What is Emphysematous Pyelonephritis?
Emphysematous pyelonephritis (EPN) is a serious infection that affects the upper part of the urinary tract, including the kidney tissues. In certain cases, it can also impact surrounding tissues of the kidney. This infection often results in gas build-up within the kidney tissues. It’s possible for gas to build up in the kidney’s central hollow area or the nearby tissue. Sometimes, there may be gas in the renal pelvis (the central part of the kidney that passes urine), or emphysematous cystitis (gas in the bladder wall and inside of the bladder), and these cases may not necessarily involve EPN.
Diabetes is the most common risk factor for EPN, with over 90% of the patients diagnosed with this condition also having diabetes. EPN is a dangerous disease, with death rates reported to be between 40% to 90%. Diagnosing this condition is similar to diagnosing acute pyelonephritis (another type of kidney infection), and proper examination using imaging techniques, especially CT (computed tomography) scans, is necessary.
Medical professionals currently use a variety of treatment strategies for EPN, including intense surgical procedures and less aggressive approaches such as drainage of fluid through a needle and antibiotic treatment.
What Causes Emphysematous Pyelonephritis?
The main bacteria responsible for EPN, or Emphysematous Pyelonephritis, are Escherichia coli and Klebsiella pneumoniae. They account for about 49% to 67% and 20% to 24% of all cases, respectively. Other types of organisms have also been linked to EPN, like Proteus, Enterococcus, Clostridium, Aspergillus, and Candida spp, though these are less common. Some EPN infections can be caused by a mix of different organisms.
Risk Factors and Frequency for Emphysematous Pyelonephritis
Emphysematous pyelonephritis (EPN), a severe kidney infection, is most often found in people with certain risk factors. In fact, over 90% of patients with this condition either have diabetes, a urinary blockage, or high blood pressure. It’s also found in patients with conditions that weaken the immune system, such as alcohol abuse, tuberculosis, or HIV/AIDS. However, having a history of urological procedures, using antibiotics in the past, or a previous hospital stay are not considered significant risk factors for this condition.
EPN is more commonly seen in older people and in women. This could be because women generally have higher instances of urinary tract infections. There are also certain factors that make the outcome worse, which include:
- Being of advanced age
- Altered mental state
- Acute kidney failure
- Low platelet count (thrombocytopenia)
- Low albumin levels in the blood (hypoalbuminemia)
- Severe protein loss in urine (severe proteinuria)
- Infections caused by multiple organisms (polymicrobial infections)
- Shock
Location can also affect EPN, with more cases reported in Asia. This contributes to it being a risk factor for the disease.
Signs and Symptoms of Emphysematous Pyelonephritis
Emphysematous pyelonephritis (EPN) is a condition that can show symptoms suddenly or develop over a two-to-three-week period. It’s possible to confuse it with a severe case of acute pyelonephritis, as the symptoms are similar. Symptoms of EPN can include high temperature, chills, painful urination, nausea, vomiting, abdominal pain, tenderness in the loin area, and either the passage of gas through urine or a crackling feeling under the skin.
- High temperature
- Chills
- Painful urination
- Nausea
- Vomiting
- Abdominal pain
- Tenderness in the loin area
- Passing gas in urine or a crackling feeling under the skin
Testing for Emphysematous Pyelonephritis
Tests for people who might have emphysematous pyelonephritis (EPN) often show signs of a higher-than-normal amount of white blood cells, sugar levels, and creatinine in the blood. Some people might also have bacteria in their blood. CT scans are the most reliable way to confirm if someone has EPN, as they can detect it with 100% accuracy. This is more accurate than other scans such as ultrasonography, which has 69% accuracy, and X-rays, which can detect EPN with 65% accuracy.
EPN is usually categorized into three different types based on what the CT scan shows:
1. Michaeli et al classification: Dating back to 1984, this method groups the disease into three stages based on the presence of gas in different parts of the body: within the kidney tissues, in the kidney and its surroundings, or spreading outside the kidney area on both sides.
2. Wan et al classification: Introduced in 1996, this system has two types: one with kidney damage showing gas but no fluid; the other showing both gas and fluid within or around the kidney or within its collecting system.
3. Huang and Tseng classification: In 2000, a more detailed classification was introduced based on the extent of the disease observed on CT scans. This system has four classes: one showing gas only in the part of the kidney responsible for urine collection; the second showing gas in the kidney tissues not extending outside; the third showing gas or abscess spreading to perinephric space (3A) or to the pararenal space (3B); and the fourth showing EPN in both kidneys or in a single functioning kidney.
This last classification system has shown a connection between a higher class, indicating a more severe disease, and a higher risk of unfavorable outcomes. It is important to distinguish between these classes to predict the disease’s course and plan appropriate treatment. Emphysematous pyelitis, which is similar to pyelonephritis and responds well to antibiotics, has a better prognosis than EPN, which requires urgent medical intervention.
Treatment Options for Emphysematous Pyelonephritis
The first step in treating a patient includes making sure they are well-hydrated through an IV, have a good supply of oxygen, their blood sugar levels are stable through insulin use, and that they are given a wide variety of antibiotics.
Antibiotics are used to combat common types of bacteria found in urinary tract infections, like E coli, K pneumoniae, and Proteus mirabilis. Consideration is also given for the presence of Pseudomonas aeruginosa and Enterococcus species. The best single-ingredient treatment options may include third- or fourth-generation cephalosporins, or carbapenems. Administering these types of antibiotics has been crucial in lowering death rates related to gram-negative systemic infections.
An alternative antibiotic treatment method would use a combination of amikacin and a third-generation cephalosporin, because these have seen low resistance rates in the mentioned bacteria. Fluoroquinolones are not usually chosen as the first choice for treatment as there’s a high resistance level due to their heavy use.
When the patient starts to show signs of improvement, such as no fever, a decrease in white blood cells, and overall increased wellbeing, then the patient can switch from intravenous to oral antibiotics. The choice of antibiotics and switch period is also guided by culture and resistance testing results. Typically, a patient is on antibiotics for two weeks, but this may vary based on their individual case.
Besides antibiotics, doctors often recommend patients have a procedure to drain fluid or pus from an abscess, especially those with EPN. However, this procedure may not be necessary for those with isolated emphysematous pyelitis. Cultures from the drainage should be examined to help guide further antibiotic treatments. The catheter can be removed when the patient shows signs of improvement, like having less discharge while the catheter is in the correct position.
If EPN is associated with urinary tract obstruction, like hydronephrosis, then it’s important to relieve the obstruction by using catheters or stents.
Nephrectomy, the surgical removal of one or both kidneys, used to be the preferred treatment for EPN. However, these days, doctors favor less invasive alternatives like percutaneous drainage and antibiotics because advances in technology have improved these methods and cut the death rate associated with EPN down to 21% from its original 40-90% range.
That being said, a nephrectomy might still be necessary for those who don’t respond well to less aggressive treatments. The type of nephrectomy needed depends on the patient’s health status and the severity of the disease.
Huang and Tseng have proposed a guide for treating EPN based on how severe the condition is. If a patient with less serious cases (Classes 1 and 2) of EPN are treated with antibiotics or drainage, they can expect good results. Those with more severe cases (Classes 3A and 3B) are split into two groups:
- Those with fewer than 2 risk factors can benefit from medicines and drainage with an 85% survival rate.
- Those with more than 2 risk factors are likely to fail when using the same strategy, and most cases in this group require a nephrectomy.
People are at a higher risk if they have diabetes, thrombocytopenia, acute kidney failure, disturbed consciousness, and shock. Those with the most severe form of EPN (Class 4) should first use medications and get drainage. If this doesn’t help, then a nephrectomy is required.
What else can Emphysematous Pyelonephritis be?
When attempting to identify Emphysematous pyelonephritis (EPN) or inflammation of the kidney due to a gas-forming infection, doctors should consider other illnesses that might have similar symptoms or appear similar in medical scans. These can include:
- Severe acute pyelonephritis: This is inflammation within the kidney. Clinically, it might be hard to differentiate this from EPN. So, medical imaging is a vital part of the diagnosis process.
- Renal abscess: In this condition, pus collects inside the kidney. It might induce symptoms akin to EPN such as fever, issues with urinating, and pain in the flank (the side of the body between the ribs and hip). Occasionally, air might form within the abscess, which can be detected in imaging tests.
- Renal trauma: An injury to the kidney, such as a blunt force or penetrating injury can damage tissue and blood vessels, creating a path for air to enter inside the kidney.
- Renal infarction: This condition is resulted from insufficient blood supply to a part of the kidney, causing tissue damage. This can also show similar symptoms as EPN and may sometimes even show gas in the kidney on medical scans.
- Gas-forming infections: Diseases caused by particular bacteria that produce gas can extend into the kidney, causing air to be present. Some of these conditions include necrotizing fasciitis and gas gangrene.
- Anatomic fistulas: These are abnormal connections between the urinary tract and gastrointestinal tract or other structures, which can let air enter the kidney.
- Xanthogranulomatous pyelonephritis: It’s a chronic and destructive form of pyelonephritis that can deteriorate the kidney. Even though gas wouldn’t generally form in this condition, it can share some clinical similarities with EPN.
- Iatrogenic causes: These are caused by medical procedures or treatments. Examples can include procedures like percutaneous nephrostomy or surgical interventions that can lead to air entering the kidney.
These conditions must be kept in mind by the doctors to reach an accurate diagnosis as they can show similar symptoms or imaging as EPN.
What to expect with Emphysematous Pyelonephritis
EPN is a serious condition that can lead to life-threatening complications requiring immediate care. A review of 37 studies that included 1145 cases of EPN and pyelitis calculated an overall death rate of 12.5%. However, this rate varies depending on how serious the disease is. Patients with more widespread cases of the disease and symptoms such as confusion, a low platelet count, large amounts of protein in urine, low albumin levels, low sodium levels, sudden kidney damage, or septic shock are linked with higher death rates.
The Huang and Tseng classification system relates a higher class, indicating a more serious or widespread disease, with an increased risk of bad outcomes.
Possible Complications When Diagnosed with Emphysematous Pyelonephritis
EPN, or Emphysematous Pyelonephritis, can result in many serious complications. These potentially severe outcomes include:
- Formation of renal (kidney) abscesses
- Acute renal failure, which is the sudden loss of kidney function
- Perinephric spread of infection, which means the infection spreads in the area surrounding the kidney
- Pneumoperitoneum, a condition where air accumulates in the abdominal cavity
- Septic shock, a severe and sometimes fatal response to infection
- Multiple organ failure, where several vital organs stop functioning properly
- Recurrence, which means the EPN can come back after treatment
Preventing Emphysematous Pyelonephritis
People who have diabetes or other risk factors should be informed about their condition and what symptoms should get a doctor’s attention. Recognizing and treating urinary tract infections early, in addition to maintaining good blood sugar control, can help avoid serious kidney infections known as emphysematous pyelonephritis.
There are easy steps everyone can take to help prevent urinary tract infections. These include keeping clean, going to the bathroom before and right after sexual activities, and drinking plenty of water. These actions can prevent harmful bacteria from entering and causing infections in the urinary tract, which could potentially lead to serious conditions like EPN.
