The Pandora's box of pre-natal screening

Four years ago, when I was pregnant, a vial of my blood was posted in a padded envelope to a genetics lab in the UK for a biochemical…

Four years ago, when I was pregnant, a vial of my blood was posted in a padded envelope to a genetics lab in the UK for a biochemical screening called the Triple Test. The test measures the levels of three hormones in a mother's blood and calculates these against her age to come up with an estimated risk of Down's syndrome and spina bifida.

I wanted this information, but was sure everything would be okay, so once the blood had been sent off, I decided not to give it another thought. I had no comprehension, really, of the Pandora's box I was opening. Because, three weeks later, my obstetrician called me on my birthday with the result: the risk that my baby had Down's syndrome was one in 20. But this was only a screening test, giving an estimate of risk; for a definitive answer, I would need a diagnostic test, amniocentesis.

There is a popular view that there is no reason to have prenatal screening and diagnosis unless you are prepared to terminate. In fact, 50 per cent of couples with affected foetuses choose not to terminate, both in this State and in the North, where termination is available in cases of foetal abnormality and/or severe risk to a mother's life.

Doctors working in foetal assessment believe that parents who know in advance are better prepared socially and medically for an affected baby. As Dr Carole Barry-Kinsella of the Rotunda Hospital, the first in the Republic to offer amniocentesis five years ago, explains: "If you are informed in advance, you can make plans for how you are going to deal with a baby that has a genetic defect. Couples who opt for pre-natal diagnosis want a choice, and don't want the lack of control that you suffer from not being informed."

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All pregnant mothers are screened through ultrasound. For those at high risk due to maternal age, family history or a previous baby with a genetic defect, about 600 foetal assessments through amniocentesis are done every year in the Republic in four hospitals: the Rotunda, the Coombe, the National Maternity Hospital, all in Dublin, and University College Hospital Galway. Amniocentesis is also conducted at the Royal Victoria Hospital in Belfast, which used to take patients from the South before foetal assessment units were opened here.

In the Republic, whether a mother receives pre-natal screening and diagnosis depends not only on which maternity hospital she attends, but also on which consultant she sees within that hospital.

"There is no uniform policy across hospitals or consultants," says Dr Declan Keane, master of the National Maternity Hospital.

Much depends on the approach of a woman's own obstetrician. The issue of amniocentesis - with the unspoken loaded question of termination hanging in the background - is such a "grey area", that "obstetricians like to know patients' attitudes before discussing it to avoid the risk of upsetting them", says Dr Peter McKenna, master of the Rotunda Hospital. In other words, the couple may have to ask.

Foetal assessment involves two kinds of tests: screening tests, which identify the population at high risk, and diagnostic tests, which give definitive answers for those at risk.

Screening tests, the most common of which is ultrasound, are reassuring for most mothers. One new way of doing ultrasound is in conjunction with nuchaltranslucency, in which the fatty pad at the back of the foetus's neck is measured. If it is more than three millimetres thick, the risk of Down's syndrome and certain other conditions is high; if it is less, the risk is low. However, this is not a definitive diagnosis; only amniocentesis provides that.

"If I was a mother who wanted to know if my child had Down's syndrome, I would not bother with the Triple Test at all because it gives no definite answer. I would go the whole way and have an amniocentesis," says Dr Keane.

At a Dublin maternity hospital, as I lay on a bed and my baby appeared on the ultrasound screen, I was asked for my informed consent and gave it. Yes, I knew that my chance of miscarriage as a result of amniocentesis was one in 100 (miscarriages occur due to the fact that the needle punctures the membrane and, if it does not seal over, the amniotic fluid leaks out.) But my chances of having a baby with Down's syndrome were one in 20, five times greater than the chance of a miscarriage. Like other women in my situation, I balanced the risk of miscarrying a healthy baby against the risk of giving birth to a baby with Down's syndrome.

Dr Barry-Kinsella refers to this logic as "risk/benefit analysis" and points out that the perception of risk is different for each woman. Some women think that a risk of one in 250 is high, others find it acceptable. "We give mothers the ballpark figures of risks, then the decision is left to the mother," says Dr Keane, reflecting policy in all the hospitals.

The decision to go ahead with amniocentesis was mine alone. While my doctor informed me of the risks, he could not tell me what to do, as is the policy amongst most obstetricians in this State. My partner supported me in whatever course I chose, which, according to Dr BarryKinsella, is typical of the majority of male partners. A fan and regular viewer of Fair City, Dr Barry-Kinsella is critical of the way amniocentesis and termination were portrayed as precipitating a marriage break-up. In reality, she has never seen such a case.

The amniocentesis lasted 30 seconds and was completely painless. A hair-thin needle was passed through my abdomen and took a sample of the amniotic fluid surrounding the foetus (but went nowhere near the foetus itself). The procedure was guided by ultrasound and performed by a practitioner in whom I had absolute confidence, although even the best practitioners sometimes lose healthy babies.

I waited nervously for any signs of impending miscarriage, but felt physically fine, although emotionally wrecked. It wasn't the procedure itself which was traumatic, rather it was the emotional roller-coaster I went through while spending four weeks awaiting the results (these days, results take about three weeks, but a new form of analysis is being developed which may give a result in 36 hours).

One day, I would tell myself that I, my partner and two young daughters could not deal with the huge burden of care involved in having a severely mentally handicapped child. The next day, I would vow - as I felt the baby moving in my womb - that I would love and care for it no matter what.

No one could help me in my dilemma as I considered the implications of termination. They weren't allowed to. Doctors operate in a twilight zone where they cannot discuss termination with patients under any circumstances, nor can they directly refer patients for terminations. "It's an Irish solution to an Irish problem," says Dr Keane.

In Northern Ireland, by contrast, couples are offered comprehensive pre-termination and post-termination counselling by teams of doctors, psychologists and geneticists. The fact that the Republic offers no such service increases the trauma for mothers who, as I did, feel isolated and afraid.

Another issue is that when couples go to the UK for terminations, they cannot get post-mortems done there. It is understood that parents have brought terminated foetuses in their hand-luggage on flights home from London in an effort to get postmortems performed in this State. Whether or not this is legal is a grey area not yet addressed by legislation.

"It would be useful if there were absolute channels in which these couples could be put. It would be nice if there was one place patients could go to get details of the diagnosis, pathology and results of post-mortem examinations," says Dr McKenna.

Post-mortems are crucial because if a child has a genetic defect, a post-mortem is usually essential in determining not just the precise nature of the abnormality, but also the parents' risk of having another affected child. In Potter's syndrome, for example, some cases carry a one-in-four risk of inheritance in a family, while others are sporadic. Without a post-mortem, parents cannot know which type their affected foetuses suffered from and thus cannot know the risks for future pregnancies.

Amniocentesis can only be used to diagnose the specific conditions that geneticists are told to look out for. The happy news that a baby does not have a specific condition does not mean that the baby is free of any of 1,000 other conditions that were not looked for.

One morning, at 22 weeks' pregnancy, after eight weeks of agonising, I awoke with the knowledge that I would keep my baby, no matter what. An hour later, I got the phone call. My son (it was a boy!) did not have Down's syndrome. To this day, I cannot say how I would have reacted if I had found out that he had been affected.

kholmquist@irish-times.ie