Final answer:
The incorrect belief that a full bladder is required for an amniocentesis indicates that the pregnant client needs further instructions regarding the procedure, which actually involves withdrawing a small amount of amniotic fluid to test for genetic abnormalities.
Step-by-step explanation:
The client who is pregnant needs further instruction about an amniocentesis procedure if she believes that 'I'll need to have a full bladder before the amniocentesis'. This statement suggests a lack of understanding of the pre-procedural requirements for an amniocentesis. Typically, a full bladder is not necessary for an amniocentesis and in fact, may need to be emptied before the procedure. The correct knowledge is that amniocentesis involves the withdrawal of a small amount of amniotic fluid for testing, which can detect genetic abnormalities in the fetus. This procedure can be instrumental in diagnosing various genetic conditions and chromosomal disorders.