Foetal surveillance

Methods

There are a variety of ways in which the foetal surveillance can be done.

Kick chart

The mother basically records how often she feels a foetal movement, with ten being considered normal. The emphasis is on change, not number. It is simple and cheap and most foetuses do have reduced movements before things start to go wrong. However, this only happens shortly before death and this hasn't been shown to reduce perinatal mortality. Plus, mothers can be made very anxious and there is a high false positive rate. Should not be used routinely.

Serial ultrasound

Abdominal and head circumferences are measured at least 2 weeks apart. This can give a growth rate where essentially you want the babies measurements to remain on roughly the same centile lines throughout the pregnancy. It's safe and used widely but 'one-off' scans in late pregnancy can be misleading.

Doppler umbilical artery wave form

Basically, used to measure blood flow from the placenta, through the umbilical artery to the foetus. It can identify which foetuses are actually IUGR and improves the outcome of high-risk pregnancy. Absence of end-diastolic flow is an earlier sign than abnormal CTG. Shouldn't be used in normal pregnancy.

Doppler of foetal circulation

Many vessels in the foetus can be seen, particularly middle cerebral artery and ductus venosus. When the baby is compromised, the middle cerebral often has low resistance compared to the aorta or renal vessels (called 'head-sparing'). Little evidence this reduces perinatal outcomes.

Ultrasound of fluid level and biophysical profile

Essentially a scoring system out of 8 with two for each of the following categories: limb movement, tone, breathing movement, liquor volume. CTG can be included to give a score out of 10. It takes a long time and shouldn't be used in low-risk pregnancy but it's pretty good when other tests aren't any use.

Cardiotography

Best of looking at the CTG bit of the foetal monitoring page.

What is a "high-risk" pregnancy?

The whole point in doing foetal surveillance is to figure out which pregnancies are "high-risk" or at least need some form of intervention. Basically, the following list is indication of high-risk:

• Pre-pregnancy - poor past obs history; previous small baby; maternal disease; assisted conception; <17 or >35 years old; smoker; drug use
• During pregnancy - hypertension/proteinuria (pre-eclampsia); vaginal bleeding; small-for-dates; prolonged pregnancy; multiple pregnancy; recurrent UTI

There's also a bunch of blood tests which are done in normal antenatal care.