queckenstedt's test: a test to determine whether there is a blockage of the spinal canal
assay: a quantitative or qualitative test of a substance (especially an ore or a drug) to determine its components; frequently used to test for the presence or concentration of infectious agents or antibodies etc.
ovulation method of family planning: natural family planning in which the fertile period is inferred from changes in the character and quantity of cervical mucus; ovulation is marked by an increase in mucus that becomes sticky and then clearer and slippery