Post-obstructive diuresis is a condition that causes prolonged urination in unusually large volumes. Treatment is not always necessary, although doctors may need to administer fluid and electrolyte replacement.

Post-obstructive diuresis causes people to pass large amounts of urine for an unusually long period. In some cases, this can lead to dehydration.

This condition occurs after a urinary obstruction causes a person’s bladder to retain too much urine. After initial drainage, increased or excessive urine production — diuresis — may continue until fluid volumes return to expected levels.

If diuresis continues beyond this, it becomes pathologic. This can cause complications such as dehydration and hypotension, or become life threatening.

This article discusses the symptoms, treatment, and risk factors of post-obstructive diuresis alongside when to contact a doctor.

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Research highlights two defining symptoms of post-obstructive diuresis. These symptoms must arise after the urinary obstruction has been addressed, for instance, after a doctor removes it during an operation. The symptoms are:

  • passing a minimum of 200 cubic centimeters (cc) of urine for at least 2 consecutive hours
  • passing over 3,000 cc of urine in 24 hours

If prolonged or excessive urination continues after fluid levels stabilize, a person may have pathologic post-obstructive diuresis.

Symptoms of dehydration

Post-obstructive diuresis and pathologic post-obstructive diuresis can lead to massive losses in fluids and electrolytes. In turn, this can cause dehydration.

According to a 2022 paper, dehydration can cause a wide range of symptoms. In adults, these include the following:

In children, dehydration can also cause changes in mental status, such as irritability or listlessness.

Treatment should aim to:

  • remove any obstruction in the urinary tract
  • correct fluid volumes
  • replenish electrolytes
  • monitor the patient

Experts suggest doctors will monitor a person with post-obstructive diuresis over 48 hours to observe how much urine they produce and respond to any complications that may arise.

A doctor may also take blood and urine samples to determine a person’s electrolyte levels and replenish fluids and electrolytes when necessary.

To replenish lost fluids, a doctor may administer an electrolyte fluid into the person’s blood. If the individual is conscious, they may also need to drink fluids.

It will typically take around 24 hours or less for fluids to regulate during post-obstructive diuresis. Pathologic post-obstructive diuresis will continue beyond this, lasting around 48 hours or longer.

Potential complications of post-obstructive diuresis, such as dehydration, may also increase a person’s recovery time.

Risk factors for post-obstructive diuresis include:

A history of multiple urinary catheterizations — when doctors place catheters into the bladder so that people can expel urine — may suggest a person has a condition that causes urinary retention. This may lead to post-obstructive diuresis.

Anyone with symptoms of urinary retention or post-obstructive diuresis should contact a doctor. This may include:

If a person has any risk factors for post-obstructive diuresis and experiences any of the above symptoms, they should contact a healthcare professional.

Post-obstructive diuresis involves excessive urination that can last for up to around 2 days. In some cases, it can lead to serious complications, such as dehydration, as fluids and electrolytes exit the body in large volumes.

Doctors may want to monitor individuals with this condition, particularly if they think they are at risk of pathologic post-obstructive diuresis.

Treatment can involve replacing fluids and electrolytes, as well as managing any potential complications. Doctors will also aim to manage or treat the underlying cause of the initial urinary retention.