Question 29.1

Created on Sat, 05/16/2015 - 19:48
Last updated on Sat, 10/24/2015 - 22:43
Pass rate: 84%
Highest mark: 8.7

Other SAQs in this paper

Other SAQs on this topic

A 24-year-old woman has the following haematology and coagulation profile post 
admission to the intensive care unit following post partum haemorrhage.

Parameter Patient Value Normal Range
White cell count 5.6 x 109/l 4.0 – 11.0
Haemoglobin 60 g/l 115 – 165
Platelets 30 x 109/l 150 – 400
PT 30.6 sec 10.5 – 13.5
APTT >150 sec 21 – 36
D-dimer >10 µgm/ml FEU <0.4
Fibrinogen 0.8 g/l 1.1 – 3.2



a) What does this pattern of coagulation abnormalities suggest?

b) List three likely causes of this coagulation profile in this patient

c) What does an elevated D-dimer indicate?

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College Answer

a) What does this pattern of coagulation abnormalities suggest 

DIC 

b) List three likely causes of this coagulation profile in this patient 

Pre-eclampsia 
Amniotic fluid embolism 
Sepsis 
Intra-uterine fetal death 
Mismatched / massive transfusion

c) What does an elevated D-dimer indicate?

Tests fibrinolysis. Measures the break down of the cross-linked fibrin

 

Discussion

This question is one of pattern recognition, and it interrogates the candidate's ability to generate a list of differential causes for DIC at the end of pregnancy.

There isn't much else this list of abnormalities could represent.

There is evidence of accelerated fibrinolysis (D-dimer elevation), a low fibrinogen suggestive of its consumption, evidence for the depletion of clotting factors (high PT and APTT) and thrombocytopenia with anaemia, suggestive of microangiopathy.

The causes of DIC are numerous, but in the context of pregnancy and PPH one can narrow down one's list of possibilities.

There are actually quite a large number of potential peripartum causes for DIC:

  • Abruptio placentae
  • Placenta accreta
  • Amniotic fluid embolism
  • Retained dead fetus
  • Abortion induced with hypertonic fluids (saline or urea)
  • Intrauterine sepsis
  • Incompatible blood transfusion
     

An excellent review article lists these, and others, and delves deep into their pathophysiology and management.

So, what indeed does an elevated D-dimer indicate? The college seems to have expected a one-line answer.

It seems to be a valuable adjunct for the laboratory diagnosis of DIC.

In essence, a D-dimer is a small protein degradation product, consising of two crosslinked D-fragments of fibrin.

A longer explanation, with pictures and extensive bibliography, is also available. The presence of an elevated D-dimer confrms that somewhere fibrin is being degraded.

References

Slofstra, Sjoukje, Arnold Spek, and Hugo ten Cate. "Disseminated intravascular coagulation." The Hematology Journal 4.1 (2013): 295-302.

Levi, Marcel, and Hugo Ten Cate. "Disseminated intravascular coagulation."New England Journal of Medicine 341.8 (1999): 586-592.

Letsky, Elizabeth A. "Disseminated intravascular coagulation." Best Practice & Research Clinical Obstetrics & Gynaecology 15.4 (2001): 623-644.

Carr, J. Meehan, M. McKinney, and J. McDonagh. "Diagnosis of disseminated intravascular coagulation. Role of D-dimer." American journal of clinical pathology 91.3 (1989): 280-287.

Adam, Soheir S., Nigel S. Key, and Charles S. Greenberg. "D-dimer antigen: current concepts and future prospects." Blood 113.13 (2009): 2878-2887.