1 Department of Obstetrics and Gynaecology, Liverpool Womens Hospital, Liverpool, Crown Street, Liverpool L8 7SS, 2 Academic Department of Obstetrics and Gynaecology, Royal Free and University College London Medical School, London, UK and 3 Department of Obstetrics and Gynaecology, Spaarne Ziekenhuis, Hoofddorp, The Netherlands
4 To whom correspondence should be addressed. E-mail: roy.farquharson{at}lwh.nhs.uk
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Abstract |
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Key words: early pregnancy/nomenclature
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Introduction: recognizing the changes |
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The traditional grouping of all pregnancy losses prior to 24 weeks as abortion may have had pragmatic origins, but it is poor in terms of definition and makes little sense. The term abortion is also confusing for the patient. She may not realize that (spontaneous) abortion is not a termination of pregnancy because medical abortion or legal abortion is used in the same way.
Increasing knowledge about early pregnancy development, with the more widespread availability of serum HCG measurement, the advent of high-resolution ultrasound and a clearer description of gestational age at pregnancy loss make for a more sophisticated assessment of miscarriage history but also help the couples awareness from as early as 5 weeks of gestation. The advent of these important information milestones has not been fully realized or incorporated into clinical event description for article publication.
The emergence of early pregnancy units (EPUs) in many hospitals has addressed the need for a dedicated clinical area for the diagnosis of miscarriage and patient support at a distressing time (Twigg et al., 2002). With the establishment of an EPU network, it becomes more important that a standardized diagnostic classification system be employed for accurate and reproducible reporting of ultrasound findings and clinical outcomes, so that direct comparisons between units can be readily understandable for both research and audit purposes.
The most recent confidential enquiry into maternal deaths conclusively demonstrates that mortality from ectopic pregnancy has not declined and is still increasing over and above rates described 10 years ago (CEMACH Report, 2004). As the EPU represents the most likely point of ectopic pregnancy diagnosis, the importance of standardized reporting of very early pregnancy changes requires a robust approach following recent recommendations (Kirk et al., 2004
).
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Duration of pregnancy |
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Clinicians do have to acknowledge that a woman does not become pregnant during the LMP or during ovulation, but exclusively after conception. Gestation is the condition of being carried in the womb during the interval between conception and birth. The term gestational age (GA) is therefore confusing, although generally accepted, and its widespread use can only be legitimized by using a proper definition. The appropriate way to overcome this confusion is to choose GA based on a theoretical ovulation plus 2 weeks. As early ultrasound measurements of the fetus (crownrump length, CRL) are reproducible (Pedersen, 1982) and more accurate than the use of the LMP, there is a need in publications to define GA based on LMP and/or ultrasound measurements.
The terms egg and ovum, sometimes used in clinical publications, should be avoided because they have also been used incorrectly for both an oocyte and an embryo (ORahilly, 1986). This author suggested that the term egg be reserved for a nutritive object only. Similarly, the use of the term embryo versus fetus is confusing as infertility specialists use embryo in the preimplantation period while anatomists use embryo until 8 weeks after implantation.
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Ultrasound criteria |
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Gynaecologists and ultrasonographers acknowledge the embryonic period by speaking about fetal heart action and fetal activity before the end of organogenesis. This evidence is vital to the patient, who sees them as clear signs of life. Embryologists, by contrast, may debate the meaning of embryo in early pregnancy, but embryo is more synonymous with cells in an IVF laboratory than as the preclinical scientific description of anatomical organogenesis. Although a clear distinction between embryonic and fetal periods is significant in teratology, we have to accept that modern terminology should reflect daily clinical practice, in which description has changed in the last two decades and is more patient-centred. The term fetus receives an ultrasound definition that includes fetal heart activity and/or a crownrump length >10 mm.
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Classification of events |
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Between 1% and 2% of fertile women will experience recurring miscarriage (RM) (Stirrat, 1990). Recently, among researchers in the field of RM, it has been recognized that the classification of pregnancy loss is more complex as the developing pregnancy undergoes various important stages, and different pathology at the time of pregnancy loss is exhibited at these different stages. As the majority of RM cases following investigation are classified as idiopathic (Stirrat, 1990
), it is generally accepted that within the idiopathic group there is considerable heterogeneity and it is unlikely that one single pathological mechanism can be attributed to their RM history. Furthermore, there is considerable debate about cause and association as the exact pathophysiological mechanisms have not been elucidated. Current research is directed at theories related to implantation, trophoblast invasion and placentation, as well as factors which may be embryopathic.
The absence of an identifiable pregnancy on ultrasound examination in combination with a positive urine or serum HCG pregnancy test is named a pregnancy of unknown location (PUL). Biochemical pregnancy loss is a better description than trophoblast in regression or preclinical embryo loss. After ultrasound identification of pregnancy, a miscarriage can be classified as early (before 12 weeks) or late (after 12 weeks).
Heterotopic pregnancy is a combination of an intrauterine pregnancy and an ectopic pregnancy. Hydatidiform mole pregnancy and partial mole would be better replaced by gestational trophoblastic disease, complete or partial.
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Future direction |
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The authors understand that a modernized classification system is not able to address every clinical scenario, but the adoption of a revised terminology is a better way forward than persisting with an antiquated description that precedes the universal use of transvaginal ultrasound findings or serum HCG levels, (Table II).
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References |
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Submitted on March 15, 2005; resubmitted on April 29, 2005; accepted on May 4, 2005.
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