This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Gynaecology & Obstetrics
What is the clinical diagnosis when a pregnant woman presents with bloody vaginal discharge through a closed cervical os during the first 20 weeks? 
Select and explain. 
A. Threatened aboion, B. Complete aboion, C. Incomplete aboion, D. Preterm labor
A: Threatened aboion
Answer: A: Threatened aboion 
Explanation: The clinical diagnosis of threatened aboion is presumed when bloody vaginal discharge or bleeding appears through a closed cervical os during the first 20 weeks (Ref: William's Obstetrics; 25th edition)