New Zealand Obstetric Ultrasound Guidelines 2019

Levels peak at 8-11 weeks. 5. After this, levels begin to fall and level at 100-130 days, (3-4 months) ... While a positive assay for serum BHCG can confirm a pregnancy as early as 8-10 days after fertilization, a uterine gestational sac cannot be reliably identified on ultrasound until 28 days (about 4 weeks… ................
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