Could Renal Abscess Be a Complication of Pyelonephritis in this Patient?

Patient Presentation
A 3-year-old female came to clinic with a 2 day history of malodorous urine and increased urinary frequency. She did not complain of pain or itching of her genitalia but her parents noted that she would “hold herself.” She began to have a high fever the night before, but was drinking well. Her parents described her as more tired but she would play more when her fever came down. There was no emesis, diarrhea, abdominal pain or rashes. The past medical history was negative. The family history was negative for kidney disease and hearing problems. The review of systems was otherwise negative. The pertinent physical exam showed a tired appearing female with a temperature of 104.1°, pulse of 120, and respiratory rate of 38, and a blood pressure of 109/69. Mucous membranes were moist and she had 2 second capillary refill. Abdominal examination was negative. Genitourinary examination showed mild erythema of the vulva. The rest of her examination was negative.

The laboratory evaluation showed a white blood cell count of 16.2 x 1000/mm2 with 50% neutrophils and 7% polymorphonuclear lymphocytes. Her C-reactive protein was 14.3 mg/dl. Her urinalysis showed a specific gravity of 1.010, positive blood, leukocyte esterase and nitrites, 50-100 white blood cells, and 5-10 red blood cells. A urine culture and blood culture were sent. The diagnosis of acute pyelonephritis (i.e. febrile urinary tract infection) was made and as the patient’s temperature had returned to normal after antipyretics, she was taking fluids easily and was playing, she was sent home on oral trimethoprim-sulfa antibiotics with instructions to follow-up the next day in clinic. Parents were also instructed to monitor her closely and if she was not able to drink, take her antibiotics, seemed more listless or the fever could not be controlled then the patient needed to be evaluated right away.

The patient’s clinical course at 18 hours showed that the blood culture grew Escherichia coli. Her urine culture also eventually grew E. coli. The family was called and the patient brought to the hospital for admission with IV antibiotics. Interval history showed that her fever was controllable, she was drinking and had taken two doses of antibiotics. The patient received 3 days of intravenous ceftriaxone and was discharged after she had been afebrile for 18 hours. After going home her parents called the hospital again because she continued to be febrile at intervals although her temperature maximum was decreasing. During her hospitalization she was noted to have mild hypertension. On day 7 she was seen again the clinic. She had been afebrile since the night prior and continued to act well. Her blood pressure had decreased but was still above the 95% for age. Because of the slow resolution of the fever and continued mild hypertension, the physician decided to recheck her laboratory tests and to order her screening renal ultrasound while still on antibiotics to determine anatomical abnormalities, vesicoureteral reflux and the possibility of renal abscess. The radiologic evaluation of a renal ultrasound was normal. Her C-reactive protein and white blood cell counts were almost normal but her urinalysis still showed 10 white blood cells and 1-2 red blood cells. Over the next month her urinalysis and blood pressure normalized.

Urinary tract infections (UTI) are common. By the age of 7 years up to 8% of girls and 2% of boys have had a UTI. The current American Academy of Pediatrics criteria for a UTI diagnosis includes presence of pyruria (determined by microscopy) or leucocyte esterase (on dipstick) AND a culture-positive urine of 100,000 colony-forming units on a voided specimen. Because of possible contamination, bagged specimens are not acceptable. Clinical pyelonephritis (ie febrile UTI) is a fairly common problem in the pediatric population.

Learning Point
Renal abscesses are uncommon with the exact incidence unknown and are defined as collections of purulent material within or adjacent to the kidney itself. The two most common bacteria are Escherichia coli (assumed to be due to ascending UTI) and Staphylococcus aureus (associated with hematogeneous spread). Patients with renal abscesses may present with clinical pyelonephritis symptoms such as fever, nausea, weight loss, dysuria, malodorous urine, abdominal or flank pain. Renal abscess should be considered when there is prolonged fever without a source and when response to treatment of clinical pyelonephritis is prolonged. Renal ultrasound is a good imaging modality for renal abscess but computed tomography may be needed to differentiate abscess from renal changes associated with pyelonephritis itself.

Overall 20-90% of children with acute pyelonephritis have some acute renal parenchymal damage with about 40% of these having renal scarring. Renal scarring may lead to hypertension, renal insufficiency and potential failure.

Complications of acute pyelonephritis includes:

  • Bacteremia and sepsis
  • Vesicoureteral reflux (VUR) – which overall usually resolves
    • Reflux related injury in females is more likely to be acquired and have less severe grades of VUR (i.e. Grades I, II, III)
    • Reflux related injury in males is more likely to be congenital (ie associated with anatomical defects) and have more severe grades of VUR (i.e. Grades III, IV, V)
  • Renal scarring
  • Hypertension – transient or permanent
  • Renal insufficiency or failure
  • Renal abscess
  • Electrolyte abnormalities or secondary pseudohypoaldosteronism

Questions for Further Discussion
1. What is the current standard in your country for evaluation of urinary tract infections in children?
2. What are the advantages and disadvantages of renal ultrasound, voiding cystourethrogram and dimercaptosuccinic acid (DMSA) renal scans in the evaluation of children with urinary tract infections?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for this topic: Urinary Tract Infections.

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

Smith EA. Pyelonephritis, renal scarring, and reflux nephropathy: a pediatric urologist’s perspective. Pediatr Radiol. 2008 Jan;38 Suppl 1:S76-82.

Koyle MA, Elder JS, Skoog SJ, Mattoo TK, Pohl HG, Reddy PP, Abidari JM, Snodgrass WT. Febrile urinary tract infection, vesicoureteral reflux, and renal scarring: current controversies in approach to evaluation. Pediatr Surg Int. 2011 Apr;27(4):337-46.

Srinivasan K, Seguias L. Fever and renal mass in a young child. Renal abscess. Pediatr Ann. 2011 Sep;40(9):421-3.

Subcommittee on Urinary Tract Infection, Steering Committee on Quality Improvement and Management, Roberts KB. Urinary tract infection: clinical practice guideline for the diagnosis and management of the initial UTI in febrile infants and children 2 to 24 months. Pediatrics. 2011 Sep;128(3):595-610.

Tolan RW. Pediatric Pyelonephritis. eMedicine.
Available from the Internet at (rev. 2/9/2012, cited 11/20/2012).

ACGME Competencies Highlighted by Case

  • Patient Care
    1. When interacting with patients and their families, the health care professional communicates effectively and demonstrates caring and respectful behaviors.
    2. Essential and accurate information about the patients’ is gathered.
    3. Informed decisions about diagnostic and therapeutic interventions based on patient information and preferences, up-to-date scientific evidence, and clinical judgment is made.
    4. Patient management plans are developed and carried out.
    5. Patients and their families are counseled and educated.
    7. All medical and invasive procedures considered essential for the area of practice are competently performed.
    8. Health care services aimed at preventing health problems or maintaining health are provided.

  • Medical Knowledge
    10. An investigatory and analytic thinking approach to the clinical situation is demonstrated.
    11. Basic and clinically supportive sciences appropriate to their discipline are known and applied.

  • Practice Based Learning and Improvement
    14. Knowledge of study designs and statistical methods to appraisal clinical studies and other information on diagnostic and therapeutic effectiveness is applied.

  • Systems Based Practice
    23. Differing types of medical practice and delivery systems including methods of controlling health care costs and allocating resources are known.
    24. Cost-effective health care and resource allocation that does not compromise quality of care is practiced.


    Donna M. D’Alessandro, MD
    Professor of Pediatrics, University of Iowa Children’s Hospital