A 24-year-old primigravida at 24 weeks gestation comes to the clinic reporting frequent, u… — USMLE Step 2 CK

A 24-year-old primigravida at 24 weeks gestation comes to the clinic reporting frequent, unprovoked nosebleeds and a new rash on her lower extremities over the past two days. She feels fetal movement and has no other complaints. Temperature is $37.0^\circ\text{C}$ ( $98.6^\circ\text{F}$ ), blood pressure is $118/76 \text{ mmHg}$ , and heart rate is $82/\text{min}$ . Physical examination reveals scattered, non-blanching, pinpoint macules over her shins and ankles. The uterus is consistent in size with a 24-week gestation, and fetal heart rate is $145/\text{min}$ with normal variability.

Laboratory results are as follows:

Laboratory Test	Result
Hemoglobin	$11.4 \text{ g/dL}$
White blood cell count	$7,800/\mu\text{L}$
Platelet count	$14,000/\mu\text{L}$
Prothrombin time	$11 \text{ s}$
Partial thromboplastin time	$28 \text{ s}$
Creatinine	$0.7 \text{ mg/dL}$

A peripheral blood smear demonstrates a few enlarged platelets with normal morphology and a lack of schistocytes. Which of the following is the most appropriate next step in management?

A
Broad-spectrum intravenous antibiotics
B
Reassurance and routine prenatal care
Administration of systemic corticosteroidsAnswer
D
Plasma exchange
E
Immediate induction of labor

Answer

Administration of systemic corticosteroids

The correct answer is administration of systemic corticosteroids. This patient presents with isolated severe thrombocytopenia and mucocutaneous bleeding (epistaxis, petechiae) at 24 weeks gestation, which is characteristic of primary immune thrombocytopenic purpura (ITP). ITP is an autoimmune condition involving IgG antibodies against platelet membrane antigens (e.g., GpIIb/IIIa). In pregnancy, treatment for ITP is indicated when the platelet count is below

30,000/\mu\text{L}

or if there is clinically significant bleeding. Systemic corticosteroids (such as oral prednisone) or intravenous immune globulin (IVIG) are the safest and most effective first-line therapies.

Step-by-Step Solution

Analyze the patient's symptoms and laboratory values.

The patient has isolated severe thrombocytopenia (platelets 14,000/μL) and mucocutaneous bleeding (epistaxis, petechiae) at 24 weeks gestation.

Identifying the primary derangement is required to formulate a differential diagnosis.

Evaluate the peripheral blood smear and coagulation profile.

Normal PT and PTT rule out consumptive coagulopathies like DIC. The absence of schistocytes rules out microangiopathic hemolytic anemias like TTP or HELLP syndrome.

Critical life-threatening causes of thrombocytopenia in pregnancy must be rapidly excluded.

Determine the most likely diagnosis and indications for treatment.

The diagnosis is primary immune thrombocytopenic purpura (ITP). Because the platelet count is below 30,000/μL and the patient is bleeding, active treatment is indicated.

Gestational thrombocytopenia does not cause severe bleeding or platelet counts < 70,000/μL, pointing to ITP which requires medical intervention.

Select the appropriate initial therapy.

Systemic corticosteroids (or IVIG) are selected as the safest and most effective first-line therapy in pregnancy.

Corticosteroids reduce immune-mediated platelet destruction and are safe in the second trimester.

Key Concept

Management of immune thrombocytopenic purpura (ITP) in pregnancy

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