Transabdominal chorionic villus sampling (CVS) for prenatal diagnosis of genetic disorders.

OBJECTIVE To determine the safety and outcome of transabdominal Chorionic Villus Sampling (CVS) for prenatal diagnosis of genetic disorders. DESIGN Descriptive study. PLACE AND DURATION OF STUDY Department of Pathology, PNS Shifa, Karachi, from January 2003 to December 2004. PATIENTS AND METHODS A total of 143 couples with request for prenatal diagnosis of various genetic disorders were studied. Transabdominal CVS was done under local anesthesia and ultrasound guidance. A Co-axial Chorion Biopsy needle set with an outer guide and an inner aspiration needle was used. The needle was introduced into the placenta in its longitudinal direction. Once the needle was adequately placed, the chorionic villi were aspirated with a to and fro jiggling movement of the aspiration needle and a suction force was applied through a syringe. Results were recorded and analyzed for descriptive statistics. RESULTS A total of 144 CVSs were done in the outdoor on 143 couples including one with a twin pregnancy. The most common indication was b-thalassaemia (97%). Most procedures (76%) were done between 12 and 14 weeks (range 10-21 weeks). All placental positions including 52% anterior and 48% posterior were approachable through the trans-abdominal route. Most aspirations were easy, however, in 28% the aspiration was difficult due to a variety of factors. The overall success rate was 100%. In 85% of the cases sample yield was >25mg while in the remaining cases 10-25mg of sample was obtained that allowed a comfortable diagnosis. The procedure related abortion occurred in 1/144 (0.7%). CONCLUSION Transabdominal CVS is a useful outdoor procedure for prenatal diagnosis. Placentae in almost any position can be approached without significant risk to the mother and the fetus.