What exactly is acute mastitis?

There are many diseases related to the breast, one of which is called acute mastitis. There are many causes of this disease, such as bacterial infection, which is more common. In addition, nipple fissures and milk stasis are also factors that cause the disease.

1. Bacterial invasion

The pathogenic bacteria of this disease are mostly Staphylococcus aureus, and a few are Streptococci. Bacteria enter through the cracks in the nipple skin or the chapped areola, spread along the lymphatic vessels to the fat and fibrous tissue between the mammary lobules and the glandular lobules, causing acute suppurative cellulitis of the breast. There are also a few cases where postpartum infection complications occur in other parts of the body, and the bacteria spread to the breast through the blood circulation, causing the disease.

2. Milk stasis

Breast milk facilitates the growth of invading bacteria. The causes of milk stasis include: ① The nipples are too small or inverted and are not corrected in time before birth, making it difficult for the baby to suck milk or even unable to breastfeed. ② Excessive milk and incomplete emptying. The mother does not understand the secretion of milk, and the excess milk cannot be discharged in time and is retained in the breast. ③ Blockage of the milk ducts makes it difficult to discharge milk. Inflammation, tumors and external compression of the milk ducts themselves can all affect normal breastfeeding.

3. Cracked nipples

After delivery, if the mother fails to master the correct breastfeeding technique, or the baby's sucking is abnormal, or if irritants such as soap or ethanol desiccant are used excessively on the nipples, or if the baby's oral motor function is disordered, nipple fissures may occur, allowing bacteria to invade through the small cracks in the nipple and reach the subcutaneous and interlobular tissues through the lymphatic vessels to cause infection. When the nipples are cracked, breastfeeding is painful and the milk cannot be fully sucked out, causing milk stasis and creating conditions for the reproduction of invading bacteria.

4. Pathogenesis

Milk stasis and bacterial invasion are two important factors of acute mastitis. It has been reported in the literature that about 40% of normal breast milk contains Staphylococcus aureus and Staphylococcus albicans, but they do not cause disease. The susceptibility of primiparas to acute mastitis is related to the fact that their milk contains a large number of desquamated epithelial cells and tissue debris, which cause blockage of the milk ducts. Blocking the milk ducts can reduce the vitality of breast tissue. In addition, the decomposition products of milk stasis make it more conducive to the growth and reproduction of bacteria, making it a good culture medium for bacteria. There are also reports that the incidence of breast cancer can be 1 times lower if the milk is completely sucked out with a breast pump after breastfeeding than if the milk is not completely sucked out after breastfeeding.

The course of acute mastitis generally goes through three stages: milk duct inflammation, mastitis and mastitis. Bacteria invade the milk ducts, ascend to the glandular lobules, stay in the stagnant milk, grow and multiply, causing acute inflammation of the milk ducts. It then spreads to the breast parenchyma, causing parenchymal mastitis. Bacteria can also travel from the damaged epithelium of nipple fissures along the lymphatic vessels into the mammary interstitium, causing interstitial mastitis. If not treated promptly or improperly at this stage, the inflammation will spread to the fat and fibrous tissue outside the breast parenchyma, leading to acute mastitis. The inflammation is localized, tissues are necrotic and liquefied, and infection foci of varying sizes fuse together to form a breast abscess. If the abscess penetrates into the loose connective tissue of the retromammary space, a retromammary abscess is formed.