Internal bleeding

Internal bleeding, also known as internal haemorrhage, occurs when blood escapes from a blood vessel and collects inside the body. Unlike a cut on the skin, this loss of blood is usually not visible from the outside. This condition is a serious medical emergency because it can be difficult to detect quickly. The severity of the situation depends on two main factors: the rate of the bleeding and its location. Bleeding in the head or torso is especially dangerous. Severe bleeding in the chest, abdomen, pelvis, or thighs can lead to hemorrhagic shock or death if medical professionals do not intervene immediately.

To understand why this is so dangerous, we must look at how the body moves blood. The body uses a closed loop system to circulate blood to all major organ systems. When a blood vessel is damaged, this closed loop is disrupted. The autonomic nervous system (ANS) attempts to compensate for this loss in two primary ways. First, the ANS causes the muscles surrounding the blood vessels to contract. This action can initially keep blood pressure within a normal range. Second, the heart begins to pump faster to deliver blood to vital organs more quickly. This rapid heart rate is known as tachycardia. If the blood pressure falls below the normal range, it is called hypotension. When a person experiences both tachycardia and hypotension, they may enter a state called hemorrhagic shock.

Medical professionals use the Advanced Trauma Life Support (ATLS) system to classify the severity of hemorrhagic shock. This system is based on estimated blood loss and changes in vital signs. Class I hemorrhage involves losing less than 15% of blood volume, with heart rates remaining mostly normal. Class II involves a loss of 15% to 30%, often resulting in cool, clammy skin and a heart rate between 100 and 120 beats per minute. Class III is more severe, with 30% to 40% blood loss, causing a drop in systolic blood pressure and altered mental status. Finally, Class IV hemorrhage occurs when more than 40% of blood volume is lost. At this stage, the patient may experience a significantly decreased or absent urine output and a very high heart rate. It is important to note that a patient can lose more than 30% of their blood volume before their vital signs or consciousness change.

There are two large categories of causes for internal bleeding: traumatic and non-traumatic. Trauma is a leading cause of death, accounting for 1.5 million of the 1.9 million annual deaths caused by bleeding. Penetrating trauma, such as a stab wound or a ballistic injury, is the most common cause of vascular injury. Blunt trauma is another cause, which can occur during high-speed deceleration in an automobile accident. Non-traumatic causes include pathological conditions or diseases. For example, high blood pressure can cause a blood vessel to rupture. Other causes include aneurysms, peptic ulcers, or an ectopic pregnancy. Diseases like cancer, hematologic disease, or Vitamin K deficiency can also lead to bleeding. Even rare viral hemorrhagic fevers, such as Ebola, Dengue, or Marburg, are linked to this condition.

Identifying the source of internal bleeding requires careful observation and testing. Doctors look for visible signs such as bruising, known as ecchymosis, or a blood collection called a hematoma. They may also check for blood in the urine, dark black stools, or bright red stools. Other symptoms include lightheadedness, fatigue, confusion, and thirst. To find the bleeding, medical teams assess circulation through palpation of pulses or doppler ultrasonography. For suspected bleeding in the abdomen, a FAST exam may be performed. If a patient's vital signs are stable, they may undergo a CT scan. However, if the patient is unstable, they may need immediate surgery instead of diagnostic imaging.

Treatment focuses on two goals: replacing lost fluids and achieving hemostasis, which means stopping the bleeding. Because most internal bleeding cannot be stopped with direct pressure, medical intervention is vital. For patients with low blood pressure, doctors use intravenous fluids or a blood transfusion. If a patient requires more than 4 units of blood in one hour, clinicians initiate a massive transfusion protocol. This protocol replaces red blood cells, plasma, and platelets in specific ratios. In the abdomen or pelvis, doctors may use a REBOA device to slow the bleeding. For bleeding in the arms or legs, a tourniquet may be used. At "junctional sites" like the groin or armpit, doctors may use an Abdominal Aortic and Junctional Tourniquet (AAJT) or special hemostatic dressings.

Internal bleeding is deeply connected to how we understand trauma care and emergency medicine. The speed of treatment is critical for survival. For example, a patient with acute internal bleeding in the thorax after trauma should be diagnosed and stabilized in the Emergency Department in less than 10 minutes. The longer it takes to achieve hemostasis for causes like a pelvic fracture or a ruptured abdominal aortic aneurysm, the higher the death rate becomes. This highlights the importance of rapid response systems in hospitals and the ongoing work of campaigns like "Stop The Bleed" to improve care for all types of injuries.