Pre-analytical errors in coagulation testing: a case series

OBJECTIVES

Prevention of pre-analytical issues in coagulation testing is of paramount importance for good laboratory performance. In addition to common issues like hemolysed, icteric, or lipemic samples, some specific pre-analytical errors of coagulation testing include clotted specimens, improper blood-to-anticoagulant ratio, contamination with other anticoagulants, etc. Prothrombin time (PT) and activated partial thromboplastin time (aPTT) are very commonly affected tests due to pre-analytical variables. The impact these parameters possess on surgical decision-making and various life-saving interventions are substantial therefore we cannot afford laxity and casual mistakes in carrying out these critical investigations at all.

CASE PRESENTATION

In this case series, a total of 4 cases of unexpectedly deranged coagulation profiles have been described which were reported incorrectly due to the overall casual approach towards these critical investigations. We have also mentioned how the treating clinician and lab physician retrospectively accessed relevant information in the nick of time to bring back reassurance.

CONCLUSIONS

Like every other critical investigation, analytical errors can occur in coagulation parameters due to various avoidable pre-analytical variables. The release of spurious results for coagulation parameters sets alarm bells ringing causing much agony to the treating doctor and patient. Only a disciplined and careful approach taken by hospital and lab staff towards each sample regardless of its criticality can negate these stressful errors to a large extent.

Diagnostic and Prognostic Significance of the Prothrombin Time/International Normalized Ratio in Sepsis and Septic Shock

OBJECTIVE

The study investigates the diagnostic and prognostic significance of the prothrombin time/international normalized ratio (PT/INR) in patients with sepsis and septic shock.

BACKGROUND

Sepsis may be complicated by disseminated intravascular coagulation (DIC). While the status of coagulopathy of septic patients is represented within the sepsis-3 definition by assessing the platelet count, less data regarding the prognostic impact of the PT/INR in patients admitted with sepsis and septic shock is available.

METHODS

Consecutive patients with sepsis and septic shock from 2019 to 2021 were included. Blood samples were retrieved from day of disease onset (ie, day 0), as well as on day 1, 2, 4, 6 and 9 thereafter. Firstly, the diagnostic value of the PT/INR in comparison to the activated partial thromboplastin time (aPTT) was tested for septic shock compared to sepsis without shock. Secondly, the prognostic value of the PT/INR for 30-day all-cause mortality was tested. Statistical analyses included univariable t-tests, Spearman's correlations, C-statistics, Kaplan-Meier analyses and Cox proportional regression analyses.

RESULTS

338 patients were included (56% sepsis without shock, 44% septic shock). The overall rate of all-cause mortality at 30 days was 52%. With an area under the curve (AUC) of 0.682 (p= .001) on day 0, the PT/INR revealed moderate discrimination of septic shock and sepsis without shock. Furthermore, PT/ INR was able to discriminate non-survivors and survivors at 30 days (AUC = 0.612; p = .001). Patients with a PT/INR >1.5 had higher rates of 30-day all-cause mortality than patients with lower values (mortality rate 73% vs 48%; log rank p = .001; HR = 2.129; 95% CI 1.494-3.033; p = .001), even after multivariable adjustment (HR = 1.793; 95% CI 1.343-2.392; p = .001). Increased risk of 30-day all-cause mortality was observed irrespective of concomitant thrombocytopenia.

CONCLUSION

The PT/INR revealed moderate diagnostic accuracy for septic shock but was associated with reliable prognostic accuracy with regard to 30-day all-cause mortality in patients admitted with sepsis and septic shock.

Usefulness of Perioperative Laboratory Tests in Total Hip and Knee Arthroplasty: Are They Necessary for All Patients?

Background

Laboratory studies are routinely obtained preoperatively and postoperatively for total hip arthroplasty (THA) and total knee arthroplasty (TKA). This study evaluates the necessity of routine, perioperative laboratory tests and identifies risk factors for laboratory-associated interventions.

Methods

This retrospective review evaluated 967 consecutive patients scheduled for primary, unilateral TKAs (n = 593) or THAs (n = 374) over an 18-month period at a single institution. Preoperative prothrombin time (PT) and International Normalized Ratio (INR), complete blood count (CBC), complete metabolic panel (CMP), and postoperative CBC and basic metabolic panel (BMP) were recorded along with any laboratory-associated intervention. Patient demographics and comorbidities identified risk factors for abnormal or actionable laboratory studies.

Results

Preoperatively, the actionable rates for PT/INR, CMP, and CBC were 0.3%, 1.4%, and 0.5%, respectively. Vascular, renal, and immunologic diseases were risk factors for an actionable CBC. Risk factors for an actionable CMP include cardiac arrhythmia and diabetes. There were no risk factors for an actionable PT/INR. Postoperatively, only 1.5% of BMPs and 1.5% of CBCs were actionable. Congestive heart failure, renal disease vascular disease, or history of cancer (P = .030) were risk factors for an actionable CBC. There were no risk factors for an actionable BMP. Patients with an abnormal preoperative lab were 2.4 times more likely to have an actionable postoperative lab. Patients with an actionable preoperative lab were 11.3 times more likely to have an actionable postoperative lab.

Conclusion

Routine preoperative and postoperative labs may not be necessary on all patients undergoing a TKA or THA. Comorbid risk factors and abnormal or actionable preoperative CMPs and CBCs can help determine the usefulness of postoperative laboratory assessments.

Fully printed prothrombin time sensor for point-of-care testing

With an increasing number of patients relying on blood thinners to treat medical conditions, there is a rising need for rapid, low-cost, portable testing of blood coagulation time or prothrombin time (PT). Current methods for measuring PT require regular visits to outpatient clinics, which is cumbersome and time-consuming, decreasing patient quality of life. In this work, we developed a handheld point-of-care test (POCT) to measure PT using electrical transduction. Low-cost PT sensors were fully printed using an aerosol jet printer and conductive inks of Ag nanoparticles, Ag nanowires, and carbon nanotubes. Using benchtop control electronics to test this impedance-based biosensor, it was found that the capacitive nature of blood obscures the clotting response at frequencies below 10 kHz, leading to an optimized operating frequency of 15 kHz. When printed on polyimide, the PT sensor exhibited no variation in the measured clotting time, even when flexed to a 35 mm bend radius. In addition, consistent PT measurements for both chicken and human blood illustrate the versatility of these printed biosensors under disparate operating conditions, where chicken blood clots within 30 min and anticoagulated human blood clots within 20-100 s. Finally, a low-cost, handheld POCT was developed to measure PT for human blood, yielding 70% lower noise compared to measurement with a commercial potentiostat. This POCT with printed PT sensors has the potential to dramatically improve the quality of life for patients on blood thinners and, in the long term, could be incorporated into a fully flexible and wearable sensing platform.

Elevated prothrombin time/international normalized ratio associated with concurrent administration of regorafenib and warfarin in a patient with advanced colorectal cancer

Background

Regorafenib and its metabolites may inhibit the activities of several CYP or UDP-glucuronosyltransferase isoforms, including that of CYP2C9. Therefore, pharmacological agents that are CYP2C9 substrates may show elevated circulating levels and enhanced drug efficacy when concurrently used with regorafenib. Previous studies showed that the area under the plasma concentration-time curve of warfarin, which is the substrate for CYP2C9, increased upon co-administration of regorafenib. However, there are no reports indicating that the anticoagulant effects of warfarin increased upon co-administration of regorafenib.

Case presentation

We report a case of a 76-year-old man with liver metastasis of colon cancer. He was treated with regorafenib at a dosage of 120 mg daily on days 1 to 21 every 4 weeks as a third-line therapy. He had a history of acute myocardial infarction and had taken 2 mg warfarin daily. Three weeks after the treatment began, PT/INR values markedly increased, although there was no hemorrhage. Administration of regorafenib and warfarin was discontinued, and then PT/INR rapidly decreased. Warfarin administration was restarted (0.5 mg daily) and the dose was increased up to 1.5 mg daily. The patient’s PT/INR values exhibited a tendency to increase when concurrently used with regorafenib, the dose of which was reduced to 80 mg daily on days 1 to 14 every 3 weeks at a physician's discretion.

Conclusions

The clinical course of this patient suggested that PT/INR might increase during concurrent use of warfarin and regorafenib. Therefore, PT/INR should be periodically monitored during the concurrent use of warfarin and regorafenib.

Anticoagulation in Patients With Cirrhosis: Caught Between a Rock-Liver and a Hard Place

OBJECTIVE

To review current literature for anticoagulation in patients with cirrhosis and provide a summary of the effects of cirrhosis on the coagulation cascade, therapeutic monitoring through interpretation of antifactor Xa (anti-Xa), activated partial thromboplastin time (aPTT), and international normalized ratio (INR) as well as current prophylaxis and treatment recommendations in cirrhotic patients.

METHODS

A systematic electronic literature search was conducted in PubMed using the key termsanticoagulation, warfarin, low-molecular-weight heparin(LMWH),unfractionated heparin(UFH),target-specific oral anticoagulants, deep-vein thrombosis(DVT),pulmonary embolism(PE),portal vein thrombosis(PVT),venous thromboembolism, anti-Xa, activated partial thromboplastin time, anticoagulation therapeutic monitoring, coagulopathy, coagulation cascade, chronic liver disease, cirrhosis, anddecompensated liver disease

STUDY SELECTION

Studies written in the English language from January 2000 to December 2015 were considered for this review article. All search results were reviewed, and the relevance of each article was determined by authors independently.

CONCLUSIONS

Patients with cirrhosis are at higher risk for both bleeding and thrombosis-related complications. Cirrhosis affects production of both procoagulant and anticoagulant factors, thus resulting in increased INR and aPTT levels and decreased anti-Xa levels. LMWH is the treatment of choice for the prevention and treatment of DVT/PE/PVT in patients with cirrhosis, and monitoring with anti-Xa levels for dose adjustment is not recommended. UFH is an alternative in cirrhotic patients for shorter-term use and in cases of severe renal dysfunction and/or hemodynamic instability. Cirrhotic patients on anticoagulation therapy should be monitored closely for signs and symptoms of bleeding and thrombosis.

A phase II study of cixutumumab (IMC-A12, NSC742460) in advanced hepatocellular carcinoma

BACKGROUND & AIMS

IGF-IR is implicated in hepatic carcinogenesis. This and preliminary evidence of biological activity of anti-IGF-1R monoclonal antibody cixutumumab in phase I trials prompted this phase II study.

METHODS

Patients with advanced HCC, Child-Pugh A-B8, received cixutumumab 6mg/kg weekly, in a Simon two-stage design study, with the primary endpoints being 4-month PFS and RECIST-defined response rate. Tissue and circulating markers plus different HCC scoring systems were evaluated for correlation with PFS and OS.

RESULTS

As a result of pre-specified futility criteria, only stage 1 was accrued: N=24: median age 67.5 years (range 49-83), KPS 80% (70-90%), 20 males (83%), 9 stage III (37%)/15 stage IV (63%), 18 Child-Pugh A (75%), 11 HBV (46%)/10 HCV (42%)/11 alcoholic cirrhosis (46%)/2 NASH (8%), 11 (46%) diabetic. Median number of doses: 7 (range 1-140). Grade 3/4 toxicities >10% included: diabetes, elevated liver function tests, hyponatremia, and lymphopenia. Four-month PFS was 30% (95% CI 13-48), and there were no objective responses. Median overall survival was 8 months (95% CI 5.8-14). IGF-R1 staining did not correlate with outcome. Elevated IGFBP-1 correlated with improved PFS (1.2 [95% CI 1-1.4]; p 0.009) and OS (1.2 [95% CI 1.1-1.4]; p 0.003).

CONCLUSIONS

Cixutumumab monotherapy did not have clinically meaningful activity in this unselected HCC population. Grade 3-4 hyperglycemia occurred in 46% of patients. Elevated IGFBP-1 correlated with improved PFS and OS.

Successful perioperative management of a patient with idiopathic thrombocytopenic purpura undergoing emergent appendectomy: Report of a case

INTRODUCTION

Idiopathic thrombocytopenic purpura (ITP) is an autoimmune disease characterized by a low platelet count and normal bone marrow. Patients with ITP undergoing surgery are thought to have increased risk for postoperative complications because of their thrombocytopenia.

PRESENTATION OF CASE

we report the case of a 66-year-old woman with ITP who required an emergency operation for acute appendicitis associated with disseminated intravascular coagulation. Preoperative therapy consisted of platelet transfusions only, and intraoperative hemostasis was achieved. Postoperatively, high-dose intravenous immunoglobulin (IVIg) therapy led to an increased, stable, and adequate platelet count and good hemostasis.

DISCUSSION

The outcome of this case suggests that IVIg therapy is not always required for preoperative management of patients with.

CONCLUSION

IVIg therapy may be useful for postoperative management after emergency surgery.