American Board of Internal Medicine (ABIM) Certification Practice Exam

What is the primary screening test for achalasia?

1. CT scan

2. Barium esophagogram

3. Magnetic resonance imaging

4. Endoscopic ultrasound

The correct answer is: Barium esophagogram

The primary screening test for achalasia is a barium esophagogram. This test involves the patient swallowing a barium solution, which then outlines the esophagus on X-ray images. It is particularly effective for detecting the characteristic signs of achalasia, such as esophageal dilation and the "bird-beak" appearance at the esophagogastric junction. These features result from the inability of the lower esophageal sphincter to relax properly, which is a hallmark of the disease. While other imaging techniques like CT scans, magnetic resonance imaging, and endoscopic ultrasound can provide useful information about the esophagus and adjacent structures, they are not typically used as first-line diagnostic tools for achalasia. CT scans may help assess mediastinal structures and complications but do not specifically highlight the functional issues associated with achalasia. Magnetic resonance imaging is generally not employed due to practical constraints and availability. Endoscopic ultrasound, although useful for evaluating submucosal lesions or local staging of cancers, is not the primary method for diagnosing achalasia. Therefore, a barium esophagogram remains the most effective initial approach for establishing the diagnosis of achalasia.