Retroperitoneal bleeding is internal bleeding that occurs in the abdominal cavity behind the peritoneum, the membrane that keeps the organs in place. This condition can be very serious and usually requires medical intervention. There are several main causes of retroperitoneal bleeding, including trauma, the use of anticoagulant medications, tumors, and ruptured abdominal aortic aneurysms.
Blunt force or penetrating trauma, such as a stab wound, can cause retroperitoneal bleeding. The most common type of trauma that results in this form of bleeding is car accidents, both to people in the car or pedestrians who have been struck. Hemorrhage in the retroperitoneal area is caused by damage to solid organs such the pancreas or kidneys, hollow organs such as the colon or duodenum, and the tearing of musculoskeletal structures. Bleeding can also result from damage to significant vascular structures such as the abdominal aorta. Damage to these areas causes blood vessels to burst, resulting in hemorrhage of varying severity.
Anticoagulant therapy, such as warfarin or heparin, can also result in retroperitoneal bleeding. This type of bleeding is often spontaneous and is due to the difficulty in controlling the effects of the anticoagulant drugs. It can also be further complicated by any underlying medical conditions of the patient. The hemorrhage itself may be a result of preweakened vascular structures and connective tissue that are ruptured due to muscle strain or a seemingly minor trauma. Diffuse, small-vessel artereoscelerosis and heparin-induced microaniopathy may also initiate bleeding.
Retroperitoneal bleeding can also be caused by tumors and even cysts in the area. Examples include renal cell carcinoma present in the kidneys. The bleeding is a result of the growth weakening the surrounding tissues, making them vulnerable to rupture. Often, the bleeding can occur without warning, and these patients are usually carefully monitored.
Finally, a ruptured abdominal aortic aneurysm can cause severe and often life-threatening retroperitoneal bleeding. The rupture occurs when the walls of the large aortic blood vessel in the abdomen balloon and subsequently burst. This type of aneurysm normally develops quite slowly, but if it is not repaired before rupture, the results can be catastrophic. Abdominal aortic aneurysms are often caused by the weakening of the arterial walls due to arteriosclerosis. Other risk factors include smoking, high blood pressure, and obesity, and the condition, which is more common in men than women, is also thought to have a genetic influence.