Perhaps from Dutch schreef line from Middle Dutch scrÄve from scriven to write from Latin scrÄ«bere ; see skrÄ«bh- in Indo-European roots.
Gastroenterologist or Hepatologist. A doctor who specializes on the liver is a hepatologist. Not to be confused with a herpatologist, who studies snakes. The answer depends on the type of problem. In our area, gastroenterologists treat most liver problems, but sometimes the treatment of hepatitis is done primarily by infectious disease specialists.
The liver would be handled by a gastroenterologist (who does the complete digestive system, as well). The kidneys a nephrologist. However, after looking at a response below, I do see that a hepatolgist does specialize in the liver after looking it up.