Routine investigations might be useful in pre-eclampsia, but not in gestational hypertension

Women referred to secondary care with suspected pregnancy-induced hypertension (PIH) are commonly investigated with blood tests and cardiotocography (CTG), regardless of the clinical severity of their condition. Over-investigation might lead to inappropriate intervention.

To investigate how often abnormal blood test and CTG results occur in women with pre-eclampsia and gestational hypertension and in women who do not have pregnancy-induced hypertension.

Retrospective case note review of 526 consecutive women referred with suspected pregnancy-induced hypertension to a district hospital. The frequency of abnormal test results and the pregnancy outcomes were analysed according to clinical classification.

36% of women referred did not meet the clinical criteria for a diagnosis of pregnancy-induced hypertension. Abnormalities of platelet count and/or liver function were seen in 11% of women with pre-eclampsia and in less than 2% of women with gestational hypertension and in a similar proportion of women who did not have pregnancy-induced hypertension. Gestational hypertension was associated with increased induction and caesarean birth rates, but not with low birthweight or preterm delivery. Progression from gestational hypertension to pre-eclampsia was not predicted by blood test abnormalities. Support for the routine use of antenatal CTG was not found.

A clinical diagnosis of pregnancy-induced hypertension should be confirmed before blood tests are ordered. The incidence of test abnormalities was only increased in pre-eclampsia and in gestational hypertension before term. CTG might only be of use in selected cases.