The main cause of low urine output in ascites is decreased systemic perfusion flow.
The main causes of ascites formation are limited lymphatic reflux, portal hypertension, and other factors affecting blood reflux resulting in decreased systemic perfusion due to leakage of fluid from the arteries and veins to the abdominal cavity, which in turn affects the decreased renal perfusion, leading to decreased urine formation.
In addition, following a decrease in systemic perfusion, in order to protect perfusion to vital organs, the glomerular entry arteries constrict, further leading to a decrease in renal perfusion and a corresponding decrease in urine output. Moreover, after the decrease in perfusion, the hypothalamus also secretes antidiuretic hormone, and the reabsorption of water increases, leading to a decrease in final urine.
After the above factors, ascites can lead to a decrease in urine output. You can go to the hospital to consult your doctor for details.