Modified stylet technique for tenting of amniotic membranes.

A modified amniocentesis technique can reduce the failure rate in cases of tenting of the membranes. Failure to aspirate amniotic fluid (AF) because of amniotic membrane tenting may persist after advancement and rotation of the needle. In such cases, the membranes may be pierced by using a stylet that is longer than the length of the needle. With the needle in the middle of a suitable AF pocket, the stylet of the needle is replaced with a longer stylet. Under real-time ultrasonographic guidance, the tip of the stylet is then rapidly advanced 5-10 mm beyond the tip of the needle. During genetic amniocentesis, we have used the longer stylet technique to pierce tented membranes without complications in 21 of 22 cases.