Transplacental needle passage and other risk-factors associated with second trimester amniocentesis

To assess the obstetric outcome of all pregnancies undergoing midtrimester amniocentesis over a 10 year period at one center and the risk-factors for pregnancy loss associated to the procedure.

All 2083 pregnancies with known pregnancy outcome and second trimester amniocentesis were included. Risk-factors for pregnancy loss were analysed by using patients' charts and a special record from the amniocentesis.

The over-all risk of pregnancy loss after second trimester amniocentesis was 1.3% (28/2083). There was a slight but nonsignificant relationship between the degree of experience of the gynecologist and risk for pregnancy loss. A more experienced operator used significantly fewer needle insertions (p<0.001). Multiple needle insertions were also associated with a slight, albeit nonsignificant, increase in incidence in fetal loss (3.8% after three or more insertions vs. 1.2% after one insertion, NS). No difference in spontaneous abortion incidence was found in patients having an anterior versus a posterior placenta, nor did transplacental needle passage increase the risk for pregnancy loss. Comparison between use of real-time ultrasonic guidance at the amniocentesis and static ultrasonography immediately prior to the procedure did not reveal any differences in the incidence in spontaneous abortion.

Second trimester amniocentesis seems to be a safe method for prenatal diagnosis. The risk for pregnancy loss was low (1.3%) and was only slightly and nonsignificantly affected by the operator's experience and multiple needle insertions. Transplacental needle passage did not affect the risk of pregnancy loss.