Intended for healthcare professionals

Letters

Antenatal screening

BMJ 1999; 318 doi: https://doi.org/10.1136/bmj.318.7186.805 (Published 20 March 1999) Cite this as: BMJ 1999;318:805

Obtaining selective consent to scanning, rather than screening, is possible

  1. Catherine Baillie, Research officer.,
  2. Jenny Hewison, Senior lecturer.
  1. Oxford University Department of Educational Studies, Oxford OX2 6PY
  2. School of Psychology, University of Leeds, Leeds LS2 9JT
  3. Psychology and Genetics Research Group, Guy's Hospital, London SE1 9RT
  4. 15 Lyefield Place, Livingston EH54 6TZ

    EDITOR—McFayden et al stated that first trimester ultrasound screening “should include the accurate presentation of all available information before screening to ensure that consent is truly informed.”1 In 1997 we evaluated the content and readability of the leaflets used in 14 centres offering first trimester nuchal translucency screening using a number of predefined variables.2

    Only one of the leaflets met all of the criteria deemed necessary for an informed choice to be made. Thirteen of the leaflets indicated that ultrasound scanning was used to screen for Down's syndrome and chromosomal abnormalities, although only two leaflets gave any description of the syndrome, and this was limited to “mental handicap.” Few of the leaflets gave information on the sensitivity or specificity of the test, or on interpreting results. Eight mentioned diagnostic testing, and two referred to the option of termination. Nine leaflets explained that nuchal translucency screening was separate from other elements of the early pregnancy scan, and four leaflets indicated that written consent was required.

    The content and readability of the leaflets used to inform women of the aims and limitations of screening for nuchal translucency varied widely but the majority could be considered as failing to meet the criteria for informed choice. Even under conditions of informed choice, however, uptake of ultrasound screening is markedly above that which would be expected for other prenatal screening tests. This high uptake has been attributed to expectant couples' overwhelming desire to “see the baby.”3

    Since the first centre was accredited by the Fetal Medicine Foundation (a charity established to provide training and audit of first trimester ultrasound screening) in 1993, uptake of nuchal translucency screening has fallen from 96.9% to 86.6% of all women having ultrasound screening (R Snijders, personal communication). This decline shows that offering the option of “selective consent” has the potential to overcome the previously reported high uptake of ultrasound screening.

    Selective consent can be easily accommodated by the early pregnancy scan because its pregnancy monitoring functions (assessing gestation and viability, and identifying multiple pregnancies) are distinct from its screening functions. Therefore, couples who wish to decline screening for chromosomal abnormalities do not have to forgo “seeing the baby” or accurately dating the pregnancy. The data suggest that an increasing, albeit small, percentage of women who have ultrasound scans are making an informed choice to selectively decline screening for chromosomal abnormalities. It may be that the way forward in facilitating informed choice for ultrasound screening is to separate “scanning” (to monitor the pregnancy) from “screening” (for fetal abnormality).

    References

    Better understanding of factors influencing uptake is needed

    1. Elizabeth Dormandy, Research associate.
    1. Oxford University Department of Educational Studies, Oxford OX2 6PY
    2. School of Psychology, University of Leeds, Leeds LS2 9JT
    3. Psychology and Genetics Research Group, Guy's Hospital, London SE1 9RT
    4. 15 Lyefield Place, Livingston EH54 6TZ

      EDITOR—There is agreement that women should receive information about ultrasound screening before it is used to detect fetal abnormalities. 1 2 Regrettably, this does not always happen.

      When women are offered biochemical screening for Down's syndrome they are provided with information, both verbal and written, before the test and are given an opportunity to decide whether they want to be screened. A similarly explicit consent procedure is needed for ultrasound screening.

      There are two difficult areas in screening regardless of whether it is ultrasonic or biochemical (or a combination of the two). Firstly, practices are inconsistent, which causes confusion. Different screening tests may be offered at the same stage of pregnancy. Even when the same test is offered, different cut off points may be used. Some screening tests express the “risk at term” and others express it at the time of screening. Some women are offered a screening test if they are younger than 37, while others are offered diagnostic amniocentesis if they are older. It is hardly surprising that there is confusion.

      Because there are variations in screening policies, screening is not provided on an equitable basis. We need a national screening framework to give guidance on which screening policies are appropriate, to monitor performance, and to provide accurate and comprehensible information for women and health professionals.

      Secondly, it is not clear why there are striking differences in the uptake of serum screening. Although about two thirds of women in the North Thames region decided to have this screening, uptake varied from 27% to 93% at different hospitals.3 These variations in uptake may be influenced by the information given before the test and by the way it is given, or by the knowledge and attitudes of the person who offers it. If a test has a “good press” then a woman is more likely to decide to have it. There is no “correct” uptake figure but it is difficult to accept that such differences reflect women's choices alone. We need to understand more about the factors influencing the uptake of both types of screening.

      References

      Women are being given incomplete information

      1. T Fitzgerald, Consultant radiologist.
      1. Oxford University Department of Educational Studies, Oxford OX2 6PY
      2. School of Psychology, University of Leeds, Leeds LS2 9JT
      3. Psychology and Genetics Research Group, Guy's Hospital, London SE1 9RT
      4. 15 Lyefield Place, Livingston EH54 6TZ

        EDITOR—There is a normal fetal loss rate during screening for maternal α fetoprotein of about 1/3000 due to inaccuracy and lack of specificity; 1/200 fetuses aborted as a result of an ultrasonically diagnosed abnormality were found not to be significantly abnormal at post mortem examination. This information was used in Oliver et al's study of informed consent.1

        The consent presumed to have been given during attendance at an antenatal consultation is not the same during attendance for a scan (even a booking scan). Methods, protocols, and gestational age specific risks should be communicated to parents, which is where the appropriate duty of responsibility resides. Despite Carroll's view, termination of pregnancy is the only practical and “useful” outcome or treatment that comes from screening for Down's syndrome2; however, the termination rate varies inversely with gestational age at diagnosis.

        The use of “reassurance scans” is increasingly prevalent in situations in which consent to serum antenatal testing has been refused, possibly since guidance from the Royal College of Obstetricians and Gynaecologists was published.3

        No clear or consistent approach to the timing and specification of consent has emerged from the correspondence or from the editorial by McFadyen et al. 2 4 It is necessary to obtain specific consent because “soft markers” and borderline appearances are increasingly identified during first trimester scans as the technology becomes more sophisticated.

        It is not feasible to be selective about results after scanning. Even patients who have said that they don't wish to be given information about an abnormality cannot not be told.

        The following points should be considered:

        • If it is desirable to obtain the views of those “in the know” to shed light on the issues discovered by patients having screening, then surely the best group to ask what their wishes were, or would be, in subsequent pregnancies is those who have had “non-reassuring events.”

        • If counselling is so important, why is a written record of details of the event so uniformly lacking from patients' records, and should patient held records include a specific consent?

        • Should sonographers be appraised of patients' wishes and modify their scanning accordingly?

        • Why is the rate of invasive testing so high in some Scandinavian areas?

        • What is the measure and amount of patient knowledge, and is there an optimum amount?5

        • Why does there appear to be a clutter of conflicting evidence and figures available to the profession, and yet information available to patients is so basic and, frankly, misleadingly so?

        References

        View Abstract