A 35-year-old woman, gravida 1 para 0, at 40 weeks gestation has a protracted labor course for which a cesarean delivery is performed under epidural anesthesia. Shortly after delivery, the patient has chest pain and difficulty breathing. She becomes hypotensive, bradycardic, hypoxic, and unresponsive, and undergoes emergency intubation. The surgical incisions begin to bleed profusely and the patient goes into cardiorespiratory arrest. She is declared dead after 30 minutes of cardiopulmonary resuscitation. The family agrees to an autopsy. Which of the following is the most likely finding during histologic evaluation of her lungs?

Question

A 35-year-old woman, gravida 1 para 0, at 40 weeks gestation has a protracted labor course for which a cesarean delivery is performed under epidural anesthesia.  Shortly after delivery, the patient has chest pain and difficulty breathing.  She becomes hypotensive, bradycardic, hypoxic, and unresponsive, and undergoes emergency intubation.  The surgical incisions begin to bleed profusely and the patient goes into cardiorespiratory arrest.  She is declared dead after 30 minutes of cardiopulmonary resuscitation.  The family agrees to an autopsy.  Which of the following is the most likely finding during histologic evaluation of her lungs?

Quizplus · Accepted Answer

11ec160b_3b1b_0373_9249_e57ba17f7b45_MD0001_00 This patient's presentation is classic for amniotic fluid embolism (AFE), a rare but catastrophic complication that can occur during pregnancy or shortly after delivery. Amniotic fluid containing arachidonic acid metabolites is thought to enter the maternal circulation through sites of uterine trauma or cervical lacerations; this results in an anaphylactoid reaction (caused by the metabolites). Amniotic fluid causes occlusion and vasospasm of the maternal pulmonary circulation, leading to left ventricular failure, decreased cardiac output, and a severe ventilation-perfusion mismatch. The resultant hypoxia and hypotensive shock may ultimately cause cardiopulmonary arrest. Tissue factor (thromboplastin) is also released from amniotic fluid and triggers disseminated intravascular coagulation, as seen in this patient. On autopsy, histology shows fetal squamous cells and mucin in the maternal pulmonary arteries. (Choice A) The hallmark of acute respiratory distress syndrome (ARDS) is the presence of hyaline membranes (red arrow) lining the alveolar ducts. ARDS is usually the result of alveolar injury from sepsis, trauma, or pneumonia and presents with cough, dyspnea, and diffuse crackles. ARDS can develop after AFE but usually in patients who survive the early acute phase of AFE, which this patient did not. (Choice B) Emphysema is a type of chronic obstructive pulmonary disease usually caused by smoking. Alveolar wall destruction results in permanent air space enlargement (red arrows) and symptoms such as exertional dyspnea, chronic cough, and sputum production. This patient's condition was acute with no sputum production. (Choice C) Aspiration pneumonia most commonly involves the lower lobe of the right lung. Histology shows inflammation and a foreign body response with giant cells. Risk factors for aspiration of gastric contents include recumbent position with impaired consciousness (eg, general anesthesia). Symptoms include hypoxia, but patients usually have fever and focal crackles. (Choice D) A fractured bone (eg, femur, pelvis) can release lipid globules into the pulmonary vasculature, resulting in fat embolism syndrome. The syndrome may present with hypoxemia, tachypnea, dyspnea, and a petechial rash 1-3 days after the orthopedic injury and is not an obstetric complication. Educational objective: Amniotic fluid embolism (AFE) is a rare and catastrophic pregnancy complication that results from amniotic fluid entering the maternal circulation. Common signs of AFE include hypoxia, hypotensive shock, and disseminated intravascular coagulation. Fetal squamous cells are seen in the pulmonary vasculature during histologic evaluation. __________ References: Amniotic fluid embolism: despite progress, challenges remain. (http://www.ncbi.nlm.nih.gov/pubmed/26485455)

A 35-Year-Old Woman, Gravida 1 Para 0, at 40 Weeks