Table 1.
Early visible intrauterine landmarks according to last menstrual dating
| Menstrual age (wks) | Gestational sac diameter (cm) | Yolk sac | Embryo and heart motion | Crown rump length |
|---|---|---|---|---|
| 5 | 1 | − | − | − |
| 6 | 1.5 | + | + | ± |
| 7 | 2 | + | + | + |
| 8 | 3 | + | + | + |
| 9–11 | 4–5 | + | + | + |
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