Discussion
AFE is a rare complication but has high fatality rate, characterized by
sudden cardiovascular collapse, dyspnea or respiratory collapse and
disseminated intravascular coagulopathy[4]. This may occur in
healthy women during pregnancy, labor or following delivery. It can
develop even after elective abortion, amniocentesis, cesarean delivery
or trauma. This condition is initiated by entry of amniotic fluid to the
blood stream of the mother which leads a serious reaction causing
cardiopulmonary arrest and massive coagulopathy[3][5].
Because AFE is a diagnosis of exclusion, a precise case definition and
criteria is difficult to establish and also other causes of maternal
collapse should be ruled out. The causes of maternal collapse could be
due to hemorrhagic shock, pulmonary embolism, anaphylaxis, septic shock,
aortic dissection [6]. Diagnosis is based upon the signs and
symptoms observed during the birth or procedure.
The associated risk factors for AFE are age more than 35 years,
multiparity, cesarean section, instrumental delivery, antepartum
hemorrhage, eclampsia, labor induction, fetal distress, fetal death,
male baby [7][8] [9].
Few authors have proposed two clinical forms of AFE typical and
atypical. Typical or classic form has three phases: phase 1 –
respiratory and circulatory disorders, phase 2- coagulation disturbances
and phase 3 -acute renal failure and acute respiratory distress
syndrome(ARDS) leading to cardiopulmonary collapse[10]. In Atypical
form, cardiopulmonary collapse doesn’t occur but first symptom is life
threatening hemorrhage due to DIC[11].
The most significant diagnosis of AFE is made by findings at autopsy,
which are limited to the lungs and clinical diagnostic criteria, and
assisted by serum markers[12]. Serum markers like C3, C4 and C1
esterase inhibitors are reduced.
The symptoms are usually sudden in onset. Acute dyspnea, agitation,
sudden chills, sweating coughing and anxiety are common premonitory
symptoms. Labored breathing and tachypnea may occur. Diagnosis can be
made by following criteria[2][13],
- Acute hypotension or cardiac arrest
- Acute hypoxia
- Coagulopathy or severe hemorrhage in the absence of other explanations
- All of these occurring during labor, cesarean delivery, dilation and
evacuation or within 30 minute postpartum with no other explanation of
findings.
In our case, this women had risk factor of fetal death and labor
induction. She didn’t have fever, obstetric hemorrhage, eclampsia or any
other identifiable cause of postpartum collapse and also, she fitted to
the above mentioned criteria of AFE, hence we had made diagnosis of AFE.
The initial phase of AFE consists mainly of right ventricular failure.
If available, transthoracic and or transesophageal echocardiography may
provide valuable information. Immediately after presentation, the
echocardiography will reveal a severely dilated hypokinetic right
ventricle (acute Cor pulmonale) with deviation of the interventricular
septum in to the left ventricle. In our case transthoracic
echocardiography was done on 3rd day which showed mild
mitral regurgitation, mild pulmonary artery hypertension without any
vegetation and clots. As patient was already stabilized, finding may not
be suggestive of AFE or pulmonary embolism. Also, early and aggressive
resuscitation with blood product to correct coagulopathy results in
improved outcomes[14].
As computed tomography angiography or ventilation perfusion scan is not
available in our center, we were not able to perform this test, which
could have been performed to rule out pulmonary embolism. As this
patient had coagulopathy, acute hypoxia and maternal collapse which is
in favor of AFE than pulmonary embolism.
Survival after AFE has improved significantly due to early recognition
and management, morbidity remains high with severe sequelae.
Neurological impairment is most common complication followed by renal
failure, cardiac failure with left ventricular impairment, arrythmia
have been reported [8].
Primary management is respiratory support and hemodynamic support with
judicious use of fluids, vasopressors, inotropes and pulmonary
vasodilators. Early diagnosis and aggressive management of patient with
resuscitation improves the survival as well as long term morbidities.