This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Gynaecology & Obstetrics
A 35-year-old woman presents with infertility and palpable pelvic mass. Her CA-125 level is 90 rnIU/mL diagnosis is: 
Select and explain. 
A. Ovarian Ca, B. Endometrioma, C. Tuberculosis, D. Borderline ovarian tumor
B: Endometrioma
Answer: B: Endometrioma 
Explanation: In this question we have insufficient information to make any definite diagnosis. At the best we can try to make the most probable diagnosis.
CA-125
• This is a non-specific tumor marker
• CA-125 is a glycoprotein which is normally not produced by ovarian epithelium but may be produced by both
malignant and benign epithelial ovarian tumors.
• Cut off level of CA-125 is < 35 U/mL.
• Levels of CA 125 can be raised in