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 treated for infertility presents with 6-week amenorrhea with urinary retention. The most likely etiology is: 
Select and explain. 
A. Retroverted uterus, B. Pelvic hematocoele, C. Impacted Cervical Fibroid, D. Carcinoma Cervix
C: Impacted Cervical Fibroid
Answer: C: Impacted Cervical Fibroid 
Explanation: The patient in the question:

Was being treated for infertility.
Now H/O 6 weeks of amenorrhea.
Presents with urinary retention.
The first diagnosis which comes in our mind is the retroverted gravid uterus.
Points which favour the diagnosis are: The woman is pregnant and has complained of urinary retention.
But friends, here it is important to understand that retroverted gravid uterus causes urinary retention at 14-15 weeks of gestation (not 6 weeks).                                                                                                                                                  

So Option "a" is ruled out
Option "b" Pelvic hematocele

"Pelvic hematocele is formed in a patient complaining of 6 weeks amenorrhea in case of ectopic pregnancy." Though pelvic hematocele causes urine retention but then other symptoms (pain) and signs of ectopic pregnancy should be present.

Option "c" Impacted cervical fibroid

"A cervical fibroid impacted in the pouch of Douglas can cause retention of urine. The onset of retention is acute and usually occurs immediately before menstruation when the uterus is further enlarged by congestion or during early pregnancy."
The fibroid is associated with infertility.
Thus, an impacted cervical fibroid can explain all features seen this woman and is our option of choice.