Anaesthesia for a breast augmentation: what is used and how your safety is looked after in theatre

It is the part of surgery that frightens people most and the one aesthetic clinic websites say least about. It is usually dispatched with “general anaesthesia, the patient feels nothing” and that is the end of it.

This page explains what it is exactly, who must give it, what is monitored while you are asleep and —the most useful part— what questions are worth asking before you sign.

Which anaesthetic is used and why

General anaesthesia, in practically every case.

Why not local. A breast augmentation requires creating a pocket beneath the gland or beneath the pectoral muscle. When the implant goes under the muscle, the subpectoral dissection demands muscle relaxation, and that is not achieved with local anaesthesia. On top of that, the duration and the patient’s position make an operation while awake uncomfortable.

What it involves. Controlled loss of consciousness, absence of pain, muscle relaxation and control of the airway and of ventilation by the anaesthetist. It is given intravenously and maintained throughout the surgery, adjusted minute by minute.

🔑 That continuous adjustment is the key and it is what the word “sleeping” conceals. A dose is not given and then left: the response is watched and corrected.

🔑 The intercostal nerve block: what is added here before starting

This is the part of this page you will not find on almost any other, and it is a decision of the clinic’s anaesthetic team, not an industry standard.

What it is. Before the surgery starts —not on finishing it—, our anaesthetists always perform an anaesthetic block of the intercostal nerves with ropivacaine, a long-acting local anaesthetic. The intercostal nerves are the ones that carry sensation from the chest wall and the breast: if they are blocked, the pain signal from the area operated on arrives far more damped.

What it is for. To improve the pain of the first 12 hours after the operation, which are the worst. It does not replace the general anaesthetic —that is still needed for the muscle relaxation and for control of the airway— and nor does it remove the pain: it is added to the anaesthetic and to the painkiller regimen, and it makes those first hours easier to get through.

What the literature says, with its limits

It is a studied technique, and the evidence is worth reading with both what is solid in it and what is weak.

The solid part. A systematic review with meta-analysis of 10 randomised trials and 565 patients undergoing aesthetic breast surgery found that, compared with the control group, the nerve block was associated with:

	Outcome
Pain	Significantly lower score at 2, 3-4, 6-8, 12-16 and 24 hours
Opioids in the first 24 h	Significantly lower consumption
Time to the first painkiller	It lengthens (about 43 minutes on average)
Need for additional pain relief	Less frequent (odds ratio 0.14)
Nausea and vomiting	Less frequent (odds ratio 0.33)
Length of the operation	No difference — it does not lengthen theatre time

🔑 Look at the 12-16 hour band: it is exactly the window we are talking about, and it is also where many patients describe the worst moment.

And a study specifically on an intercostal block with 0.2% ropivacaine in breast augmentation —injected into the third to sixth intercostal spaces on both sides— measured pain scores on arrival in recovery of 3.5 out of 10 against 7.1 in the group without a block, and a faster discharge.

⚠️ What has to be said about the other side. The meta-analysis pools different kinds of block, not the intercostal one alone, and its statistical heterogeneity is high in several outcomes. And not every piece of work points the same way: there is a randomised placebo-controlled study in subpectoral augmentation that found no difference, although it was published as a conference communication and so carries less weight. And in the published studies the block is usually placed at the end of the surgery: that placing it before starting is better is reasonable, but it is not proven, and it is not claimed here to be.

Risks. Like any block, it has its own: puncture of neighbouring structures, toxicity of the local anaesthetic if it passes into the blood in quantity, and —in the chest wall— the remote possibility of a pneumothorax. It is uncommon, and it is the reason an anaesthetist does it and not just anyone. No complications were recorded in the breast augmentation series cited.

Who must give it

A doctor specialising in Anaesthetics and Intensive Care, devoted to that throughout the operation.

It is not an organisational detail: it is the difference between an operating theatre and a room. The surgeon is operating; somebody has to be watching your observations, your airway and your response to the drugs and nothing else.

⚠️ And it is one of the things you can check beforehand. What qualifications Spanish regulations require in order to perform aesthetic surgery, and what authorisation the centre must hold, is explained in the page on who is allowed to operate on you in aesthetic surgery in Spain.

The pre-anaesthetic assessment

It is a prior consultation, not a formality on the day of surgery, and it is what authorises the operation from the anaesthetic point of view.

🔑 Here it is carried out by the anaesthetist themselves, days before the surgery. Not on the day, not over the phone and not by the surgeon: the doctor who is going to put you to sleep sees you beforehand, with time to ask for whatever is missing if something does not add up. That is the difference between an assessment and a rubber stamp.

What is reviewed:

• Your medical record and your history.
• Allergies and previous reactions to anaesthetics, your own or in your family.
• All your medication, including contraceptives, supplements and herbal products.
• The preoperative tests, which here are preoperative blood tests and an electrocardiogram, plus whatever is called for by your age and your history.
• The airway, with a specific examination.
• The fasting that applies to you, which is not always the standard one.

🔑 That last point deserves attention. If you take a GLP-1 agonist —the drugs used for type 2 diabetes and for weight control—, your preparation may be different. In a study using gastric ultrasound, 56% of those taking them had increased residual gastric content despite having observed the fast, against 19% of those who did not. And stopping the drug was not associated with less gastric content: what changes what is done is saying so. It is set out in full in the page on the preoperative preparation.

What happens while you are asleep

You are monitored continuously. The standard in a general anaesthetic includes:

• Electrocardiogram, for the heart rhythm.
• Pulse oximetry, for oxygen saturation.
• Blood pressure.
• Capnography, which measures exhaled CO₂ and confirms that ventilation is correct.
• Temperature, because surgery cools you down.

The depth of anaesthesia, the muscle relaxation and the fluid therapy are controlled as well.

And there is an additional watch specific to this operation: control of bleeding. In the series that achieved the fastest published recovery, one of the factors identified was haemostasis with zero tolerance even of the smallest bleeding — which also depends on keeping blood pressure where it should be during the operation.

And if a complication arises

It is the question hardest to answer with anything other than a reassuring sentence, so here it is in concrete terms. The operating theatre holds all the medication and all the equipment needed to resuscitate and to control a patient’s observations: it is not equipment that has to be fetched, it is where it should be before the surgery begins.

🔑 And there is a decision before that one, which is the one that really matters: higher-risk cases are always operated on in hospital, where an intensive care unit is available. The question “what happens if something goes wrong?” is answered above all by choosing the place well, and that choice is made beforehand, at the pre-anaesthetic assessment.

Waking up and the hours that follow

Waking is gradual and happens in the operating theatre itself or in the recovery area, under observation until your observations and your level of consciousness are right.

From that moment until discharge you are monitored by nurses expert in post-operative care: the hospital team if you had your operation there, and specialist clinic staff if it was in its own theatre. And your surgeon comes to see you at intervals during that time, not just at the end.

What is usual:

• Drowsiness for a few hours.
• A dry or sore throat, if an airway device was used.
• Nausea or vomiting, which are the commonest side effect of a general anaesthetic and which are prevented and treated as a matter of routine.
• A feeling of cold or shivering, also common and passing.

⚠️ You cannot drive or take important decisions in the following 24 hours, and you need someone with you to get home.

Pain: what you can expect

A breast augmentation is not an operation with severe pain: what is usually described is pressure and tightness, with added muscular discomfort if the implant goes under the pectoral.

And how much it hurts varies from one patient to another, without that meaning anything different was done to one than to another: the plane the implant goes in, its volume and how each body reacts all play a part.

🔑 It is an argument for asking what pain relief regimen is followed —here it is three synergistic oral painkillers: two baseline ones alternated plus one for breakthrough pain— rather than for assuming it will hurt as much as it hurt someone you know.

And in the first few hours there is one more layer, which is the one nobody mentions: the intercostal block with ropivacaine placed before starting. Between the two, the first 12 hours are usually spent with discomfort rather than pain.

The risks of the anaesthetic

They exist and they have to be known, although in a healthy patient and in elective surgery of this length they are uncommon.

The usual, passing effects: nausea, vomiting, a sore throat, drowsiness, shivering.

The less common complications include reactions to the drugs, airway-related problems and, exceptionally, serious cardiovascular or respiratory complications.

⚠️ The complication most closely related to what you can control is aspiration of stomach contents, and that is why fasting and a complete declaration of your medication matter so much.

⚠️ The specific figures for anaesthetic risk depend on each patient’s state of health and on the type of surgery, and this page deliberately does not publish them: they are information for the pre-anaesthetic assessment and for the anaesthetic-specific consent form, which here is signed separately from the surgical one — two documents, two signatures, and it is not a duplicated formality: the anaesthetic has its own risks and its own information.

The five questions worth asking before you sign

They apply here and at any other centre:

1. Who is going to give the anaesthetic and what is their speciality?
2. Where does the operation take place and what does that theatre have available?
3. Is there a pre-anaesthetic assessment beforehand, and when?
4. What happens if a complication arises during the surgery? There should be a concrete answer, not a reassuring one.
5. What monitoring is there from the time I wake up until I go home?

🔑 And a clue for interpreting the answers: all five allow a concrete answer. If one of them is answered with a reassuring generality, that is the information.

Frequently asked questions

Can a breast augmentation be done under local anaesthesia?

In practice, no. Creating the pocket, especially beneath the pectoral muscle, requires muscle relaxation, and the duration and the position make an operation while awake unworkable. It is done under general anaesthesia.

Who is going to put me to sleep?

The anaesthetist: a doctor specialising in Anaesthetics and Intensive Care, devoted to that job throughout the operation. They are also the person who carries out your pre-anaesthetic assessment, days before the surgery.

Am I going to feel anything during the operation?

No. General anaesthesia means controlled loss of consciousness and absence of pain, and it is maintained and adjusted continuously throughout the surgery.

Am I going to feel sick when I wake up?

It is the commonest side effect of a general anaesthetic. It is prevented and treated as a matter of routine, and it usually settles in the first few hours.

I take a weight-loss drug. Do I have to tell the anaesthetist?

Yes, without exception. In a study using gastric ultrasound, 56% of those taking a GLP-1 agonist had increased gastric content despite having observed the fast, against 19% of those who did not. And stopping it on your own initiative was not associated with a lower prevalence: what makes it possible to adapt the preparation is saying so.

Is anything done to make the first few hours less painful?

Yes, and it is the most distinctive thing here: before the surgery starts the anaesthetist places a block of the intercostal nerves with ropivacaine, a local anaesthetic that helps control the pain of the first 12 hours. It is added to the general anaesthetic and to the painkillers, it does not replace them. In aesthetic breast surgery, nerve blocks are associated with less pain at 2, 6, 12 and 24 hours, fewer opioids and less nausea, without lengthening the operation.

How long does the anaesthetic take to wear off?

Waking is gradual and the drowsiness lasts a few hours. You cannot drive or take important decisions in the following 24 hours, and you need someone with you.

Does it hurt a lot afterwards?

What is usual is pressure and tightness rather than pain, and it varies from one patient to another. The regimen here is two baseline painkillers alternated and one for breakthrough pain, designed to get ahead of the pain rather than chase it.

Sources

• Sen S, et al. Glucagon-Like Peptide-1 Receptor Agonist Use and Residual Gastric Content Before Anesthesia. JAMA Surgery, 2024. PMID 38446466. — 124 participants who had followed the fasting guidelines: prevalence of increased residual gastric content of 56% in users of a weekly GLP-1 agonist against 19% in non-users; adjusted prevalence ratio of 2.48 (95% CI: 1.23-4.97); no association between how long the drug had been stopped and the prevalence; the authors conclude that the fasting duration suggested by current guidelines may be inadequate in this group, with an increased risk of aspiration under anaesthesia.
• Tebbetts JB. Achieving a predictable 24-hour return to normal activities after breast augmentation: Part II. Plastic and Reconstructive Surgery, 2002. PMID 11786828. — Among the factors identified for rapid recovery are prospective haemostasis with zero tolerance of bleeding and optimal use of muscle relaxants during the subpectoral dissection.

• Ou Y, Wu M, Liu D, Luo L, Xu X, Panayi AC, He J, Long Y, Feng J, Nian M, Cui Y. Efficacy and Safety of Nerve Block for Postoperative Analgesia in Patients Undergoing Breast Cosmetic Surgery: A Systematic Review and Meta-analysis of Randomized Controlled Trials. Aesthetic Plastic Surgery, 2024. PMID 36939869. — Meta-analysis of 10 randomised trials and 565 patients undergoing breast surgery for aesthetic purposes: compared with the control, the nerve block was associated with significantly lower pain scores at 2, 3-4, 6-8, 12-16 and 24 hours; lower opioid consumption in the first 24 h (mean difference −9.02; 95% CI: −14.29 to −3.75); longer time to the first painkiller (+43.15 min; 95% CI: 4.74-81.56); a lower incidence of additional pain relief (OR 0.14; 95% CI: 0.07-0.28) and of postoperative nausea or vomiting (OR 0.33; 95% CI: 0.22-0.48); no difference in the length of the operation. Level of evidence II. ⚠️ It pools different kinds of block and the heterogeneity is high in several outcomes (I² of 95-96% in opioid consumption and in the time to the first painkiller).
• Kang CM, Kim WJ, Yoon SH, Cho CB, Shim JS. Postoperative Pain Control by Intercostal Nerve Block After Augmentation Mammoplasty. Aesthetic Plastic Surgery, 2017;41(5):1031-1036. PMID 28791441. — 44 patients undergoing breast augmentation with an implant; 34 of them were injected with 0.2% ropivacaine into the third, fourth, fifth and sixth intercostal spaces on both sides. Pain scores (VAS) of the block group against the control: 3.50 ± 1.81 vs 7.1 ± 0.74 on arrival in recovery, 3.03 vs 7.00 at 30 min, 2.68 vs 5.50 at 60 min and 2.00 vs 4.60 at 120 min, with a significant difference at every time point; time to discharge of 189.71 min against 489.00 min; no complications recorded. ⚠️ Level of evidence IV, and in this piece of work the block was given just before waking, not before starting.
• Li X, Li Y. Nerve Block on Pain After Mammaplasty: A Meta-Analysis of randomized controlled studies. 2022. PMID 35096690. — Four randomised trials: the nerve block was associated with a marked reduction in pain (mean difference at one hour of −1.84; 95% CI: −2.49 to −1.20) and in painkiller consumption. ⚠️ Only four trials, all with fewer than 100 patients.

Book your consultation

If what worries you most is the anaesthetic, that is a perfectly valid reason to ask for a consultation — and to ask the five questions on this page. At our practice in Valencia we explain how the operation is organised and who is in the theatre, before you sign anything.

Clinical confirmation by the surgeon

Last reviewed: 9 September 2026. This content is for information only and does not replace an individual assessment by a healthcare professional.