26 years old G1, P0 comes to the OG department with complains of moderate amount of vaginal bleed which she noticed while she was bathing. On examinations, there are no uterine contractions or pain or abdominal cramps. Blood pressure-120/76 mmHg, Pulse rate- 84/min, temperature- 37.6 C, Respiratory rate-16/ min. On speculum examination, small clot was noted at the level of vault. There was no bleeding or abnormal mass. Cervix was closed. Bimanual examination is uneventful. Diagnosis is