10 USMLE Renal and Urology Questions with Answers and Explanations (Set 1)

These 10 USMLE renal and urology practice questions cover kidney transplant rejection, ACE inhibitors and creatinine, urinary tract infections, pyelonephritis, urge incontinence, scrotal masses, drug nephrotoxicity and inguinal hernia in infants. Each question includes the correct answer and an explanation.

Written by Dr. Ray Makar, MD, author of the Repeated USMLE Questions eBook series.

Prefer video? Watch daily USMLE case questions on MedFocus by Dr. Ray on YouTube.

How to use this page: read the question, pick your answer, then tap Show Answer and Explanation.

Questions

Question 1. A 46-year-old man underwent a kidney transplantation last week due to chronic renal failure. The surgery was successful and the transplanted kidney started to produce urine during the operation. Today, his urine examination shows high creatinine and low urinary output. He has no pain or fever. A biopsy taken from the transplanted kidney shows cellular infiltrate. Which of these cells is responsible for this patient’s recent condition?

A- B Lymphocytes
B- Cytotoxic T-cells
C- Fibrocytes
D- Plasma cells
E- T-helper cells

The scenario describes a 46-year-old man who recently underwent a kidney transplantation and now presents with high creatinine and low urinary output, along with cellular infiltrate noted on biopsy of the transplanted kidney. This constellation of findings suggests the possibility of acute cellular rejection, which is a common complication following organ transplantation.
In acute cellular rejection, the recipient’s immune system recognizes the transplanted organ as foreign and mounts an immune response against it. This immune response primarily involves T lymphocytes, particularly cytotoxic T-cells (CD8+ T-cells), which directly attack and damage the transplanted tissue.
The correct answer is B

 

Question 2. A 72- year-old man with a long history of hypertension and coronary artery disease presents for a follow up examination. He took metoprolol for many years. He started taking enalapril last week. His blood pressure is now under control. Physical and laboratory examinations are unremarkable except for a slight increase in serum creatinine. What is the best explanation for this abnormality?

A- Increased glomerular filtration rate (GFR)
B- Blocking of efferent arteriole vasoconstriction
C- Drug-induced tubular obstruction
D- Renal interstitial nephritis
E- Increase absorption of water in the proximal convoluted tubules

ACE inhibitors lead to increase of blood creatinine which reaches its peak by the end of the first week. It is caused by inhibition of efferent arteriolar vasoconstriction leading o afferent arteriolar vasodilatation and decreased glomerular filtration rate. This is the reason that ACEI shouldn’t be used in cases of renal insufficiency.
The correct answer is B

 

Question 3. A 4-year old girl is brought to the clinic by her mother complaining of fever and abdominal pain since yesterday. Today, she looks uncomfortable during micturition. On examination, her temperature is 100.8 F, her pulse is 100/min. and her suprapubic area is soft and tender. Her blood analysis shows increased neutrophils. Her urinalysis is positive for organisms and leukocytes. What is the drug of choice for this condition?

A- Ciprofloxacin
B- Chloramphenicol
C- Co-trimoxazole
D- Rifampin

This is a case of bacterial urinary tract infection. E-Coli is the most common organism associated with this condition. The drug of choice is co-trimoxazole. It is safe to use at her age.
Ciprofloxacin is indicated in complicated cases of urinary tract infections. It is not recommended as the first line of treatment due to its side effects. Chloramphenicol and rifampin are not recommended for this age nor this condition.
The correct answer is C

 

Question 4. A 68-year-old woman presents to her physician with a complaint of urinary incontinence. She is a nursing home resident and her staff tells you that the patient feels desire to void but she cannot hold it to the restroom. She has no pain, dysuria or hematuria. She has a long history of hypertension and she takes metoprolol and hydrochlorothiazide. Which of the following is the most appropriate first step of management?

A- Discontinue metoprolol
B- Discontinue hydrochlorothiazide
C- Try timed voiding
D- Prescribe tolterodine therapy
E- Refer to a urologist

This is a classic case of overactive bladder with urgency incontinence. Timed voiding, which means to encourage the patient to use the restroom every 2 hours or so, should be recommended to avoid urgent voiding. There is no evidence that discontinuation of metoprolol or hydrochlorothiazide will improve this condition. Tolterodine is effective in cases of overactive bladder but non-pharmacologic treatment should be applied first. This is a case of primary care physician but if the treatment failed or complications occur then, she should be referred to a urologist.
The correct answer is C

 

Question 5. A 55 year-old man presents to the clinic because today he noticed that his left scrotum has suddenly gotten larger. He has no fever or pain. Examination reveals enlarged left scrotum with no tenderness or any signs of inflammation. There is a worm-like mass posterior to the left testicle. The scrotum transilluminates and is not reducible on compression or when the patient lies down. What is the best next step in management?

A- Assurance and follow up in 2 weeks
B- Abdominal CT scan
C- MRI of the pelvis
D- Urine culture
E- Refer to surgery for urgent reduction

This is a case of combined varicocele and hydrocele. Sudden onset and non-reducible mass suggest obstruction of venous drainage. Left testicular vein drains into left renal vein, so, any compression on the left renal vein causes left varicocele. Most cases of renal cell carcinoma in men are accompanied by left varicocele. For this reason, abdominal CT scan is the best next step to evaluate for any masses or tumors.
The correct answer is B

 

Question 6. A 37-year-old man visits his physician with complaints of sore throat, fever and muscle aches for 4 days. Throat swab is negative. His physician discussed with him the use of antibiotics in his case. The patient had read in an old magazine that one of the antibiotics is effective but his physician explains that this antibiotic is highly nephrotoxic. Which one of these antibiotics is the most nephrotoxic?

A- Ampicillin
B- Amoxicillin
C- Cloxacillin
D- Methicillin
E- Rifampin

Methicillin is the most known nephrotoxic out of the list. Its usage is discontinued in a lot of countries because its extreme nephrotoxicity.
The correct answer is D

 

Question 7. A 47-year-old man with a history of chronic renal failure presents to the clinic for a follow-up after a kidney transplant three weeks ago. His surgery was successful, and his transplanted kidney started producing urine right after the operation. However, today his urine output drops and his serum creatinine begins to rise. There is no fever or dysuria. Urinalysis shows no abnormality. Biopsy from the transplanted kidney shows cellular infiltrate of cytotoxic cells (CD8). What is the most likely diagnosis of this condition?

A- Normal reaction
B- Hyperacute rejection
C- Acute rejection
D- Chronic rejection
E- Acute pyelonephritis

This is an acute rejection. It happens in the first three months after transplantation and is caused by discrepancy between human leukocytes antigen of the host and the graft. It is mediated by cytotoxic cells.
Hyperacute rejection is very rare now due to advanced tests prior to tissue transplantation. It is caused by pre-formed antibodies against the donor’s kidney cells. It occurs during the surgery or minutes to few hours after the transplantation and leads to complete destruction of the transplanted kidney.
Chronic rejection occurs months or years after the transplantation and caused by scarring within the transplanted kidney. It can be prevented by regular visits with laboratory tests.
Other options are just distractions.
The correct answer is C

 

Question 8. A 90-year-old man is hospitalized from falling and breaking his hip. He has been already in the hospital for 6 days when he developed a burning sensation upon urinating. An analysis of his urine shows plenty of gram positive cocci and leukocytosis. The attendant physician treats him with trimethoprim-sulfamethoxazole. However, the fever still persists. After 2 more days, the patient develops a new holosystolic murmur radiating to the axilla and a low-grade fever is still persisting. Out of the following, which would be the first line treatment for the cause of the possible infection?

A- Ampicillin
B- Gentamicin
C- Piperacillin
D- Vancomycin

Enterococcus is one of the most common causes of nosocomial urinary tract infection, along with subacute endocarditis. Ampicillin is known to be the standard prescribed medication for treating enterococcus infections.
The correct answer is A

 

Question 9. A 68 year-old woman complains of fever, anorexia and right flank pain for 2 days. She vomited twice today. On physical examination, her temperature is 101.3 F and there is moderate tenderness on the right costovertebral angle. Her urinalysis shows leukocytes and pus cells. What is the most appropriate next step of management?

A- Hospitalization and intravenous antibiotics
B- Outpatient wide spectrum antibiotics and schedule a visit after 3 days
C- Collect blood and urine samples for culture
D- Schedule MRI of the abdomen and pelvis
E- Schedule Intravenous pyelogram

Rule of thumb: any case of pyelonephritis, endocarditis or any expected sepsis, collect blood and urine samples for culture before administration of antibiotics. Very important repeated topic in all steps of USMLE. Collect for culture first….please don’t forget that…..MRI and IVP could be done later if the case is complicated but history, examination and urinalysis are enough for diagnosis of most cases of acute pyelonephritis.
The correct answer is C

 

Question 10. A 9-month-old boy is brought to the clinic by his mother who is concerned that the boy developed swelling in his right scrotum. On examination, there is a scrotal mass that disappears when pushing it back to the external inguinal ring. When the boy cries, the mass is felt again protruding out of the external inguinal ring. What is the most likely etiology of this condition?

A- Defect in the inguinal canal
B- Defect in the pelvic floor
C- Patent processus vaginalis
D- Defective closure of tunica vaginalis
E- Undescended testis

The most important cause of inguinal hernia in infants is patent processus vaginalis which fails to be obliterated after descending of testes. Persistent lumen of tunica vaginalis causes hydrocele, not hernias.
The correct answer is C

 

High-yield points from this set

  • Rising creatinine days to weeks after a kidney transplant with a T-cell infiltrate = acute rejection (cytotoxic CD8 T cells).
  • A small creatinine rise after starting an ACE inhibitor is expected: loss of angiotensin II efferent arteriole constriction.
  • E. coli is the most common cause of UTI.
  • Urge incontinence in the elderly: start with behavioral therapy such as timed voiding.
  • A new left varicocele that does not empty when lying down in an older man: look for a renal mass with CT.
  • Methicillin is classically linked to acute interstitial nephritis.
  • Enterococcal UTI that spreads to the heart valves is treated with ampicillin (often with gentamicin).
  • Pyelonephritis: collect urine and blood cultures before starting antibiotics.
  • Indirect inguinal hernia in infants is due to a patent processus vaginalis.

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