Hemorrhage - Types & Classification

Hemorrhage is defined as the escape (extravasation) of blood from the cardiovascular system into tissues, tissue layers, or body cavities. It results from vessel damage and is worsened by defects in clotting.

1. Classification by Origin (Source Vessel)

Type	Characteristics
Capillary	Oozing from small vessels; common in contusions, congestion
Venous	Steady, dark red flow; less pressure than arterial
Arterial	Bright red, pulsatile, forceful; most dangerous
Cardiac	From heart itself (e.g., rupture of ventricle post-MI)

The Essentials of Forensic Medicine and Toxicology (36th ed.), p. 299

2. Classification by Location

External Hemorrhage

Blood exits the body surface. Dangerous if a large vessel is involved - partial transection of an artery prevents vessel retraction, so bleeding is often worse. Sudden loss is more dangerous than slow loss, as the body cannot compensate quickly enough.

Internal Hemorrhage

Blood accumulates inside body cavities or tissues. Named by location:

Term	Location
Hemothorax	Pleural cavity
Hemopericardium	Pericardial sac
Hemoperitoneum	Peritoneal cavity
Hemarthrosis	Joint space
Hematoma	Localized clotted blood in a tissue (any site)

Internal bleeds do not cause iron deficiency anemia because iron is efficiently recycled from phagocytosed red cells.

Robbins & Kumar Basic Pathology, p. 82

3. Classification by Cause

Type	Definition
Traumatic hemorrhage	Bleeding due to wounds (lacerations, fractures, penetrating injuries)
Spontaneous hemorrhage	Bleeding without trauma - due to hemorrhagic diatheses, vascular disease, neoplasm, inflammation
Primary hemorrhage	Occurs at the time of injury
Secondary (Reactionary) hemorrhage	Delayed - occurs hours to >24 hours after injury due to: rise in BP on recovery from shock, muscular movement dislodging a clot, or vessel wall erosion from infection

4. Classification by Morphology / Size

This is the most clinically used morphological classification:

Petechiae

Size: 1-2 mm
Pin-point hemorrhages into skin, mucous membranes, or serosal surfaces
Caused by: thrombocytopenia, platelet dysfunction, loss of vascular wall support (e.g., scurvy)
Origin: capillary or venular

FIG. 3.4A - Punctate petechial hemorrhages of the colonic mucosa, a consequence of thrombocytopenia

Purpura

Size: 3-5 mm
Caused by: same as petechiae, plus trauma, vasculitis, increased vascular fragility

Ecchymoses

Size: 1-2 cm
Subcutaneous hematomas - colloquially "bruises"
Color changes over time reflect hemoglobin breakdown:
- Red-blue (fresh) → hemoglobin
- Blue-green → biliverdin/bilirubin
- Golden-brown → hemosiderin
Phagocytosed and degraded by macrophages

Hematoma

A localized, usually clotted collection of blood within a tissue forming a tumor-like swelling
Range from trivial (bruise) to fatal (retroperitoneal hematoma from ruptured aortic aneurysm)

Apoplexy

Large effusion of blood into an organ
Term commonly used for cerebral hemorrhage

FIG. 3.4B - Fatal intracerebral hemorrhage showing a large dark hematoma displacing brain tissue

5. Factors Determining Clinical Impact

The significance of a hemorrhage depends on four key variables:

Volume lost - rapid loss of >20% blood volume causes hypovolemic shock even in healthy adults; up to 20% may be tolerated well
Rate of bleeding - sudden loss is more dangerous than equivalent slow loss
Location - trivial in subcutaneous tissue, fatal in the brain (as shown above)
Health of the individual - those with heart/lung disease decompensate at lower volumes

Summary Diagram of Classification

HEMORRHAGE
│
├── By VESSEL SOURCE → Capillary / Venous / Arterial / Cardiac
│
├── By LOCATION → External / Internal (Hematoma, Hemothorax, Hemopericardium,
│                                       Hemoperitoneum, Hemarthrosis)
│
├── By CAUSE → Traumatic / Spontaneous
│              Primary / Secondary (reactionary)
│
└── By MORPHOLOGY → Petechiae (1-2mm) → Purpura (3-5mm) 
                    → Ecchymosis (1-2cm) → Hematoma → Apoplexy

Sources:

Robbins & Kumar Basic Pathology - pp. 82-83 (morphological classification, clinical impact)
The Essentials of Forensic Medicine and Toxicology, 36th ed. (2026) - p. 299 (vessel-source classification, primary/secondary hemorrhage)

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