Construction of a family pedigree in genetic counseling before amniocentesis.

The construction of a family pedigree consumes an average of 15-20 minutes during a typical preamniocentesis counseling session. The records of 1,131 patients were reviewed to determine whether development of a pedigree before amniocentesis reveals conditions other than those for which the patient was referred often enough to justify the time spent in the process. The patients were referred for a variety of reasons, with increased maternal age the most common. A positive finding in the pedigree was any condition other than that for which the patient was referred and that required additional comments or testing. It was found that 72.15% of the pedigrees contained at least one other positive finding. Thus, construction of a pedigree before genetic amniocentesis is a valuable objective since it reveals, in the majority of cases, additional factors that may influence the current or future pregnancies or may provide information for other family members.