What Is Sterile Pyuria?

Medically Reviewed by Carol DerSarkissian, MD on February 21, 2024
3 min read

Pyuria is a condition defined by the increased presence of white blood cells in urine. Although a urinary tract infection is the most common cause of sterile pyuria, other conditions may be involved. 

Doctors define pyuria as the presence of 10 white blood cells in each millimeter cube of the urine. Sterile pyuria, in contrast, is a type of pyuria in which no bacteria are present in the urine. This could be due to a medical condition, non-detected bacteria, or another germ, such as a virus. 

Sterile pyuria is a common condition affecting 2.6% of men and 13.9% of women. Broadly speaking, though, sterile pyuria could be non-infectious or infectious, depending on your particular condition. 

Sterile pyuria can have two types of causes: infectious or non-infectious. 

Infectious causes 

In the general population, urinary tract infections caused by bacteria are very common. They are typically treated using antibiotic therapy. 

If a urinary tract infection has been recently treated, it can present itself as sterile pyuria within two weeks, even with an antibiotic dose. 

In sexually active young adults, the most common germ found during diagnostic tests is Chlamydia trachomatis. Doctors might test for infection with Chlamydia trachomatis and Mycoplasma hominis, genitalium and Ureaplasma urealyticum when sterile pyuria is detected.

People with chronic sterile pyuria may be exposed to the condition due to an atypical infection, such as renal tuberculosis. This manifestation is rare but can be damaging if not treated in the early stages. Doctors may suspect this if you come from a developing country, you are immunocompromised, or you show signs of unintended weight loss. 

Non-Infectious Causes 

Sterile pyuria could also be caused as an aftereffect of radiotherapy involving the urinary tract or the pelvis. In some cases, inflammation in the pelvis may also cause sterile pyuria, particularly if the appendix is too close to the ureter or the bladder. 

Pyuria could also be due to a physiological change in the body, such as pregnancy or post-menopausal changes. 

For pregnant women showing signs of urinary tract infection, the urine samples are taken before and after they take antibiotics to prevent the development of sterile pyuria. 

Sterile pyuria could also occur due to an underlying disease, such as: 

  • Renal calculi 
  • Lupus 
  • Diabetes 
  • Malignant hypertension
  • Kawasaki disease 

Human immunodeficiency virus (HIV infection) can also cause sterile pyuria. A study involving 104 patients with untreated HIV showed that 13% of them had pyuria. 

The symptoms of sterile pyuria differ based on your individual condition. However, some common symptoms include cloudy urine, nausea, vomiting, bladder pain, fever and chills, discharge, and abdominal pain. 

If you experience any of these symptoms and have recently had a urinary tract infection, speak with your doctor right away. 

Your doctor will begin by taking your medical history, asking about recent exposure to any virus, bacteria, or fungi. They will also check for underlying diseases, such as hypertension, swollen joints, and skin rashes. 

They may also send your urine sample for culture. Upon investigating the findings, they will provide a treatment plan. 

In some cases, additional tests, like a complete blood count test, liver function test, and renal function test, are also done. If a patient is sexually active, the doctor will send swabs in for testing to check for Chlamydia and Gonorrhea

If there is a suspicion that the condition is due to a fungal infection, the doctor will send your urine sample for urine microscopy. This is a technique in which the urine is checked under a microscope to see if fungal growth is taking place. 

The results of imaging studies in aspergillus or candida infections show any "fungal balls" that cause defects in the bladder. 

The treatment for sterile pyuria depends on its cause. If the doctor diagnoses a urinary tract infection, they will give you antibiotics as a treatment plan. For fungal infections, you may be given antifungal medications. 

If sterile pyuria does not go away after you take the prescribed dose of antibiotics, you may have another medical condition, such as hypertension or Kawasaki disease. The doctor will treat those conditions if that is the case. 

Since sterile pyuria is often caused due to an infection, complications can occur if the underlying infection spreads to other parts of the body. 

If the condition is left untreated, it could even cause death. Therefore, it is vital to seek professional help if you are experiencing any symptoms of pyuria.