4 weeks PO my breast has had discharge. Should I be worried?

Although your question isn’t
totally clear, I’m assuming that you’re referring to post-operative nipple
discharge.It’s important to realize
that breast surgery can occasionally stimulate lactation.This is usually a self-limited process that resolves with
the passage of time.Nevertheless, it
should be evaluated and monitored by your surgeon.It’s important to rule out other causes of nipple
discharge and to make sure that secondary complications such as infection don’t
develop.When these steps are taken,
most patients have a relatively uneventful recovery.

Anytime that you have leaking from your incision, especially for an extended period of time, then you need to be evaluated by your surgeon.  You need to go soon rather than later if you have any pus or fever or chills.  

Did you have implants as well?
Is this discharge from the nipple or incision?
Does it a have an odor?
Is it white (pus-like), bloody, clear, or oily?
Is the skin black?
Do you have a fever or are the wound edges red?
All of these may be indicative of the underlying problem and may represent different causes.
Generally lactation occurs from the nipple with a clearing whitish drainage with minimal odor and frequently ocurs with placement of implants.
Please consult with your physician to evaluate other possible causes.

I fully agree with the other opinions given. You need to see your docor immediately for this. Your prognosis does also depend somewhat on the character of the drainage (e.g is it clear? red? foul-smelling? purulent?) Also - is the outer skin red at all? Signs such as these may indicate an infection or the presence of tissue that is not healthy inside of your breast (fat necrosis). Most likely, however, you have a fluid collection (seroma) which should be drained and followed closely afterwards. If your doctor is unwilling to see you or deal with this problem, then find another board certified plastic surgeon in your area who should be readily qualified to handle the situation appropriately and, just as important, provide the proper follow-up.

There are several questions that will help clarify this matter.
Is the discharge from the nipple or from the incisions?
Is there redness?
What does the discharge look like?
Are you having fevers or chills?
There are many possibilities.
The discharge could be a draining liquifying hematoma or serous collection. This may or may not require treatment (drainage typically).
The discharge could represent an infection - however it would be atypical for an infection to be brewing for three weeks without larger systemic issues.
The discharge could also represent liquefying fat.
As always, these concerns should be addressed with your treating physician. I hope this helps.
Steven Williams, MD