How does pregnancy affect nephrolithiasis?
Nephrolithiasis is the most common nonobstetric cause of abdominal pain during pregnancy.
Pregnancy is characterized by factors that promote (increased urinary calcium and uric acid, decreased peristalsis of the ureter, and dilatation of the collecting system) and prevent (increased urinary magnesium, citrate, and acid glycoproteins) stone formation.
Stones may be difficult to diagnose because hydronephrosis is normal in pregnancy, and use of computed tomography (CT) scans is generally contraindicated in pregnancy. Additionally, on kidneys, ureters, bladder (KUB) x-rays, radiopaque stones may be obscured by the fetal skeleton, especially in the third trimester when stones are most common.
Indications for intervention include intractable pain, infection, complete obstruction, or obstruction of a solitary kidney. Treatments include extraction of the stone by a skilled urologist or placement of percutaneous nephrostomy tubes. Pregnancy is considered a contraindication to lithotripsy.
