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amniotic fluid embolism

Epidemiology: 1) rare, 1 case per 8,000-30,000 pregnancies 2) occurs in full-term pregnancy in a multiparous patients 3) induction of labor doubles risk [2] Pathology: 1) tears in both fetal membranes & uterine veins 2) circulatory collapse may occur when amniotic fluid reaches lungs 3) respiratory distress & shock followed in 3- minutes to 4 hours by disseminated intravascular coagulation (DIC) 4) intense fibrinolysis may accompany or follow the DIC Clinical manifestations: 1) occurs during labor, during labor, cesarean delivery, dilation & evacuation, or within 30 minutes postpartum 2) has also occurred during abortion, after abdominal trauma, & during amnioinfusion 3) acute hypotension or cardiac arrest 4) acute hypoxia, dyspnea 5) coagulopathy or severe hemorrhage in the absence of other explanations 6) seizure: tonic clonic seizures are seen in 50% of patients 7) cough: generally a manifestation of dyspnea 8) cyanosis: as hypoxia/hypoxemia progresses, circumoral & peripheral cyanosis & changes in mucous membranes may occur 9) fetal bradycardia: in response to the hypoxic insult, fetal heart rate may drop to less than 110 beats per minute (bpm) 10) pulmonary edema: generally identified on chest radiograph. 11) cardiac arrest 12) uterine atony: results in excessive bleeding after delivery 13) may often be subclinical 14) rarely, may be catastrophic Laboratory: 1) arterial blood gas (ABG) a) changes consistent with hypoxia/hypoxemia b) decreased pH c) decreased pO2 d) increased pCO2 e) base excess increased 2) complete blood count (CBC) with platelets a) hemoglobin & hematocrit levels generally normal b) hrombocytopenia is rare 3) prothrombin time & activated partial thromboplastin time a) prothrombin time (PT) is prolonged because clotting factors are used up b) activated partial thromboplastin time (aPTT) may be normal or shortened 4) blood type & screen in anticipation of blood transfusion Special laboratory: - ECG may show tachycardia, ST segment & T-wave changes, & findings consistent with right ventricle strain. Radiology: - chest radiograph posteroanterior & lateral, generally nonspecific, but evidence of pulmonary edema may be observed. Management: 1) treatment is supportive a) administer oxygen to maintain normal saturation b) intubate if necessary c) treat shock d) consider pulmonary artery catheterization in patients who are hemodynamically unstable e) continuously monitor the fetus f) treat coagulopathy with FFP for a prolonged aPTT, cryoprecipitate for a fibrinogen level less than 100 mg/dL, & transfuse platelets for platelet counts less than 20,000/uL 2) fibrinolytic inhibitors a) epsilon-amino-caproic acid b) tranexamic acid 3) Surgery a) emergent cesarean delivery in arrested mothers who are unresponsive to resuscitation 4) follow-up a) women who survive AFE will probably require ICU admission b) left heart failure is a common late occurrence c) survivors will probably have neurologic sequelae - consult neurologists as needed

Related

amniotic fluid pulmonary embolism (PE)

General

pregnancy disorder; obstetric disorder; pregnancy complication embolism

References

  1. Medical Knowledge Self Assessment Program (MKSAP) 11, American College of Physicians, Philadelphia 1998
  2. Kramer MS et al, Amniotic-fluid embolism and medical induction of labour: A retrospective, population-based cohort study. Lancet 2006, 368:1444 PMID: 17055946 - Moore J, Amniotic fluid embolism: On the trail of an elusive diagnosis. Lancet 2006, 368:1399 PMID: 17055926
  3. eMedicine: Amniotic fluid embolism http://www.emedicine.com/Med/topic122.htm