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 woman presents with amenorrhea of 6 weeks duration and lump in the right iliac fossa. Investigation of choice is : 
Select and explain. 
A. USG abdomen, B. Laparoscopy, C. CT scan, D. Shielded X-ray
A: USG abdomen
Answer: A: USG abdomen 
Explanation: Ans. is a i.e. USG abdomen The answer quite obvious and l do not think you need any reference for this one. X-ray and CT Scan should be avoided during pregnancy due to risk of radiation exposure.