Gravindex Explained

Gravindex
Purpose:	pregnancy test

Gravindex is an agglutination inhibition test performed on a urine sample to detect pregnancy.^[1] It is based on double antigen antibody reaction. The test detects the prevention of agglutination of HCG-coated latex particles by HCG present in the urine of pregnant women.^[2]

Procedure and results

Kits commercially available contain two reagents; one is a suspension of HCG-coated latex particles, and the other is a solution of HCG antibodies. One drop of the urine is mixed with one drop of antibody solution for one minute on a black glass slide. One drop of the HCG-coated latex particles is added to the slide and left for one minute.

• If the level of HCG is too low, the antibodies will remain to agglutinate the HCG-coated latex particles. If agglutination occurs, the subject is not pregnant.
• If the level of HCG is high, the HCG will bind to the antibodies, and thus no agglutination with the HCG-coated latex particles occurs. If no agglutination occurs, the subject is pregnant.

Notes and References

1. Book: MCH Research Series . 1974 . Health Services Administration, Bureau of Community Health Services. . 8–9 . en.
2. Book: Khurana . Indu . Concise Textbook of Human Physiology - E-Book . Khurana . Ayushi . 2022-07-06 . Elsevier Health Sciences . 978-81-312-6474-4 . 422 . en.