画像検査 III: コンピュータ断層撮影（CT検査）

A CT scan of the genitourinary tract uses X-rays and computer processing to generate detailed cross-sectional images of the kidneys, ureters, bladder, and adrenal glands. This noninvasive imaging technique reveals the urinary system's anatomy and can detect abnormalities such as kidney stones, tumors, cysts, infections, and injuries to these structures.

Renal function assessment is critical because contrast dye is eliminated through the kidneys. Patients with impaired renal function require closer monitoring after the procedure, as contrast agents can potentially worsen kidney function. This evaluation ensures patient safety and guides decisions about contrast administration and post-procedure hydration protocols.

During image acquisition, the patient lies supine on the CT table and holds their breath briefly to prevent motion artifacts. The scanner rotates around the patient, capturing several cross-sectional images of the genitourinary tract within seconds or minutes. The patient is monitored throughout using a camera and intercom system to ensure safety and compliance.

IV contrast dye is injected through an IV line to enhance visualization of blood vessels and soft tissues within the urinary system. Patients may experience a warm sensation or metallic taste during injection. The contrast improves image clarity for detecting pathology, though its use depends on the specific clinical scenario and patient factors such as renal function and allergies.

Essential preparations include reviewing medical history for iodine or contrast allergies, assessing renal function, confirming NPO status for 4 hours, obtaining written informed consent, and instructing the patient to remove metallic objects like jewelry and dental prosthetics. These steps ensure safety, prevent image distortion, and reduce aspiration risk during the procedure.

After contrast administration, monitor the patient for 15-30 minutes for delayed reactions such as rash, nausea, or difficulty breathing. Encourage fluid intake to help flush the contrast medium through the urinary system. Document the procedure details including contrast type and volume, observed reactions, and discharge instructions regarding result timing and follow-up appointments.

CT imaging diagnoses kidney stones, tumors, cysts, and congenital anomalies in the kidneys, ureters, and bladder. It also evaluates trauma to urinary structures, stages and monitors cancers like renal cell carcinoma and bladder cancer, and identifies complicated urinary tract infections including pyelonephritis and abscesses.