Pregnancy Risk Management 2020

Pregnancy Risk Management List

  • Rubella, Syphilis, Hep B, Hep C, HIV (initially or at 28 weeks)
  • Parvovirus, Cytomegalovirus and Toxoplasmosis
    – If found to be negative before or early in the pregnancy, this can be crucial for diagnosing and managing a new infection during the pregnancy.
    – CMV and Parvo occur especially in families with small children and healthcare workers
    – Herpes past infection may make a vaginal delivery undesirable or unsafe.

A foetal heartbeat can be seen from about 3.3 weeks from conception, initially only by vaginal scan.

It is more reliably seen from 6.0 weeks from LMP.

If CRL only used: 9 – 11: weeks

If CRL + HC + AC + FL are used:13 weeks

The extra measurements can help decide if the foetal CRL is short, average length or long and hence derive a more accurate estimate of EDD

If uterine artery flow waveform is notched at 11 – 14 weeks, Odds Ratio = 5

Blood test HCG + PAPP-A 10.4 – 13.6weeks

PLUS ultrasound measurement of nuchal translucency.

Combined false negative for T21 13% using 1:350 risk.

Blood test HCG + PAPP-A 10.4 – 13.6weeks

PLUS ultrasound measurement of nuchal translucency.

Combined false negative for T21 13% using 1:350 risk.

  • PAPP-A <0.42
    – Placental dysfunction Odds Ratio 2.7
    – Premature delivery Odds Ratio 2.3
  • PAPP-A < 0.2 Very high risk of major malformations which may not cause a detectable chromosomal abnormality.

2 or 3 hour 75g load GTT, BGA even if Rh+, HIV (if not already done)

Can be checked at 28 weeks or later by taking a high vaginal swab. Test has uncertain benefit.

  • Some early tests give baselines which are very useful later in the pregnancy, including
    – Hb, platelets, glucose, uric acid/urate, blood group and antibodies, Vitamin D.
  • Vitamin A may be recognised soon as an important test.

Unfortunately, not taught in many places. It can indicate:

  1. The baby very unlikely to fit through the pelvis or
  2. A vaginal delivery would give a high risk of foetal and/or maternal damage.

Best at 12 – 13.6 weeks. Later gives more information.

Highly recommended even if NT not wanted

Gives the risk of Trisomy 13,18,21, X & Y chromosome aneuploidy.

False negative rate for T21  0.2%,

Cost $400+ for trisomies and sex, $600+ if extra tests.  

  • Many international experts are now advising action at a much lower NT risk, e.g.1:1,000 to 1:3,000, without solid evidence for which is best.
  • My manipulation of the data suggests that using 1:2,700 will pick up most of the 13% missed.
  • Best at 20 – 21.6 weeks.

    The later the scan, the more can be seen.

At 28 weeks, followed if test is negative patient is given injections of Anti-D at 28 and 34 weeks

If indicated, useful at 32 – 34 weeks for growth, morphology and placental function and position.

Various parameters used and may pick up unsuspected placental dysfunction which may be critical.

This is the most exciting development after taking a long time to find clinical relevance.

  • I now use a combination of:
    – amniotic fluid volume as seen on an office ultrasound scan
    – plus the middle cerebral artery wave-form and pulsitility index
  • Sounds complicated but can be done easily on many office scanners if they have colour doppler (most have it)
    – If both are abnormal, urgent delivery may be needed within 24 – 48 hours.

I believe that using this monitoring may significantly reduce the stillbirth rate