A 78-year-old man was diagnosed to have left emphysematous pyelonephritis with disseminated intravascular coagulopathy. Incisional drainage and a pigtail catheter placement were performed as the initial surgical treatment. Four days after the operation, contrast-enhanced computed tomography revealed a massive hematoma around the left kidney; therefore, urgent angiography was performed.

The trunk of the left renal artery was engaged with a 4 Fr Shepherd’s hook catheter. Digital subtraction angiography (DSA) with an iodinated contrast agent demonstrated good anatomical images of renal arteries, but did not reveal hemorrhage. In contrast, CO2-DSA with a wide imaging range demonstrated the bleeding site, but did not provide good anatomical images (Fig. 1a, b; Movie 1). The sequential use of both contrast agents, thus allowed to exploit the best of both methods: good anatomical images with the iodinated contrast agent and better localization of the bleeding with CO2-DSA.

Fig. 1
figure 1

Angiography images. a Angiography with an iodinated contrast agent shows no bleeding. b Angiography with CO2 clearly shows bleeding (arrow) near the location of the pigtail catheter (asterisk)

Full size image

In addition to the kidney-friendly nature, the interest in using CO2 angiography for the detection of minor hemorrhages is due to the low viscosity and high and rapid diffusion. Furthermore, the availability of the high-performance angiography system, which can reduce various artifacts, contributed to the good quality images of CO2-DSA.