Fetal blood sampling in early labour: is there an increased risk of operative delivery and fetal morbidity?

Intrapartum fetal blood sampling performed at early cervical dilatation and delivery outcomes

BACKGROUND

Intrapartum fetal blood sampling (FBS) is a fetal well-being diagnostic test for cardiotocogram abnormalities.

AIM

The aim of this study was to determine whether women who had their first FBS at <4 cm cervical dilation had an increased risk of operative delivery (caesarean section, instrumental delivery) compared to those women who had their first FBS ≥ 4 cm dilation.

MATERIALS AND METHODS

Retrospective cohort study involving labouring women who underwent FBS in a tertiary centre between 2015 and 2017. Women who had their first FBS at <4 cm dilation were compared to those who had their first FBS at ≥4 cm. The primary outcome was operative delivery (caesarean, instrumental delivery); secondary outcomes were neonatal complications. Univariate logistic regression was used to assess the association between degree of cervical dilation at first FBS and study outcomes.

RESULTS

Among 591 women, 39 (6.6%) had their first FBS at <4 cm cervical dilation. Women in the ≥4 cm group were less likely to have a total of ≥2 FBS (P = 0.003). There was no difference in the primary outcome between the two groups. Women who had the first FBS at <4 cm dilation were twice as likely to have a caesarean section delivery (odds ratio 2.06, 95% confidence interval 1.06-3.98), although 41% had a vaginal birth (instrumental and spontaneous). There were no differences in rates of resuscitation or admission to nursery between groups.

CONCLUSION

Women who had their first FBS < 4cm cervical dilation were twice as likely to have a caesarean section compared to women who had their first FBS ≥ 4 cm. However, 41% had a vaginal birth, and there were no differences in fetal outcomes.

Cervical dilatation and grade of doctor affects the interval between decision and result of fetal scalp blood sampling in labour

Fetal scalp blood sampling (FSBS) is used to provide information regarding fetal acid-base status during labour. This study assessed the interval between the decision to perform the procedure and obtaining the result and evaluated whether it is affected by cervical dilatation or the experience of the doctor. The median time for FSBS was 10 min. When cervical dilatation was ≤4 cm samples took approximately 30% longer to obtain. After adjustment for dilation, there were no significant differences between different grades of doctors. FSBS is shorter than previously reported; clinicians should be aware that procedures in early labour take longer to complete.