containing or consisting of both blood and serous fluid .eg: tuberculous or malingnant ulcers.
Sero-sanguine refers to having a temperament that is a combination of serene or calm (sero) and lively or passionate (sanguine). It suggests a balance between being composed and spirited in one's behavior and emotions.
Serous fluid is a clear straw like "plasma" fluid whereas sanguine refers to blood. So this describes a clear plasma like fluid that has some streaks of blood in it.