There is often a great deal of debate in the breastfeeding community and among breastfeeding mothers as to whether it is safe to purchase a used breast pump or receive one from another mother. Double electric breast pumps are quite expensive, usually between $250 and $500, and so it is quite tempting. The Medela Pump-in-Style is a popular pump that indicates it is single-user designed.
The common assumption about single-user pumps is that they are designed this way as a scam for pump companies to be able to sell a new pump to each mother. Despite warnings, mothers commonly share these pumps with woman friends and family members. For pumps that designate themselves as designed for single-use, as a Lacation Educator, I simply CAN NOT recommend using a pump previously used by another woman.
While it is incredibly rare, it is possible to contract a serious pathogen, such as AIDS or hepatitis from such a pump. I will say that if you DO, despite warnings, buy or obtain a previously used pump, be sure to do so from a friend or family member only that you know personally and are quite confident (as much as you can be) of their health history -- never purchase a pump from a stranger on eBay, Craigslist or other similar used source.
However, it is important to know that health concerns are not the only limitation of single-user pumps. The reason they cost in the $300-$500 range, as opposed to hospital grade pumps which range from $500 up to $1000s of dollars is because they aren't built to last as long at top performance. Each time a pump pumps, that is a cycle. Single-user pumps perform optimally for only a limited number of cycles and then performance will decrease over time. This is probably ok for a mother who can afford to have reduced performance once the milk supply and pumping skill and habits are established, and as baby's milk needs drop with the introduction of foods or reductions in the number of feedings per day.
But if a new mom receives a used pump and uses it to help establish or increase milk supply, or to establish a pumping routine when first returning to work if the baby's milk volume needs are high, she could be doing herself a big disservice. For milk supply issues, I generally ALWAYS recommend renting a hospital grade pump. And if pumping substantially, be sure to understand the possible relative performance of a used pump. Note that this can also affect a mother pumping for subsequent children with an old pump, although it helps to have experience with good pumping habits as well as the increased prolactin receptors already available to establish good supply with each child.
Before considering purchasing or accepting a used pump, be sure to understand the health concerns as well as the performance concerns involved in this decision. In that decision, do consider that in the end, the cost of a new pump is negligible compared to the cost of formula as well as the "payback" in potential health impacts on your child from providing breast milk. Finally, if you do decide to pursue a used pump, consider looking for a pump that is designed for multi-users, such as the Hygeia Enjoye or Endeare (if purchasing new, you may also want to consider an EnJoye as an alternative to the single-user Pump-in-Style, especially for less-frequent use which theoretically leaves more cycles for another mother).