A 12-year-old girl is brought to the clinic by her parents after she is found to have hypertension by her school nurse. The patient has no symptoms and reads a book during the office visit. The girl immigrated to the United States two months ago and had not received routine well-child care. She has had several episodes of fever and abdominal pain, which her parents had treated with over-the-counter antibiotics that were available in her country of origin. The patient's blood pressure is elevated on several readings in the office. There is no family history of hypertension. Renal ultrasound reveals dilated calyces with overlying cortical atrophy bilaterally, mostly in the upper and lower poles. Which of the following is the most likely cause of this patient's condition?

Question

A 12-year-old girl is brought to the clinic by her parents after she is found to have hypertension by her school nurse.  The patient has no symptoms and reads a book during the office visit.  The girl immigrated to the United States two months ago and had not received routine well-child care.  She has had several episodes of fever and abdominal pain, which her parents had treated with over-the-counter antibiotics that were available in her country of origin.  The patient's blood pressure is elevated on several readings in the office.  There is no family history of hypertension.  Renal ultrasound reveals dilated calyces with overlying cortical atrophy bilaterally, mostly in the upper and lower poles.  Which of the following is the most likely cause of this patient's condition?

Quizplus · Accepted Answer

11ec160b_3a53_6d11_9249_bb1ee8f8ee77_MD0001_00 This patient's history of recurrent fever and abdominal pain along with imaging findings consistent with renal scarring indicate recurrent pyelonephritis. Pyelonephritis results from retrograde flow of infected urine from the bladder into the ureter. Normally, the ureters travel through the bladder wall at an oblique angle. When the bladder fills, the intramural ureter becomes compressed. This flap-valve mechanism prevents retrograde flow of urine. However, this mechanism does not work correctly if the ureter enters the bladder wall at a more perpendicular angle, a condition known as vesicoureteral reflux (VUR). Patients with VUR are at much higher risk for chronic pyelonephritis. Inflammation can occur from pyelonephritis or from VUR itself due to hydrostatic pressure on the papillae. Ongoing injury leads to renal scarring, most commonly at the upper and lower poles of the kidney in which compound papillae are found. Compound papillae are always open, unlike simple papillae in the mid kidney, and are therefore much more susceptible to dilation and subsequent injury. If uncorrected, VUR can lead to loss of nephrons and secondary hypertension. (Choice A) Autosomal dominant polycystic kidney disease generally presents in adulthood with hematuria, hypertension, and renal insufficiency. Symptomatic patients will have nephromegaly and diffuse parenchymal cysts on ultrasonography. (Choice B) Malignant hypertension refers to very high blood pressure that develops rapidly and causes end-organ damage. Affected patients can present with vision changes, encephalopathy, and renal failure. This patient has no evidence of acute end-organ dysfunction, and her imaging is more consistent with VUR and chronic pyelonephritis. (Choice C) Multicystic dysplastic kidney (MCDK) is a nonhereditary renal malformation characterized by multiple noncommunicating cysts with intervening dysplastic tissue. Unilateral MCDK may be clinically silent, but bilateral MCDK presents with early, severe renal insufficiency due to absence of functional renal tissue. (Choice D) Posterior urethral valves can present with bilateral hydronephrosis and calyceal dilation due to obstruction of urine flow in the urethra. However, posterior urethral valves result from a malformation of the Wolffian duct, and therefore only occur in males. Educational objective: Vesicoureteral reflux is caused by retrograde urine flow from the bladder into the ureter. The hydrostatic pressure of refluxing urine along with infections due to ascending bacteria causes inflammation. The compound papillae in the upper and lower poles of the kidney are most susceptible to reflux-induced damage, which appears as dilated calyces with overlying renal cortical scarring. __________ References: Vesicoureteral Reflux and Reflux Nephropathy (http://www.ncbi.nlm.nih.gov/pubmed/21896376)

A 12-Year-Old Girl Is Brought to the Clinic by Her