Blocked Milk Duct

A blocked milk duct is a plugged duct that blocks flow of milk, causing a tender wedge-shaped lump in the breast, usually in one breast. It results from milk stasis, thick milk, pressure from clothing, poor emptying or a milk bleb at the nipple opening. It is common in breastfeeding women, and matters because untreated blockage leads to mastitis and abscess.

• Risk factors: missed feeds, oversupply, tight bras, sleeping position, weaning, nipple milk blister, previous blocked duct or mastitis, poor latch.
• Often follows a missed feed or a long gap overnight.
• Most clear within 24 to 48 hours.

Women have a small tender hard lump or wedge-shaped area in the breast, sometimes with redness and warmth, that is relieved by feeding. A white spot may be seen at the nipple opening. Fever is absent or mild.

• Lump 1 to 3 cm, mobile, smooth and tender.
• Pain eases after a feed and returns as the breast refills.
• Differential diagnosis: milk stasis, mastitis, galactocele, breast abscess, fibroadenoma, lactating adenoma, lipoma, inflammatory breast cancer, periductal mastitis.
• Complications: mastitis, breast abscess, recurrent blockages, galactocele, early weaning.

The diagnosis is clinical, with ultrasound for lumps that persist.

• Palpation of the lump, warmth and redness; inspection of the nipple for a white blister; observation of a feed.
• Temperature, pulse; examine the axilla for nodes.
• Breast ultrasound if no improvement after 5 days, fluctuance, or a firm mass beyond 2 weeks.
• Biopsy if the mass persists after resolution of lactation or has suspicious features.

The principle is to clear the blockage with frequent feeding, gentle massage and heat, and to treat infection if it develops.

• Supportive: feed or express every 2 to 3 hours with the chin directed toward the lump; warm compress or warm shower for 5 minutes before feeding; gentle massage from behind the lump toward the nipple during the feed; vary feeding positions; cold compress after feeds; wear a loose bra; rest and fluids.
• Pharmacological: paracetamol 1 g oral 6-hourly (maximum 4 g in 24 hours); ibuprofen 400 mg oral 8-hourly with food for 3 to 5 days; sunflower lecithin 1200 mg oral 3 to 4 times daily for recurrent blockage; if mastitis develops (fever, red wedge, flu-like illness): flucloxacillin 500 mg oral 6-hourly for 10 days, or cefalexin 500 mg oral 6-hourly for 10 days; penicillin allergy: clindamycin 300 mg oral 6-hourly for 10 days.
• Procedures: unroofing of a nipple blister with a sterile needle after warm soaking; ultrasound guided aspiration of a galactocele or abscess.
• Special groups: women with diabetes who have mastitis are treated with a full 10 to 14 day course and followed closely; breastfeeding continues from the affected breast, as these antibiotics are compatible with it.
• Red flags: fever above 38.5 degrees Celsius, spreading red area, fluctuant swelling, pus, severe pain, hard lump persisting beyond 2 weeks, skin changes or nipple retraction.
• Follow-up: review in 48 hours; ultrasound at 5 days if no improvement; breast examination at 6 weeks or 6 weeks after weaning; imaging for persistent lump.