Precautions a medical assistant should take to protect against contamination during urinalysis?

You'll find most of this information under "Universal Precautions".

Assuming the patient can void on his/or her own into a cup (such as at a doctor's office), the precautions would be minimal but nonetheless important. Put on gloves. Wrap a paper towel around the outside of the filled cup (almost all patients "miss" sometimes). Run the test; discard the urine per your facility's policies. Remind yourself to NOT touch other items or your face, even while wearing gloves.

When you have finished your work, remove your gloves from the top of one; pull the second glove into the first glove (inside out) and dispose of them per your facility's policies. Immediately wash your hands with soap and hot running water (remember to sing Happy Birthday to wash long enough). Don't substitute a hand sanitizer for actually washing your hands.

Most medical employees make one big mistake when handling bodily fluids. They do the right thing by wearing gloves but--- then they forget the rules, and touch their faces, rub their mouths, rub their eyes. Remember: As long as your gloves are ON, both hands are "dirty". Conversely, if doing a sterile dressing for example, during the treatment both gloved hands are "sterile" and after the treatment is done both gloved-hands are "dirty".

The second big mistake made is thinking "I wore gloves so I don't have to wash my hands, or I can wash them later." Wrong. Gloves only give partial protection. Handwashing is absolutely necessary to help prevent the spread of disease.