American Board of Internal Medicine (ABIM) Certification Practice Exam

In the staging of rectal cancer, what additional evaluations are required?

1. Pelvic ultrasound and chest X-ray

2. Endorectal ultrasonography or pelvic MRI

3. Fecal occult blood testing and colonoscopy

4. CT of the abdomen only

The correct answer is: Endorectal ultrasonography or pelvic MRI

In the staging of rectal cancer, the use of endorectal ultrasonography or pelvic MRI is crucial as these modalities provide detailed imaging of the rectal wall and surrounding structures. Endorectal ultrasonography allows for the assessment of the depth of tumor invasion and the presence of any regional lymphadenopathy, which are key factors in determining the stage of the cancer. Similarly, pelvic MRI provides high-resolution images that can identify the extent of the disease, particularly in relation to adjacent organs and structures, which is vital for planning treatment. Both of these imaging techniques help in accurately determining the T (tumor) and N (lymph node) classifications in the AJCC staging system, influencing the management and treatment options for the patient. While other methods of evaluation may be useful in different contexts, they do not offer the same level of specific information required for appropriate staging of rectal cancer.