Baseline parameters for rotational thromboelastometry in healthy labouring women: a prospective observational study

OBJECTIVE

The aim of this study was to establish rotational thromboelastometry (ROTEM^® ) baseline parameters in labouring women at term gestation. The secondary aim was to compare these reference ranges with those from previous studies on labouring women and from the manufacturer.

DESIGN

A prospective, observational study.

SETTING

Tertiary referral hospital.

PARTICIPANTS

Healthy women in labour.

METHODS

Ethics approval was granted for an opt-out recruitment approach. ROTEM^® testing was performed in labouring women at term gestation. Women with any condition affecting coagulation were excluded. ROTEM^® Delta reference ranges were derived by calculating the 2.5% and 97.5% centiles for INTEM/EXTEM/FIBTEM parameters including amplitude at 5 minutes (A5), coagulation time (CT) and maximum clot firmness (MCF).

MAIN OUTCOME MEASURES

ROTEM^® parameters were measured in labouring women before delivery. The following tests were performed: FIBTEM, EXTEM and INTEM.

RESULTS

One hundred and twenty-one women met the inclusion criteria, with a mean (± SD) age of 29.6 ± 5.4 years and median (interquartile range) gestation of 39.4 weeks (37.4-40.4 weeks). Seventy-five (62.0%) women were nulliparous and 71 (58.7%) delivered vaginally. The median and interquartile ranges for selected ROTEM^® parameters were: FIBTEM A5, 21 mm (IQR 18-23 mm); EXTEM A5, 55 mm (52-58 mm); and EXTEM CT, 52 seconds (48-56 seconds).

CONCLUSIONS

The FIBTEM/EXTEM/INTEM amplitudes were higher than the manufacturer's reference ranges for non-obstetric patients. The FIBTEM MCF upper and lower limits were higher and the EXTEM/INTEM CT was shorter and narrower in range. This study provides reference ranges for ROTEM^® values in healthy labouring women at term gestation with uncomplicated pregnancies.

TWEETABLE ABSTRACT

This is the first study to report on ROTEM^® reference ranges with over 120 healthy labouring women of normal weight at term gestation.

Baseline parameters for rotational thromboelastometry (ROTEM®) in healthy pregnant Australian women: a comparison of labouring and non-labouring women at term

BACKGROUND

Rotational thromboelastometry (ROTEM®) is a point-of-care coagulation test. Reference ranges in non-labouring women have recently been established from a cohort of women presenting for elective caesarean delivery using the recommended minimum sample size of 120. This study aimed to present baseline parameters for labouring and non-labouring women and to compare the mean values of these ROTEM® parameters.

METHODS

Ethical approval was granted for an opt-out recruitment approach for labouring women and written consent was obtained from non-labouring women (data published previously). ROTEM® testing was performed in these two cohorts at term gestation. Women with any condition affecting coagulation were excluded. ROTEM® Delta reference ranges were derived by calculating the 2.5 and 97.5 percentiles for INTEM/EXTEM/FIBTEM amplitude at 5 min (A5), coagulation time (CT), maximum clot firmness (MCF) and clot formation time (CFT).

RESULTS

One hundred and twenty-one labouring and 132 non-labouring women met inclusion criteria. The mean values for selected ROTEM® parameters for labouring and non-labouring women respectively were: FIBTEM A5, 21.05 and 19.7 mm (P=0.008); EXTEM A5, 54.8 and 53.2 mm (P=0.025); and EXTEM CT, 52.2 and 53.7 s (P=0.049). Significant differences between the groups were observed in measures of clotting onset and clot firmness.

CONCLUSIONS

We demonstrated a significant decrease in the mean time-to-clotting onset in labouring women compared with non-labouring women. Mean values for measures of clot firmness were greater in labouring women. In comparison to previously established ROTEM® baseline parameters for non-labouring women, this study provides evidence that there is greater hyper-coagulability in labouring women.