Prenatal Diagnosis

PRENATAL GENETIC DIAGNOSIS: Rationale detects elevated level of AFP (Alpha-KetoProtein) test to indicate the presence of a neural-tube defect in a developing fetus. 1. 2. 3. 4. 5.

Ultrasonography Radiography Fetoscopy Amniocentesis (14-16 wks of pregnancy) Chorionic sampling Rh incompatibility Tay-Sachs disease PKU (Phenyl-ketonuria) Down’s syndrome (women above 35) Huntington’s chorea METHODS OF PRE-NATAL DIAGNOSIS;

1.

Amniocentesis:

puncture of the amniotic sac via transabdominal approach in order to obtain amniotic. Accomplished by introducing a needle through the abdominal wall and uterus of the pregnant womAn. About 300 cc of amniotic fluid is extracted. This contains fetal cells which are cultured for 3 to 4 weeks, before they are examined in the laboratory. Detects chromosomic abnormality or other congenital defects of the fetus. The results of amniocentesis are valid only when the examination is done at least after 16 weeks of gestation. During this time there is a good relation between fetal size and the amount of amniotic fluid. The cells obtained are cultured for 3 weeks in the laboratory. Thus there is no way of diagnosing until after 20 weeks of gestation. (1)

2.

Fetoscopy:

3.

Funiculocentesis:

4.

Ultrasonography:

5.

Radiology:

6.

Chorionic biopsy:

direct visualization of the placenta and the fetus utilizing fiber optic instruments. -

- blood samples are extracted from the umbilical cord by means of an ultrasound-guided needle. Better than fetoscopy and is morally licit. - ultrasonographic imaging of the organs and soft tissues. -direct fetal radiography (simple fetography) and contrast radiography (amniography).

- a sample of tissue of the chorionic villi is obtained for the purpose of chromosomic or biochemical analysis. This is accomplished via the transcervical or transabdominal approach. Chorionic biopsy gives faster results than amniocentesis. Both procedures, however, are viewed with ethical reservations.

ETHICAL EVALUATION OF AMNIOCENTESIS: Risks in amniocentesis: 1. 2. 3. 4. 5.

Complication of pregnancy and delivery; Increase in the index of pre-maturity and prenatal morbidity; Error in diagnosis. Incidence of hemorrhage, placental detachment, spontaneous abortion, fetal and maternal mortality – 1 to 2%. Maternal death – rare (one for every 20,000 amniocentesis)

(2)

Criteria to be amniocentesis:

followed

regarding

risks

of

A diagnostic test must not carry more than 2% risk. If the probability of discovering genetic pathology in a fetus is 2%, one may resort to amniocentesis only exceptionally, because the method carries the same or even a greater risk for the fetus itself. Therefore, amniocentesis is only recommended for pregnancies with a high probability of chromosomic abnormality or congenital defect in the fetus: - elderly primigravida, familial history, etc. To date: there is no available treatment for congenital abnormalities discovered “in utero” or at birth. Whenever the results of amniocentesis are positive for congenital disease, the only alternative that can be offered is abortion. QUESTION? - Why undergo a risky diagnostic test when the only therapeutic alternative is induced abortion? There are human and ethical reservations besides scientific limitations in genetic counseling and prenatal diagnosis.

(3)

IS PRENATAL DIAGNOSIS MORALLY LICIT? Donum vitae, no. 2, answers the ethical implications: 1.

It is licit if it respects the life and integrity of the embryo and human fetus and is directed towards safeguarding or healing an individual. Pre-natal diagnosis enables one to know the conditions of the embryo and of the fetus when still in the mother’s womb. It permits early diagnosis and more effective application of certain therapeutic, medical or surgical procedures. Such diagnosis is permissible: a)

2.

with the consent of the parents after they have been duly informed; b) if the methods employed safeguard the life and integrity of the embryo and the mother, without subjecting them to disproportionate risks. Pre-natal diagnosis is illicit, i.e., goes against the Moral Law when depending on the results, selective induced abortion is intended. “A diagnosis of malformation or hereditary disease must not be equated with a death sentence”. Therefore, it is gravely illicit to perform pre-natal diagnosis: c) when a woman requests diagnosis with the deliberate intention of procuring abortion once malformation or abnormality of the fetus is confirmed. d) When the husband or other relatives or anybody were to advise or impose on the expectant mother undergoing a diagnostic test with the aim of proceeding to abortion when the results show abnormal findings. These persons would incur the penalty of excommunication if they have facilitated or assisted in the abortion. (Cfr. Code

of Canon Law, can. 1329, par. 2 in relation to can. 1398). (4)