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

OBJECTIVE: 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. MATERIAL AND
METHOD: 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.
RESULTS: 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.
CONCLUSION: 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.