Cause:
2 requirements: 1) reticuloendothelial system blockade by pregnancy, endotoxin, radiation, steroids, colloid, and 2) clotting system activated by:
Pathophys:Fibrinogen is low due to consumption and rapid lysis; tissue damage esp in CNS, lung, and kidneys from thrombotic ischemia
More common than TTP. Increased incidence in OB esp with septic abortions, abruptio, eclampsia, mole, amniotic fluid embolus, missed abortion, retained dead fetus, fatty liver of pregnancy (Ann IM 1983;98:330); leukemias, cancers, and all cases of severe tissue damage; freshwater drownings; gram-negative sepsis
Sx:Bleeding, coma; fever only if there is a secondary cause of fever, unlike TTP
Si:Palpable purpuric rash (r/o allergic vasculitis); shock, hypotension; oozing/bleeding at all sites
Renal cortical necrosis, ATN, Sheehan's syndrome, acute cor pulmonale, adrenal insufficiency (rarely fatal)
r/o other microangiopathic anemias: TTP, HELP, HUS, malignant HT, and chemoRx-induced types
Lab:
Hem: Smear shows microangiopathic anemia with helmets and other fragments. Platelets <100 000. ESR = 0 (afibrinogenemia). PT, very sensitive (R. Hillman 3/86), and PTT prolonged. Fibrinogen <40 mg %; low levels of II (hence PT long), VIII, V (<50% is diagnostic). Fibrin split products (D-dimers) markedly elevated; prolonged thrombin time. Elevated antithrombin III (Hillman 3/86)
Urine:Hematuria, isosmolar anuria late when ATN develops
Rx:Treat primary problem; replace factors, eg, fresh-frozen plasma and platelets; perhaps heparinize at low doses like 300-400 U/h or w LMW heparin, possibly antithrombin III, to break the consumption cycle; never do so in face of liver disease, and only as a last resort if chronic cause and uncontrollable bleeding
Of snake bite: antivenom repeatedly to reverse DIC