Intrusive Tests - A Doctor Replies

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In March 1996 in Intrusive Tests - A Personal View, Susan Lewis questioned the need for painful, intrusive tests to diagnose or monitor Gauchers disease if other less invasive tests were available. Prof Timothy Cox replies:

I sympathise completely with nearly everything said in the article but would advise a few words of caution.

Bone Marrow Biopsies

Usually bone marrow investigations are unnecessary for making a diagnosis, provided there isn't a hurry. The alternative, enzyme tests (taken from blood samples), need to be set up and thought about and may take two weeks or more to get the results back from a proper reference laboratory. There are in fact two forms of bone marrow biopsy: bone marrow aspiration and trephine biopsy.

Bone marrow aspiration (which I have had done twice myself) is uncomfortable at the time but is rapid and safe - and can be interpreted within 24 hours. A small needle is placed into the bone (usually in the back of the pelvis) under local anaesthetic and a syringe is used to suck up the liquid tissue. Where there is an urgency for diagnosis, I think bone marrow aspiration has its place particularly in children and young adults where Gauchers disease is amongst the many other possibilities for someone with an abnormal blood count with or without enlargement of the spleen or liver.

Trephine biopsy Sometimes, because of the infiltration with Gauchers tissue, no material of diagnostic significance is drawn out by bone marrow aspiration. Under these circumstances the results of a trephine biopsy, where a deep conical core of marrow and bone is removed usually from the pelvic region, are decisive.

This is a painful investigation and should normally only be performed once. It may lead to bruising and quite a lot of pain; in children it is usually done under general anaesthetic. This itself has attendant risks.

I should point out that the differential diagnosis of Gauchers disease, particularly in children who are not members of ethnic groups in which the frequency is increased, would include neuroblastoma, leukaemia, lymphoma and all manner of other conditions and I don't feel the use of diagnostic marrow should be discouraged in the first instance. Usually however marrow investigations should not be carried out in the follow-up of patients with known Gauchers disease just to judge the result of therapy.

Sometimes, as happened recently in one of our cases, where a patient with Gauchers disease who has received treatment suddenly had a deteriorating blood count relating to infection, again the marrow is the site of the disorder and infiltration by tumour (for example myeloma) may need exclusion from a marrow sample.

Liver Biopsies

As to the question of follow-up liver biopsies, I believe this is unsupportable. Sometimes it is necessary to know whether a patient with Gauchers disease has developed the rare but serious complication of cirrhosis of the liver and a further liver biopsy may be needed to determine this for prognostic (predictive) health reasons.

Liver biopsy is painful and carries a defined though small risk of injury, especially in people with Gauchers disease who may have subtle distur-bances of blood coagulation, platelet function and low platelet counts.

X-Rays and Other Scans

X-rays do carry a defined risk from inducing malignancy although diag-nostic X-rays at the present time try to minimise this. X-rays, however, are part of the follow-up of patients over years and are probably the only way to obtain a confident picture of the effects of the condition on the whole skeleton.

I don't feel young children should be subjected to unnecessary follow-up skeletal X-rays but, from time to time, say every two years or so, skeletal X-rays can be valuable and certainly should be, if at all possible, obtained before treatment is started.

MRIs are, as far as we know, entirely safe since they do not involve irradiation but I appreciate that these machines are claustrophobic and especially frightening for young children. In Cambridge we are attempting to get our colleagues to use spiral ultrasound examination, much less invasive and less frightening for follow-up volume measurements of the organs in the tummy.

CT Scans, although less frightening than the MRI scan apparatus, do carry themselves a defined risk of irradiation. They may be more pleasant but the patient is exposed to a great deal more radiation.

Ultrasound I would encourage the use of ultrasound although without care this can press on a sensitive liver or spleen.

Intrusive Tests - A Personal View
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Source: Gauchers News September 1996

© Copyright Gauchers Association 1996