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.