A retroperitoneal hematoma is a collection of blood that forms in the retroperitoneal space, the area deep in your abdomen behind the membrane that lines your abdominal cavity. Because this space houses major blood vessels, kidneys, and parts of the digestive tract, bleeding here can range from a small, self-limiting pocket of blood to a life-threatening emergency. The condition is most commonly caused by blunt trauma, but it can also develop spontaneously in people taking blood-thinning medications or after certain medical procedures.
Where the Bleeding Happens
The retroperitoneal space sits between the inner lining of the abdominal cavity (the peritoneum) and the muscles of the back wall. It’s not a single open chamber. Instead, it’s divided into compartments separated by layers of tissue called fascia. The kidneys, adrenal glands, and their blood supply sit in the central compartment. The pancreas, parts of the small intestine, and sections of the colon occupy the front portion. The back portion is mostly filled with fat and connects across the midline, which is one reason bleeding can spread from one side to the other.
This space contains the aorta, the body’s largest artery, along with the inferior vena cava, renal arteries, and a dense network of smaller vessels. Damage to any of these structures can produce rapid, significant bleeding that pools in the surrounding tissue rather than draining into the abdominal cavity itself. Because the blood is trapped behind the peritoneum, retroperitoneal hematomas can grow quite large before they produce obvious external signs.
Common Causes
Retroperitoneal hematomas fall into two broad categories: traumatic and nontraumatic.
Traumatic Causes
Blunt trauma accounts for the majority of retroperitoneal hematomas. Car accidents, falls, and direct blows to the abdomen or back create compressive and deceleration forces that crush or shear blood vessels and organs. Typical injuries include bleeding around the kidneys, pancreatic damage, and pelvic hematomas from fractured pelvic bones that tear nearby blood vessels. Penetrating trauma, such as gunshot wounds or stab wounds, can also cause retroperitoneal bleeding by directly lacerating vessels or organs in the space.
Nontraumatic Causes
Nontraumatic cases are split into spontaneous and iatrogenic (caused by a medical procedure). Spontaneous retroperitoneal hematomas are strongly linked to blood-thinning medications. Between 50% and 89% of patients with spontaneous cases are on some form of anticoagulant therapy, and about one-third of those patients are also taking antiplatelet drugs. Other risk factors include age over 70, female sex, pregnancy, liver cirrhosis, kidney disease, and hardening of the arteries. The underlying mechanism likely involves weakened small blood vessels that rupture under normal pressures.
Iatrogenic cases typically follow procedures that access blood vessels through the groin, such as cardiac catheterization. Although the incidence of retroperitoneal bleeding after these procedures has decreased over the years, it remains a recognized complication. The bleeding originates from the puncture site in the femoral artery and tracks backward into the retroperitoneal space.
Symptoms and Physical Signs
The hallmark symptoms are abdominal pain, flank pain, and back pain, often appearing suddenly and worsening over hours. After procedures involving a groin puncture, tenderness and swelling near the groin are the most common early findings. Some people also experience lightheadedness, rapid heart rate, or a drop in blood pressure as blood loss progresses.
Several visible skin changes can develop, though they tend to appear days into the illness rather than immediately. Grey Turner’s sign is bruising along the flank that can appear red, purple, green, or yellow depending on how far the blood cells have broken down. Cullen’s sign is similar bruising around the belly button. Fox’s sign shows up as discoloration on the upper thigh just below the groin crease, and Bryant’s sign presents as a bluish tint on the scrotum. These signs indicate that blood has tracked through tissue planes from the retroperitoneal space to the skin surface. They typically show up around day three or four, so their absence early on does not rule out significant bleeding.
How It Is Diagnosed
A contrast-enhanced CT scan is the gold standard for identifying a retroperitoneal hematoma. The scan shows the size and location of the blood collection and, critically, whether there is active bleeding. When contrast dye is seen leaking outside of a blood vessel on the scan (called contrast extravasation), it is one of the strongest predictors that the bleeding will need to be stopped with a procedure or surgery rather than managed with observation alone. Repeat imaging may be used to track whether the hematoma is stable, shrinking, or expanding over time.
Treatment Approaches
Treatment depends on the size of the hematoma, whether bleeding is ongoing, and what caused it in the first place. Many retroperitoneal hematomas, particularly smaller ones that show no signs of active bleeding on a CT scan, are managed conservatively. This means close monitoring in a hospital setting with repeated blood counts, blood pressure checks, and follow-up imaging to confirm the bleeding has stopped and the hematoma is not growing.
If the CT scan shows contrast extravasation or the patient’s vital signs are deteriorating, more aggressive intervention is needed. One option is angiographic embolization, a minimally invasive procedure where a catheter is threaded into the bleeding vessel and the leak is sealed from the inside. In cases involving major vessel damage, organ injury, or penetrating trauma, open surgical exploration may be necessary to find and control the source of bleeding directly.
For patients whose hematoma developed because of blood-thinning medications, the anticoagulant is typically paused or reversed to give the body a chance to stop bleeding on its own. The decision about when (or whether) to restart the medication is made on a case-by-case basis, weighing the risk of further bleeding against the reason the patient was on blood thinners in the first place.
Potential Complications
Beyond the immediate danger of blood loss, retroperitoneal hematomas can cause problems by pressing on nearby structures. One well-documented complication is femoral nerve palsy. The femoral nerve runs between two muscles in the pelvis that merge into a tendon near the hip. When a hematoma forms in this area, blood pools downward due to gravity and can compress the nerve as it passes through the inguinal region. This compression causes weakness in hip flexion and knee extension, along with numbness on the front of the thigh and inner leg. Femoral nerve palsy from anticoagulant-related hematomas has been reported at rates between 0.6% and 6.6% in different studies.
Large hematomas can also compress the kidneys or ureters, obstruct blood flow in major vessels, or become infected. In some cases, the sheer volume of blood lost into the retroperitoneal space is enough to cause hemorrhagic shock, requiring emergency resuscitation with fluids and blood products.
Recovery and Outlook
Small to moderate hematomas that are managed without surgery generally reabsorb on their own over weeks to months as the body gradually breaks down and clears the pooled blood. During this time, you can expect periodic follow-up imaging to confirm the hematoma is shrinking. Pain often improves well before the hematoma fully resolves on a scan. If femoral nerve compression occurred, recovery of nerve function can take weeks to several months and sometimes requires physical therapy to rebuild strength in the affected leg.
For larger or more complex cases, particularly those requiring surgery or embolization, hospital stays are longer and recovery timelines are less predictable. The overall outlook depends heavily on the cause and severity. A small iatrogenic hematoma after a catheterization procedure typically resolves with conservative care and carries a good prognosis. A massive hematoma from high-energy blunt trauma with multiple injured vessels is a far more serious situation with higher risks of complications and a longer road to recovery.