Why is "The Leech" an appropriate and significant name for this chapter?

Chapter 9 is called "The Leech" for two reasons. First, it references medical history, that leeches were used medicinally. Secondly, it is a name that is symbolic of Chillingworth, both because he is a doctor who might use leeches, and because the relationship Hawthorne creates between Dimmesdale and Chillingworth is akin to a leech sucking blood from an animal in the way Chillingworth latches onto the minister.