Urinary tract stones in pregnancy

The presence of stones during an otherwise uneventful pregnancy is a dramatic and potentially serious issue for the mother, the fetus, and the treating physicians alike. The incidence and predisposing factors are generally the same as in nonpregnant, sexually active, childbearing women. Unique metabolic effects in pregnancy such as hyperuricuria and hypercalciuria, changes in inhibitors of lithiasis formation, stasis, relative dehydration, and the presence of infection all have an impact on stone formation. The anatomic changes and physiologic hydronephrosis of pregnancy make the diagnosis and treatment more challenging. Presenting signs and symptoms include colic, flank pain, hematuria, urinary tract infection, irritative voiding, fever, premature onset or cessation of labor, and pre-eclampsia. The initial evaluation and treatment are again similar to those used for the nonpregnant population. The most appropriate first-line test is renal ultrasonography, which may, by itself, allow the diagnosis to be made and provide enough information for treatment. Radiographic studies, including an appropriately performed excretory urogram, give specific information as to size and location of the stones, location of the kidneys, and differential renal function and can be used safely, but the ionizing radiation risks should be considered. All forms of treatment with the exception of extracorporeal shock wave lithotripsy and some medical procedures are appropriate in the pregnant patient. Close coordination by the urologist, the obstetrician, the pediatrician, the anesthesiologist, and the radiologist is required for the appropriate care of these patients.