Hi coloured discharge is a sign of onfection. Sometimes certain strain of organisms like b strepto coccus can cause preterm labour in ypur case being 17 weeks tecniquely we will say you can abort. As a gynaec i will send for cervical swab culture urine culture and possilbly glucose challangetest if family history of diabetes. If result comes positive you will be given course of broad spectrum antibiotoc. Ultrasound scan will be performed to rule out any funelling and to confirm cervical os is closef and cervical length is ok.hope my answer cleared your douby.