Hemostaseological Management of Urological Operations in Patients Taking Aspirin Using the Thrombostat 4000

Abstract

A clinical study was started in order to examine the suitability of the Thrombostat (in vitro bleeding test) (IVBT) as a diagnostic tool to prevent perioperative bleeding due to aspirin (ASA) and/or platelet function disorders of other origins. This report is based on preliminary data. Eighty three patients who had ingested ASA in the last two weeks and/or with a history of bleeding and/or documented hemorrhagic disorders requiring distinct urological operations, were included in the study. In all patients the IVBT with CaCl₂ , in addition to common coagulation tests, were performed. Thirteen patients stopped ASA ingestion until IVBT became normal and did not show any increased bleeding tendency. The residual patients were classified by the various operations. The following operation groups were formed: Male genitals (n = 11), inguinal/suprapubic operations (n = 7), transurethral tumor resections of the bladder (TURB) (n = 17), transurethral prostate resection (TURP) (n = 12), tumor nephrectomy (n = 8), radical prostatectomy (n = 9). Thirty six patients with a history of ASA use, but normal IVBT, served as control group (C). Thirty one patients with a history of ASA ingestion had normal in vivo bleeding times (BT) and abnormal IVBT with CaCl₂ (A). Seven patients had a bleeding history and/or documented hemorrhagic disorders (B). None of the patients (A) with abnormal IVBT but normal BT displayed clinically relevant bleeding. However, the blood loss was somewhat higher compared to the controls (C), especially in patients with TURB and radical prostatectomy (not significant). The only real bleeding complication occurred in an ASA patient (TURB), who was subjected to surgery by error. Anesthesia had already started, when abnormality of BT (>15 min) and IVBT (m“infinite ”) were measured. Operative revision was necessary and revealed that the blood loss (>3 L) was based on diffuse microvascular bleeding. The majority of the patients with a bleeding history and/or documented hemorrhagic disorders (B) showed an increased bleeding tendency, which could be managed without relevant blood loss, except in two patients, one with factor XIII deficiency (25%) and ASA intake, and the other with undetected mild congenital platelet disorder (storage pool disease?). The IVBT proved suitable as screening test for platelet function disorders. Major bleeding complications could be prevented by its use. A history of low-dose ASA ingestion without prolongation of BT, but abnormal IVBT, also seemed to increase the bleeding tendency; however, the clinical relevance has to be demonstrated by an extended clinical study.

Keywords

bleeding time - aspirin - urologic surgery - Thrombostat - acetylsalicylic acid

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