Disseminated intravascular coagulation and thrombotic thrombocytopenic purpura/hemolytic uremic syndrome

Disseminated intravascular coagulation

Thrombotic thrombocytopenic purpura/hemolytic uremic syndrome

Meningococcemia, pneumococcemia, staphylococcemia, gonococcemia

Rocky Mountain spotted fever

Immune thrombocytopenic purpura

Henoch–Schönlein purpura

Hemorrhagic drug reaction

Stevens–Johnson syndrome/toxic epidermal necrolysis

Viral hemorrhagic fever (Hanta, Lassa, dengue)

Table 49.2. Conditions associated with DIC

Severe infection/sepsis

Trauma (including neurotrauma)

Solid and myeloproliferative malignancies

Transfusion reactions

Rheumatological conditions (adult-onset Still’s disease, systemic lupus erythematosus)

Obstetric complications (amniotic fluid embolism, abruptio placentae, HELLP, eclampsia)

Vascular abnormalities (Kasabach–Merritt syndrome, large vascular aneurysms)

Liver failure

Envenomations

Hyperthermia/heatstroke

Hemorrhagic skin necrosis (purpura fulminans)

Transplant rejection

HELLP, hemolysis, elevated liver enzymes, and low platelet count.

DIC develops 6–48 hours after a physiological insult. Many of the patients developing this condition are already hospitalized.
Patients will have diffuse petechiae, purpura, bleeding from their mucous membranes, and oozing from intravenous or surgical sites.
Laboratory investigations will show:
- Thrombocytopenia
- Anemia
- Increased international normalized ratio (INR), prothrombin time (PT), and activated partial thromboplastin time (aPTT)
- Increased D-dimer
- Increased fibrin split products (FSP)
- Decreased fibrinogen (may be normal since fibrinogen is an acute-phase reactant).

Patients with DIC may present with life-threatening conditions associated with a coagulopathy:
- Pericardial tamponade
- Massive gastrointestinal bleeding
- Pulmonary hemorrhage
- Intracranial hemorrhage.
They may also present with life-threatening conditions attributed to a hypercoagulable state:
- Cerebrovascular accident (CVA)
- Mesenteric ischemia and thrombosis
- Venous thromboembolic events (VTEs) such as pulmonary embolus (PE) or deep vein thrombosis (DVT).

The classic presentation of TTP involves a pentad of symptoms that include fever, neurological signs, anemia, thrombocytopenia, and renal dysfunction. This collection of symptoms is only seen in 20–30% of cases and it is strongly recommended to suspect the condition and manage it as such if a patient exhibits three or more of those features (Table 49.3).
The disease is termed HUS when renal failure predominates over neurological symptoms.
HUS is most commonly seen in children and often follows an infectious illness, usually diarrhea. It is classically associated with E. coli O157:H7.

Table 49.3. Symptoms associated with TTP

Finding	Mechanism
Fever	Acute-phase reaction
Altered mental status	From cerebral microvascular thrombosis
Anemia	From MAHA and thrombosis
Thrombocytopenia	From direct platelet activation
Renal dysfunction	From renal microvascular thrombosis