Should I Take Primolut Depot Injections For Spotting During Pregnancy?

hi, In my urine test report urine routine microscopic ,it was found crystals -amorphous phosphates. I was in the ninth week 5 days that time , I told my doctor that i have found light pink/brown colour spotting . So She advised me to take Primolut depot -hydrxyprogesterone caproate 500 mg injection (2ML, Ampoule) once in three weeks .then she would take a radiology scan. I want to know do i have to take thses injections and are these safe during pregnancy . Also what does crystals -amorphous phosphates in the report mean. is there any risk for me or baby .Kindly advise.