A 28-year-old primigravid woman at 26 weeks gestation is evaluated in the clinic for a dul… — USMLE Step 2 CK

A $28$ -year-old primigravid woman at $26$ weeks gestation is evaluated in the clinic for a dull ache in her right lower back and flank over the past week. She reports no fever, chills, nausea, vomiting, dysuria, or changes in urinary frequency. Her temperature is $37.0^\circ\text{C}$ ( $98.6^\circ\text{F}$ ), blood pressure is $110/68\text{ mm Hg}$ , and pulse is $82/\text{min}$ . Physical examination reveals a gravid uterus consistent with gestational dates. There is mild right-sided flank fullness but no exquisite costovertebral angle tenderness on deep palpation.

Laboratory studies show:
Leukocyte count: $13,500/\text{mm}^3$
Hemoglobin: $11.2\text{ g/dL}$
Blood urea nitrogen: $6\text{ mg/dL}$
Serum creatinine: $0.5\text{ mg/dL}$
Urinalysis: negative for leukocyte esterase, nitrites, and blood; trace protein; $1$ - $2\text{ WBCs/hpf}$ .

A right upper quadrant and renal ultrasound demonstrates moderate dilation of the right renal pelvis and proximal ureter, which tapers smoothly at the pelvic brim. The left kidney and urinary tract are normal.

Which of the following is the most appropriate next step in management?

Reassurance and continued routine prenatal careCevap
B
Admission for intravenous ceftriaxone therapy
C
Prescription for oral nitrofurantoin
D
Placement of a right ureteral stent
E
Non-contrast computed tomography of the abdomen and pelvis

Cevap

Reassurance and continued routine prenatal care

The correct approach is reassurance and continued routine prenatal care. This patient is exhibiting classic, normal physiologic adaptations to pregnancy. During pregnancy, progesterone induces smooth muscle relaxation, leading to decreased ureteral peristalsis. Additionally, the gravid uterus naturally undergoes dextrorotation (rotation to the right), which mechanically compresses the right ureter against the right iliac artery at the level of the pelvic brim. This results in right-predominant physiologic hydronephrosis and hydroureter, which can cause a mild, dull flank ache. Furthermore, her laboratory findings demonstrate other expected physiologic changes: a dilutional anemia, a mildly elevated leukocyte count (which can normally rise to

15,000/\text{mm}^3

during pregnancy), and a decreased serum BUN and creatinine secondary to a

50\%

increase in the glomerular filtration rate. Because her urinalysis is completely normal (ruling out infection) and her ultrasound shows smooth tapering characteristic of external compression rather than an obstructing stone, no medical or surgical intervention is warranted.

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Analyze the patient's symptoms and vital signs.

The patient has a mild right flank ache without fever, abnormal vitals, or symptoms of lower urinary tract infection.

Establishing the absence of systemic inflammatory signs helps differentiate physiologic discomfort from an acute pathological process like pyelonephritis.

Evaluate the laboratory values against pregnancy-specific reference ranges.

The leukocyte count (

13,500/\text{mm}^3

), decreased BUN (

6\text{ mg/dL}

), decreased creatinine (

0.5\text{ mg/dL}

), and trace proteinuria with a negative urinalysis are all identified as normal.

Pregnancy causes physiologic leukocytosis (up to

15,000/\text{mm}^3

) and increased glomerular filtration rate (GFR), which lowers baseline BUN and creatinine.

Interpret the ultrasound findings in the context of the patient's pregnancy.

The right-sided pelvicalyceal and ureteral dilation tapering at the pelvic brim represents physiologic hydronephrosis of pregnancy.

Progesterone causes ureteral smooth muscle relaxation, and the dextrorotated gravid uterus mechanically compresses the right ureter against the iliac vessels at the pelvic brim, causing right-predominant dilation.

Determine the next best step in management.

Select reassurance and continued routine care, as no pathological condition is present.

Interventions such as antibiotics, invasive stenting, or further radiation-based imaging are contraindicated for normal maternal adaptations.

Anahtar Kavram

Physiologic right-sided hydronephrosis and leukocytosis are normal adaptations during pregnancy that require reassurance rather than medical or surgical intervention when urinalysis is normal.

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Cevap

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