphasizing the periphery of the coverslip, since urinary elements tend to gather at the edges.
Switch to ×40 power to focus on specific urinary elements such as cells, casts, and crystals. Use ×100 power as needed for specific identification.
++++++++++