Prothrombin time is increased in?

NHM UP Staff Nurse - 2016

Pathology & Genetics

Hard

Appeared in: NHM UP Staff Nurse - 2016

Explanation

Prothrombin Time (PT) evaluates the integrity of the extrinsic and common pathways of the coagulation cascade.
All three options listed—Heparin therapy, Obstructive jaundice, and Haemorrhagic disease of the newborn—can disrupt these pathways, leading to a prolonged PT.
Obstructive jaundice and Haemorrhagic disease of the newborn both cause Vitamin K deficiency, which is essential for synthesizing clotting factors II, VII, IX, and X.
Heparin, an anticoagulant, primarily affects the intrinsic pathway (monitored by aPTT) but can also prolong PT at higher doses by inhibiting factors in the common pathway.
Because all individual options are correct causes of increased PT, the most comprehensive and correct answer is 'All'.

Option A: This option is correct, but it is not the only correct one. Obstructive jaundice and haemorrhagic disease of the newborn also increase PT.
Option B: This option is correct, but it is not the only correct one. Heparin therapy and haemorrhagic disease of the newborn also increase PT.
Option C: This option is correct, but it is not the only correct one. Heparin therapy and obstructive jaundice also increase PT.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Causes of prolonged Prothrombin Time (PT) as background academic context rather than a clinical decision trigger.
Nurses must understand the implications of a prolonged PT, as it indicates an increased risk of bleeding. Patients should be monitored for signs like bruising, petechiae, hematuria, or melena.
PT is often reported as an International Normalized Ratio (INR), which standardizes the results. Nurses monitor PT/INR levels closely in patients on warfarin (Coumadin) to ensure they are within the therapeutic range.
For a patient with obstructive jaundice and a prolonged PT, the nurse should anticipate orders for parenteral Vitamin K administration and prepare for safe administration.

How to Approach the Question

First, understand the core of the question. It asks for conditions that increase Prothrombin Time (PT).
Define Prothrombin Time. Recall that PT measures the extrinsic and common pathways of blood coagulation.
Analyze each option individually to see how it affects these pathways.
Evaluate Option A (Heparin): Recall that heparin is an anticoagulant. While it's primarily monitored by aPTT (intrinsic pathway), high doses can affect the common pathway, thus increasing PT.
Evaluate Option B (Obstructive Jaundice): Connect this to the malabsorption of fat-soluble Vitamin K, which is crucial for synthesizing clotting factors in the extrinsic and common pathways.
Evaluate Option C (Haemorrhagic disease of newborn): Recognize this as a state of Vitamin K deficiency, which impairs clotting factor synthesis.

Concept Tested & Keywords

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