A nurse is preparing to assess fetal heart tones for a client who is at 12 weeks of gestation.

Which of the following actions should the nurse take?

The correct answer is choice A. INR.

Warfarin is a vitamin K antagonist that inhibits the synthesis of factors II, VII, IX, and X in the liver.

These factors are part of the extrinsic and common pathways of coagulation, which are measured by the prothrombin time (PT) and the international normalized ratio (INR).

The INR is a standardized way of reporting the PT that accounts for the variability of different reagents and instruments.

The INR is used to monitor the therapeutic effect of warfarin and to adjust the dose accordingly.

The target INR range depends on the indication for warfarin, but it is usually between 2 and 3 for most conditions.

Choice B is wrong because fibrinogen level is not affected by warfarin.

Fibrinogen is a precursor of fibrin, which forms the final step of the coagulation cascade.

Fibrinogen level can be decreased in conditions such as disseminated intravascular coagulation (DIC), liver disease, or severe bleeding. Choice C is wrong because aPTT is not affected by warfarin.

aPTT measures the intrinsic and common pathways of coagulation, which are mainly dependent on factors VIII, IX, XI, and XII.

These factors are not inhibited by warfarin.

aPTT is used to monitor the effect of heparin, a direct antithrombin agent that inhibits thrombin and factor Xa.

Choice D is wrong because platelet count is not affected by warfarin.

Platelets are cell fragments that adhere to damaged blood vessels and form aggregates to initiate hemostasis.

Platelet count can be decreased in conditions such as immune thrombocytopenia (ITP), heparin-induced thrombocytopenia (HIT), or bone marrow suppression.

Normal ranges:

• INR: 0.8-1.2
• Fibrinogen: 200-400 mg/dL
• aPTT: 25-35 seconds
• Platelet count: 150-450 x 10^9/L References:

Choice A option

Fibrinogen level: Fibrinogen is a protein involved in the blood clotting process, but in this case, it is not appropriate because is not the primary laboratory test used to monitor warfarin therapy. Monitoring fibrinogen levels is more relevant in assessing bleeding disorders or certain medical conditions.

Choice B option

PTT (Partial Thromboplastin Time): PTT is another laboratory test used to evaluate blood clotting function, particularly the intrinsic pathway of the clotting cascade. PTT is not routinely used to monitor warfarin therapy; it is more commonly used to monitor other anticoagulant medications like heparin.

Choice C option

The nurse should plan to report the client's INR (International Normalized Ratio) to obtain a prescription for the client's daily warfarin. INR is a critical laboratory test used to monitor the effectiveness and safety of warfarin therapy.

Warfarin is an anticoagulant medication commonly prescribed to prevent and treat blood clots. It works by interfering with the body's ability to use vitamin K to form blood clots. Monitoring the INR is essential because it indicates how long it takes for the blood to clot, and it helps determine if the client's warfarin dosage needs adjustment to achieve the desired level of anticoagulation.

Choice D option

Platelet count: Platelet count is essential to assess the number of platelets in the blood, which are crucial for normal clotting. However, platelet count monitoring is not the primary focus when prescribing warfarin. It is typically used to evaluate thrombocytopenia (low platelet count) or other conditions affecting platelet function.