A breast flange, also called a breast shield, is the funnel-shaped component of a breast pump that fits over the nipple and areola. Its function is to create an airtight seal and draw the nipple into the tunnel to efficiently extract milk. Most pump kits come with a standard size, typically around 24 millimeters, but flanges are available in a wide variety of sizes. A proper fit is necessary for effective milk expression. The question of using a single flange on both breasts, either simultaneously or sequentially without cleaning, is common, balancing convenience versus hygiene concerns.
Understanding the Breast Flange
The breast flange interacts directly with the body’s milk-producing system. Flange size is determined by the diameter of the nipple at its base, which can change throughout the pumping journey. Using a flange that is too large can pull too much areola tissue into the tunnel, causing swelling and discomfort. A flange that is too small can cause painful rubbing and friction, and both incorrect sizes can reduce milk removal or lead to tissue damage.
Proper sizing is important because some people require different-sized flanges for each breast, as nipples can vary in diameter. The correct fit ensures the nipple moves gently and freely within the flange tunnel without touching the sides, maximizing comfort and milk output. Since the flange interfaces with the skin and milk ducts, it collects skin cells, milk residue, and natural microbial flora. This contact with biological material makes interchangeability a matter of hygiene and safety.
The Hygiene Factor: Cross-Contamination Risks
While it is technically possible to switch a single flange between breasts during a pumping session, this practice is strongly discouraged without thorough cleaning. The primary concern is the risk of cross-contamination, which involves transferring microorganisms from one breast to the other. Breast milk and breast skin contain bacteria, and the balance of bacteria may differ between the two sides.
Transferring a used flange can introduce potentially harmful bacteria, such as Staphylococcus species, or yeast, such as Candida albicans (thrush). This microbial transfer increases the risk of developing a breast infection, such as mastitis, which involves inflammation of the breast tissue. Mastitis can be caused by bacteria entering the breast through a cracked nipple or an incompletely drained milk duct. Introducing pathogens via a contaminated flange contributes to this risk.
Even if a person is single-pumping and switching sides, the milk residue left inside the flange and collection kit acts as a growth medium for any present microorganisms. This residue, if transferred, can potentially seed an infection in the other breast.
Practical Pumping and Cleaning Guidelines
The safest practice, whether dual-pumping or single-pumping, is to use separate, clean flanges and collection kits for each breast. This method eliminates the risk of transferring bacteria or yeast. For those single-pumping and moving the device between breasts, the flange and all parts that contact milk should ideally be washed immediately between uses, but this is often impractical.
If cleaning the entire kit between sides is not possible, a person should at least wipe the inside of the flange tunnel and the surrounding area thoroughly with a clean wipe or cloth. This is a compromise and not a substitute for proper washing and sanitizing, which should occur after every pumping session. After each use, all disassembled parts that contact milk must be washed with warm, soapy water and rinsed under running water.
For extra protection, pump parts should be sanitized at least once daily, especially for infants under three months old or those with compromised immune systems. Sanitizing methods include boiling the parts in water for five minutes or using a steam sterilizer, following manufacturer’s directions.
Pump parts should always be allowed to air-dry completely on a clean towel or drying rack before being stored. This prevents the growth of mold or bacteria.