Background: First-trimester bleeding is one of the most common obstetric complications, occurring in 25% of all pregnancies. The clinical diagnosis of threatened miscarriage is presumed when bloody vaginal discharge or bleeding appears through a closed cervical os during the first half of pregnancy. Objective: The aim of the present study was to investigate the relationship between sonographic findings, progesterone level and serum CA-125 in women presenting with symptoms of threatened abortion and first trimesteric pregnancy outcome. Subjects and Methods: This a case-control study included a total of 120 pregnant women between 7- and 13- weeks' gestation in which a singleton embryo with evident cardiac activity was initially documented completed the study, attending at Gynecological and Obstetric Department in Zagazig University Hospital and Mit Ghamr General Hospital. This study was conducted between July 2016 to February 2018. Results: There was no significant difference among groups in CRL and GSD but YSD was significantly higher among cases. CA 125 was significantly higher in actual miscarriage with a level 47.9IU/ml (±31.52) between those who had actual miscarriage before 13 weeks and 17.4IU/ml (±10.67)between those who continued pregnancy after 13 weeks while progesterone showed level 11.1ng/ml (±10.38)between those who aborted before 13 weeks and a level of 11.6ng/ml (±6.19) between those who continued. GSD and YSD significantly higher in actual miscarriage as the mean was 51.4mm (±18.56) and 6.73mm (±0.6) respectively for those who aborted and 38.52mm and 6.11mm respectively for those who continued pregnancy. Conclusion: The use of ultrasound and maternal serum CA-125in the first trimester represents non-invasive, early and fast methods that can be considered as a good predictor for the outcome of pregnancy in cases with threatened abortion.