A 23-year-old previously healthy girl involved in a motor vehicle accident is brought to ICU with multiple rib fractures and laceration of her left forearm. , no acute bleeding, She is haemodynamically stable and there is no evidence of acute bleeding. She has the following coagulation profile:

Test

Result

Normal range

INR

1.1

0.8-1.2

Prothrombin time

11

10-15

APTI

73

35-45

APTT after protamine

69

35-45

APTI with 50% normal plasma

53

35-45

Fibrinogen

3.4

2.5-5

a)  What is the likely explanation for the APTT result?  Give reasons.

b)  What further test would you order  to confirm  the aetiology of the coagulopathy?

c)  What vascular complication is this patient at risk of?

d)  What drugs might be suitable for DVT prophylaxis in this patient?

[Click here to toggle visibility of the answers]

College Answer

a)  What is the likely explanation for the APTT result?  Give reasons.

Antiphospholipid antibody syndrome

Reasons: .
1)  Lack of correction with protamine excludes heparin as a cause of prolonged APTT 

2)  Lack of correction with normal plasma excludes clotting faetor deficiency. Prolongation despite normal plasma suggests circulating anticoagulant. Normal INR and PT and fibrinogen exclude DIC. In a young woman, antiphospholipid antibody syndrome

b)  What further test would you order  to confirm  the aetiology of the coagulopathy?

Lupus anticoagulant

c)  What vascular complication is this patient at risk of?

Recurrent DVTarterial thrombosis

d)  What drugs might be suitable for DVT prophylaxis in this patient?

Short term-aspirin /heparin
Long term-warfarin

Discussion

This is another one of those "why is my APTT so high" questions.

Specifically, this question closely resembles the following questions:

In this case, for some reason somebody gave the trauma patient some protamine. More commonly one would use a heparinase assay or the combination of thrombin time and reptilase time to exclude the effects of heparin, but a "protamine challange" is one way of doing it.

Antiphospholipid syndrome is discussed in greater detail elsewhere.

In brief, the major criteria for diagnosis require one clinical criterion (eg. thrombosis) and one laboratory criterion (eg. a positive anti-β2-glycoprotein-I antibody).

The laboratory tests one could order are as follows:

  • Lupus anticoagulant
  • Anticardiolipin antibody
  • anti-β2-glycoprotein-I antibody
  • Antiprothrombin antibody

The antiphospholipid syndrome patient is prone to simultaneously clotting and bleeding.

The specific list of complication is as follows:

  • DVT
  • PE
  • miscarriage
  • cerebral sinus thrombosis
  • arterial thrombosis

The most recent management guidelines suggest long term warfarin, with a target INR of 2.5.

References

References

Miyakis, Spyridon, et al. "International consensus statement on an update of the classification criteria for definite antiphospholipid syndrome (APS)." Journal of Thrombosis and Haemostasis 4.2 (2006): 295-306.

 

Cervera, Ricard, and Gerard Espinosa. "Update on the catastrophic antiphospholipid syndrome and the “CAPS Registry”.Seminars in thrombosis and hemostasis. Vol. 38. No. 4. 2012.

 

Keeling, David, et al. "Guidelines on the investigation and management of antiphospholipid syndrome." British journal of haematology 157.1 (2012): 47-58.