Assertion: fistula's tract | /r/HasProperty | difficult to demonstrate
Facets:
value: often
type: TEMPORAL
Source sentences:
text: Colovesical fistulas and its cause can be characterized in a number of ways, although the fistulous tract itself is often difficult to demonstrate.
text: Colovesical fistulas and its cause can be characterized in a number of ways, although the fistulous tract itself is often difficult to demonstrate.