Ultrasonography

Wild and Reid described transvaginal ultrasonography with a rigid transducer in 1957. This type of transducer was, however, never used in clinical practice. With the development of high-frequency transvaginal transducers in 1983, ultrasound became an important tool in the diagnosis of early pregnancy.26-27 The gestation sac can be visualized from around 36 days from the last menstrual period (LMP), when it reaches a size of 2-4 mm, corresponding to a level of hCG of 800 to 3200 IU/L.28 The yolk sac can be observed when the gestational sac exceeds 10 mm.11,29 Once the gestation sac reaches 20 mm, the embryo should be identi-fied.30,31 One-third of normal viable embryos with a crown-rump length (CRL) of less than 5 mm have no demonstrable cardiac activity. Therefore, repeated scanning with an interval of a few days is necessary before the definite diagnosis of non-viable pregnancy is made.32 We know that a small or irregular gestational

Gestational Sac

Figure 5.1 Four different ultrasound classifications of miscarriage: (a) early fetal demise (formally missed miscarriage); (b) early embryonic demise (formally blighted ovum or anembryonic pregnancy); (c) incomplete miscarriage; (d) 'complete miscarriage' should now be included under the umbrella term 'pregnancy of unknown location'.

Figure 5.1 Four different ultrasound classifications of miscarriage: (a) early fetal demise (formally missed miscarriage); (b) early embryonic demise (formally blighted ovum or anembryonic pregnancy); (c) incomplete miscarriage; (d) 'complete miscarriage' should now be included under the umbrella term 'pregnancy of unknown location'.

sac, discrepancies between the CRL and pregnancy length and an abnormal pattern of embryonic heart rate are predictors of a poor pregnancy outcome.31,33 The presence of subchorionic bleeding per se does not seem to be a negative prognostic sign, unless it is located at the level of the definitive placenta, i.e. under the cord insertion.31,34 The absence of an intrauterine gestational sac when hCG levels are above 1000IU/L is highly suspicious of an ectopic pregnancy.29,35

In cases of non-viability, ultrasound allows us to evaluate the amount of retained products of conception in the uterus and thus may lead to an avoidance of unnecessary intervention in apparent complete miscarriages.19,36-38 In cases of miscarriage, it is possible to differentiate roughly between four different ultrasound features:

1. 'Intra-uterine fetal demise', also called 'missed miscarriage' (Figure 5.1a).

2. 'Embryonic demise', also called 'blighted ovum', characterized by an empty gestational sac (Figure 5.1b), or 'anembryonic pregnancy'.

3. 'Complex mass', characterized by areas of different echogenicity caused by bleeding in the gestational sac (Figure 5.1c). This is known as an incomplete miscarriage.

4. Finally 'complete miscarriage' (Figure 5.1d), where an empty uterine cavity is noted or where there is only a minimal, non-significant amount of retained products with an antero-posterior diameter less than 15 mm in the longitudinal view of the uterus. The antero-posterior diameter is measured in between the myometrium and endometrium border as shown in Figure 5.1b.

The term should now be included under the umbrella term 'pregnancy of unknown location'.

In first trimester pregnancies an acellular fluid occupies the intervillous space. An increase in the placental blood flow in complicated pregnancies compared with normal pregnancies has been shown with Doppler ultrasound.39 This also correlates with histo-pathological findings suggesting that miscarriage begins with dislocation and disruption of the trophoblastic shell with premature entry of maternal blood into the intervillous space.31 It is possible that blood flow patterns in the inter-villous space, demonstrated by Doppler ultrasound, could be used to forecast the outcome of expectant management of miscarriage.40,41

100 Pregnancy Tips

100 Pregnancy Tips

Prior to planning pregnancy, you should learn more about the things involved in getting pregnant. It involves carrying a baby inside you for nine months, caring for a child for a number of years, and many more. Consider these things, so that you can properly assess if you are ready for pregnancy. Get all these very important tips about pregnancy that you need to know.

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Responses

  • elsa
    What is incomplete miscarriage?
    2 years ago
  • jyri
    How to know if my miscarriage is complete?
    2 years ago

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