Blood Draws After Mastectomy: What New Research Shows

A reader recently asked me a question:

“Our Breast surgeons have been pushing back on the requirement for limb alerts for mastectomy and axillary breast surgery inpatients saying that lab draws can be performed on either arm. We have been seeing more mastectomy patients, and dealing with difficult draws. Have phlebotomy standards for this change been considered?”

When I got this question from a lovely woman who clearly cares about her patients, I didn’t think I would find much new info, but I thought I would give it a quick look to see if anything had changed in the last few years regarding mastectomies and blood draws. To my surprise, there is new research that contradicts what we have always been taught. The short answer is: the standard of care hasn’t changed, but the science behind it has gotten a lot more interesting. Here’s what you need to know.

What We’ve Always Been Taught — And Why

The concern about drawing blood from the ipsilateral arm (same side as the mastectomy) centers on the lymphatic system. When lymph nodes are removed during a mastectomy — especially during an axillary lymph node dissection — the body’s ability to drain fluid from that arm is compromised. The fear has always been that a venipuncture could trigger or worsen lymphedema, a chronic condition that involves swelling, pain, and recurring infections.

The theoretical reasoning made sense: a tourniquet restricts venous and lymphatic flow temporarily, a needle stick creates a small wound that needs to heal, and there’s always the potential for introducing bacteria. In an arm with compromised lymphatic drainage, the thinking was that these procedures could overwhelm the system and trigger lymphedema. Blood pressure cuffs were restricted for the same reason — repeated pressure and restriction on an arm that can’t drain fluid efficiently seemed risky.

But here’s the thing: that reasoning was based on logic and caution, not on documented cases of venipuncture or blood pressure cuffs actually causing lymphedema. The studies showing a direct link simply didn’t exist. CLSI’s own document acknowledges this, stating that “studies on the safety of venipunctures performed on the same side of the body as a mastectomy are scant and inconclusive.”

The precaution became standard practice anyway — which isn’t necessarily wrong. In the absence of data, erring on the side of patient safety makes sense. But it also means we’ve been following a restriction based on theoretical risk rather than proven harm.

The CLSI standard (PRE02, published in 2025) is clear: written physician permission is required before performing a venipuncture on the same side as a mastectomy. This applies regardless of how long ago the surgery occurred, and it applies to bilateral mastectomies too.

That standard hasn’t changed. But the science behind it? That’s been evolving.

What the Research Actually Shows

When I started looking into this, I found something surprising: the evidence that venipuncture on the ipsilateral arm actually causes lymphedema is weak — not because it’s been disproven, but because it was never proven in the first place.

The traditional guidance came from theoretical concern and clinical caution. It made logical sense to avoid unnecessary stress on an arm with compromised lymphatic drainage. But correlation doesn’t equal causation, and nobody had really studied whether venipuncture, tourniquets, or blood pressure cuffs were causing lymphedema in these patients.

Some recent studies finally examined the question directly.

The 2016 Memorial Sloan Kettering Study

This study (available through PubMed as PMC4872021) looked at over 600 breast cancer patients and examined whether ipsilateral blood draws, blood pressure measurements, injections, and even air travel were associated with lymphedema development. The findings: no significant association between ipsilateral blood draws and lymphedema. The researchers concluded that blanket restrictions on ipsilateral arm use may not be supported by evidence.

The Johns Hopkins Evidence-Based Practice Project (2024–2025)

This one got my attention. Published through the Oncology Nursing Society (ons.org and PMC12124877), this project actually changed protocol at Johns Hopkins. Nurses and phlebotomists drew from the ipsilateral arm in breast cancer patients with appropriate screening and tracked outcomes. The result? Zero lymphedema cases across over 100 patients. Based on these findings, Johns Hopkins implemented a system-wide policy change.

While I don’t have all the details regarding the policy change, it seems they don’t restrict most patients to the unaffected/less affected arm anymore. If anyone reading this has access to the full protocol or works at a facility that’s implemented similar changes, I’d love to hear the details in the comments.

The Asdourian Study on Bilateral Mastectomy Patients

One additional study worth mentioning looked specifically at bilateral mastectomy patients — a population that poses a particular challenge since there’s no unaffected arm available. Asdourian and colleagues examined 327 patients who had bilateral procedures and found that blood pressure monitoring, injections, and blood draws showed no increased risk of lymphedema even when both arms had been affected by surgery.

The Recall Bias Problem

Here’s something important to understand about how this restriction became so widespread: retrospective studies looking at lymphedema and needle sticks are sometimes confounded by recall bias. Patients who develop lymphedema are more likely to remember blood draws, injections, or other interventions on the affected arm and attribute the lymphedema to them — even when there’s no actual causal relationship. The largest early study found that of 188 women, only 18 remembered any type of skin puncture, and of those 18, eight developed lymphedema. But the problem is that patients who didn’t develop lymphedema were less likely to remember or report minor procedures, creating a false association.

This recall bias likely contributed to the restriction becoming standard practice. Patients developed lymphedema, looked for a cause, remembered a blood draw, and the connection seemed obvious — even though the prospective studies show no actual correlation. It seems lifestyle habits are a bigger possible contributing factor.

So Can We Change Our Practice?

Here’s where we need to be careful.

The research is promising. It suggests the risk of lymphedema from a venipuncture may be much lower than we thought — or possibly nonexistent. And here’s something particularly important: based on the evidence, drawing from the ipsilateral arm may actually be safer than resorting to alternative sites like the feet, which carry higher infection rates and are more difficult to access successfully. The traditional approach of making repeated attempts on the unaffected arm or moving to the feet may pose more risk to the patient than a single clean draw from the ipsilateral arm would.

But the CLSI standard hasn’t been updated. PRE02 came out in 2025 with the exact same wording on mastectomies as the previous version (GP41). And in phlebotomy, the CLSI standard is the recognized standard of care. It’s the benchmark your practice will be measured against if something goes wrong. Until CLSI revises PRE02, physician permission is still required.

That requirement exists for good reasons:

• You typically don’t know the extent of the patient’s lymph node removal
• You’re not in a position to assess individual risk factors for lymphedema
• The physician — especially the surgeon or oncologist — is the appropriate person to make that call

Following the standard isn’t just about protecting yourself. It’s about making sure the person with the most clinical knowledge about that specific patient is involved in the decision.

What this research might do is change the standard itself down the line. Some facilities are already piloting protocol changes based on these findings. But those are institutional decisions made with medical, surgical, and legal teams involved. They’re not individual decisions made at the bedside.

What Good Practice Looks Like Right Now

Until standards are updated, here’s how to handle this:

Follow the CLSI standard. Physician permission must be documented before drawing from the ipsilateral arm. If you can’t get permission and there are no other acceptable sites, escalate to your supervisor.

Know your facility’s protocol. Some facilities may have already implemented updated policies based on this research. If yours has, make sure you understand what documentation is required. It may also be worth checking into what caused the policy change? Is it evidence based using studies such as these? Or is it a manager who heard “We don’t need to be so strict about mastectomy draws” and changed the policy. All policy changes should have good reasons backed up on paper.

Apply the standard consistently. Unless your facility’s policy specifically says otherwise, the same standard applies to all mastectomy patients. And remember, that it is still preferred to stick on the less affected side.

Communicate with patients. Many breast cancer patients know about these discussions and may question the restrictions, especially if they’ve read the recent research. You can acknowledge the science is evolving while explaining you’re following your facility’s current protocol.

Looking Ahead

To the woman who emailed me with her questions about this subject - I appreciate your dedication to your job and your patients. It takes special people to critically think and push back on policies that might be problematic. Finding safe solutions that follow CLSI standards and facility policies are always worth the trouble, though it can be stressful to try to implement change.

The conversation around ipsilateral arm use is a good example of how evidence-based practice works. Standards aren’t static. They evolve as research accumulates. We’re finally getting actual data on a question that’s been answered with caution rather than clear evidence for decades.

I wouldn’t be surprised to see this change in the next version of PRE02 (Collection of Diagnostic Venous Blood Specimens). When CLSI does revisit it, the revision will likely be informed by research like what’s coming out of the studies mentioned above. Until then, follow your facility’s protocols and stay aware of CLSI updates. Professional practice requires consistency and institutional oversight when we deviate from established guidelines.

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