Learning About Breast Cancer
In Australia the surgeries occur at the same time - we get the radiotracer injection the day before or the morning of our surgery, for small tumours a guide wire is inserted under local anaesthetic to identify the tumour location accurately for the surgeon, a low compression mammogram image is taken also to assist with surgical tumour location, then once we are in the surgical theatre and have been given the general anaesthetic, a wand is waived over our armpit to detect the hottest radioactive node, it is then removed, often felt by hand for rice like graininess [a sign of cancer cells] and sent off to pathology for testing while the lumpectomy is being done. The results for the sentinel node are phoned back to the theatre - if the sentinel node is clear of cancer, normally no more nodes are taken and we are stitched up. If the sentinel node has cancer cells, then they normally remove nodes till they get to the point where they appear cancer free. It is like working your way through a bunch of grapes.
The in-surgery sentinel node pathology testing I referred to has a false negative rate of 5-10% ie., the node reads as clear but later and more thorough pathology testing may detect cancer cells. The in-surgery node testing is done by slicing the nodes into fine slices, and examining them but it is always possible for cancer cells to hide inside slices, or outside the slices being examined and also for the technician to make a human error and not see cancer cells. So that is one reason I can think of why someone could be called back for more extensive node removal. The remaining nodes sample are usually sent off with the excised tumour for deeper pathology testing. That can throw up more issues.
It is not clear from your question if you have the sentinel node testing done at the time of your lumpectomy or not.
There may well be other legitimate reasons for returning for a separate operation to remove your lymph nodes , but the first thing I would do is ask the surgeon to tell you why it all was not done in the one procedure, with the one general anaesthetic for you to recover from and one off work/recuperation period?
You deserve very clear statements in that explanation.
I sincerely hope it has nothing to do with the surgeon maximising their income by performing two separate operations, requiring two lots of general anesthesia on you, longer recovery period, more stress, more time off work etc.
Then you can make up your mind if the answers you received are convincing, reasonable and stack up to professional practice or not.