American Board of Internal Medicine (ABIM) Certification Practice Exam

What is the preferred diagnostic imaging modality for pregnant patients suspected of having nephrolithiasis?

1. X-ray

2. CT scan

3. Ultrasonography

4. MRI

The correct answer is: Ultrasonography

Ultrasonography is the preferred diagnostic imaging modality for pregnant patients suspected of having nephrolithiasis due to its safety profile. During pregnancy, the need to minimize radiation exposure to both the mother and fetus is paramount. While other imaging techniques such as X-rays and CT scans can provide detailed views of kidney stones, they involve ionizing radiation, which poses potential risks during pregnancy. Ultrasonography is a non-invasive, radiation-free technique that allows healthcare providers to visualize the kidneys, ureters, and bladder effectively. It can detect the presence of stones and assess complications such as hydronephrosis without exposing the developing fetus to harmful radiation. Additionally, ultrasonography is readily available in most clinical settings and can be repeated for monitoring if necessary. MRI, while safe in terms of radiation, is generally not the first-line imaging modality for nephrolithiasis due to limited availability and longer acquisition times. It is more useful for evaluating soft tissue concerns rather than for assessing kidney stones. Given these considerations, ultrasonography stands out as the most appropriate and safest choice for diagnosing nephrolithiasis in pregnant patients.