From the Guidelines
When a patient has no distended bladder but is not producing urine, immediate evaluation for acute kidney injury (AKI) or urinary tract obstruction is essential, and the best next step is to place a Foley catheter to confirm the absence of urine in the bladder and rule out urinary retention, as recommended by the American Heart Association/American Stroke Association 1. To further assess the patient's condition, basic labs including BUN, creatinine, electrolytes, and urinalysis should be obtained to evaluate kidney function.
- Order renal ultrasound to evaluate for hydronephrosis or obstruction, as it has the greatest diagnostic value in detecting hydronephrosis associated with acute urinary tract obstruction 1.
- If the patient is hemodynamically unstable, provide IV fluid resuscitation with normal saline or lactated Ringer's at 10-20 mL/kg bolus, followed by reassessment.
- Consider nephrotoxic medication review and immediate discontinuation of potential offenders like NSAIDs, certain antibiotics, or contrast agents.
- Monitor urine output, vital signs, and fluid balance hourly, and if the patient shows signs of hyperkalemia, acidosis, or volume overload, urgent nephrology consultation and possible dialysis may be needed. This approach addresses the three main causes of acute anuria: prerenal (inadequate perfusion), intrinsic renal damage, or postrenal obstruction, with the goal of quickly identifying the cause and preventing further kidney injury. The use of color Doppler to assess global perfusion and confirm arterial and venous patency may also be beneficial in evaluating the patient's condition 1. It is essential to note that a normal kidney size suggests AKI rather than CKD, and increased renal echogenicity is associated with acute and chronic medical renal disease, but this is nonspecific and does not correlate well with renal function 1.
From the Research
Patient Assessment
- When a patient has no distended bladder but is not producing urine, it is essential to assess the patient's volume status and determine the underlying cause of the issue 2.
- A focused history and physical examination, including a neurologic evaluation, should be performed to identify potential causes of urinary retention, such as obstructive, infectious, inflammatory, iatrogenic, or neurologic factors 3.
Diagnostic Testing
- Measurement of postvoid residual (PVR) volume of urine can help diagnose urinary retention, with a PVR volume greater than 300 mL measured on two separate occasions and persisting for at least six months indicating chronic urinary retention 3.
- Renal ultrasonography may be necessary to evaluate for postrenal causes, such as obstructive uropathy, especially in patients with risk factors like prostatic hypertrophy 2.
Management
- Initial management of urinary retention involves assessment of urethral patency and prompt and complete bladder decompression by catheterization, with suprapubic catheters improving patient comfort and decreasing bacteriuria and the need for recatheterization in the short term 3.
- Diuretics, such as furosemide, may be used to manage volume overload in patients with acute kidney injury (AKI), with the majority of clinicians targeting a diuresis of >or=0.5-1.0 ml/kg/h 4.
- The use of furosemide with matched hydration, such as with the RenalGuard System, may reduce the incidence of contrast-induced AKI in high-risk patients undergoing interventional procedures 5.
Further Evaluation and Treatment
- If the patient's urine output does not improve with initial management, further evaluation and treatment by a nephrologist or urologist may be necessary to determine the underlying cause and develop a treatment plan 2.
- Pharmacist-led quality-improvement programs and acute kidney injury care bundles may also be beneficial in reducing nephrotoxic exposures and improving patient outcomes 2.