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Ifeanyichukwu Ifechidere: The Most Misunderstood Cause of a Prolonged APTT in the Laboratory
Ifeanyichukwu Ifechidere/LinkedIn
Apr 15, 2026, 16:54

Ifeanyichukwu Ifechidere: The Most Misunderstood Cause of a Prolonged APTT in the Laboratory

Ifeanyichukwu Ifechidere, Specialist Biomedical Scientist at Sheffield Teaching Hospitals NHS Foundation Trust, shared a post on LinkedIn:

” ‘Prolonged APTT: bleeding risk’… right?

This is one of the most misunderstood assumptions in coagulation.

Because one of the commonest causes of prolonged APTT in the lab…

  • does NOT cause bleeding at all.

In fact — it’s often associated with the opposite.

Let’s talk about Lupus Anticoagulant (LA)

Despite the name, it is: Not necessarily linked to lupus

Not an anticoagulant in the body

It is a prothrombotic antibody

So why does it prolong APTT?

Lupus anticoagulant interferes with: Phospholipid-dependent clotting assays

In vitro (in the lab):

It binds phospholipids in the test reagent

Disrupts clot formation

  • Leads to prolonged APTT

But in vivo (in the patient):

It promotes thrombosis, not bleeding

Associated with:

  • Venous thromboembolism
  • Recurrent miscarriages
  • Antiphospholipid syndrome

Why it confuses so many:

Because the pattern looks like a bleeding disorder:

Prolonged APTT

Sometimes no correction in mixing study

Easily mistaken for:

  • Factor deficiency
  • Factor inhibitor

Key distinguishing features:

  • Mixing study

Often fails to correct (inhibitor pattern)

  • Incubation

No time-dependent effect (unlike factor VIII inhibitors)

  • Clinical picture

No bleeding history

May have thrombotic history

Confirmatory tests

  • Dilute Russell Viper Venom Test (dRVVT)
  • Phospholipid neutralisation studies

The critical takeaway:

Not all prolonged APTTs indicate bleeding risk.

And missing lupus anticoagulant can lead to:

  • Misinterpretation
  • Delayed thrombosis risk recognition
  • Incorrect clinical decisions

Want a simple way to interpret coagulation results with confidence?

I’ve created a free cheat sheet that breaks down patterns like this — clearly and practically.

Download it.

Because in coagulation, confidence doesn’t come from memorising — it comes from understanding what the result is really telling you..”

Ifeanyichukwu Ifechidere: The Most Misunderstood Cause of a Prolonged APTT in the Laboratory

Other posts featuring Ifeanyichukwu Ifechidere on Hemostasis Today.

aPTT bleeding disorders Factor VIII Inhibitors Health Hematology Hemophilia Hemostasis Hemostasis News Hemostasis Today Ifeanyichukwu Ifechidere Medicine mixing study
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