Understanding Blood in Urine During Pregnancy: Causes & What to Expect

Question
I am 16 weeks pregnant and the last 2 times I have seen my OB they have found blood in my urine so this last time I went in they cultured it but there is no protein or bacteria present.  My bladder feels tender.  They said they are just going to watch it since I have no other symptoms.  Could you please tell me some of the most common causes for this problem? Thank you in advance for you answer.

Answer
With blood in your urine, you may be beginning a urinary tract infection (bladder infection). A culture will, indeed, rule out a bladder infection if there is less than 100,000 colonies of any bacteria. A culture takes 48 hours to be processed. If there were no bacteria in your urine, and the culture was negative, I would not worry and I agree that it should only be watched, since you have no further symptoms. Don't worry.