Retroperitoneal Hematoma

What the retroperitoneum is

The abdomen has two main compartments. The peritoneal cavity at the front holds the stomach, liver and most of the bowel. The retroperitoneum lies behind it, against the back wall. It contains the kidneys and adrenal glands, the aorta and inferior vena cava, the pancreas, parts of the duodenum and colon, the ureters, and the psoas muscles that run from the spine to the hips.

Blood that leaks here spreads through loose tissue and can collect in large volumes, sometimes several liters, before it presses on anything. That is why a retroperitoneal bleed can be life-threatening yet initially cause only vague back pain.

Surgeons divide the retroperitoneum into three zones, which guide trauma management:

Causes

Trauma

Blunt trauma from car crashes, falls and crush injuries is a major cause. Pelvic fractures tear the many veins in the pelvis. Kidney injuries and lumbar spine fractures also bleed into this space. Penetrating wounds can damage any of the major vessels.

Ruptured abdominal aortic aneurysm

An abdominal aortic aneurysm is a ballooned section of the aorta. Most ruptures bleed into the retroperitoneum, which may briefly contain the bleed and allow time to reach surgery. The classic picture is sudden severe back or abdominal pain, a pulsating mass and collapse.

Blood thinners and bleeding disorders

Spontaneous retroperitoneal bleeding, often into the psoas or rectus sheath muscles, is a known complication of anticoagulants (warfarin, apixaban, rivaroxaban, heparin). The risk is higher with older age, kidney failure, high INR levels and combined antiplatelet therapy. People with hemophilia and other clotting disorders are also at risk. See anticoagulant-associated bleeding.

Medical procedures

Catheters placed through the femoral artery in the groin, for heart catheterization, stent placement or other interventions, can puncture the artery above the groin crease and bleed backward into the retroperitoneum. Kidney biopsies, surgery and lumbar procedures are other causes.

Other causes

• Kidney tumors, especially angiomyolipoma, which can bleed spontaneously (Wunderlich syndrome)
• Adrenal hemorrhage
• Severe pancreatitis eroding nearby vessels
• Rupture of other artery aneurysms, for example of the renal or splenic artery

Symptoms

Symptoms depend on how fast and how much blood is lost:

• Pain in the back, flank, lower abdomen, groin or hip. It may be dull and vague at first.
• Signs of blood loss: dizziness, fainting, fast heart rate, pale and clammy skin, low blood pressure and confusion. These signal hemorrhagic shock.
• Femoral nerve compression: a psoas hematoma can press on the femoral nerve, causing thigh numbness, weakness straightening the knee, and a hip held bent because straightening it hurts.
• Bruising: blood tracking to the skin can cause bruising of the flanks (Grey Turner sign) or around the belly button (Cullen sign). These appear hours to days later.
• Abdominal swelling or a tender mass.
• Blood in the urine if the kidney is injured.

Diagnosis

1. Rapid assessment of airway, breathing, circulation, heart rate and blood pressure.
2. Blood tests: hemoglobin (which may be normal early and fall over hours), blood type and crossmatch, clotting tests (INR, aPTT), kidney function and lactate.
3. CT scan with contrast: the key test in a stable patient. It shows the size and location of the hematoma and, in the arterial phase, any "contrast blush" that marks active bleeding.
4. Bedside ultrasound: in unstable trauma patients, it checks for free fluid and an aortic aneurysm, though it sees the retroperitoneum poorly.
5. Angiography: used to both find and treat a bleeding artery.

Treatment

Initial resuscitation

Intravenous fluids and blood transfusion restore circulation. Blood thinners are stopped and reversed with vitamin K, prothrombin complex concentrate or a specific reversal agent such as idarucizumab or andexanet alfa, depending on the drug.

Stable hematoma without active bleeding

Many spontaneous and some traumatic hematomas are managed without an operation. The space is enclosed, so pressure from the blood can help stop the bleed (tamponade). Care includes monitoring in hospital, repeat blood counts and transfusion as needed.

Active bleeding

• Angioembolization: an interventional radiologist threads a catheter to the bleeding artery and blocks it with coils or particles. This is the first choice for pelvic and many spontaneous bleeds.
• Endovascular repair: a stent graft for a ruptured aortic aneurysm or a punctured femoral artery when the anatomy allows.
• Open surgery: for ruptured aneurysms not suitable for stenting, central (zone 1) traumatic hematomas, or bleeding that cannot be controlled otherwise.

Complications and outlook

Possible complications include shock and organ failure, abdominal compartment syndrome, femoral nerve damage with lasting thigh weakness, infection of the hematoma, and kidney injury. The outlook depends mostly on the cause. Small anticoagulant-related bleeds that are caught early usually resolve over weeks to months as the body reabsorbs the blood. A ruptured aortic aneurysm has a high death rate, even with surgery, which is why screening and elective repair of large aneurysms are recommended.

Frequently asked questions

What is a retroperitoneal hematoma?

It is a pocket of blood that collects in the retroperitoneum, the space behind the abdominal organs that contains the kidneys, aorta and psoas muscles. It can be caused by trauma, aneurysm rupture, blood thinners or medical procedures.

What are the symptoms of a retroperitoneal bleed?

Common symptoms are back, flank, abdominal or groin pain, dizziness, a fast heartbeat and fainting from blood loss. Thigh numbness or weakness can occur if the blood presses on the femoral nerve. Bruising on the flanks may appear later.

How is a retroperitoneal hematoma diagnosed?

A contrast CT scan is the main test. It shows where the blood is, how much there is and whether bleeding is still active. Blood tests check hemoglobin and clotting, and angiography can locate and treat a bleeding artery.

Can a retroperitoneal hematoma heal on its own?

Small, stable hematomas without active bleeding often do. The body gradually reabsorbs the blood over weeks to months. Monitoring in hospital, reversing blood thinners and blood transfusion may be needed in the meantime.

How long does it take for a retroperitoneal hematoma to resolve?

Small collections can shrink noticeably in 2 to 4 weeks. Large hematomas can take 2 to 3 months or longer to disappear on scans. Nerve symptoms from compression may take several months to recover.