The evaluation of mastitis begins with a history and physical exam.

Physical findings in a woman with mastitis include:

• Nipple drainage:
• Pus draining from the nipple
• Skin redness over the breast
• Breast swelling
• Breast tenderness
• Swollen glands under the arm

Tests that may be used to evaluate mastitis include:

• Complete blood count
• Bacterial culture:
• Identifies the type of bacteria causing the infection
• Breast ultrasound