How Do Professionals Test For Cri Du Chat? Doctors usually test for cri-du-chat by hearing the infant's cat-like cry. Other ways are microcephaly, poor muscle tone, and mental disabilities. It is also possible to test for cri-du-chat before the baby is born. Testing can be done either on a tiny sample of tissue from outside the sac where the baby develops or on a sample of the amniotic fluid that surrounds the baby.