NU-621 Herzing University – A 23-year-old woman was married a year ago. Since then, she has experienced five attacks of acute cystitis, all characterized by dysuria, increased frequency, and urgency.

QUESTION

A 23-year-old woman was married a year ago. Since then, she has experienced five attacks of acute cystitis, all characterized by dysuria, increased frequency, and urgency. Each infection responded to short-term treatment with trimethoprim sulfamethoxazole. The recurrences occurred at intervals of 3 weeks to 3 months following completion of antibiotic therapy. For the past two days, the woman has been experiencing acute flank pain, microscopic hematuria, dysuria, increased frequency, and urgency.

Her vital signs are T = 37.9°C, P = 106, R = 22, and BP = 130/75 mm Hg. Physical examination reveals costovertebral tenderness, mild tenderness to palpation in the suprapubic area, but no other abnormalities.

1. What are possible reasons for this woman’s pain? List possible differential diagnosis and explain each?
2. What diagnostic tests should you order to confirm diagnosis?
3. What are the possible causes of recurrent lower UTIs?
4. What are the differences when comparing prerenal acute renal failure, intrarenal acute renal failure, and postrenal acute renal failure? Give examples of each.

ANSWER

Possible Differential Diagnoses for the Woman’s Pain

Renal Calculi (Kidney Stones): Acute flank pain, microscopic hematuria, and associated urinary symptoms can be indicative of renal calculi. The pain is typically colicky and radiates to the groin or lower abdomen. The presence of costovertebral tenderness suggests renal involvement.

Pyelonephritis: Inflammation of the kidneys, usually caused by a bacterial infection, can present with symptoms similar to cystitis but with additional signs of systemic infection such as fever, chills, and malaise. Flank pain, microscopic hematuria, and costovertebral tenderness are common in pyelonephritis.

Interstitial Cystitis (Painful Bladder Syndrome): This is a chronic condition characterized by bladder pain and urinary symptoms similar to those of cystitis (Lim, 2023). The recurrent nature of the symptoms and the lack of response to antibiotic therapy suggest interstitial cystitis as a possible diagnosis.

Ureteral Obstruction: A blockage in the ureter, which connects the kidneys to the bladder, can cause flank pain, hematuria, and urinary symptoms. The pain may be colicky and may worsen with fluid intake or movement. Ureteral obstruction can result from conditions such as kidney stones or tumors.

Diagnostic Tests to Confirm Diagnosis

To confirm the diagnosis and differentiate between the possible causes, the following diagnostic tests may be ordered

Urinalysis: This test will help evaluate the presence of infection (e.g., the presence of leukocytes and bacteria) and the extent of hematuria (red blood cells in the urine).

Urine Culture and Sensitivity: A urine culture will help identify the causative organism and determine the appropriate antibiotic treatment.

Imaging Studies: An ultrasound or CT scan of the abdomen and pelvis may be performed to assess the kidneys, ureters, and bladder (“Urinary Tract Imaging,” 2023b). This can help identify any stones, detect kidney enlargement or inflammation, and rule out other structural abnormalities.

Possible Causes of Recurrent Lower UTIs:

Incomplete Treatment: In some cases, the initial treatment of a urinary tract infection (UTI) may not completely eliminate the bacteria, leading to recurrence.

Reinfection: External factors such as sexual intercourse or poor hygiene can introduce new bacteria into the urinary tract, causing reinfection.

Structural Abnormalities: Certain anatomical abnormalities, such as vesicoureteral reflux (backward flow of urine from the bladder into the ureters) or urethral strictures, can increase the risk of recurrent UTIs.

Immune Deficiency: Conditions that weaken the immune system, such as diabetes or HIV/AIDS, can make individuals more susceptible to recurrent infections.

Hormonal Changes: Some women may experience recurrent UTIs related to hormonal changes during the menstrual cycle or menopause.

Differences between Prerenal, Intrarenal, and Postrenal Acute Renal Failure

Prerenal Acute Renal Failure: Prerenal acute renal failure is caused by factors external to the kidneys that result in reduced blood flow to the kidneys. This can be due to conditions such as dehydration, severe blood loss, or decreased cardiac output. For example, if a patient experiences significant blood loss due to trauma, the reduced blood volume may lead to inadequate perfusion of the kidneys, resulting in prerenal acute renal failure.

Intrarenal Acute Renal Failure: Intrarenal acute renal failure refers to damage or injury to the structures within the kidneys themselves (Basile et al., 2012). This can occur due to conditions such as acute tubular necrosis (ATN), glomerulonephritis, or kidney infections. For instance, if a patient develops ATN following exposure to nephrotoxic drugs or severe ischemia, it can lead to intrarenal acute renal failure.

Postrenal Acute Renal Failure: Postrenal acute renal failure occurs due to obstruction of urine flow beyond the kidneys. Obstruction can result from conditions like urinary stones, tumors, or bladder outlet obstruction. For example, if a patient has an enlarged prostate gland that compresses the urethra, it can obstruct the urinary flow, leading to postrenal acute renal failure.

In summary, prerenal acute renal failure is caused by reduced blood flow to the kidneys, intrarenal acute renal failure involves damage within the kidneys themselves, and postrenal acute renal failure occurs due to obstruction of urine flow beyond the kidneys. These distinctions are important for determining the underlying cause and guiding appropriate management for acute renal failure.

References

Basile, D. P., Anderson, & Sutton, T. A. (2012). Pathophysiology of Acute Kidney Injury. Comprehensive Physiology, 1303–1353. https://doi.org/10.1002/cphy.c110041 

Lim, Y. (2023, May 3). Interstitial Cystitis. StatPearls – NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK570588/ 

Urinary Tract Imaging. (2023b). National Institute of Diabetes and Digestive and Kidney Diseases. https://www.niddk.nih.gov/health-information/diagnostic-tests/urinary-tract-imaging#:~:text=Renal%20scan%2C%20also%20called%20kidney%20scan.&text=There%20are%20different%20types%20of,%2C%20CT%20scans%2C%20and%20MRIs.