and Paula Briggs2
(1)
Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria, Australia
(2)
Sexual and Reproductive Health, Southport and Ormskirk Hospital, Southport, UK
Early Pregnancy Loss
Definition
First trimester pregnancy loss is usually called a “miscarriage”. However “early pregnancy loss”(EPL) is all encompassing as it also includes ectopic pregnancy.
Incidence
The reported incidence for EPL varies with age.
12–19 years : 13 %
20–24 years: 11 %
25–29 years: 12 %
30–34 years: 15 %
35–39 years: 25 %
43–44 years: 51 %
>45 years: 93 %
In addition to the reported incidence described above, subclinical pregnancy loss is common and often occurs without the woman being aware of having been pregnant.
Increased paternal age is also a risk factor for early pregnancy loss.
Aetilogy and Pathogenesis
Congenital
Most early pregnancy loss is unexplained. Chromosomal analysis is not usually carried out on the products of conception, unless the woman has had several pregnancy losses. A woman who has suffered three EPLs is called a “habitual aborter”. However from examining the products of conception of spontaneous aborters it appears that one of the commonest causes for EPL is aneuploidy (chromosomal abnormality).
Traumatic
Surgical trauma can be a cause of early pregnancy loss. With ready access to legal abortion this is a rare cause of EPL.
Inflammatory
Many infections can result in EPL. These include rubella, toxoplasma, herpes infection, CMV, Listeria, Syphilis, or any febrile illness.
Vascular
Many women experience bleeding in early pregnancy, but this is not always associated with EPL. Implantation bleeding is a common cause of blood loss in early pregnancy. This occurs in the process of the placenta burrowing into the endometrium. If this results in disruption of placental function to a degree where survival of the embryo/foetus is not possible, EPL occurs.
Haematogenous
It is believed that thrombophilia (increased tendency for thrombosis) may be a cause for EPL. The hypothesis is that the small arterioles in the placenta are blocked by blood clot, and hypoxia results.
Endocrine
Thyroid disease, diabetes, and PCOS are associated with a higher risk of EPL.
Psychogenic
Stress and emotional problems may be associated with EPL, but there is no evidence for this.
Iatrogenic
Removal of the corpus luteum before 12 weeks of gestation will cause EPL. The placenta does not produce sufficient oestrogen and progesterone until that time, to maintain the early pregnancy.
Clinical Assessment
History
The important questions are:
Gestation (time since last normal menstrual period)
Amount of bleeding and whether tissue has been lost
Presence of pain
Examination
Is the cervix is open or closed
Uterine size
does this correspond to gestation
Investigations
Biochemistry – quantitative measurement of bHCG (each laboratory has its own normal range). Serial measurements of bHCG are useful as in a viable pregnancy, the level should double every 36 h.
Ultrasound – this is the best diagnostic test to assess early pregnancy with bleeding. However a single ultrasound examination is not diagnostic especially if the time of conception is uncertain. A second scan 7 days later should show appropriate growth and development. The important diagnostic features include the gestational sac diameter, the presence of a yolk sac, crown-rump length and foetal heart beat and rate (Table 24.1).
Table 24.1
Summary of the clinical features of threatened, inevitable, incomplete and missed EPL
Bleeding
Pain
Cervix
Ultrasound
Threatened
Slight
Nil
Closed
Foetal heart
Inevitable
Significant
Yes
Open
No fetal heart
Incomplete
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