Discussions for Module 2:  Amniotic Fluid Embolus, Obstetrics

Questions are answered by module author: Sharon Davies MD FRSPC

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Question:

Shall I know why multiparous parturients are prone for AFE over primigravida.

Mar. 11, 2010 11:38 AM, S.A

Dr. Davies replies:

Actually parity is NOT a risk factor for AFE. Morgan did indeed suggest that multigravida patients were at a higher risk but the subsequent AFE registry data by Clark did not support this concept. Therefore, today we do not believe that a muligravida patient is necessarily at a higher risk.

 

Question:

Do we still follow the older coagulation pathway-Intrinsic /Extrinsic pathway?

Mar. 11, 2010 11:38 AM, S.A


Dr. Davies replies:

You are absolutely correct. Although many of us still use these terms, to be totally accurate and "up to date", we should not. The two pathways are the contact activation pathway (previously the intrinsic pathway) and the tissue factor pathway (previously the extrinsic pathway). The tissue factor pathway is the primary pathway for the initiation of coagulation. Thank you for pointing this out. I will make the changes in the module.


Question:

The incidence of seizures quoted in discussion was about 10% in AFE. Is it secondary to hypoxia/ any other underlying mechanism?

Mar. 11, 2010 11:38 AM, S.A


Dr. Davies replies:

I have always personally believed that the “seizures” or “seizure like” activity that is sometimes observed is due to acute hypoxia. However, except for describing this as one of the modes of presentation, I am not aware of any other underlying mechanism that they have been attributed to. If anyone else has any further information in this regard, please relay it to me.


Question:

Are you aware of any case reports documenting acute pulmonary hypertension and right heart failure in humans?

Feb. 12, 2008 10:57:16 AM, Anonymous

Dr. Davies replies:

There are now documented cases of acute pulmonary hypertension and RHF in the literature. This is now discussed in full in the updates (highlighted in bold blue text) in the module. Please refer to the section on the "Pathophysiology" under the section entitled "Hemodynamic Changes".

 

Question:

I have read recently that uterine stimulants for the induction of labour increase the risk of an amniotic fluid embolus. Please comment.

Feb. 12, 2008 10:55:11 AM, Anonymous

Dr. Davies replies:

You are correct. There has been some recent investigations regarding this association. The AFE module has been updated and you can see the complete discussion of the issue in the module. Go to the section on the "Natural History" and refer to the section under "Incidence and Mortality". The new information is found in bold blue text.

 

Question:

Can AFE present as respiratory distress and/or pulmonary edema as the only CLINICAL manifestation of the syndrome?

Nov. 10, 2005 at 12:58, K.H.

Dr. Davies replies:

Yes, this is possible. However, it is always important to make sure you rule out other causes of respiratory distress/pulmonary edema before making the diagnosis of AFE as it is a diagnosis of EXCLUSION. It is possible that with the entry of aminotic fluid all the patient may experience is mild shortness of breath and then recovers uneventfully. Others may go on to develop a severe ARDS type picture, consumptive coagulopathy,etc. Once again,the clinical cource most likely depends on the patient's response to the foreign material as suggested by Clark regarding the "anaphylactoid syndrome of pregnancy".

 

Question:

I often wonder how many women have "small" or "subclinical" AFEs - sort of like the small/subclinical fat emboli which I have always been led to believe can be seen on echo during hip surgery. I have noticed on occasion during C/S patients complaining of a bit of shortness of breath and even desaturating a touch - I wonder if this is due to small emboli or simply a result of a pregnant patient in the supine position with a regional block to T4?

Nov. 10, 2005 at 12:57, H.F.

Dr. Davies replies:

Although we do not know the actual numbers, it is very likely that some of these patients are having small AFE. We do know from doppler studies that air emboli occur during CSection so it is very likely that amniotic fluid(AF) enters the same way in some cases. The consequences will in turn depend on the patient's response to the foreign substances. In essence then, the symptoms you are observing are most likely due to either air or AF. It has been my experience that most of the time that I observe this is after the baby has been delivered. This would be the time that the membranes are no longer intact and the potential for AF to enter the mom's circulation exists.

 


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