Postobstructive Diuresis

Urinary retention is a relatively common urological issue observed in both inpatient and outpatient settings. The diagnosis should be strongly suspected in any patient presenting with lower abdominal discomfort and any degree of urinary symptoms. Retention can be confirmed through assessment of post-void residual volume using bladder ultrasound or catheterization.  Postobstructive diuresis (POD) may develop following the acute drainage and decompression of a distended bladder, leading to prolonged polyuria accompanied by excessive loss of salt and water. POD is characterized by prolonged urine production of 200 mL or more for at least 2 consecutive hours following the relief of urinary retention. Alternatively, it may be defined as exceeding 3000 mL within a 24-hour period.  Timely identification of POD is essential, as it can affect up to 50% of patients and, if left untreated, can potentially progress to a life-threatening condition such as polyuria as a result of obstruction release. This may include: Insertion of a Foley catheter for obstructed bladder. Percutaneous nephrostomy. Double-J stent in patients with a bilateral or unilateral ureteric obstruction in a single-functioning kidney. Normal maximum bladder capacity is about 450 to 500 mL. Pathologic POD can lead to severe complications, including dehydration, electrolyte imbalances, hypotension, hypovolemic shock, and even death. Treatment typically involves coordinated efforts from an interprofessional healthcare team to deliver urgent care and potential hospitalization until resolution.