pregnancy test

• the first step in a positive pregnancy test is a sample containing HCG molecules

  
• the second step is that HCG attaches to the granule antibody complexes

  
• the third step is the first band of immobilised HCG antibodies trap the coloured granules that are bonded to the mobile HCG antibodies. there is always a Control Strip where any un-bonded mobile antibodies bind to show the test was successful.

  
• a negative pregnancy test will only show the Control Strip because there are no HCG molecules available for the mobile antibodies.