Final answer:
Repeating b-hCG testing is commonly done to assess fetal viability and to monitor ectopic pregnancies; it is not for diagnosing gestational diabetes.
Step-by-step explanation:
The question "Why would you repeat the b-hCG in this case?" pertains to the use of beta-human chorionic gonadotropin (b-hCG) levels in medical diagnosis. While b-hCG is known for confirming pregnancy, its serial measurement can provide much more information. Repeating b-hCG testing is most commonly done to assess the progress of the pregnancy, specifically to check for fetal viability and to monitor the progression or treatment of an ectopic pregnancy. Rising levels of b-hCG typically indicate a normal, healthy pregnancy, whereas decreasing levels could suggest a possible miscarriage or ectopic pregnancy. It is not used to diagnose gestational diabetes, which involves measuring blood glucose levels, not b-hCG.