The testis if undescended... descends in first 3 mths after birth.. if it hasn't descended till 3 mths n baby is not premature , such babies usually need surgery which should ideally be done by 6months age.
You will get differing opinions about the age at which surgery is to be done from different doctors.
Ideal age to operate a undescended testis is at 6mths...
Please consult a pediatric surgeon/ ped.urologist who routinely do such operations, and I m one of them.
Next Steps
consult pediatric surgeon