iRADiX

Of all the things in life, it is the uncertainty of the future that is the most perplexing to the human beings. We try to gauge the future though scientific and non-scientific means and hedge our forecasts using the terms probability or likelihood or some other jargon. Still, it is the wait that gnaws our heart, doesn’t let us sleep peacefully and makes us prone to panic attacks.

As Radiologists we are the masters of forecasting. A look at a scan and we decide how much longer a person may live, whether he can be cured or what are his chances of having a normal life. We use our imperfect knowledge and imperfect tests to determine someone’s fate. But imperfect tests are all we have, however might a layperson clamor for simple yes-no answers from us.

So often the anticipation of joy turns into fear of unknown, because of our imperfect ways to predict future.

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The couple looked a bit out of place in my waiting room. They were on the later side of middle age and looked stoic, rather than the usual young boisterous couples who come for obs/ gynae ultrasound scans. The man had his hair peppered with white, the woman looking matronly with ample girth. I guessed they must be in for some perimenopausal complaint but I was wrong.

Raj (45 years) and Sunita (40 years) were shy narrating the history- of missing periods, delayed realization that it could be due to pregnancy and then hurrying to their doctor, who in turn referred the patient to me. Sure, it required a brief ultrasound examination to confirm a 7 wks pregnancy with a strong heart beat.

In my experience, most of the middle aged couples choose not to disturb the already established equilibrium of the family and quietly do away with such accidental conceptions. But again they surprised me by declaring that they were keen to continue this pregnancy.

“We had a 15 year old son who died in an accident three years back. I think God is sending my son back to me...” Sunita told me, trying to hold back tears. Raj was not so sure; he wasn’t keen on rearing up a child in old age. I could imagine the calculations going on his mind; when the child will be 20 years old, by then he may be too old or dead.

But Sunita was adamant, she wanted this child. So I referred them back to their gynecologist for guidance and counseling about the issues related to pregnancy at the age of 40. I briefly told them about the risk of chromosomal abnormalities associated with advanced maternal age and about various screening protocols. We fixed an appointment for ultrasound scanning at 12 wks to assess early fetal morphology, nuchal translucency/ nasal bones analysis and biochemical tests.

But somehow Sunita couldn’t make it for 12 wks ultrasound, probably because it was not stressed too much by the gynecologist. Ist trimester screening is still to catch on, even in Metros.

Then one day Sunita came to me in a near panic, clutching a sheaf of reports.

“Doc, something is not right with my baby!!” was her first statement.

“Calm down, calm down! Tell me what has happened..’

“Well, we were getting periodic check ups and our gyne said everything was normal. Then she asked us to get a Triple test done to rule out Down’s syndrome. I got the results today and it shows my baby has Down’s!!”

Raj was very stoic, kept consoling Sunita. It took some time for me to calm Sunita down and go through her reports.

It turned out that the Triple test had turned up ‘screen positive’. It is not an unusual finding in a woman of 40+ age with pregnancy. At this age the background risk is too high (nearly 1 in 100) that biochemical tests will turn out to be positive in many. Triple test is a ‘screening test’ and as with other screening tests, it picks up far too many pregnancies ‘at risk’ than there actually are. The current standard of care is to confirm it with a ‘diagnostic test’- an amniocentesis or chorionic villus sampling. Accordingly I advised Sunita to get counseling from a geneticist or perinatal specialist and to get an amniocentesis done.

“But isn’t this test showing that my baby has Down’s?” Sunita asked.

“No, this is just a screening test. Think of it as a speeding ticket. The policemen stop a speeding car above a certain speed limit because it can cause an accident. But not all speeding cars cause accident, do they? In fact most of them don’t. ”

“I don’t want to get this amniocentesis done; in fact my gyne told me that there is a lot of risk of abortion or injuring the baby. I don’t want to hurt my child…”

“Yes, there is a risk but it’s a small one, even less than 1%”

“But I don’t want to take that risk.”

“See right now your risk of having a child with Down’s syndrome is much greater than the risk of abortion from amnio, based on your age and this biochemical screening. But finally it is you who has to decide what choice you want to make.”

“Can’t you do an ultrasound and tell me whether my baby is alright or not?”

“Yes, I can do a detailed sonography and look for signs found in most fetuses with Down’s syndome, but ultrasound is not diagnostic.”

Raj intervened and asked me to do a scan. Fortunately there were no soft markers or structural abnormalities in the fetus.

“Thank God, my baby is okay” Sunita exclaimed when I informed her about the result of ultrasound.

“Doctor are you 100% sure that our baby is normal?” Raj also joined in.

“I told you that ultrasound is not diagnostic. In approximately 10-30% fetuses there may not be any abnormality which can be picked up on ultrasound, plus there are some anomalies which I may not be able to see at this gestational age. A normal ultrasound has decreased your risk considerably, but still there is a certain risk. If you want 100%, then you have to get an amnio done.” I explained.

Buoyed by the favorable ultrasound report, they declined to consider amniocentesis or even meet a genetic counselor and went home happy. But after a few weeks, doubt crept up in their mind and again they called me. We went through the explanations about limitations of these tests again. And again I asked them to consult a genetic counselor.

“But what more can a genetic counselor tell us more? I showed your report to three gynecologists and they all said that my baby is normal.”

“Yes they may be right, but still there is a chance of Down’s syndome, a small one but not ignorable.”

“I think between a blood test and your report, I would prefer to believe in your report.” With that she indirectly placed the burden of outcome on me.

I scanned her again a few more times during her pregnancy in late second and early third trimester, chiefly to assuage Sunita’s doubts which arose often and quickly subsided. Luckily no abnormalities ever appeared, and with each scan Sunita and I were reassured. But around 34 wks the fetus showed mild IUGR and mere mention of even minor discrepancy in growth brought forth all the old doubts back in Sunita’s mind. Her incessant questioning sometimes even made me look at things in doubt. What if I have failed to pick up subtle things? What if Sunita delivers a ‘funny looking kid’? As her due date came near, I found myself praying for everything to turn out all right.

At last Sunita delivered. A male baby, a bit on skinny side but normal nevertheless. The parents were overjoyed and claimed him to be the rebirth of their lost son. After a few days the family came to my clinic. They were profuse in their gratitude to me.

“I think that Triple test was wrong. Since the day we got it done, it gave us needless anxiety.” Raj commented during our conversations. I chose not to defend the test at the happy occasion and kept mum.

“But we had full faith in you and your report, Doctor” a beaming Sunita said, cradling her son in her arms.

I wish I could share their confidence in me. Burdened with data provided by countless research I know the limitations of these tests. Trying to predict future causes a lot of anxiety, which in hindsight appears needless when things turn out just fine.

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The issues of prenatal testing and particularly Down’s syndrome screening are complex, right from whether we should do any form of prenatal testing at all. A number studies are being conducted world wide in various formats, all working towards a common goal- a safer and accurate prenatal diagnosis. Though variety of screening protocols have evolved (biochemical and sonologic testing; Ist trimester and 2^nd trimester protocols; sequential, integrated and contingent protocols), the optimum method for screening is still elusive. Every one wishes to avoid an amniocentesis unless when absolutely necessary; but which patients need an amniocentesis and whether it can be avoided altogether are still being worked out. Nevertheless, the uncertainty a patient faces in deciding the course of action is immense, and often they are not able to understand the risks and choices presented to them, preferring simple yes/no answers. This uncertainty is also shared by their doctors as well, who at their end have varying interpretations of tests and their results, further muddling the issues and sometimes suffering from ‘paralysis by analysis’.

Some recent research findings on Down’s syndrome screening can be found here:

Contingent screening for Down syndrome—results from the Faster trial Cuckle et al. Prenat Diagn 2008; 28: 89–94.

http://www3.interscience.wiley.com/journal/117902582/abstract?CRETRY=1&SRETRY=0