Answer to Pterodactyls

Question: Where in the pelvis do kidney stones become trapped?

Correct answer is D, the juncture of the ureter and the bladder. While stones are known to be trapped at three locations, including where the renal pelvis joins the ureter and the ureter crosses the pelvic brim, the stem of the question asked the location of entrapment in the pelvis. Hence, these marked sites are not correct answers to the question.  The location indicated by label 2 is the boundary of the abdomen-pelvis. Kidney stones could get trapped here, but after the ureter crosses this point it is generally not an area where stones become trapped until it enters the bladder.

1.= Renal pelvis-ureter junction

2.= Ureter in abdomen

3.= Ureter in abdomen

4.= Ureter entering bladder

5.= Bladder

Answer to this question is based on material presented in lectures 3 of the Pelvis Lecture Series.