How is an underdeveloped or absent thumb diagnosed?
Thumb hypoplasia and aplasia are usually detected during your baby’s first newborn exam.
Seeing this deformity will prompt your child's doctor to look for other deformities that are sometimes associated with this condition.
An x-ray can help doctors examine the internal structures of your child’s thumb.
Other tests will depend on whether the doctor believes the thumb deformity is associated with another condition.