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Letters

Congenital anterior abdominal wall defects

BMJ 1997; 314 doi: https://doi.org/10.1136/bmj.314.7077.371a (Published 01 February 1997) Cite this as: BMJ 1997;314:371

A national congenital malformations register is needed

  1. Carole Luck, Consultant radiologista,
  2. Jacqui Scrutton, Ultrasonographera
  1. a Heatherwood Hospital, Ascot SL5 8AA
  2. b Information and Statistics Division, NHS in Scotland, Edinburgh EH5 3SQ
  3. c Darlington Memorial Hospital, Darlington DL3 6HX
  4. d Northern Congenital Abnormality Survey, Newcastle upon Tyne NE2 4AA
  5. e Department of Epidemiology and Public Health, University of Newcastle, Newcastle upon Tyne NE2 4HH
  6. f Departments of Fetal Medicine and Paediatric Surgery, Leeds General Infirmary, Leeds LS2 9NS

    Editor–Kelvin H Tan and colleagues' paper analysing the incidence of congenital abdominal wall defects highlights the need for adequate antenatal and postnatal data collection nationwide.1 The authors retrospectively analysed abdominal wall defects coded according to the ninth revision of the International Classification of Diseases, using data from the Office of Population Censuses and Surveys (now the Office for National Statistics). It is not possible to differentiate between gastroschisis and exomphalos with these codes, and reanalysis of the original forms was therefore necessary. Records of the incidence of such defects may be influenced by differing regional uptakes of abortion services and variations in methods and skill in antenatal diagnosis and postnatal management. There are too many variables in the study to draw firm conclusions.

    In our unit, with 17 000 deliveries over the past seven years, there were seven cases of exomphalos and four of gastroschisis. Six fetuses with exomphalos and one with gastroschisis were terminated after detailed counselling and karyotyping. These diagnoses are now made at between 11 and 14 weeks' gestation as part of the nuchal thickening programme. Earlier diagnosis tends to influence the decision to terminate and emphasises the need for meticulous record keeping.

    Data from the Office for National Statistics are unsuitable for epidemiological research because of underreporting, but such research is vital to support current trends in primary health care. In the same issue of the BMJ a news item reports on the Gulf war syndrome2; the possibility of associated fetal anomalies cannot be analysed because of inadequate data. A further news article reports a possible connection between fluoxetine and minor birth defects.3 Do we have to have another disaster of thalidomide proportions before a national register of congenital malformations is instigated?

    One of us (JS) wrote her master of science dissertation on the provision of local registers of congenital malformations in England and Wales. In 1995 there were nine such registers, situated in different health regions and with varying catchment areas. Two registers related to regional referral centres, one covered roughly half a region, and the six others served entire regions (old boundaries). Figure 1 shows the areas covered. Several centres stated that their funds were precarious, and most relied on voluntary notification from motivated maternity units.

    FIG 1
    FIG 1

    Catchment areas for nine local registers of congenital malformations in England and Wales. Lines indicate new regional boundaries

    The Office for National Statistics collects national data, but the data are inadequate. Local registers collect adequate data but are not nationwide. A national lobby is urgently needed to initiate and fund a congenital malformations register.

    References

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    Rate of abdominal wall defects is higher in Scotland than England and Wales

    1. James Chalmers, Consultant in public health medicineb,
    2. Joan Forrest, Data managerb,
    3. Beatrice Cant, Senior health information scientistb,
    4. Mark Hollinsworth, Statistical support officerb
    1. a Heatherwood Hospital, Ascot SL5 8AA
    2. b Information and Statistics Division, NHS in Scotland, Edinburgh EH5 3SQ
    3. c Darlington Memorial Hospital, Darlington DL3 6HX
    4. d Northern Congenital Abnormality Survey, Newcastle upon Tyne NE2 4AA
    5. e Department of Epidemiology and Public Health, University of Newcastle, Newcastle upon Tyne NE2 4HH
    6. f Departments of Fetal Medicine and Paediatric Surgery, Leeds General Infirmary, Leeds LS2 9NS

      Editor–Kelvin H Tan and colleagues report their analysis of routine data on abdominal wall defects in England and Wales.1 In response to this, we have performed an initial analysis of Scottish data for a similar period using the congenital anomaly register, which is maintained by the information and statistics division of the NHS in Scotland.

      The method of data collection is substantially different in Scotland from that in England and Wales and takes advantage of record linkage in the Scottish morbidity recording (SMR) systems. There is no specific notification system for recording congenital anomalies, but, instead, data are captured and matched with probability linkage techniques from the record of a live birth (SMR11), the record of discharge from a neonatal unit (SMR11(E)), the Scottish stillbirth and neonatal death survey, and the registrar general's death records and record of discharge from an acute hospital (SMR1) for children aged under 1 year. This latter data source is valuable for children requiring operations in the first year of life.

      Table 1 shows the data for the years 1988-95. The overall rate of abdominal wall defects for this period was 3.49 per 10 000 births (1.89 for gastroschisis and 1.22 for exomphalos). For the period 1988-93, which is closer to the years studied by Tan and colleagues (1987-93), the rates were 3.25, 1.60, and 1.17 respectively. This compares with the rates for England and Wales of 2.15, 1.11, and 0.92 respectively.

      Table 1

      Number of cases of abdominal wall defects in Scotland (with relevant code according to International Classification of Diseases, ninth revision), 1988-95

      View this table:

      Obviously, the numbers are small and so it is difficu to separate any trend from random variations, but, as with the data for England and Wales, the number of cases of exomphalos seems to be stable. Unlike in England and Wales, however, there was no pronounced upward trend in the number of cases of gastroschisis, although the number was high in 1994.

      Although we acknowledge the different method of data collection, there seems to be a higher rate of abdominal wall defects in Scotland than in England and Wales. This is in keeping with the increasing gradient from south to north observed by Tan and colleagues.

      References

      1. 1.

      Authors' figures for Northern region are underestimates

      1. E Dillon, Consultant radiologistc,
      2. M Renwick, Coordinatord,
      3. J Rankin, Senior research associatee
      1. a Heatherwood Hospital, Ascot SL5 8AA
      2. b Information and Statistics Division, NHS in Scotland, Edinburgh EH5 3SQ
      3. c Darlington Memorial Hospital, Darlington DL3 6HX
      4. d Northern Congenital Abnormality Survey, Newcastle upon Tyne NE2 4AA
      5. e Department of Epidemiology and Public Health, University of Newcastle, Newcastle upon Tyne NE2 4HH
      6. f Departments of Fetal Medicine and Paediatric Surgery, Leeds General Infirmary, Leeds LS2 9NS

        Editor–Kelvin H Tan and colleagues report an increase in the incidence of gastroschisis in England and Wales between 1988 and 1993, using data from the Office of Population Censuses and Surveys (now the Office for National Statistics).1 The Northern regional fetal abnormality survey has collected data on all fetal abnormalities arising in the population of the former Northern region since 1984, whether occurring in miscarriages, terminations, or registered births.2

        Our experience of abdominal wall defects during the five years 1988-92 has been reported,3 and we have detected no rise in the incidence of gastroschisis or fall in the incidence of exomphalos during this period (table 1). Preparation of the published report entailed review of all original hospital case records, as a result of which 11 cases originally classified as exomphalos were reclassified as gastroschisis. It should be noted that our mean incidence for all cases of gastroschisis and exomphalos (4.90 (95% confidence interval 3.94 to 5.87)) for the five years greatly exceeds the figure quoted by Tan and colleagues for the Northern region in their table 5. We suspect that misclassification in the earlier years and absence of data on unregistered births account for most of the apparent change in incidence that they report.

        Table 1

        Number of infants with exomphalos and gastroschisis born in 1988-92 to mothers resident in former Northern region by year of birth (including non-registered births), with incidence per 10 000 registered births and 95% confidence interval

        View this table:

        Our data suggest that 40% of cases of exomphalos are associated with other structural abnormalities and 28% with chromosomal anomalies, usually a trisomy.3 This is not so with gastroschisis, which is usually an isolated defect. In the future we would therefore expect gastroschisis to form an increasing proportion of anterior abdominal wall defects among registered births because of improved antenatal classification and increased terminations of babies with exomphalos.

        The true incidence of congenital anomalies cannot be ascertained from notifications to the Office for National Statistics alone because its records are known to be incomplete. We strongly support Lyn Chitty and Joseph Iskaros's recommendation that local population based malformation registers such as ours should be set up.4 We would urge these to register all abnormalities, including those in miscarriages and terminations, and would also encourage stronger collaboration between the registers already in existence.

        References

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        Gastroschisis has a good prognosis

        1. Mark D Stringer, Consultant paediatric surgeonf,
        2. Gerald Mason, Consultant in fetomaternal medicinef
        1. a Heatherwood Hospital, Ascot SL5 8AA
        2. b Information and Statistics Division, NHS in Scotland, Edinburgh EH5 3SQ
        3. c Darlington Memorial Hospital, Darlington DL3 6HX
        4. d Northern Congenital Abnormality Survey, Newcastle upon Tyne NE2 4AA
        5. e Department of Epidemiology and Public Health, University of Newcastle, Newcastle upon Tyne NE2 4HH
        6. f Departments of Fetal Medicine and Paediatric Surgery, Leeds General Infirmary, Leeds LS2 9NS

          Editor–Kelvin H Tan and colleagues and Lyn Chitty and Joseph Iskaros discuss possible reasons for an increase in the incidence of gastroschisis in England and Wales.1 2 We were alarmed to read that more than one in five pregnancies with fetal gastroschisis in the North West Thames region were terminated during 1990-3.1 Only 5-10% of fetuses with gastroschisis have additional anomalies,3 and gastroschisis has a good prognosis postnatally, with at least 90% survival.4 Furthermore, the limited data on long term outcome are encouraging, with most patients achieving normal growth and development and enjoying healthy life-styles.5

          During the past four years we have managed 32 newborn infants with gastroschisis in our regional surgical neonatal unit, 29 of whom have survived. On the basis of the incidence reported by Tan and colleagues and our regional birth rate, we would have expected 22 babies with gastroschisis. This supports our impression that few pregnancies in which the fetus has gastroschisis are terminated in our region. To our knowledge, during the past four years only one such pregnancy has been terminated at our institution. This was in a woman requesting a termination on social grounds at 15 weeks' gestation; the gastroschisis was an incidental finding. With fetal gastroschisis, prospective parents should be offered counselling by both an obstetrician and a paediatric surgeon if they are to be adequately informed about the fundamental aspects of this condition and its outcome.

          References

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