Treatment for Postrenal ARF
Obstruction relief is the goal of treatment of postrenal ARF. If the problem is bladder outlet obstruction due to an enlarged prostate (benign prostate hyperplasia, BPH), the placement of a catheter into the bladder (through the urethra) will alleviate the obstruction temporarily. The prostate should be examined and treated properly.
If there are kidney stones in both ureters, the stones must be removed. If the physician is unable to remove the stones, the patient may need to be fitted with tubes that drain urine from the kidneys through an opening in the skin (called percutaneous nephrostomy tubes).
Complications of Postrenal ARF
The treatment of urinary obstruction is associated with a variety of complications.
Gross hematuria (a large amount of bloody urine) can occur when the catheter is placed in patients who have bladder outlet obstruction. This happens because the sudden decrease in pressure causes the bladder veins to bleed. Unfortunately, slow decompression of the bladder does not prevent hematuria.
Reflex hypotension (low blood pressure) is a rare complication that can occur if a patient experiences sudden stimulation of the vagus nerve during catheter insertion.
Postobstructive diuresis is high urine output that may, initially, exceed 500 to 1000 milliliters per hour. This frequently occurs after an obstruction is removed. The renal tubules typically cannot reabsorb water and electrolytes in a normal manner after having been obstructed for a period of time.
Rarely, a person suffers severe dehydration and requires large amounts of intravenous fluids.
Postrenal ARF Prognosis
The rate of recovery is largely determined by the duration and severity of obstructive disease. In general, the extent of recovery is determined within 7 to 14 days after the obstruction has been removed. Some patients may require short-term treatment with dialysis, until their renal function recovers. Hemodialysis involves removal of waste products from the blood via mechanical filtration outside of the body.
Along with the loss of renal function, some people with postrenal ARF develop irreversible tubular defects, which may produce the following symptoms:
- Hyperkalemia (excess amount of potassium in the blood)
- Metabolic acidosis (excess amount of chloride in the blood)
- Polyuria (large daily output of urine)