Abstract Number: PB0702
Meeting: ISTH 2020 Congress
Background: Mixing studies have been classically used as the first step in the investigation of a prolonged APTT.
Aims: We aimed to investigate the information provided by APTT mixing studies performed prior to surgery from August 2018 to December 2019.
Methods: Abnormal APTT were investigated by mixing studies.
Results: Eleven cases with abnormal APTT in a preoperative screening were investigated. In two cases the mixing study did not correct APTT. After a 2 hours incubation period, 4 additional cases showed APTT inhibition. Six cases had positive lupus anticoagulant (LAC), five of them with prolonged mixing studies, and one with normal mixing study. Low levels of factor XII were found in this patient. Regarding surgery outcome, within the 6 positive LAC patients one major bleeding event was observed after spinal metastases resection in the only case with normal mixing study, three cases were operated without complications (bariatric surgery, anal fistula, and arteriovenous fistula), while two cases have not been operated (renal transplantation and hysterectomy). One patient with a prolonged mixing study and normal levels intrinsec pathway factors was not investigated for LAC and successfully underwent an appendicectomy. In three cases with normal mixing studies, lupus anticoagulant tests were negative. Two of them had low factor XII levels and underwent a knee arthroplasty and a lithotripsy without hemorrhagic events, another patient had a very slight decrease in factor VIII and IX levels, and suffered a catastrophic hemorrhage during a pleural tumor resection due to cava vein laceration, while the fourth patient had slightly low levels of factor VIII, and underwent a knee arthroscopy without complications.
Conclusions: In our experience, none of the patients with TTPA inhibition after a mixing study suffered a hemorrhagic complication during surgery. All the patients with an abnormal mixing study who were tested for LAC had a positive result.
To cite this abstract in AMA style:
Nomdedeu M, Cañamero E, Sarrate E, Sorigue M, Grau J, Mesa A, Ruiz L, Exposito F, Comes M, Espasa A, Orna E, Hernandez I, Morales C, Navarro T. APTT Mixing Studies in the Preoperative Setting [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/aptt-mixing-studies-in-the-preoperative-setting/. Accessed March 21, 2024.« Back to ISTH 2020 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/aptt-mixing-studies-in-the-preoperative-setting/