Anal Fissure?

+ASH+

My daughter has had a little bit of blood in her diapers (not every diaper - but those that do have it are little specks or one small spot). I've already taken her to the doctor (she was a preemie, so I don't take this lightly). Her doctor was not overly concerned, but she did want to discover the cause so she ordered lab work on the stool. We're waiting on the results, which take a few days. 

My question - are anal fissures possible even if all of her bowel movements are liquid? I know they are common with hard stools (my younger son had that problem as a baby) but DD is breastfed and all of her BMs are liquid. However, she does struggle and strain with some and when she has them, they are usually very forceful (when I'm holding her and she finally works them out, I can feel a punch). Because of this, I'm wondering if fissures are possible. Anyone else experience this?