Amniotic Vesicle.

Amniotic Vesicle.
The amniotic vesicle can first be palpated at 35 days when it is 7.5 mm in diameter; at 42 days the diameter is 15 mm, at 48 days 35 mm, at 52 days 55 mm, at 58 days 75 mm, at 62 days 90 mm, and at 65 days 105 mm. Initially the vesicle is turgid. After 60 days the vesicle becomes more flaccid which allows direct palpation of the small fetus.

Drost M (1982)