Detection of low levels of HCG by simple immunoassays, and clinical implications.

Traditional, less sensitive simple immunoassays ('Placentex' and 'Pregnosis') were performed concurrently with newer, more sensitive, but simple immunoassays ('Sensitex' and a capillary tube pregnancy test) and radioimmunoassays for beta-HCG from two commercial sources (Roche Diagnostics and Monitor Science Corporation). Generally these various assays agreed, but of particular importance for the early screening of urinary HCG (prior to the first missed but expected period) was that the commercial half-unit tube test ('Sensi-tex') gave early positive results comparable to the half-unit research capillary tube test previously reported. These sensitive simple immunoassays (SSIA) may improve the management of patients very early in pregnancy and following termination of pregnancy.