The presence of esophageal varices (clinically significant portal hypertension) is another risk factor needed to take into account when predicting surgical risks in patients with advanced liver disease or liver cirrhosis.
A 52-year old male with compensated advanced liver disease due to primary sclerosing cholangitis, is in need of partial nephrectomy because of renal cell carcinoma.

According to the Baveno VII criteria, what should be your first step to get more information about the presence or absence of portal hypertension?