Physiologic clot strength by thromboelastography at extremely low and normal platelet counts in thrombocytopenic pregnant patients.

BACKGROUND

Thrombocytopenia in pregnancy poses challenges for neuraxial anesthesia decisions. Guidelines consider platelet counts ≥70×109/L safe in low-risk patients, but uncertainty persists at lower levels. Thromboelastography (TEG) measures real-time clot dynamics and may offer physiologic insight beyond standard labs. Modern TEG runs multiple assays in parallel, including citrated kaolin (overall clot strength), citrated rapid TEG (accelerated clotting), and citrated functional fibrinogen (fibrinogen contribution). Its maximum amplitude (MA) reflects final clot strength and may help assess bleeding risk, but its relation to platelet count in pregnancy is not well defined.

OBJECTIVES

To evaluate the relationship between thromboelastography (TEG) maximum amplitude (MA) and platelet count in pregnant patients with and without thrombocytopenia, and to determine the ability of MA (across CK, CRT, and CFF assays) to discriminate clinically relevant thrombocytopenia (<70×10⁹/L).

METHODS

This prospective observational study enrolled pregnant patients with and without thrombocytopenia, defined as platelet count <70×109/L or gestational thrombocytopenia ≤150×109/L. Blood samples were analyzed on the TEG 6s platform to obtain MA values. Clinical data included demographics, comorbidities, anesthetic management, and delivery outcomes. The primary outcome was correlation between MA and platelet count, assessed using Pearson correlation and linear regression. Receiver operating characteristic curves evaluated the ability of MA to discriminate platelet counts <70×109/L. Bleeding symptoms were assessed using the International Society on Thrombosis and Haemostasis Bleeding Assessment Tool questionnaire.

RESULTS

Thirty-one patients were enrolled. Log10 platelet count correlated strongly with maximum amplitude from citrated kaolin thromboelastography (MA-CK; r = 0.75), citrated rapid thromboelastography (MA-CRT; r = 0.73), and citrated functional fibrinogen (MA-CFF; r = 0.52). MA-CK demonstrated the best discrimination for platelet count <70×109/L (area under the receiver operating characteristic curve = 0.855). Most patients reported low or no bleeding symptoms. No significant correlation was observed between MA and International Society on Thrombosis and Haemostasis Bleeding Assessment Tool scores. No neuraxial hematomas occurred.

CONCLUSIONS

MA strongly correlates with platelet count in thrombocytopenic parturients even at low platelet counts, offering physiologic insight into clot strength and bleeding risk. These findings validate MA as a physiologic correlate of platelet-based clot strength. Thromboelastography may offer complementary physiologic insight into clot strength in parturients with low platelet counts, which can inform-but should not replace-clinical judgment.