Koskivaara won her first World Cup medal in 1989 with the relay. In Sweden, the Finns Marja-Liisa Portin , Ulla Mänttäri , Annika Viilo and Koskivaara took third place behind Sweden and Czechoslovakia. In 1993, Koskivaara won the complete set of medals at the Nordic Championships in Sipoo , Finland . On the short distance she came third behind her compatriot Kirsi Tiira and the Norwegian Ragnhild Bente Andersen , and on the long distance she was second behind Andersen. In the season with Marja-Liisa Portin, Marja Pyymäki and Kirsi Tiira, she won the gold medal. At the World Championships in 1993 in the United States, she was third on the short distance behind the Swedes Anna Bogren and Marita Skogum . On the long distance she was fourth in Skogum's victory. She also won the silver medal with the Finnish women's relay. In 1995 in Detmold , at the same time as the Briton Yvette Hague , she was second in the long distance World Championship behind Katalin Oláh from Hungary. The Finnish season won the world title with Kirsi Tiira, Reeta-Mari Kolkkala , Koskivaara and Annika Viilo.
Koskivaara ran for the clubs Mynämäen Suunnistajat 52 , Vakka-Rasti , Pargas IF and Turun Suunnistajat . In 1999 she won the Tiomila with Pargas .