This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Medical & Surgical Illness Complication Pregnancy, Subject name: Gynaecology & Obstetrics
A 25-year-old primigravida with 20 weeks of pregnancy has a first episode of a symptomatic bacteriuria. The risk of having pyelonephritis is: 
Select and explain. 
A. No risk with first episode, B. 5%, C. 15%, D. 25%
D: 25%
Answer: D: 25% 
Explanation: Ans. is d, i.e. 25%Ref. Dutta Obs. 7/e, p 299Twenty-five percent of these women are likely to develop acute pyelonephritis, usually in third trimester, if left untreated.