What causes internal bleeding?
Bleeding most often occurs due to injury, 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 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
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
- 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 it is hit by a fist or a
ball. 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 to occur. This is
often the mechanism for intracranial bleeding
such as epidural and
subdural hematomas and subarachnoid hemorrage 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.
Bleeding may occur with broken bones. Bones contain the bone marrow in which
blood production occurs. They have rich blood supplies, and significant amounts
of blood can be lost with fractures. The break of a long bone such as the thigh bone
result in the loss of one unit (350 cc to 500cc) of blood. Flat bones such as the pelvis
require much more force to cause a fracture, and many blood
vessels that surround the structure can be torn by the trauma and cause massive
Bleeding in pregnancy is never normal, though not uncommon in the first
trimester, and is a sign of a potential miscarriage. In the first few weeks of
pregnancy, there is concern that vaginal bleeding is a potential sign of tubal
or ectopic pregnancy, in which 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 situtaions.
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
Long-term alcohol abuse can also 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, and these swollen blood vessels that line the esophagus are prone to bleeding. As well, alcohol can be directly irritating to the lining of the stomach, leading to inflammation that can result in bleeding.