The primary focus of this study was on the potential of CO2 angiography to reduce the risk of repeat bleeds in patients with diverticular bleeding. The rebleeding rate tended to be lower in the CO2 angiography group than in the ICM angiography group. Furthermore, CO2 angiography demonstrated an ability to detect bleeding sources that were not evident on ICM angiography, indicating its usefulness in the diagnosis and treatment of diverticular bleeding. This finding suggests that CO2 angiography can facilitate more accurate identification of bleeding sources and enable TAE, potentially reducing the risk of rebleeding. To the best of our knowledge, this study provides the first detailed analysis of clinical outcomes using CO2 angiography, and its results are expected to contribute to improved diagnostic and treatment approaches in clinical practice.
In this study, the rate of detection of active bleeding was 47.6% using CO2 angiography and 33.3% using ICM angiography after embolization procedures. Although our detection rate using CO2 angiography is lower than the 57% reported previously [11], we found that CO2 angiography could reveal bleeding sources that were not identified by ICM angiography. The difference in detection rates between the studies may reflect variations in patient populations and sample sizes. The detection rate was within the range reported for provocative angiography using urokinase or heparin (30–50%) [12, 17, 18]. Provocative angiography may also promote bleeding at puncture sites and other bleeding not related to lower gastrointestinal hemorrhage [12, 19]. Complications from CO2 angiography in the lower gastrointestinal tract were minor and transient, confirming the safety of this procedure. These findings indicate that CO2 angiography is useful for diagnosis of active bleeding in cases of diverticular hemorrhage. CO2 angiography may also be a safe alternative for patients with renal dysfunction or allergies to ICM, so has the potential for broader application in diagnosing and treating lower gastrointestinal bleeding.
Our rebleeding rate in the CO2 angiography group was 6.9%, which is significantly lower than the previously reported rebleeding rates of 17–28% after TAE and the rate of 53% when embolization could not be performed owing to an inability to confirm active bleeding [10]. This could be attributed to the vasodilatory effect and low viscosity of CO2. Typically, vasoconstriction and thrombus formation play a role in hemostasis during bleeding [20]; however, owing to its properties, CO2 is thought to dilate these constricted vessels and leak from thin vessel branches and thrombi, potentially promoting bleeding. By inducing bleeding, embolization can be performed, potentially reducing the risk of rebleeding. Although there have been concerns about an increase in adverse events after embolization, the frequency of major ischemic complications in this study was not significantly different from that previously reported [6, 8, 9]. These results indicate that CO2 angiography could be an effective option for management of the risk of rebleeding and have significant implications for treatment strategies in patients with diverticular bleeding.
This study had several limitations. First, it had a retrospective design, which means that the possibility of bias cannot be excluded. Second, the small sample size may limit the generalizability of the results and the statistical power of the analysis. Third, the lack of consistency in choice of embolic material and variations in the application of CO2 angiography by different operators could have affected treatment outcomes. Moreover, as noted in previous research [21], lower gastrointestinal bleeding is intermittent, which means that the timing of examination could have significantly affected the rate of detection by CO2 angiography. Therefore, it is not possible to completely exclude the impact of timing on the detection rate. A randomized controlled study is necessary to address this problem.