Breast exams are more accurate during breastfeeding. For women who are breastfeeding, localized lumps can form due to incorrect breastfeeding positions or damage to the nipple area, as well as bacterial invasion. This is when diseases such as acute mastitis and breast hyperplasia can occur and can be detected by ultrasound or breast ultrasound. Although there are changes in the breast during breastfeeding, the instrumental examination is still accurate and does not affect the final result. When breast examination is performed during breastfeeding, low and medium echogenic inflammatory masses or other lesions can be detected. Mastitis or nipple inflammation is most common during breastfeeding and does not affect the test. If breast disease is detected, stop breastfeeding to avoid affecting the baby. If there is any abnormality in the breast during breastfeeding, you must go to the hospital for examination and treatment in time to avoid delaying the condition.