Tissue Expander Breast Reconstruction: The Complete Guide (Expander, Filling, Implant)
Updated: Sep 11
A tissue expander is a temporary, empty implant. It is placed in the chest after a mastectomy (removal of the breast). Over a few weeks it is slowly filled with salt water to stretch the skin. When the skin is ready, a second operation swaps the expander for a permanent breast implant. This guide explains every step: placing the expander, the filling visits, the exchange, how long an expander can stay in, and the risks.
The animation shows the general path from tissue expander to implant. The exact steps can differ per hospital and per patient.
In this article
What is a tissue expander?
A breast tissue expander is a soft silicone shell with a small valve (port). It is placed empty or partly filled. Over several visits, the surgeon adds sterile salt water (saline) through the port. The skin and tissue on top slowly stretch. You can compare it with skin that stretches slowly during pregnancy.
The expander is not the final result. It is a placeholder. It makes room for the permanent implant that comes later. That is why this method is called two-stage implant reconstruction: stage one is the expander, stage two is the implant.
Many expanders have a small magnet in the port. The magnet helps the team find the port at each filling visit. It can also mean that an MRI scan is not possible, or needs extra care, while the expander is in. Tell every doctor and radiographer that you have an expander.
Who is a tissue expander for?
Tissue expander reconstruction is one of the most common ways to rebuild the breast after a mastectomy. It is often chosen when:
The skin is tight or a lot of skin was removed, so a permanent implant does not fit safely in one step.
Reconstruction is done later (delayed), months or years after the mastectomy, when the chest skin has tightened.
You want to avoid a longer operation with your own tissue, such as a DIEP flap.
Your final breast size is not yet clear and you want to adjust it step by step.
You want a shorter operation and a faster first recovery.
An expander is less suitable if the skin is thin and damaged by earlier radiotherapy, or if you strongly prefer one operation. Your surgeon will look at your skin, your breast size and your other treatments before giving advice.
Step 1: placing the tissue expander
The expander is placed in a first operation. Often this happens right after the mastectomy, under the same anaesthetic. It can also be done later, in a separate operation. The surgeon creates a pocket in the chest, places the empty or partly filled expander, and closes the skin. The operation takes about 1 to 2 hours. Most women go home the same day or after one night. Thin drains remove fluid for 7 to 14 days.
Sometimes a support sheet (acellular dermal matrix, ADM) or a mesh is added. This gives extra cover along the lower edge of the expander and helps to shape the pocket.
Above or under the muscle: prepectoral vs subpectoral placement
There are two places for the expander. Under the chest muscle (subpectoral) was the standard for many years. The surgeon partly frees the large chest muscle from the ribs and slides the expander under it. The muscle gives extra cover over the expander. The downside is more tightness and pain in the first weeks. The breast can also move when you tense the muscle, which is called animation.
Above the muscle (prepectoral) is used more and more. The expander sits directly under the skin and the remaining fat, on top of the muscle. It is often wrapped in ADM or mesh. The muscle is not touched. This usually means less pain, a faster recovery and no animation. It does need a good, well-supplied skin cover to be safe.
Neither option is better for everyone. Skin thickness, radiotherapy, your body shape and your surgeon's experience all play a role. Ask which placement your surgeon suggests for you, and why.
Want to compare both positions in detail? Read more about prepectoral vs subpectoral breast reconstruction: the implant above or under the muscle.
Step 2: filling the tissue expander
After the first weeks of healing, usually 2 to 3 weeks, the filling visits start. This part is called expansion. It is done in the outpatient clinic, without anaesthetic.
What does a filling visit feel like?
Each visit is short, often 15 to 30 minutes. The team finds the port, often with a small magnet finder, and marks the spot. The skin is cleaned. A thin needle goes through the skin into the port. Then sterile saline is slowly added with a syringe. Most women feel little or no pain from the needle, because the skin over the chest is often numb after a mastectomy. You may feel pressure or tightness as the fluid goes in.
How often and how much?
Fills are usually every 1 to 2 weeks. The amount per visit depends on your skin and on how it feels for you. The full filling often takes 6 to 8 weeks. Some women need fewer visits, some more. The expander is often filled a little beyond the planned final size. This gives the surgeon room to shape a natural breast at the exchange.
Pain and daily life during expansion
Tightness and pressure are normal for 1 to 2 days after each fill. Simple painkillers are usually enough. If a fill feels too much, say so. The team can add less, or wait a bit longer. Between visits you can do most normal things: walking, desk work, and driving once you feel safe. Avoid heavy lifting and hard chest exercise until your team says it is fine. A soft, supportive bra without underwire is often comfortable in this period.
Step 3: tissue expander to implant exchange
When the filling is complete and the skin has settled, usually 1 to 3 months after the last fill, the second operation follows. The surgeon removes the expander through the old scar, adjusts the pocket, and places the permanent implant. Small extra steps can be done at the same time: fat grafting (lipofilling) to smooth the edges, or a lift or reduction of the other breast. Nipple reconstruction usually comes later. The operation takes about 1 to 2 hours. Most women return to normal activities in 2 to 3 weeks.
Read the full article about this operation: Tissue expander to implant exchange: what to expect from the second surgery.
Silicone or saline implant?
Silicone gel implants feel soft and natural. Newer cohesive gel keeps its shape even if the shell breaks. Saline implants are filled with sterile salt water. If a saline implant leaks, the breast deflates and you notice it quickly. Both types have a silicone shell. Most women choose silicone gel for the feel. Your surgeon will discuss shape, size and type with you before the exchange.
How long can tissue expanders be left in?
A tissue expander is designed as a temporary device, not as a permanent implant. In most cases it stays in for a few months: the time needed to fill it, to let the tissue settle, and to plan the exchange. Sometimes it stays in longer. Common reasons are chemotherapy, radiotherapy, wound healing problems, or simply your own wish to wait.
There is no strict rule for the maximum time. Many women keep an expander longer than planned without problems. But the longer it stays in, the more the risks add up. The shell can wear, the capsule around it can harden, and a fully filled expander can feel firm and less comfortable than an implant. That is why most teams aim to exchange it once your treatment allows. If you have had an expander for a long time and no exchange is planned yet, ask your team about the timeline.
Tissue expanders and radiotherapy
Radiotherapy changes the skin and tissue of the chest. It makes them tighter, thinner and less well supplied with blood. That matters for an expander, which relies on healthy skin that can stretch.
Combining a tissue expander with radiation carries a higher chance of problems, around 20 to 25 percent. Problems include infection, the expander becoming exposed through the skin, and capsular contracture (hard scar tissue around the expander). If radiotherapy is planned, teams often choose one of these paths:
Place the expander and fill it before radiotherapy, then do the exchange several months after radiotherapy has finished.
Delay the whole reconstruction until after radiotherapy.
Use your own tissue (a flap, such as a DIEP or latissimus dorsi flap) instead of, or together with, an implant.
Alternatives to the two-stage expander
Direct-to-implant reconstruction
Here the permanent implant is placed during the mastectomy, in one operation, without an expander. This works best when the skin is of good quality, the breast is not very large, and no radiotherapy is planned. The advantage is one operation. The trade-off is less control over the final size and a higher chance that the skin is under too much stress.
The Becker expander breast implant
The Becker expander is a combined device. Inside is a layer of silicone gel, plus a saline chamber that can be filled through a small port. The port sits under the skin and is connected by a thin tube. Once the filling is complete, the port and tube are removed in a small procedure, and the device stays in place as the permanent implant.
The main aim is to avoid a full second operation. The trade-off is that the shape and feel are less easy to fine-tune than with a separate exchange, and the port can cause discomfort or need earlier removal. Some surgeons use the Becker expander often, others rarely. It is neither better nor worse than the two-stage method for everyone. Ask whether it fits your situation.
Risks of a tissue expander
Like every operation, tissue expander reconstruction has risks. Most women go through the process without major problems. It is still good to know what can happen, so you recognise the signs early.
Infection
A small number of women get an infection around the expander, most often in the first weeks. Signs are redness, warmth, increasing pain, fever, or fluid from the wound. Antibiotics can sometimes solve it. If not, the expander must be removed, and a new one can be placed after a few months.
Capsular contracture
The body always forms a thin layer of scar tissue (capsule) around an expander or implant. In some women this capsule becomes thick and tight. The breast then feels hard and can look higher or rounder. This is more common after radiotherapy. It is often treated at the exchange, when the surgeon can release or remove the capsule.
Expander shifting or rotating
An expander can move upwards, sideways or turn around in the pocket. This can make the breast look uneven during expansion. Usually the surgeon corrects the pocket at the exchange. Rarely, an earlier operation is needed.
Extrusion and skin breakdown
If the skin is thin, or the expander is filled too fast, the skin over it can break open. The expander then becomes visible (extrusion). This needs surgery, often removal of the expander. That is why the team fills slowly and watches the skin closely.
Other possible problems
Other problems are fluid collection (seroma), a leaking port or shell that makes the expander deflate, a port that is hard to find, and limits on MRI scans while the expander is in. Always contact your team if something changes, hurts more, or worries you.
Recovery after tissue expander surgery
After the expander is placed, expect moderate discomfort for 3 to 7 days. Prescribed painkillers usually keep this under control. Drains stay in for up to 14 days. For about 6 weeks, keep your arm below shoulder height and avoid straining the chest: no heavy lifting, dog-walking with a pulling lead, or vacuuming. Light work is often possible after 2 to 3 weeks, full activity after 4 to 6 weeks.
With a prepectoral expander, the first weeks are often easier, because the chest muscle is not lifted. With a subpectoral expander, tightness and muscle pain can last a little longer.
After the exchange to the permanent implant, recovery is milder. Most women need 1 to 2 weeks of rest and are back to normal activities in 2 to 3 weeks. The final shape shows after 2 to 3 months, when the swelling has gone down.
Frequently asked questions about tissue expanders
What is a breast tissue expander?
A breast tissue expander is a temporary, adjustable implant with a small valve. It is placed in the chest after a mastectomy and slowly filled with sterile salt water over several weeks. It stretches the skin to make room for the permanent implant, which is placed in a second operation.
How long does tissue expander reconstruction take?
The whole process usually takes 4 to 6 months. Filling visits start 2 to 3 weeks after the first operation and take place every 1 to 2 weeks. The exchange to the implant follows 1 to 3 months after the last fill.
Does filling a tissue expander hurt?
The needle itself is rarely painful, because the chest skin is often numb after a mastectomy. Most women feel pressure or tightness for 1 to 2 days after each fill. Simple painkillers are usually enough. If a fill feels too much, the team can add less or wait longer.
How long can tissue expanders be left in?
A tissue expander is a temporary device. In most cases it stays in for a few months, until filling is complete and the exchange can be planned. It can stay longer if chemotherapy, radiotherapy or healing problems delay the exchange. There is no strict maximum, but the longer it stays, the more the risks of hardening, wear and discomfort add up. Discuss the timeline with your team.
Is a tissue expander placed above or under the muscle?
Both are possible. Under the chest muscle (subpectoral) gives extra cover but more tightness and a longer recovery. Above the muscle (prepectoral) usually means less pain and no movement of the breast when you tense the muscle, but it needs good, thick skin. Your surgeon chooses based on your skin, radiotherapy and body shape.
What is a Becker expander breast implant?
The Becker expander is a combined device: an implant with silicone gel and a saline chamber that can be filled through a small port. After filling, the port is removed and the device stays in as the permanent implant. It aims to avoid a full second operation, but the final shape is harder to fine-tune. Some surgeons use it often, others rarely.
Can I have a tissue expander after radiotherapy?
Yes, but the chance of problems is higher, because radiated skin is tighter and heals less well. Infection, the expander becoming exposed and capsular contracture are more common. Many teams prefer to fill the expander before radiotherapy, to delay reconstruction, or to use your own tissue such as a DIEP or latissimus dorsi flap.
What happens at the tissue expander to implant exchange?
The surgeon removes the expander through the old scar, adjusts the pocket and places the permanent implant. This takes about 1 to 2 hours and is usually a day-case or one-night stay. Fat grafting or a change to the other breast can be done at the same time. Most women are back to normal activities in 2 to 3 weeks.
Questions to ask your surgeon
Would you place the expander above or under the muscle for me, and why?
How many filling visits do you expect, and how much time between them?
If I need radiotherapy, how does that change the plan and the timing of the exchange?
How long do you expect my expander to stay in before the exchange?
What are my options if I get an infection or the skin becomes too thin?
Open the Breast Reconstruction Decision Guide to explore your options and prepare questions for your treatment team.
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Written by Dr. Mahyar Foumani, plastic and reconstructive surgeon specializing in breast reconstruction. Based on the book 'Breast Reconstruction Explained.'
This article is education, not medical advice
This article explains in plain words how breast reconstruction works. It is meant to help you understand what is possible, so that you and your doctor can make a good decision together. It does not replace personal medical advice.
Every situation is different. What is best for you depends on your body, your illness, your treatment and your own wishes. So always follow the advice of your own doctor or care team. Do you have symptoms, or are you unsure about something? Please contact your doctor or GP. In an emergency, call your local emergency number.
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