12.
Beta-HCG in early pregnancy.
| a. | output doubles every 1.5 - 3 days in early pregnancy | |
| b. | tests may detect LH due to the shared alpha chain | |
| c. | levels which rise less than 50% in 48 hours at 6 weeks may indicate ectopic pregnancy | |
| d. | levels > 8,000 i.u./l with no scan evidence of an intrauterine pregnancy strongly suggest ectopic pregnancy | |
| e. | levels < 1,000 i.u./l. at 8 weeks suggest ectopic pregnancy or pregnancy failure | |
| f. | production peaks at 20 weeks | |
| g. | levels are below normal in hydatidiform mole | |
| h. | levels are increased in multiple pregnancy | |
| i. | modern pregnancy tests will always detect a healthy pregnancy by the day the next period is due | |
| j. | modern pregnancy tests may become negative after 20 weeks |