EP11.11: Non‐invasive estimation of hemoglobin in pregnancy using pulse co‐oximetry

Anemia complicating pregnancy is an important cause of maternal morbidity. We aimed to investigate the accuracy of a non-invasive device to measure hemoglobin in pregnancy, and to assess if cutaneous pulse co-oximetry results are influenced by skin pigmentation. It was a prospective study involving the clinical investigation of a medical device. Hemoglobin was estimated before planned Caesarean section using a non-invasive point-of-care device (Massimo Pronto pulse co-oximeter) and full blood count. Bias and 95% limits of agreement were examined for pulse co-oximeter and laboratory hemoglobin estimation. Variability of accuracy of the pulse co-oximeter device was assessed in the six Fitzpatrick scales of skin tone. Of the 122 women recruited, twelve (9.8%) had hemoglobin values below 105 g/L. The Pronto device showed a significant positive bias. The mean difference was 23.4 (SD: 11.97) g/L. The 95% limits of agreement between the Pronto device and the laboratory estimation were -0.06 to 46.9 gm/L. The difference between the two methods was unrelated to the skin pigmentation. The area under the ROC curve was 0.705 (95% CI: 0.817 – 0.593, p = 0.013) for the detection of anemia. The point-of-care device overestimates the hemoglobin readings in pregnant women; needing a correction to estimate the real value. Accuracy is unaffected by skin pigmentation. The device may be a potentially useful screening tool, and avoids repeated pricks and blood samples, thus improving patient experience and decreasing the burden on laboratories.