Hematoma

By Nick Peplow·Gender-affirming surgery coordinator

Last reviewed 27 September 2026· How this site is researched

A hematoma is blood collecting under the skin after surgery, from a small vessel that starts bleeding again once the wound has been closed. It is the commonest early complication of top surgery and one of the commonest reasons for an urgent return to theatre. Most appear in the first day or two. A small one is a nuisance; a large one left overnight, pressing on thin skin and fresh nipple grafts, can cost you part of the result, which is why this is the complication on this site where hours count.

How common it is

The open published series put it at somewhere between one in twenty and one in eight top surgery patients. In Rifkin and colleagues' 2022 series from one surgeon, 5.6% of 390 double incision patients had a hematoma and about 3% went back to theatre for it; the peri-areolar group was 3.1%, a gap too small to mean much. Vico and Salmon (2024) recorded 5.2% across 155 double incisions done without drains, and six of those eight were drained with a syringe in clinic. Wolf and Skorochod (2025) saw 12% in 267 mastectomies.

The studies disagree about which technique bleeds more: Wolf and Skorochod found free nipple grafts lowered the risk, a series they cite found more returns to theatre with grafts, and Rifkin found no real difference. Your surgeon's own rate is the more useful number.

Why it happens, and who is more at risk

Double incision lifts a wide sheet of skin off the chest wall, leaving a raw surface full of small sealed vessels. As blood pressure comes back up after the anaesthetic, one can reopen. Coughing, vomiting, straining on the toilet, lifting and reaching all push the pressure higher. Blood then fills the space faster than the drain can clear it, or clots in the tube and stops it draining at all.

Things that raise the odds:

• Blood thinners, aspirin, ibuprofen, and supplements such as fish oil and vitamin E, which is why most surgeons hand you a stop list
• High blood pressure, especially untreated
• Smoking and other nicotine; a 2022 systematic review, summarised by Wolf and Skorochod, found enough evidence to link smoking to hematoma
• A previous breast reduction, by far the strongest factor in Wolf and Skorochod's series, though that rests on a handful of cases
• More blood lost during the operation itself, which Vico and Salmon linked to a hematoma afterwards

One thing lowers them. Tranexamic acid (TXA) is a drug given through the drip during surgery to help blood clot. A 2025 review by Pollack and colleagues, pooling seven studies and 2,534 patients, found it cut hematoma by about 41% and unplanned returns to theatre by about 62%, with no rise in blood clots. Applied directly to the wound instead, it made no difference. Not every surgeon uses it, and it is a fair thing to ask.

What it looks like after top surgery

The giveaway is one side changing. Hematomas are nearly always one-sided, so compare left with right, in a mirror, in good light.

• One side larger, rounder, firmer or higher than the other, and getting more so
• Tightness or pressure that builds instead of easing, often throbbing
• Pain on one side well beyond the other
• Skin over the swelling stretched, shiny, or turning purple or dark
• The drain on that side filling with bright red blood, or producing almost nothing while that side swells, which can mean the tube has clotted
• Bruising spreading quickly across the chest or down the side

It can build over an hour or over a day. Bruising on both sides that fades from purple to yellow over a fortnight is ordinary healing. A seroma, clear fluid rather than blood, usually turns up later and feels soft and sloshy. You don't have to tell the two apart: a side that has changed is a call either way.

After other operations

The same bleed can follow any operation. It looks different by site.

• Neck. After an Adam's apple reduction, a swelling neck matters because it sits over the windpipe. Any trouble breathing, noisy breathing or difficulty swallowing is an emergency.
• Jaw, chin and cheeks. Swelling of the face is expected and roughly even. One cheek or one side of the jaw swelling well beyond the other, tense and painful, in the first day or two is the pattern to report.
• Metoidioplasty, phalloplasty and scrotoplasty. A tense, dark, painful swelling under the shaft skin, in the scrotum, at the groin or at a donor site.
• Hysterectomy. The bleeding is internal, so there's nothing to see. Belly pain that keeps increasing, a swelling abdomen, feeling faint or a racing heart are the signs.

What to do

Contact your surgical team straight away, day or night, rather than waiting for your next appointment, if one side has swollen more than the other, pain or tightness is building on one side, a drain is filling fast with fresh blood, or the skin over a swelling is darkening. If you can't reach them quickly, go to an emergency department. Take your discharge papers.

Call your local emergency number if:

• you feel faint, clammy, confused or breathless, or your heart is racing, which can mean real blood loss
• your neck is swelling after neck surgery, or breathing or swallowing is getting harder
• a wound is bleeding through its dressings and doesn't stop with ten minutes of firm pressure
• after a hysterectomy, belly pain is increasing and you feel faint

The calls I've taken on the first night nearly all started with some version of "this is probably nothing, but one side looks bigger". That is the call to make, at that hour. Don't loosen or remove the vest to have a look unless the team tells you to. A photo of both sides in the same light helps whoever answers.

What happens next

A small, stable hematoma may be left alone, or given extra compression, while the body breaks the blood down over a few weeks. One that is still liquid can be drained with a needle in clinic, which is how Vico and Salmon handled most of theirs. Anything large or growing goes back to theatre, usually the same day. Under general anaesthetic the surgeon reopens part of the incision, washes out the clot, seals the vessel and closes again, often with a fresh drain. Most people go home that day or the next.

Dealt with promptly, it rarely changes the final result, though your recovery restarts a few days behind. Left alone, a large one can starve the skin and grafts above it, give infection somewhere to grow, and harden into a firm lump of scar tissue that may need cutting out later.

Lowering your risk

Give your surgeon every medicine and supplement you take, stop nicotine for as long as they say, take the stool softener, and keep the compression on and the drain log going so a change stands out. The exercise page covers when lifting comes back.

At the consultation I would ask three things: their own hematoma rate and how many of those go back to theatre, whether they use TXA, and whether a return to theatre is included in the fee. If you're travelling for surgery, add a fourth, which is who answers the phone on the first night and where you go if nobody does. Among the patients I've coordinated through Bangkok hospitals, the ones who got through a bleed with the least drama had those answers written down before the operation.

This page is information, not medical advice. Your surgical team decides what a swelling is and what to do about it.