When performing a double-contrast cystogram, which substances are injected into the bladder?

In a double-contrast cystogram, the use of both air and a soluble positive-contrast medium plays a crucial role in enhancing the visualization of the bladder's interior during imaging. The positive-contrast agent, typically a radiopaque solution such as iodinated contrast, provides clear outlines of the bladder walls and potential abnormalities by absorbing X-rays and appearing white on the radiograph. This visibility is vital for locating issues such as tumors, stones, or other anomalies.

The introduction of air as the negative-contrast agent serves to create a distinct contrast with the positive agent. When air is introduced, it does not absorb X-rays, which allows the air-filled areas to appear darker on imaging. This combination of media helps delineate the bladder's morphology, enhancing the likelihood of identifying small lesions and providing a more comprehensive assessment of bladder conditions.

This technique is valuable in urology and diagnostic imaging, as it maximizes the clarity and detail of the images captured, leading to better diagnosis and treatment planning. The other options do not encompass the necessary combination of both types of contrast media to achieve the intended diagnostic efficacy of a double-contrast cystogram.