What causes internal bleeding?
Bleeding most often occurs due to injury or wound, and depending upon the circumstances, the amount of force required to cause bleeding can be quite variable. Some people can experience spontaneous bleeding not necessarily related to any injury, wound, or trauma.
Most people understand that falling from a height or being involved in a car accident can inflict great force and trauma upon the body. If blunt force is involved, the outside of the body may not necessarily be damaged, but enough compression may occur to internal organs to cause injury and bleeding.
- Imagine a football player being speared by a helmet to the abdomen. The spleen or liver may be compressed by the force and cause bleeding inside the organ. If the hit is hard enough, the capsule or lining of the organ can be torn, and the bleeding can spill into the peritoneum (the space in the abdominal cavity that contains abdominal organs such as the intestines, liver, and spleen).
- If the injury occurs in the area of the back or flank, where the kidney is located, retroperitoneal bleeding may occur.
- The same mechanism causes bleeding due to crush injuries. For example, when a weight falls on a foot, the weight doesn't give, nor does the ground. The force needs to be absorbed by either the bone or the muscles of the foot. This can cause the bone to break and/or the muscle fibers to tear and bleed.
- Other structures are compressible and may cause internal bleeding. For example, the eye can be compressed in the orbit when a fist or ball hits it. The globe deforms and springs back to its original shape. Rarely, intraorbital hemorrhage (caused by orbital trauma) may occur.
Deceleration may cause organs in the body to be shifted inside the body. This may shear blood vessels away from the organ and cause bleeding. This is often the mechanism for intracranial bleeding such as epidural and subdural hematomas and subarachnoid hemorrhage or bleeding. Force applied to the head causes an acceleration/deceleration injury to the brain, causing the brain to "bounce around" inside the skull. This can tear some of the small bridging veins on the surface of the brain and cause bleeding. Since the brain is encased in the skull, which is a solid structure, even a small amount of blood can increase pressure inside the skull and decrease brain function. The shaking within the skull may also cause bleeding within the brain tissue itself (intracerebral hemorrhage).
Organs within the abdominal cavity are often attached by a pedicle (stalk) to arteries and veins that provide blood supply. In a deceleration injury, the pedicle can shear off, tearing the blood vessels, causing bleeding.
Internal bleeding may occur with broken bones that contain bone marrow in which blood production occurs. These bones have a rich blood supply, and significant amounts of blood can be lost with fractures. The break of a long bone such as the thighbone (femur) can result in the loss of one unit (350 cc to 500 cc) of blood. Flat bones such as the pelvis require much more force to cause a fracture. The trauma from the fracture can tear many blood vessels surrounding the structure, which causes massive internal bleeding.
Bleeding in pregnancy is never normal. Bleeding during the first trimester of pregnancy is a sign of a potential miscarriage, and is not uncommon. Moreover, vaginal bleeding during the first few weeks of pregnancy may be a possible symptom and sign of a tubal or ectopic pregnancy. In an ectopic pregnancy, the placenta and the fetus implant in the Fallopian tube or another location outside of the uterine cavity. As the placenta grows, it erodes through the tube or other involved organs and may cause fatal bleeding unless the ectopic pregnancy is recognized and treated.
Bleeding after 20 weeks of pregnancy may be due to placenta previa or placental abruption, and urgent medical care should be accessed. Placenta previa describes the situation in which the placenta attaches to the uterus close to the opening of the cervix and may cause painless vaginal bleeding. Abruption occurs when the placenta partially separates from the uterine wall and causes significant pain with or without bleeding from the vagina.
Bleeding after surgery
Whenever a surgeon cuts into the body, the potential for immediate and delayed bleeding exists. When the operation is near completion, the surgeon tries to make certain that all bleeding has been controlled. This can be done by identifying and tying off blood vessels with sutures or using staples or clips to maintain hemostasis (hemo=blood + stasis=inactivity, lack of flow). Cautery can be used to burn blood vessels to prevent them from bleeding. A little bleeding can be expected in most situations.
Sometimes, however, bleeding may occur after the surgery is performed. Blood vessels that have been cut may go into spasm with no evidence of bleeding. They may relax and begin bleeding many hours or days after the completion of a procedure. Similarly, sutures, staples, or clips can dislodge and allow a blood vessel to bleed. Many times the bleeding is self-limited as the body is able to repair itself. On occasion, the patient needs to be returned to the operating room so that the surgeon can explore the area and find the bleeding site. Depending upon the situation, an interventional radiologist may be able to find the bleeding blood vessel and repair it.
Internal bleeding may occur spontaneously, especially in those people who take anticoagulation medications or who have inherited bleeding disorders. Routine bumps that occur in daily life may cause significant bleeding issues.
Internal bleeding in the gastrointestinal tract may be caused as a side effect of medications (most often from nonsteroidal anti-inflammatory drugs such as ibuprofen and aspirin) and alcohol. These substances can cause inflammation and bleeding of the esophagus, stomach, and duodenum, the first part of the small intestine as it leaves the stomach.
Long-term alcohol abuse can cause liver damage, which may cause bleeding problems through a variety of mechanisms including decreased protein and clotting factor production. Cirrhosis, or scarring of the liver, changes blood flow to the liver and leads to portal hypertension (increased pressure within the blood vessels that supply the liver).
Esophageal varices (swollen blood vessels around the esophagus) may develop when the liver's blood supply is altered, which has a tendency to make the swollen blood vessels that line the esophagus bleed. Moreover, alcohol directly irritates the lining of the stomach, which leads to inflammation that can cause bleeding.