unreliable measure
unreliable results
unreported association
unreported complication

unresectable disease
unresectable HCC
unresectable hepatocellular carcinoma
unresectable squamous cell carcinoma
unresolved

unresolved issue
unresolved issues
unresolved loss
unresolved problem
unresolved questions

unresponsive
unrestrained rats
unrestricted Hartree
unripe fruits
unsafe sex