>> -----Original Message-----
>> From:        Graham Jones [SMTP:[log in to unmask]]
>> Sent:        19 June 2002 12:32
>> To:  [log in to unmask]
>> Subject:     Re: Negative serum hCG and radiological investigations.
>>
>> Dear Colleagues,
>>
>> I am replying to the current postings concerning hCG testing to exclude
>> pregnancy.
>>
>> I would propose a slightly different view on the topic. If we ask the
>> question "why are we trying to detect very early pregnancies?" The obvious
>> answer is to avoid damage to the conceptus. What kind of damage are we
>> trying to avoid? We are obviously very keen to avoid any possible
>> teratogenic effects of therapeutic of diagnostic interventions (drugs and
>> X-rays). I place this first at least partly because of the huge
>> medico-legal implications of errors at this stage of life. We should also
>> be trying to avoid early foetal loss, but at the very early stages of
>> pregnancy it is very difficult to separate foetal loss due to an
>> intervention from the very high rate of natural foetal loss.
>>
>> As far as I can see from the literature as well as discussions with
>> colleagues in this area the chance of malformations due to any
>> intervention
>> in the first 2 weeks is very, very low. We know that we can remove whole
>> cells without affecting the outcome of the foetus and at this stage we
>> have
>> completely undifferentiated cells. Organogenesis does not commence until
>> about 20 days after conception at which stage nearly all pregnancy tests
>> will become positive. The possible outcome of an intervention may be an
>> increase in foetal loss which, as I said above, is difficult to
>> distinguish
>> from normal events.
>>
>> I make these comments not to be cavalier about very early human life, but
>> just to say that going to great lengths to exclude very early pregnancy
>> before certain interventions may not produce any appreciable changes in
>> outcome.
>>
>> I will add a couple of the quotes I came across in searching around this
>> topic a few years ago. Of course I welcome any other thoughts on this
>> topic.
>>
>> General: "During the predifferentiation period in early gestation, the
>> conceptus is generally resistant to production of congenital
>> malformations,
>> although embryonic death or abortion may occur."
>>         Schardein, J. Chemically induced Birth defects (2nd Ed) P5. Marcel
>> Dekker
>> Inc New York. 1993.
>>
>> Substance must be administered during organogenesis to induce a
>> teratogenic
>> effect. In humans this is between 20 and 55 days after conception (35-70
>> days after LMP).
>>         Schardein, P5&6.
>>
>> Radiation: "250 Rads given before 2 or 3 weeks gestation increased
>> spontaneous abortion, but did lead to severe congenital anomalies."
>>         Burrow and Ferris. Medical complications during pregnancy. P546.
>> WB
>> Saunders Company 1988.
>>
>> Regards,
>>
>> Graham
>> Graham Jones
>>
>> Staff Specialist in Chemical Pathology
>> St Vincent's Hospital, Sydney
>> Victoria St, Darlinghurst, 2010
>> NSW, Australia
>> Ph: (02) 8382-2170  Fax (02) 8382-2489
>> [log in to unmask]
This all sounds very logical but I don't think my medical defence would
be very impressed if I said it didn't really matter if an early foetus
was irradiated.  I would be taken to the cleaners for a very large
amount.  Presumably, the radiologists are concerned because there is the
perception that the foetus will be damaged, whether or not this is
proven.  If I fail to detect a pregnancy because the woman passed a
dilute urine which did not give a detectable hCG, but which could have
been detected using a more reliable serum test with a lower detection
limit, I have not given the best medical care, and the cash till will
ring.
Trevor
--
Trevor Gray
Dept. of Clinical Chemistry,
Northern General Hospital,
Sheffield S5 7AU

0114 271 4309

------ACB discussion List Information--------
This is an open discussion list for the academic and clinical
community working in clinical biochemistry.
Please note, archived messages are public and can be viewed
via the internet. Views expressed are those of the individual and
they are responsible for all message content.

ACB Web Site
http://www.acb.org.uk
List Archives
http://www.jiscmail.ac.uk/lists/ACB-CLIN-CHEM-GEN.html
List Instructions (How to leave etc.)
http://www.jiscmail.ac.uk/