Urinalysis and Body Fluids 6th Edition by Majorie DiLorenzo, Susan Strasinger

Exercise 36

A significant rise in the OD of amniotic fluid at 450 nm indicates the presence of which analyte?

A. Bilirubin

B. Lecithin

C. Oxyhemoglobin

D. Sphingomyelin

Step 1 of 2

Amniotic fluid:

Fetus is surrounded by a membranous sac called amnion. The existence of amniotic fluid can be seen in amnion.

Spectrophotometric analysis:

Spectrophotometric analysis is used to measure amniotic fluid bilirubin using serial dilutions.

• In the spectrophotometric, optical density (OD) of fluid is measured in between 365 nm (nanometer) and 550 nm intervals

• The OD at 365 nm is the highest wavelength point and OD at 550 nm is the lowest wavelength point of normal fluid

• A significant increase in OD to 450 nm can be seen when bilirubin presence is detected in the fluid. This wavelength is the maximum bilirubin absorption

Therefore, the significant rise OD at 450 nm indicates presence of “bilirubin”. Hence, the correct answer is option.