STEP 1 — MCQs (NO answers here)

MCQ 1 — Core Definition

DIC is best defined as:

a. A hereditary coagulation factor deficiency

b. Systemic activation of coagulation with microthrombi in microcirculation

c. Localized venous thrombosis

d. Isolated platelet destruction

e. Purely a fibrinolytic disorder

MCQ 2 — Dual Clinical Nature

DIC can present as:

a. Only thrombosis

b. Only bleeding

c. Both widespread microthrombi and a bleeding disorder

d. Only anemia

e. Only hemolysis

MCQ 3 — “Consumptive Coagulopathy”

The term “consumptive coagulopathy” refers to:

a. Consumption of RBCs causing anemia

b. Consumption of platelets and coagulation factors during uncontrolled clotting

c. Consumption of vitamin K

d. Consumption of fibrin split products

e. Consumption of albumin

MCQ 4 — Frequency Compared to Congenital Disorders

DIC:

a. Is rarer than all congenital coagulation disorders combined

b. Causes bleeding less often than hemophilia A

c. Probably causes bleeding more often than all congenital coagulation disorders combined

d. Never causes bleeding

e. Is purely asymptomatic

MCQ 5 — Two Main Triggers

DIC is usually triggered by:

a. Hypercalcemia and anemia

b. Release of tissue factor or widespread endothelial injury

c. Isolated thrombocytopenia

d. Hyperlipidemia

e. Hypoglycemia

MCQ 6 — Extrinsic vs Intrinsic Pathway

Which statement is correct?

a. Only the intrinsic pathway is involved in DIC

b. Only the extrinsic pathway is involved in DIC

c. Either extrinsic (tissue factor) or intrinsic (factor XII activation) pathway can initiate clotting, both converge on thrombin

d. DIC does not involve thrombin

e. Fibrinolysis is not activated in DIC

MCQ 7 — Normal Limiting Factors of Coagulation

Under normal conditions, coagulation is limited by all EXCEPT:

a. Clearance of activated factors by macrophages and liver

b. Endogenous anticoagulants (e.g., protein C)

c. Activation of fibrinolysis

d. Continual massive tissue factor release

e. Thrombomodulin activity

MCQ 8 — Common Sources of Tissue Factor in DIC

Important tissue factor sources in DIC include all EXCEPT:

a. Placenta in obstetric complications

b. Certain cancer cells (acute promyelocytic leukemia, adenocarcinomas)

c. Amniotic fluid

d. Normal resting endothelium

e. Monocytes stimulated by endotoxin

MCQ 9 — Cytokines and Endothelium

IL-1 and TNF contribute to DIC mainly by:

a. Increasing thrombomodulin expression

b. Stimulating endothelial tissue factor expression and decreasing thrombomodulin

c. Inhibiting tissue factor

d. Completely blocking thrombin formation

e. Stimulating albumin synthesis

MCQ 10 — Endothelial Injury Causes

Widespread endothelial injury that can cause DIC may be due to all EXCEPT:

a. Immune complex deposition (e.g., SLE)

b. Temperature extremes (heat stroke, burns)

c. Infections (meningococci, rickettsiae)

d. Systemic inflammatory response syndrome (SIRS)

e. Simple mild dehydration only

MCQ 11 — Major Clinical Settings

DIC is most often associated with:

a. Iron deficiency and hyperthyroidism

b. Sepsis, obstetric complications, malignancy, and major trauma (especially brain)

c. Asthma and COPD

d. Isolated hypertension

e. Simple varicose veins

MCQ 12 — Microvascular Consequences

Widespread fibrin deposition in microcirculation leads to:

a. Hyperperfusion of organs

b. Ischemia, microinfarcts, and microangiopathic hemolytic anemia

c. Only edema

d. Only petechiae without organ damage

e. Purely venous congestion

MCQ 13 — Bleeding Mechanism in DIC

Bleeding in DIC is largely due to:

a. Isolated platelet overproduction

b. Depletion of platelets and clotting factors and activation of fibrinolysis

c. Isolated factor VIII deficiency

d. Lack of fibrinogen breakdown

e. High vitamin K levels

MCQ 14 — Plasmin Effects

Plasmin in DIC:

a. Only breaks down fibrin

b. Breaks down fibrin and also degrades factors V and VIII

c. Has no role in DIC

d. Only enhances platelet aggregation

e. Inhibits fibrinolysis

MCQ 15 — Fibrin Degradation Products (FDPs)

Fibrin degradation products in DIC:

a. Enhance platelet aggregation

b. Inhibit platelet aggregation, have antithrombin activity, and impair fibrin polymerization

c. Have no effect on hemostasis

d. Only cause vasoconstriction

e. Only increase thrombin activity

MCQ 16 — Acute vs Chronic DIC Pattern

Acute DIC (e.g., obstetric) is typically dominated by:

a. Thrombosis

b. Bleeding

c. Only hemolysis

d. Asymptomatic lab changes

e. Hypertension

Chronic DIC (e.g., in cancer) tends to show:

a. Predominantly thrombosis-related manifestations

b. Pure bleeding without thrombosis

c. Only anemia

d. Only renal failure

e. No clinical expression

MCQ 17 — Common Clinical Presentations

The onset of DIC is most often heralded by:

a. Sudden hypertension

b. Jaundice

c. Prolonged postpartum bleeding or appearance of petechiae/ecchymoses

d. Isolated arthralgia

e. Purely neurological symptoms

MCQ 18 — Laboratory Findings

Typical lab findings in DIC include:

a. Thrombocytosis, normal PT, normal PTT

b. Thrombocytopenia, prolonged PT and PTT, increased fibrin split products

c. Normal platelets, prolonged PT only

d. Normal tests

e. Only increased fibrinogen

MCQ 19 — Prognosis and Therapy

Which statement is TRUE regarding treatment?

a. Acute DIC is trivial and self-limited

b. Acute DIC can be life-threatening and may require heparin or replacement with fresh frozen plasma

c. Chronic DIC never needs treatment

d. Treating the underlying cause is not important

e. Antiplatelet drugs alone cure all DIC

MCQ 20 — Morphology: Organ Involvement

Microthrombi in DIC are most often found in arterioles and capillaries of:

a. Kidneys, adrenals, brain, heart

b. Skin only

c. Muscles only

d. Intestine only

e. Joints only

MCQ 21 — Severe Renal Involvement

Severe DIC in kidneys can cause:

a. Simple hematuria only

b. Bilateral renal cortical necrosis

c. Medullary cysts only

d. Hydronephrosis

e. Nephrotic syndrome alone

MCQ 22 — Named Syndromes

Which of the following are classic complications of DIC due to involvement of specific organs?

a. Marfan and Ehlers-Danlos syndromes

b. Waterhouse-Friderichsen and Sheehan postpartum pituitary necrosis

c. Klinefelter and Turner syndromes

d. Cushing syndrome and Addison disease

e. Only Libman-Sacks endocarditis

STEP 2 — ANSWERS + SHORT EXPLANATIONS

MCQ 1 — b

DIC = systemic activation of coagulation with widespread microthrombi in microcirculation.

MCQ 2 — c

DIC gives both:

• Microthrombi → tissue hypoxia, microinfarcts
• Bleeding → consumptive coagulopathy + fibrinolysis

MCQ 3 — b

“Consumptive” = platelets and clotting factors are used up by uncontrolled clotting.

MCQ 4 — c

DIC probably causes more bleeding than all congenital coagulation disorders combined.

MCQ 5 — b

Two main triggers:

• Tissue factor release
• Widespread endothelial injury

MCQ 6 — c

Both extrinsic (tissue factor) and intrinsic (factor XII) can initiate → both pathways converge on thrombin formation.

MCQ 7 — d

Normal limiting factors: clearance, anticoagulants, fibrinolysis, thrombomodulin. Continual massive tissue factor release is actually a DIC trigger, not a limiter.

MCQ 8 — d

Tissue factor sources: placenta, cancer cells, amniotic fluid, monocytes (via endotoxin). Normal quiescent endothelium does not release TF.

MCQ 9 — b

IL-1 and TNF: ↑ tissue factor on endothelium, ↓ thrombomodulin → more thrombin, less protein C activation.

MCQ 10 — e

Endothelial injury causes: immune complexes (SLE), heat stroke/burns, infections (meningococci, rickettsiae), SIRS. Simple mild dehydration is not one of them.

MCQ 11 — b

Classic associations: sepsis, obstetric complications, malignancy, major trauma (especially brain).

MCQ 12 — b

Widespread fibrin → ischemia, microinfarcts, and RBC damage → microangiopathic hemolytic anemia.

MCQ 13 — b

Bleeding from platelet and factor depletion + plasmin activation (fibrinolysis).

MCQ 14 — b

Plasmin cleaves fibrin and also factors V and VIII → worsens coagulation factor depletion.

MCQ 15 — b

Fibrin degradation products (FDPs) inhibit platelet aggregation, have antithrombin effect, and impair fibrin polymerization.

MCQ 16 — b / a

• Acute DIC (e.g., obstetric) → dominated by bleeding.
• Chronic DIC (e.g., cancer) → tends to show thrombosis-related manifestations.

MCQ 17 — c

Often first noticed as prolonged postpartum bleeding or petechiae/ecchymoses.

MCQ 18 — b

Labs: thrombocytopenia, prolonged PT and PTT, increased fibrin split products.

MCQ 19 — b

Acute DIC can be life-threatening → treat with heparin or FFP, and always treat underlying cause.

MCQ 20 — a

Microthrombi: especially in kidneys, adrenals, brain, heart, but no organ is spared.

MCQ 21 — b

Severe renal involvement → bilateral renal cortical necrosis.

MCQ 22 — b

Named complications:

• Waterhouse-Friderichsen (adrenal hemorrhagic necrosis)
• Sheehan postpartum pituitary necrosis (anterior pituitary).

STEP 3 — HIGH-YIELD NOTES (EXAM-READY)

1. Core Concept

• DIC = systemic activation of coagulation → widespread fibrin microthrombi in microcirculation.
• Dual effect:
• Thrombosis → tissue hypoxia, microinfarcts, organ dysfunction.
• Bleeding → from consumption of platelets/factors + fibrinolysis.
• Called “consumptive coagulopathy” because platelets and clotting factors are used up.
• Clinically, DIC likely causes more bleeding than all congenital coagulation disorders combined.

2. Pathogenesis: How DIC Starts

Two main triggers:

1. Release of tissue factor / thromboplastic substances
• Placenta (obstetric complications).
• Cancer cells — especially acute promyelocytic leukemia, adenocarcinomas.
• Amniotic fluid.
• Monocytes stimulated by endotoxin/exotoxin in sepsis.
2. Widespread endothelial injury
• Immune complex deposition (e.g., SLE).
• Temperature extremes (heat stroke, burns).
• Severe infections (meningococci, rickettsiae).
• SIRS (systemic inflammatory response syndrome) in sepsis or major systemic insults.

Mechanisms:

• IL-1 and TNF:
• ↑ tissue factor on endothelium.
• ↓ thrombomodulin → less protein C activation.
• Net result:
• More thrombin generation.
• Blunting of normal anticoagulant pathways.

3. Thrombosis + Bleeding Mechanism

A. Thrombotic Component

• Widespread fibrin deposition within small vessels (arterioles, capillaries).
• Consequences:
• Microvascular occlusion → ischemia, microinfarcts in vulnerable organs.
• RBCs damaged in narrowed fibrin-lined vessels → microangiopathic hemolytic anemia.

B. Bleeding Component

• Platelets and clotting factors are consumed → thrombocytopenia, low clotting factors.
• Fibrinolysis is secondarily activated:
• Plasmin cleaves:
• Fibrin → fibrin degradation products.
• Factors V and VIII → further depletion.
• Fibrin degradation products:
• Inhibit platelet aggregation.
• Have antithrombin effects.
• Impair fibrin polymerization.
• Outcome: hemostatic failure → bleeding.

🌡️ DIC — Pathogenesis Flowchart (Arrow Style)

Triggers of DIC

→ Release of tissue factor / thromboplastic substances

(placenta, amniotic fluid, APL, adenocarcinoma, endotoxin-activated monocytes)

OR

→ Widespread endothelial injury

(SLE immune complexes, burns, heat stroke, severe infections, SIRS)

↓

IL-1 & TNF effects

→ ↑ Tissue factor expression

→ ↓ Thrombomodulin → ↓ Protein C activation

↓

Procoagulant shift

→ Increased thrombin generation

→ Suppressed anticoagulant pathways

↓

Widespread fibrin deposition in small vessels

↓

Microvascular thrombosis

→ Ischemia

→ Microinfarcts

↓

RBC shearing in fibrin-lined vessels

→ Microangiopathic hemolytic anemia

↓

Consumption of platelets + clotting factors

→ Thrombocytopenia

→ Low clotting factor levels

↓

Secondary fibrinolysis increases

→ Plasmin cleaves fibrin, Factor V, Factor VIII

→ Fibrin degradation products:

→ inhibit platelet aggregation

→ have antithrombin effects

→ impair fibrin polymerization

↓

Final outcome: Thrombosis + Bleeding (hemostatic failure)

4. Major Clinical Settings

DIC commonly associated with:

• Sepsis (gram-positive and gram-negative).
• Obstetric complications:
• Placental abruption.
• Retained dead fetus.
• Amniotic fluid embolism.
• Malignancy, especially:
• Acute promyelocytic leukemia.
• Adenocarcinomas (mucin, TF).
• Major trauma, particularly brain trauma (fat and phospholipids activate intrinsic pathway).

5. Clinical Features

• Acute DIC:
• Often in obstetric or major trauma settings.
• Dominant feature: bleeding.
• Clinical picture:
• Postpartum hemorrhage.
• Petechiae, ecchymoses.
• GI or urinary tract bleeding.
• Shock, acute renal failure, dyspnea, cyanosis, convulsions, coma in severe cases.
• Chronic DIC:
• Often in malignancy.
• Dominant feature: thrombosis (recurrent microthrombi).
• May be detected incidentally by abnormal labs.

Laboratory Findings

• Thrombocytopenia.
• Prolonged PT and PTT.
• Decreased fibrinogen (often).
• Increased fibrin split products (FDPs, D-dimers).

6. Prognosis and Treatment

• Prognosis:
• Depends on underlying cause and severity of coagulation/fibrinolysis.
• Acute DIC may be rapidly fatal if not controlled.
• Management:
• Always treat the underlying cause (sepsis, retained placenta, tumor, trauma).
• Supportive:
• Fresh frozen plasma (replace factors).
• Platelets if needed.
• In acute DIC with predominant thrombosis, heparin may be used cautiously.

7. Morphology

• Microthrombi most often in kidneys, adrenals, brain, heart, but can affect any organ.

Kidneys

• Glomeruli: small fibrin thrombi.
• May show:
• Endothelial swelling.
• Focal glomerulitis.
• Small cortical infarcts.
• Severe: bilateral renal cortical necrosis.

Adrenals

• Involvement may cause Waterhouse-Friderichsen syndrome:
• Massive adrenal hemorrhage and necrosis.
• Associated with severe meningococcal sepsis.

Brain

• Microinfarcts ± hemorrhage.
• Leads to neurologic signs (often bizarre or multifocal).

Anterior pituitary

• DIC may contribute to Sheehan postpartum pituitary necrosis.

Skin and Mucosa

• Petechiae and ecchymoses:
• Skin.
• Serosal surfaces (pleura, pericardium, peritoneum).
• Lungs.
• Urinary tract mucosa.

DISSEMINATED INTRAVASCULAR COAGULATION (DIC) — COMPLETE MASTER TABLE