What is acute mastitis? Authoritative experts explain to you

The so-called acute mastitis is an acute suppurative infection that occurs on the basis of ordinary infection. The symptoms of this infection are more serious and pose a greater threat to women's health, so it needs timely treatment and cannot be delayed any longer.

1. What is acute mastitis?

Acute mastitis is an acute suppurative infection of the breast, an inflammation of the connective tissue in and around the mammary ducts. It often occurs in postpartum and lactating women, especially primiparas. Literature reports that 50% of acute mastitis occurs in primiparas, and the ratio of primiparas to multiparas is 2.4:1. It can occur at any time during lactation, but is most common 3 to 4 weeks after delivery, so it is also called puerperal mastitis.

2. Causes of Acute Mastitis

1. Cracked nipples

It is usually caused by incorrect breastfeeding posture, the baby not sucking the nipple and most of the areola in the mouth, and breastfeeding on one side for too long.

2. Blocked milk ducts

It is common in secondary milk stasis, and its main causes are incomplete breast suction, irregular and frequent breastfeeding and local pressure on the breast. Milk stasis is also common in people with hypoplastic nipples (such as inverted nipples), which affects breastfeeding. In addition, the breast milk of primiparas contains more exfoliated epithelial cells, which are more likely to cause blockage of the mammary ducts and aggravate milk congestion.

3. Bacterial invasion

The main pathogen of acute mastitis is Staphylococcus aureus, and Streptococcus is less common.

(1) Bacteria can directly invade through the milk ducts, which are prone to infection due to milk congestion and retention. Because retained milk is easy to decompose, the decomposition products are acidic, which not only irritates the mammary ducts but also serves as a good culture medium for bacterial reproduction.

(2) Bacteria can enter the nipple through small wounds or cracks, and invade the breast interstitium through the lymphatic vessels to form cellulitis.

(3) Pathogens that infect other parts of the mother's body during the postpartum period can circulate through the blood and cause breast infection.

(4) Another route of infection is that pathogens in the infant's body (such as oral and nasopharyngeal infections) directly invade the mammary lobules along the mammary ducts during breastfeeding, grow and multiply in the stagnant milk, and cause breast infection.

4. Milk stasis

(1) First-time mothers have no experience in breastfeeding and produce a lot of milk. Babies are often unable to suck out all the milk, causing excess milk to accumulate in the glandular lobules, which is conducive to the growth and reproduction of bacteria. The breast milk of primiparas contains relatively more exfoliated epithelial cells, which can easily cause blockage of the mammary ducts and aggravate milk congestion. The accumulation of milk promotes acute inflammation.

(2) If a primipara does not clean her nipples regularly during pregnancy, the epithelium will become fragile. If the baby sucks for too long, the nipple epidermis will become softened and prone to cracking. When cracking occurs, the baby's sucking will cause severe pain to the mother, affecting adequate breastfeeding. The breasts will not be easily emptied and milk will easily accumulate. In addition, if the nipples are underdeveloped, short, flat, small, or inverted, milk is more likely to accumulate.

3. Clinical manifestations of acute mastitis

1. Stasis mastitis

It occurs in the early postpartum period (usually about 1 week after delivery). Because first-time mothers lack experience in breastfeeding, it is easy for milk to accumulate and not be emptied on time. The patient felt varying degrees of pain and swelling in both breasts and had a moderate fever (around 38.5°C). Examination of the breasts reveals fullness, redness (congestion) on the surface, and tenderness, but the symptoms usually disappear after the milk is expressed. However, if not treated in time, or if the nipple is small and is broken by the newborn's sucking, the retained milk may be contaminated by purulent bacteria. Therefore, excess milk must be drained and nipples must be kept clean.

2. Suppurative mastitis

It is usually caused by infection of staphylococci or streptococci through a ruptured nipple. As mentioned earlier, postpartum milk accumulation can easily lead to infection if it is not emptied in time. After bacteria invade the mammary ducts, they continue to invade the parenchyma, which can cause various types of suppurative mastitis.

(1) Inflammation spreads to the superficial lymphatic vessels, leading to erysipelas-like lymphangitis. The patient develops a sudden high fever, often accompanied by chills, breast tenderness, and red spots or lines on the local skin, which are characteristic of this type.

(2) The inflammation is confined to the connective tissue of the areola, forming a subareolar abscess.

(3) The infection spreads along the lymphatic vessels into the breast stroma, from the surface to the base, across the breast tissue. Interstitial abscess is formed due to suppuration of connective tissue. This type of abscess may be confined to a single breast lobule or may spread to the majority of the breast.

(4) The infection spreads rapidly, reaching deep into the loose connective tissue behind the breast between the base of the breast and the pectoralis major muscle, forming a retromammary abscess.

The area where inflammation or abscess is located will show redness, swelling and tenderness. The abscess area may feel fluctuating when pressed. If necessary, a test puncture can be performed to extract pus for bacteriological examination and a drug sensitivity test for reference in selecting antibiotics.