Caution Regarding Short-Term Increases in Ammonia Levels Following Splenic Artery Embolization.

Aim: The effects of partial splenic embolization (PSE) on hepatic encephalopathy, a portal hypertension-related disease, are not well established. This study aimed to investigate changes in ammonia levels by PSE and to identify determinants of postprocedural changes in patients with or without portosystemic shunts (PSSs).

Methods: The present retrospective study included 136 patients with hypersplenism who underwent PSE at our hospital. The patients were divided into the PSS (-) group, comprising 90 patients without PSSs with a diameter of ≥ 8 mm, and the PSS (+) group, comprising 46 patients with PSSs with a diameter of ≥ 8 mm. Ammonia levels were evaluated, and biochemical and imaging findings were assessed before and at 1 month after PSE.

Results: Overall, PSE significantly increased ammonia levels despite postprocedural hepatic function amelioration and hepatic venous pressure gradient reduction. Increased ammonia levels were observed postoperatively in 73.3% and 63.0% of patients in the PSS (-) and PSS (+) groups, respectively. The procedure induced a significant increase in ammonia levels in the PSS (-) group; in contrast, the increase was not statistically significant in the PSS (+) group. Preprocedural Child-Pugh scores of < 8 and splenic non-infarction volume of ≥ 120.32 cm³ in the PSS (-) group, as well as preprocedural splenic artery diameter-to-common hepatic artery diameter ratios of < 1.4 and concomitant splenic vein-derived shunt vessels in the PSS (+) group, were significant and independent determinants of postprocedural ammonia-level increase.

Conclusions: PSE generally poses a high risk of short-term increase in ammonia levels, particularly in patients without PSSs.