Sat27November0445PM 35

Which of the following are true of an amniotic fluid embolism?

True / False

It is associated with developing DIC Correct

It causes pulmonary hypertension Correct

Diagnosis is primarily made by laboratory testing Correct

Most cases occur post partum Correct

Neurological impairment is common in survivors Correct

Explanation

Amniotic fluid embolism (AFE) is a rare but potentially fatal syndrome that is unique to pregnancy.

The pathophysiology of AFE remains unclear. In 1995, it was proposed that the syndrome arose from an immune rather than embolic process. This new theory stated AFE is caused by fetal antigens in the amniotic fluid stimulating a cascade of endogenous immune mediators, producing a reaction similar to anaphylaxis.

AFE is thought to occur in two phases:

Phase 1 - Amniotic fluid and fetal cells enter the maternal circulation resulting in the release of biochemical mediators which cause pulmonary artery vasospasm followed by pulmonary hypertension. This results in elevated right ventricular pressures and right ventricular dysfunction, which will lead to hypoxaemia and hypotension with associated myocardial and capillary damage.

Phase 2 - Left ventricular failure and pulmonary oedema occurs. Biochemical mediators trigger DIC leading to massive haemorrhage and uterine atony.

The incidence of AFE has been reported to range from 1 in 8000 to 1 in 80000 deliveries. The syndrome typically occurs during labour (70%), soon after delivery (11%), or during second-trimester dilation and evacuation procedures.

AFE may present with maternal collapse, associated with breathlessness, cyanosis, hypotension, dysrhythmias, and DIC. However, the presentation can be more subtle than this.

The diagnosis is based on clinical grounds and exclusion of other causes. There is no pathognonomic laboratory test as yet.

The key factors in the management of AFE are early recognition, prompt resuscitation, and delivery of the fetus.

Survival after AFE has improved significantly. Although mortality rates have declined, morbidity remains high with severe sequelae, particularly neurologic impairment.

Reference:

Clark SL, Pavlova Z, Greenspoon J, et al. Squamous cells in the maternal pulmonary circulation. Am J Obstet Gynecol. 1986;154:104-6.

Dedhia JD, Mushambi MC. Amniotic fluid embolism. Contin Educ Anaesth Crit Care Pain. 2007;7(5):152-156.

Lee JH, et al. Amniotic fluid embolism that took place during an emergent Cesarean section -A case report-. Korean J Anesthesiol. 2010;59 Suppl:S158-62.

Rudra A, et al. Amniotic fluid embolism. Indian J Crit Care Med. 2009;13(3):129-35.

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Average score: 84.17%

Times answered: 288