Frequency of Vascular Complications: What Is Actually Known

"How often does this happen?" is the most natural question a patient asks, and the most honest answer is an uncomfortable one: nobody knows precisely. Serious vascular events with fillers, such as occlusion, necrosis, and vision loss, are described as rare, but the word "rare" here comes from a collection of reports, not from a robust registry. Understanding why changes the way you talk to the patient and the way you prepare.

This text gives no numbers, because the available numbers do not support a safe conclusion. It explains why, which sources exist, which biases distort each one, and how the professional should use this uncertainty. For how to respond to an event, see visual complication after filler and skin necrosis: course and care.

Why is there no reliable number?

To estimate a frequency, you need two things: the numerator (how many events occurred) and the denominator (how many procedures were performed). In facial harmonization, both have problems.

These biases push estimates in different directions. That is why any isolated number, whether reassuring or alarmist, should be read with suspicion.

What sources exist?

Each source shows one slice, and none is a mirror of the whole.

1. Case reports and case series. They describe the clinical picture, the area, the product, and the course. Useful for recognizing patterns and for teaching. They cannot be used to estimate frequency.
2. Systematic reviews of reports. They aggregate published cases and identify the most-described areas and outcomes. They inherit the limitations of the reports.
3. Health agency databases. They gather voluntary adverse event reports. They are valuable, but depend on who reports; in Brazil, the topic relates to technovigilance and ANVISA (the Brazilian health regulatory agency). See also reporting an adverse event to Notivisa.
4. Registries from societies or manufacturers. They may hold valuable data, but are not always open and may reflect commercial interests.
5. Surveys of professionals. They ask whether the professional has ever had an event. They report the prevalence of experience, not risk per procedure, and depend on memory and participation.
6. Lawsuits and professional boards. They reveal serious cases that reach conflict, not the real distribution.

What does the literature describe most consistently?

Despite the uncertainty about the rate, some patterns appear repeatedly and guide prevention:

• Serious events concentrate in areas with anastomoses between vascular systems and small-caliber vessels linked to the ocular circulation, such as the glabella, nose, nasolabial fold, temples, and periorbital area. The reasoning is covered in vascular anastomoses of the face and vascular danger zones of the face.
• Reports of vision loss are generally associated with injections into territories that communicate with the ophthalmic artery. The pathways involve vessels such as the supratrochlear artery and the angular artery.
• The time to recognition and response is described as a relevant factor for the outcome, although no universal time limit can be set.
• Anatomical variations in course and caliber explain why even experienced professionals can have events. See vascular anatomical variations.
• It is not a problem of hyaluronic acid alone: events are described with other materials too, including biostimulators, as in vascular occlusion from a biostimulator.

What to do with this uncertainty day to day?

Uncertainty is not an excuse to downplay; it is a reason to prepare. Some practical decisions:

• Treat the frequency as unknown and the consequence as serious. The prevention decision should weigh severity, not only probability.
• Have the plan ready before the procedure: hyaluronidase available, a defined response, referral contacts, and team training. See complication SOP and office emergency kit.
• Know the anatomy of the area you work in, including its variations, and know when not to treat.
• Obtain real consent. The patient should know, without alarmism, that serious risks exist in sensitive vascular areas. See informed consent by procedure.
• Record and report. Every well-documented event contributes to collective knowledge; see recording the complication in the patient record.

How to talk about frequency with the patient?

The patient wants a number, and the professional does not have one. The solution is to give an honest answer in plain language, without promising total safety or frightening them unnecessarily.

Avoid "that never happens to me" and "it's very rare" with no context. The first is an impossible promise; the second, used as a shield, empties the consent of meaning.

What would change the picture?

A more reliable picture of frequency would require organized registries of procedures and events, with common definitions and easier reporting. Until that exists, the community depends on reports and local initiatives. Each professional contributes by recording well, reporting, and discussing cases responsibly, without exposing patients. Knowing the levels of evidence helps interpret what gets published.

And in Harmy?

Summary

There is no reliable number for the frequency of vascular complications with fillers. The sources are fragmented and biased, and the professional should treat the risk as real, serious, and underestimated. What is within your reach is to know the anatomy, be prepared, obtain honest consent, and report.