This prospective observational, non-interventional, single-center study aims to evaluate whether the viscoelastic parameter PLTEM, derived from ROTEM® sigma testing (EXTEM-A5 minus FIBTEM-A5), can accurately estimate platelet count in obstetric patients with thrombocytopenia and/or severe postpartum hemorrhage.

The study will include pregnant women older than 18 years managed during labor and delivery at the Hospital General Universitario Gregorio Marañón, Madrid (Spain).

The primary objective is to validate the clinical usefulness of PLTEM as a rapid point-of-care tool to support clinical decision-making regarding neuraxial anesthesia and transfusion management in obstetric emergencies.

Obstetric hemorrhage remains the leading cause of maternal mortality worldwide. In Spain, recent studies estimate an incidence between 2% and 5%. The main causes include uterine atony, genital tract trauma, retained placental tissue, and coagulation disorders. Early recognition and management of coagulation abnormalities are essential to reduce maternal morbidity and mortality.

Viscoelastic testing using rotational thromboelastometry (ROTEM® sigma) provides dynamic real-time assessment of coagulation and has become increasingly integrated into obstetric hemorrhage management algorithms. Platelet function plays a major role in clot formation, and impairment of platelet quantity or function may influence transfusion strategies and the safety of neuraxial anesthesia techniques.

The PLTEM parameter (Platelet contribution to clot firmness) estimates platelet contribution to clot strength and is calculated as the difference between EXTEM-A5 and FIBTEM-A5. In other clinical settings, PLTEM-derived measurements have demonstrated the ability to estimate platelet count with good accuracy. However, evidence validating its utility in obstetric patients remains limited.

The hypothesis of this study is that PLTEM may provide a reliable and rapid estimation of platelet count in urgent obstetric settings, thereby optimizing clinical decision-making, facilitating safer neuraxial anesthesia management, and improving transfusion practices.

This is a prospective, observational, non-interventional, single-center study conducted at the Hospital General Universitario Gregorio Marañón, Madrid (Spain). The study population will include pregnant women older than 18 years attended during labor and delivery who present with thrombocytopenia of any etiology and/or develop postpartum hemorrhage greater than 1,500 mL. Patients who decline participation will be excluded.

Clinical and laboratory data will be collected as part of routine care during the intrapartum and immediate postpartum periods. Variables recorded will include demographic characteristics, conventional laboratory parameters, ROTEM® variables, neuraxial anesthesia procedures, quantification of hemorrhage, transfusion requirements, need for reintervention, and maternal complications.

The primary objective is to validate the clinical usefulness of PLTEM in the obstetric setting and assess its correlation with conventional platelet count measurements. Secondary objectives include evaluation of additional ROTEM® parameters associated with coagulation abnormalities, assessment of transfusion requirements and hemorrhagic outcomes, and exploration of the relationship between thrombocytopenia, fibrinogen levels, and other factors contributing to obstetric coagulopathy.

The estimated minimum sample size is 85 patients, adjusted for an anticipated 20% loss rate. Statistical analyses will be performed using SPSS version 29.0. The study period will extend from protocol approval until completion of recruitment, with an anticipated completion date of December 2026.

Inclusion criteria:

• Parturients with a suspicion or confirmed thrombocytopenia before delivery (platelet count < 120x10^9/L),
• Parturients with severe postpartum haemorrhage (blood loss >1500 mL) with a suspicion of thrombocytopenia.

Exclusion criteria:

• parturient age under 18 years;
• refusal to participate

Cohort of consecutive consenting patients with suspicion and/or confirmed thrombocytopenia admitted in the labor ward, the obstetric operating room or the obstetric post anaesthetic care unit for delivery in a tertiary university hospital in Madrid-Spain for a period of 1 year.

This was not considered in the design of the research.