A rectus sheath hematoma is a collection of blood that forms inside the sheath surrounding the rectus abdominis, the paired “six-pack” muscles running vertically down the front of your abdomen. It happens when a blood vessel inside or near these muscles ruptures, allowing blood to pool in the tissue. While relatively uncommon, it can mimic more serious abdominal emergencies and sometimes requires hospital care, particularly in people taking blood thinners.
How It Happens
The rectus muscles are supplied by a pair of arteries called the epigastric arteries, which run along the back surface of the muscles. Smaller branches extend into the muscle tissue itself. When one of these vessels tears, blood leaks into the fibrous sheath that wraps around the muscle, forming a hematoma.
The tear can happen from a direct blow to the abdomen, a hard fall, or an unusually forceful contraction of the abdominal wall. Violent coughing, straining, sneezing, or intense exercise can all generate enough force to rupture a small artery. In some cases, the trigger is surprisingly minor, especially in older adults or people whose blood doesn’t clot normally.
Who Is Most at Risk
Blood-thinning medications are the single biggest risk factor. In one large review, nearly 70% of patients with a rectus sheath hematoma were on some form of anticoagulation therapy. These medications make it easier for a small vessel tear to bleed significantly and harder for the body to seal it off on its own.
Other factors that raise the risk include older age, pregnancy, recent abdominal surgery, chronic coughing from lung disease, and conditions that weaken blood vessel walls. People who are frail or have multiple chronic illnesses are both more likely to develop the problem and more likely to have a complicated course if they do.
What It Feels Like
The hallmark symptom is sudden, sharp abdominal pain, usually on one side. The pain tends to get worse with movement, coughing, or tensing the abdominal muscles. You may feel or see a firm, tender lump in the abdominal wall. Unlike pain from an internal organ, this pain stays in the same spot and doesn’t shift when you change position.
Depending on how much blood collects, the area may become swollen and discolored. A large hematoma can cause bruising that spreads across the lower abdomen or into the flank. In severe cases, significant blood loss leads to lightheadedness, a fast heart rate, and a drop in blood pressure.
Because the pain and mass sit in the abdomen, rectus sheath hematomas are frequently mistaken for appendicitis, ovarian cysts, hernias, or even abdominal tumors. This misdiagnosis is common enough that clinicians have developed specific bedside tests to tell the difference.
Two Classic Physical Exam Signs
Two maneuvers help distinguish an abdominal wall problem from something deeper inside the abdomen. The first, known as the Fothergill sign, involves feeling the mass while the patient tenses the abdominal muscles (by lifting the head off the pillow, for example). A mass inside the abdominal wall stays palpable and becomes fixed in place when the muscles contract. A mass from an internal organ, by contrast, becomes harder to feel because the tightened muscles shield it.
The second, the Carnett sign, works in two stages. First, the examiner presses deeply to find the most tender spot while the muscles are relaxed. Then the patient tenses the abdomen again, and the examiner re-applies pressure with the fingertips. If the tenderness persists or increases with the muscles contracted, the pain is coming from the abdominal wall itself rather than from an organ underneath. When both signs are positive, a rectus sheath hematoma becomes a strong possibility.
How It Is Diagnosed
A CT scan of the abdomen is the most reliable way to confirm the diagnosis. It clearly shows the size and location of the blood collection, whether the bleeding is still active, and how far the hematoma extends. It also rules out the more serious intra-abdominal conditions that the hematoma can mimic.
Ultrasound can also detect a hematoma and is sometimes used as a first step, especially in pregnant patients or when quick bedside imaging is needed. However, CT provides more detail and is generally preferred when available. Blood tests checking your hemoglobin level and clotting function help gauge how much blood has been lost and whether clotting problems need to be addressed.
How Severity Is Graded
Rectus sheath hematomas are typically graded on a three-tier scale based on imaging findings:
- Grade I: A small hematoma contained within the muscle itself. These don’t cross the midline and usually resolve on their own without complications.
- Grade II: A larger collection that extends beyond the muscle into the space between the muscle and the surrounding sheath but remains within the sheath boundaries. These may cause a noticeable drop in blood counts.
- Grade III: A large hematoma that breaks through the sheath and spreads into the broader abdominal wall or pelvis. These can cause significant blood loss and may require active intervention.
Treatment and Recovery
Most rectus sheath hematomas, particularly Grade I and many Grade II cases, are managed conservatively. That means rest, ice on the area, pain control, and monitoring blood counts over the following days. If you’re on a blood thinner, your medical team will weigh the risks of pausing or reversing the medication against the reason you’re taking it in the first place.
For hematomas that continue to grow or cause hemodynamic instability (falling blood pressure, rising heart rate, dropping hemoglobin), more active treatment is needed. The most common next step is an interventional radiology procedure in which a catheter is threaded into the bleeding artery and the vessel is sealed off from the inside. Surgery to evacuate the hematoma and tie off the bleeding vessel is reserved for cases that don’t respond to less invasive measures.
Small hematomas typically reabsorb over a period of several weeks to a few months. During this time you may feel a residual firmness in the abdominal wall, and the skin discoloration gradually fades. Larger hematomas take longer to resolve and occasionally leave behind a calcified mass or a persistent lump of scar tissue that the body slowly breaks down.
How Serious It Can Be
For most people, a rectus sheath hematoma resolves completely with conservative care. In one single-center study, about 77% of patients achieved full recovery regardless of the treatment approach used. However, the condition can be life-threatening in certain populations. The overall mortality rate is around 4% in the general population but rises to as high as 25% in patients on anticoagulants.
Importantly, the severity of the hematoma itself isn’t the main predictor of death. In that same study, mortality was not significantly associated with hematoma size, blood test results, or which treatment was used. What did predict worse outcomes was the burden of other chronic illnesses. For every additional point on a standardized comorbidity index, the odds of in-hospital death increased by 46%. In other words, it’s the overall health of the patient, not the hematoma alone, that determines how dangerous the situation becomes.