Pathology · Year 2 · from Pathology
Case 3: Disseminated Intravascular Coagulation (DIC)
Patient Demographics
- Age: 45 years old
- Sex: Female
- Occupation: Elementary school teacher
Chief Complaint
"High fever, confusion, and bleeding from IV sites"
History of Present Illness
A 45-year-old woman was admitted 2 days ago for community-acquired pneumonia. Despite initial improvement on antibiotics, she acutely deteriorated with spiking fevers to 40°C, altered mental status, and hypotension. The nursing staff notes she is bleeding from IV sites and has developed bruising. She has petechiae on her chest and arms. Her urine output has dropped significantly over the past 6 hours. She has no prior history of bleeding disorders.
Physical Examination
- Vital Signs: BP 78/42 mmHg (on vasopressors), HR 128 bpm, RR 32/min, Temp 39.8°C (103.6°F), SpO2 89% on 100% FiO2
- General: Critically ill, intubated, sedated
- Skin: Diffuse petechiae, ecchymoses at IV sites and blood pressure cuff site, acral cyanosis of fingers and toes
- Cardiovascular: Tachycardic, weak peripheral pulses
- Lungs: Coarse breath sounds bilaterally, requiring mechanical ventilation
- Abdomen: Distended, decreased bowel sounds
- Extremities: Cool, mottled, cyanotic digits bilaterally
Diagnostic Workup
Laboratory Studies:
| Test | Result | Reference Range |
|---|---|---|
| WBC | 2,100/μL | 4,500-11,000/μL |
| Hemoglobin | 8.2 g/dL | 12-16 g/dL |
| Platelets | 28,000/μL | 150,000-400,000/μL |
| PT | 28 seconds | 11-15 seconds |
| INR | 2.6 | 0.8-1.2 |
| PTT | 68 seconds | 25-35 seconds |
| Fibrinogen | 85 mg/dL | 200-400 mg/dL |
| D-dimer | >20,000 ng/mL | <500 ng/mL |
| Lactate | 8.2 mmol/L | 0.5-2.0 mmol/L |
| Creatinine | 3.4 mg/dL | 0.7-1.3 mg/dL |
Peripheral Blood Smear:
- Schistocytes (fragmented RBCs)
- Decreased platelets
- Left shift with toxic granulations in neutrophils
Imaging:
- Chest X-ray: Bilateral diffuse infiltrates consistent with ARDS
Microbiology:
- Blood cultures: Gram-negative rods (later identified as Streptococcus pneumoniae)
Pathology Correlation
This case demonstrates Disseminated Intravascular Coagulation (DIC):
- Pathophysiology:
- Massive tissue factor release from sepsis triggers coagulation cascade
- Widespread fibrin deposition in microvasculature
- Consumption of platelets and clotting factors
- Secondary fibrinolysis generates D-dimer
- Paradox of simultaneous thrombosis AND bleeding
- Laboratory Findings:
- Thrombocytopenia: Platelets consumed in microthrombi
- Prolonged PT/PTT: Clotting factors consumed
- Low fibrinogen: Converted to fibrin and degraded
- Elevated D-dimer: Indicates fibrinolysis of clots
- Schistocytes: RBCs sheared by fibrin strands
- Clinical Manifestations:
- Bleeding: Petechiae, oozing from puncture sites (consumption of factors)
- Thrombosis: Acral cyanosis, organ ischemia (microvascular occlusion)
- Organ failure: Kidney, lung, liver damage from microthrombi
- Underlying Causes:
- Sepsis (most common) - endotoxin/tissue factor
- Obstetric complications - amniotic fluid, placental abruption
- Malignancy - procoagulant factors
- Massive trauma - tissue factor release
Clinical Image
Peripheral blood smear from a patient with DIC demonstrating schistocytes (fragmented red blood cells, arrows). These helmet-shaped and triangular RBC fragments result from mechanical shearing as red cells pass through fibrin strands deposited in the microvasculature. The presence of schistocytes indicates microangiopathic hemolytic anemia.
Image Source: Wikimedia Commons - "Schistocytes" License: CC BY-SA 4.0 URL: https://commons.wikimedia.org/wiki/File:Schistocytes_in_DIC.jpg
Diagnosis
Septic Shock with Disseminated Intravascular Coagulation secondary to Streptococcus pneumoniae bacteremia
Treatment
- Treat underlying cause: Broad-spectrum antibiotics, source control
- Hemodynamic support: IV fluids, vasopressors (norepinephrine)
- Component replacement:
- Platelet transfusion (keep >50,000 if bleeding)
- Fresh frozen plasma (replace clotting factors)
- Cryoprecipitate (replace fibrinogen, target >100 mg/dL)
- Packed RBCs for anemia
- Respiratory support: Mechanical ventilation for ARDS
- Renal support: Continuous renal replacement therapy if needed
- Do NOT give anticoagulation in acute bleeding DIC
Teaching Points
- DIC is always secondary to an underlying condition - treat the cause
- The paradox of DIC is simultaneous thrombosis and bleeding
- Schistocytes on blood smear indicate microangiopathic hemolysis
- D-dimer is markedly elevated due to fibrinolysis
- Fibrinogen drops as it is converted to fibrin and degraded
- Sepsis is the most common cause of DIC in hospitalized patients
- The coagulation cascade is triggered by tissue factor released during sepsis
- Multi-organ failure results from widespread microvascular thrombosis