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The embryo toxicity test

letto 26503 volte | autore: Claudio Manna, ginecologo specialista in fecondazione assistita (vai al curriculum)

         

A biological test that identifies any anti – embrional activity in the immune system. 

Some  anglo-saxon researches, in the prestigious English and American universities (Oxford and Harvard),  have developed a biological test that identifies a particular anti-embryonal activity of the immune system of women who present with poly-abortivity or absence of implantation.

The embryo toxicity test is performed using the 4 day old embryos of mice (blastocysts) cultivated for three days in the presence of the serum of the woman affected by poly-abortivity. The number of embryos that show “hatching” and “outgrowth”, that is the number of embryos that hatch out of the pellucid and implant on the Petri capsule. The use of a definitely fertile woman’s serum allows us to decide if the serum of the patient is embryo toxic.

This test seemingly identifies the presence of a hyper-production  of type Th1 (interleuchina and interferon –y in particular)  linfochine and interferons with cytotoxic effects, that damage the embryo.  The serum concentration of this peptide does not vary according to the menstrual cycle, consequently it is possible to analyse the possible presence of the embryo-toxic factor using a blood test performed on any day of the cycle.

 This clinical exam was invented by J. Sargeant  at Oxford University in England and successively modified by J. Hill of Harvard University in the United States.  The information regarding the clinical results has been published in international scientific journals these being JAMA (Journal of American Medical Association) American Journal of Obstetrics and Gynaecology, Fertility and Sterility American Journal of reproductive Immunology.

From these studies it is evidenced that 30-40% of women with recurring abortion result positive for the embryo toxic factor without any correlation with the possible presence of auto antibodies or other possible causes of abortion.  This test has been accepted by the American Food and Drug Administration (FDA), the highest authority in the United States for the control of  drugs and diagnostic exams, as a clinical test to perform on patients with recurrent abortions and lacking implantation.  The test is performed in a way that allows for the use of embryos obtained from 5 different mice, and at least 20 blastocysts per patient.  This is done in order to avoid that the test depends on the animal used and in order to have a statistically significant number of embryos to evaluate the sample tested and for control.

This test allows for the identification of a group of patients who show an immune response to abnormal T cells that can cause the elimination of the embryo, that, otherwise, would  not be identified using the clinical examinations generally used for the diagnosis of recurrent abortion.  The patients who test positive for the embryo toxicity factor do not generally test positive for other immunological tests, and are often helped by cortisone therapy.

About one third of patients who test negative for all the other exams result positive for the embryo toxic factor.  The execution of the test in these women allows for specific treatment.  Even though the test is not easy to perform, and has a significant cost, it could provide essential information towards the treatment of these patients.  To perform the test 5ml of blood has to be drawn and  serum obtained that has to be refrigerated and delivered the same day or frozen.

  • The risk is calculated singularly for each embryo

The results of the biochemical test and of the ultrasound are combined to formulate the specific risk for chromosomal pathology. The Duotest is capable of identifying a large number of cases of Downs Syndrome, Trisomia 18 and Trisomia 13.  This exam is capable of identifying about 65% of the pathological cases with a 5% false positive margin.

If the tests show increased risk, this does not necessarily mean the  foetus has problems, but it may be opportune to deepen the investigation with an amniocentesis. In the case of a negative test one cannot completely exclude the possibility of foetal problems, because, even though it is reliable, this investigation remains probabilistic and gives an idea of the risk percentage, but does not give a diagnosis.  It should be remembered that the exam is not an alternative to an amniocentesis, in the case of  a high risk pregnancy because of advanced age or because of family history.

Disclaimer: the information provided on this site is designed to support, not replace, the relationship that exists between a patient/site visitor and his/her existing physician.

venerdì 21 marzo 2008


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