How long does it normally take for a karyotype result to come back?

Karyotype. That can vary from lab to lab. Have the doctor check the lab and see if they can give you an estimate. I find the ones that I order can take 2-3 weeks.
Routine 2 weeks. A new rapid fish technique can provide selected chromosome study (karyotype) results) in 24 hours if a specific disorder (e.g., down, turner, trisomy 18 syndrome) is suspected. Routine karyotyping takes a minimum of 7 days (cells must be stimulated and arrested in metaphase) with 2-4 weeks average for reports (due to laboratory processing, etc.).