Obstetrics and Gynaecologycommon
A 31-year-old primigravida at 33 weeks gestation reports one week of intense generalised itching that is worst at night and most severe over her palms and the soles of her feet. There is no rash apart from scratch marks on her arms and abdomen, and she is not jaundiced. Her observations are normal and fetal movements are unchanged. Which one of the following investigations is most likely to confirm the diagnosis?