An established patient presents for evaluation at 32 weeks gestation due to concerns about… — USMLE Step 2 CK

An established patient presents for evaluation at $32$ weeks gestation due to concerns about her heart and breathing. The $26$ -year-old gravida $1$ para $0$ reports that over the past month, she has felt easily winded when climbing stairs and noticed her shoes feel tight by the end of the day. She occasionally feels her heart racing when resting. Vital signs are temperature $37.0^\circ$ C ( $98.6^\circ$ F), blood pressure $112/68$ mmHg, pulse $98$ /min, and respirations $18$ /min. Cardiovascular examination reveals a prominent point of maximal impulse displaced slightly to the left, along with a grade II/VI systolic ejection murmur at the left upper sternal border. There is $1+$ bilateral lower extremity pitting edema up to the ankles. Pulmonary auscultation is clear. Urine dipstick yields negative results for protein. Which of the following is the most appropriate action at this time?

Reassurance and continuation of routine prenatal careAnswer
B
Transthoracic echocardiogram
C
Compression ultrasonography of the lower extremities
D
24-hour urine collection for total protein
E
Pulmonary function testing

Answer

Reassurance and continuation of routine prenatal care

The correct course of action is to provide reassurance and continue routine prenatal care. This patient is exhibiting classic, normal physiologic adaptations to pregnancy. The enlarging gravid uterus pushes the diaphragm upward, shifting the heart upward and to the left, which displaces the point of maximal impulse. Simultaneously, maternal blood volume expands significantly, leading to an increased cardiac output and a subsequent benign systolic flow murmur. Subjective dyspnea (often termed 'dyspnea of pregnancy') is common and driven by progesterone's stimulatory effect on the medullary respiratory center, causing hyperventilation (increased minute ventilation). Bilateral, painless pitting edema in the lower extremities is a result of the gravid uterus compressing the inferior vena cava, decreasing venous return. Because her blood pressure is normal, her lungs are clear, and her symptoms lack red flags (such as a diastolic murmur, focal chest pain, or unilateral leg swelling), these findings are benign and do not require further workup.

Step-by-Step Solution

Evaluate the patient's symptoms of dyspnea, dependent edema, and palpitations in the context of her gestational age.

The symptoms align with typical third-trimester physiologic adaptations.

Pregnancy induces significant cardiovascular and respiratory changes to accommodate the growing fetus.

Assess the physical examination findings (displaced point of maximal impulse, systolic ejection murmur, normotension, negative urine protein).

All findings lack pathologic features. There is no hypertension, no diastolic murmur, and lungs are clear.

Differentiating physiologic from pathologic states prevents unnecessary testing. The PMI shifts due to the enlarging uterus pushing the diaphragm upward. The systolic murmur is a flow murmur resulting from increased blood volume.

Determine the appropriate clinical management based on the normal physiologic assessment.

The patient requires reassurance rather than diagnostic testing.

Performing invasive or extensive testing for normal pregnancy changes leads to overmedicalization and patient anxiety.

Key Concept

Physiologic adaptations to pregnancy include increased plasma volume (causing systolic flow murmurs and edema), diaphragmatic elevation (displacing the point of maximal impulse), and progesterone-induced hyperventilation (causing subjective dyspnea).

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