Blood tests for investigating maternal wellbeing. 4. When nausea and vomiting in pregnancy becomes pathological: hyperemesis gravidarum.

Nausea and vomiting in pregnancy (NVP) is commonplace, with many midwives frequently counselling women in their care. But how do midwives know when NVP becomes pathological? Although hyperemesis gravidarum (HEG) is less common, midwives must be able to recognise and differentiate between these two conditions, especially as HEG has the potential to have a detrimental effect on maternal and fetal wellbeing. The physiological impact of HEG is well documented but what often goes unacknowledged is the psychological, social, occupational and familial impact it also has on a woman's life. Knowledge about the aetiology of HEG and treatment options available is essential but a timely initial diagnosis is paramount. For this to occur the midwife must be skilled in history taking, clinical examination and utilisation of serum blood tests--specifically electrolytes and urea. An understanding of how electrolyte levels can cause pathology is vital if the midwife wishes to interpret blood tests for women with this condition.