Seeing pink, red, brown, or rust-colored streaks in breast milk can cause immediate alarm for a parent. This discoloration is due to the presence of blood, which may appear as streaks, clots, or a general tinting of the milk. The causes for blood in breast milk are usually benign, temporary, and not harmful to the baby. Understanding these reasons provides clarity and helps determine the appropriate course of action.
Mechanical and Vascular Causes
Nipple trauma is a common source of blood in breast milk, often resulting from a poor latch or excessive friction from an incorrectly sized breast pump flange. Cracks or abrasions on the nipple skin can bleed directly into the milk flow, typically presenting as bright red streaks or clots.
Small blood vessels, or capillaries, within the breast tissue can rupture. This often occurs due to forceful breast massage, rough handling, or using a breast pump with a vacuum setting that is too high. This micro-trauma releases small amounts of blood into the milk ducts.
“Rusty Pipe Syndrome” occurs in the early postpartum period, usually within the first week after birth. This results from the rapid increase in blood flow and vascular engorgement as the breasts transition to mature milk. The increased pressure causes blood to seep into the ducts, resulting in milk that appears dark brown, orange, or rust-colored. This condition is self-limiting and typically resolves within a few days to a week.
Causes Related to Infection and Inflammation
Mastitis is an infection causing inflammation, swelling, and pain, often accompanied by systemic symptoms like fever and body aches. The inflammation increases pressure on the tissues and capillaries, leading to blood leaking into the milk.
If left untreated, mastitis can progress to a breast abscess, a localized collection of pus. In these cases, the blood is usually accompanied by other signs of infection, distinguishing it from mechanical causes.
An intraductal papilloma is a small, non-cancerous growth inside a milk duct. These benign tumors are the most frequent cause of bloody nipple discharge unrelated to injury or the early postpartum period. The bleeding is often spontaneous and usually affects only a single milk duct in one breast.
Safety of Feeding When Blood is Present
In most cases, the blood is maternal in origin and poses no threat to the infant’s health, as the small amount ingested is digested like any other swallowed substance. It is safe and recommended to continue breastfeeding or feeding the expressed milk, as this maintains the milk supply and helps clear the ducts.
The iron content in the milk may irritate the baby’s stomach, causing increased spitting up or vomiting. Babies may also pass darker or black-flecked stools, which is digested blood and not usually a cause for concern.
Rare exceptions exist where feeding the milk must be paused. This applies if the mother has a blood-borne infection, such as HIV or Hepatitis C, where blood in the milk could increase the risk of transmission. In these situations, medical guidance must be followed closely.
Diagnosis and Management
If blood in the milk persists beyond a few days, professional evaluation is warranted. A healthcare provider will begin with a physical examination to look for signs of nipple trauma, engorgement, or a palpable mass. Note any other symptoms, such as fever, warmth, or pain, which might indicate an infection like mastitis.
If the bleeding is persistent, spontaneous, or localized to a single duct, diagnostic testing is necessary. An ultrasound is a common tool used to visualize the breast tissue and milk ducts, helping to identify underlying masses, such as an intraductal papilloma or an abscess. Though extremely rare, conditions like breast cancer can cause bloody discharge, emphasizing the need for professional diagnosis when bleeding is unilateral or ongoing.
For management, treating the underlying cause is the primary strategy. If nipple trauma is the source, working with a lactation consultant to improve the latch or adjusting pump settings can promote healing. If an infection is suspected, a medical provider may prescribe antibiotics.