Examkin

Question

Difficulty: HardNormal Pregnancy and Prenatal Care

A 25-year-old primigravid woman at 29 weeks gestation is evaluated in the obstetric clinic for a three-day history of right-sided flank discomfort. She describes the sensation as a mild, constant ache. She reports increased urinary frequency over the past month but specifically denies dysuria, hematuria, fever, chills, or nausea. Her temperature is 37.0°C (98.6°F), blood pressure is 114/72 mmHg, heart rate is 84/min, and respiratory rate is 16/min. Physical examination shows a gravid, non-tender abdomen with a fundal height of 29 cm. There is no costovertebral angle tenderness. A clean-catch urinalysis is negative for leukocyte esterase, nitrites, and blood. Due to the patient's persistent concern, a renal ultrasound is performed, revealing moderate dilation of the right renal pelvis and proximal ureter that tapers smoothly at the pelvic brim. The left kidney and ureter appear normal. No echogenic shadowing structures are seen. Which of the following is the most appropriate next step in management?

  1. Counsel the patient on expected anatomical changes and proceed with scheduled obstetric visitsAnswer
  2. B
    Prescribe an empiric course of oral cephalexin
  3. C
    Perform a low-dose, non-contrast computed tomography scan
  4. D
    Admit the patient for intravenous hydration and parenteral antibiotics
  5. E
    Arrange for urgent urologic consultation for cystoscopy

Answer

Counsel the patient on expected anatomical changes and proceed with scheduled obstetric visits.
This patient's presentation and ultrasound findings are highly characteristic of physiological hydronephrosis of pregnancy. During pregnancy, elevated progesterone levels cause smooth muscle relaxation, leading to decreased ureteral peristalsis. Additionally, the enlarging gravid uterus mechanically compresses the ureters as they cross the iliac vessels at the pelvic brim. This compression is significantly more pronounced on the right side due to the natural dextrorotation of the uterus and the protective cushioning effect of the sigmoid colon on the left ureter. Consequently, up to 80% of pregnant women develop some degree of asymptomatic or mildly symptomatic hydroureteronephrosis, typically peaking in the third trimester. Because the patient lacks signs of urinary tract infection (negative urinalysis, afebrile) and nephrolithiasis (no severe colicky pain, no hematuria, and the dilation tapers specifically at the pelvic brim rather than the ureterovesical junction), no further diagnostic or therapeutic intervention is necessary. She should be counseled on these expected anatomical changes and continue her routine prenatal care.

Step-by-Step Solution

1
Analyze the patient's symptoms and vital signs.
The patient has mild right flank ache and urinary frequency, but is afebrile with normal vital signs, no CVA tenderness, and a completely normal urinalysis.
This effectively rules out acute cystitis and acute pyelonephritis.
2
Interpret the ultrasound findings.
The ultrasound shows right-sided hydroureteronephrosis tapering at the pelvic brim without any visible stones.
Tapering at the pelvic brim is the pathognomonic location for extrinsic compression by the gravid uterus, differentiating it from a distal obstructing stone at the ureterovesical junction.
3
Determine the appropriate management.
Identify the condition as physiological hydronephrosis of pregnancy, which requires observation only.
Because this is a normal anatomical adaptation of the second and third trimesters, no medical or surgical intervention is warranted.

Key Concept

Physiological hydronephrosis of pregnancy presents as asymptomatic or mildly symptomatic right-predominant ureteral dilation due to uterine compression at the pelvic brim. In the absence of infection or true obstruction, it requires only reassurance and routine prenatal care.
Rate this question

Topics

Normal Pregnancy and Prenatal Care

More questions from this topic