Hepatitis C is passed through blood to blood contact. It is not found in other body fluids such as semen. The most common way it is passed in BC is through sharing needles, or a needle stick injury.
Oral sex is a negligible risk, which means there is a potential for getting Hepatitis C if there was blood present, but the chances of getting Hepatitis C in this way are very low.
If you did not see any blood then there should be little chance that you put yourself at risk with oral sex.
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