How long does sperm live in the uterus and fallopian tubes?
Sperm normally remains active for up to 72 hours after ejaculation and can lead to conception any time within this period.
Amniocentesis: Guiding the needle
First, to help the doctor be absolutely precise when inserting the needle, an ultrasound scanner is used to establish the exact position of the fetus and the placenta. Second a fine needle is inserted into the womb and into a pool of amniotic fluid.