There are some specific changes that occur during pregnancy that affect the urinary tract. The Ureters which are dilated and called hydronephrotic, increase in size approx. 1 cm due to increased renal vascular and interstial volume during pregnancy. The collecting system and ureters during this time also decrease there ability to peristals(contract), resulting in dilation. The change usually occur in the second trimester and subsides after delivery. Your right, there often is not a true obstruction but rather an external obstruction, the size of the uterus and its position can cause this dilation. Often position changes will help the uterus fall away from the ureters and decrease your pain and pressure.
If you continue to have pain, or ever get an infection, this could be potentially dangerous to your child. This could lead to a premature delivery. A stent is a reasonable option. Discuss the options with your doctor, I think he or she knows what is right.
This information is provided for general medical educational purposes only. Please consult your physician for diagnostic and treatment options pertaining to your specific medical condition. More individualized care is available at the Henry Ford Hospital and its satellites (1 800 653-6568).