Which imaging modality is preferred for suspected nephrolithiasis in pregnancy?

Which imaging modality is preferred for suspected nephrolithiasis in pregnancy?

• A. Low-dose noncontrast computed tomography
• B. Ultrasonography of the kidneys and bladder
• C. Magnetic resonance imaging without contrast
• D. Plain abdominal radiography

Answer: (B)

In pregnancy, the imaging choice for suspected nephrolithiasis is ultrasound of the kidneys and bladder because it provides useful information about obstruction without exposing the fetus to radiation. Ultrasound can reveal hydronephrosis or other signs of urinary tract obstruction that point toward a stone, and it’s safe, widely available, and can be done quickly at the bedside. If ultrasound doesn’t clearly explain the symptoms and suspicion remains high, MRI without contrast is a safe next step, since it avoids radiation and can evaluate alternatives or complications, though it isn’t as sensitive for detecting stones themselves. Low-dose noncontrast CT would give the most definitive stone visualization but involves ionizing radiation, which we try to avoid during pregnancy. Plain abdominal radiography also exposes the fetus to radiation and misses many stones (especially radiolucent ones), making it less useful as a first-line test in this setting.

In pregnancy, the imaging choice for suspected nephrolithiasis is ultrasound of the kidneys and bladder because it provides useful information about obstruction without exposing the fetus to radiation. Ultrasound can reveal hydronephrosis or other signs of urinary tract obstruction that point toward a stone, and it’s safe, widely available, and can be done quickly at the bedside. If ultrasound doesn’t clearly explain the symptoms and suspicion remains high, MRI without contrast is a safe next step, since it avoids radiation and can evaluate alternatives or complications, though it isn’t as sensitive for detecting stones themselves. Low-dose noncontrast CT would give the most definitive stone visualization but involves ionizing radiation, which we try to avoid during pregnancy. Plain abdominal radiography also exposes the fetus to radiation and misses many stones (especially radiolucent ones), making it less useful as a first-line test in this setting.