“Fat globules” or “chunks” in milk are actually just coagulated milk comprised of normal milk contents — proteins, cholesterol/lipids, and general ductal debris (dead cells), usually in the setting of hyperlactation (oversupply) and exclusive pumping.
Fat globules generally will persist until someone stops exclusive pumping. The key is to understand these aren’t dangerous and the breastmilk simply needs to be swirled to make it more liquid again.
We had a recent case like this in our NICU of an EP mom. We sent the more solid components to our breast pathologists. Under the microscope, it just looked like what we would expect of colostrum — lots of protein (all the pink color) and not much else. No bacteria, no biofilm, nothing else strange:
Colostrum under the microscope, comprised mainly of protein (pink background).
Coagulated colostrum.
Coagulated colostrum.