Question 8.1

Angoff score
5.77
Highest mark
9.25
Pass rate
??
Other SAQs in this topic:
Other SAQs in this paper:

A 25-year-old pregnant patient, G3P2 and 30/40 gestation with a 5-day history of anorexia, nausea and vomiting presents to hospital after a convulsion and is transferred immediately to your intensive care unit. The following blood results are obtained:

Full blood count

Patient

Reference

Haemoglobin

177 g/L*

120-160

White Cell Count

25.4 x 109/l *

4.0 -11 .0

Platelet Count

29 x 109/l*

150-350

Biochemistry

Patient

Reference

Sodium

127mmol/L*

135-145

Potassium

2.3 mmol/L*

3.5-5.2

Chloride

84 mmol/L*

95 - 105

Bicarbonate

28 mmol/L*

22 - 32

Urea

29 mmol/L*

3.0-8.0

Creatinine

354 μmol/L*

45-90

Coagulation

Patient

Reference

International normalised ratio (INR)

1.1

0.9-1.3

Prothrombin time

15 secs

12 – 16.5

APTT (Activated partial prothrombin time)

28 secs

27- 38.5

Fibrinogen

5.7 g/L*

2.0 – 4.0

D-Dimer

16.8 mg/L*

< 0.5

Explain the MAJOR abnormalities in this patient. (4 marks)

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College answer

Syllabus topic/section:

2.1.11    Obstetric Intensive Care: Physiological changes related to pregnancy: L1


Discussion: 

This question was an obstetric data question and was generally answered well by most candidates.

Question 8.1 required an explanation of the major abnormalities contextualised to the described patient. For example, severe hypokalaemia and hypochloraemia related to nausea and vomiting.
 

Discussion

The word MAJOR is bolded and capitalised, but how major is major?
What follows is a list of ALL abnormalities. The lesser known "Explain" vocabulary term was used here, which is an excellent use of it; whereas "interpret" may simply lead the trainee to parse the results and retrieve stored lists of differentials, "explain" calls on them to create a plausible narrative for the story of how the abnormal results became abnormal.

  • Haemoglobin is high: this suggests haemoconcentration, as a pregnant woman should not have that much haemoglobin
  • WCC is raised, potentially due to a concurrent infection
  • Thrombocytopenia: could this be TTP, HUS, HELLP, or sepsis with DIC?
  • Hypokalemia hyperchloremia and alkalosis are the consequences of volume loss, as they tend to follow aldosterone release. Aldosterone instructs the collecting duct to retain sodium, dropping potassium in the process, and increasing the strong ion difference which promotes the storage of CO2 as HCO3.
  • Hyponatremia is probably the hypervolemic hyponatremia of renal failure.
  • The urea and creatinine are raised, and the urea:creatinine ratio is 0.08 (or, 80, depending if you prefer to do your maths before after). This falls into the category of "normal" urea-creatinine ratios.
  • The coags are normal except for the fibrinogen, which is appropriately raised for pregnancy, and  D-dimer

References

Bremme, Katarina A. "Haemostatic changes in pregnancy." Best practice & research Clinical haematology 16.2 (2003): 153-168.

Moore, Lisa E., and Nigel Pereira. "Physiological changes of pregnancy." Maternal Critical Care: A Multidisciplinary Approach 107 (2013).

Katz, D., and Y. Beilin. "Disorders of coagulation in pregnancy." BJA: British Journal of Anaesthesia 115.suppl_2 (2015): ii75-ii88.

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