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The X-ray is not as accurate as most people think.  Many children (and also adults) are diagnosed with “pneumonia” in ERs, Emergency Clinics, and even physician’s offices when they really do not.  The X-ray does not see bacteria.  It sees fluid, mucous, congestion, or any stuff.  The mucous in the chest could be allergy like asthma, bacterial pneumonia, viral (pneumonia) infection like a bad chest cold or flu, fungal infection, or even rarely cancer.  The radiologist reads the X-ray as “pneumonia” but that is the radiologist’s term for congestion.  And the radiologist does not know the patient so he will call it pneumonia if there is very little congestion not wanting to miss it and get sued later.  Some physicians will also over call the diagnosis not wanting to get sued.  Most patients with an asthmatic attack or flu will have an abnormal X-ray.  When there is what is called a consolidation, where the whole lobe of the lung is a white out, then it is most likely a bacterial pneumonia.  But many X-rays have steaks or some fluffiness that is called “pneumonia”. 

 I do not take many X-rays since most cases it will not help us doctors.  If there is fever, cough, and I can hear what is called “rales” in the chest, then there is most likely pneumonia and I will treat no matter what the X-ray shows.  And if there is a child that is not ill, has mild cough, mild fever, and normal sounding chest with no labored breathing, then there is no bacterial pneumonia and why take an X-ray that may show congestion.  The X-ray frequently lags behind the patient’s condition.  So the X-ray may be normal early on in pneumonia, and the abnormalities can persist in the X-ray for months even though the patient is cured.  X-rays can also cause cancer later in life so why expose them unless needed.  A history and physical is more important. 

 So the X-ray is not a microscope and does not see bacteria.  For comparison; if there is mucous in your nose that is clear allergy mucous or there could be green infected mucous, when we X-ray your nose, it will show congestion but we will not know if it is clear or infected boogers.  

 Dr. Knapp

See summaries of Medical Studies and Articles written about this:

1.  The Journal of Pediatrics

The cause and clinical manifestations of pneumonia were studied in 98 pediatric outpatients. A viral diagnosis was established in 38 (39%) of the 98 patients, and a bacterial diagnosis in 19 (19%). Ten (53%) of the 19 patients with bacterial pneumonia had a concurrent viral infection. No clinical, laboratory, or radiographic findings that would reliably differentiate viral from bacterial infection were identified. This study suggests that  the clinical, laboratory, and radiographic findings in patients with bacterial infection may be indistinguishable from findings in patients with viral infection.

2.  Radiologic Technology,

The chest radiograph is a popular diagnostic tool in the care of patients suspected of having pneumonia but has a low diagnostic yield in many cases. The clinical utility of the chest film could be improved by careful clinical examination of the patient before obtaining the radiograph, especially in pediatric patients.

3.  Clinical Pediatrics

The chest roentgenograms of 128 consecutive ambulatory children with radiologic pneumonia were read independently and without clinical information by a faculty general pediatrician (Ped), a pediatric radiologist (R-P) and a general radiologist (R-G). Readings were compared with results of viral titers and bacterial cultures.  The three observers agreed on a correct reading in only three children with viral and three with bacterial pneumonia. Because of poor observer agreement and appreciable false-negative errors when viral and bacterial readings were compared to titer increases and positive bacterial cultures, respectively, we conclude that radiographic findings are poor indicators of etiology diagnosis in ambulatory childhood pneumonias and, of themselves, are an insufficient data base for making therapeutic decisions.

4.  Archives of Argen Pediatrics

To evaluate the accuracy of World Health Organization (WHO) method of interpreting chest radiographs on identifying young children with bacterial pneumonia, and to compare its accuracy with other method. Chest radiographs from children aged under 5 years old hospitalized for pneumonia, with microbiological evidence of bacterial or viral infection, were evaluated. 108 chest radiographs were evaluated (87 viral, 21 bacterial). There was a specificity of 50-60% for diagnosing bacterial vs viral chest infections.

5.  Clinical Pediatrics

The difficulty of diagnosing pneumonia by chest x-ray in children less than 4 years of age was studied by comparing the chest roentgenograms of 34 healthy children with the chest roentgenograms of 34 children previously diagnosed as having pneumonia. Review of these films without knowledge of the previous interpretation and without clinical information disclosed variations regarding the roentgenographic confirmation of pneumonia in 24 percent of the cases and variations regarding the location of the lesion in about 50 percent of the cases.

6.  Pediatrics

The need for follow-up roentgenograms documenting complete clearing of pulmonary infiltrates in the pediatric patient with acute pneumonia was studied prospectively. Seventy of 129 children enrolled in the study had a repeat roentgenogram within three to four weeks after initial diagnosis. Twenty percent of this group had residual pulmonary infiltrates. Of the two thirds of those who returned for a second follow-up roetgenogram, the infiltratrates had cleared completely within three months. Routine repeat chest roentgenograms may not be necessary unless there is clinical evidence of persistent respiratory difficulty or failure to thrive.

7.  Pediatric Pulmonology

This study assessed the clinical value of routine follow-up chest radiographs in hospitalized children with community-acquired pneumonia.  ……   In conclusion, routine follow-up chest radiographs are not needed in childhood community-acquired pneumonia if the child has a clinically uneventful recovery.

8.  Acta Pediatrica

To evaluate the value of radiographic follow-up of community-acquired pneumonia in children who are previously healthy. …..   Such patients may have some benefit from control radiographs, but only in terms of detecting the chronic disease at an earlier stage, not in altering the clinical course. Such modest benefits must be weighed against the consequences of providing follow-up to a large number of healthy children, and making lots of abnormal findings with no clinical significance. CONCLUSION: Control radiographs are not very valuable in children who are otherwise healthy.

9.  Acta Radiologica  

Radiological Findings in Children with Acute Pneumonia: Age More Important Than Infectious Agent
Purpose: To evaluate whether radiological findings and healing time in children with pneumonia are correlated to etiologic agent.
A total of 346 children with radiologically verified acute pneumonia, and with accomplished serological tests for bacteria and viruses, were included in the study. Five etiological groups were analysed: children with bacterial etiology only, with viral etiology only, with mixed bacterial and viral etiology, with Mycoplasma only, and children with no etiology.  The chest films of each etiological group were analysed and the findings were correlated to the children's age. The radiological findings did not differ between the etiological groups. Radiological findings correlated significantly with the patient's age.
Result: Conclusions about the etiology could not be drawn from the chest X-ray findings.

Here is a newsymail I sent out in Sept2011

2011 October 1 issue of Clinical Infectious Diseases will present this information and recommendations.

The Pediatric Infectious Diseases Society (PIDS) and the Infectious Diseases Society of America (IDSA) convened an expert panel to review the management of Community acquired Pneumonia (CAP). The PubMed database was reviewed through May 2010. The expert panel included clinicians and investigators who represented community pediatrics, public health, critical care, emergency medicine, hospitalist medicine, infectious diseases, pulmonology, and surgery.   The first-ever guidelines on the diagnosis and treatment of CAP in infants and children, from PIDS and IDSA, emphasize the importance of immunizations  (Prevnar), including a yearly influenza vaccine, to protect children from life-threatening pneumonia.  A 13-member panel, led by John S. Bradley, MD, with the Department of Pediatrics, University of California San Diego School of Medicine and Rady Children's Hospital of San Diego, in California, authored the new guidelines published online August 30 and to appear in the print October 1 issue of Clinical Infectious Diseases. The document presents 92 specific recommendations in all, each with varying levels of evidence.

Recommendations for Diagnosis  "Diagnostic methods and treatments that work well in adults may be too risky and not have the desired result in children,"  Regarding diagnosis, the guidelines state that blood cultures should not be routinely performed in nontoxic, fully immunized children with CAP treated in the outpatient setting. "In these cases, there is no need to perform unnecessary medical interventions such as using x-rays (which expose the child to radiation needlessly) or prescribing antibiotics (which kill bacteria, not viruses, and may foster drug-resistant bacteria)," the written release states.  The guidelines also recommend that infants 3 to 6 months old with suspected bacterial pneumonia be hospitalized.

Amoxicillin Sufficient for First-Line Therapy In addition, amoxicillin should be used as first-line therapy for bacterial pneumonia, but more powerful antibiotics are not needed. Methicillin-resistant Staphylococcus aureus should be considered as a cause of pneumonia if first-line treatment is unsuccessful.  According to the guidelines, overtreatment is a critical concern. Most cases of pneumonia in preschool-aged children are of viral origin and will therefore not develop into life-threatening bacterial pneumonia. 

"With these guidelines, we are hopeful that the standard and quality of care children receive for community-acquired pneumonia will be consistent from doctor to doctor — providing much better treatment outcomes," Dr. Bradley indicates.  "Pneumonia is one of the most common reasons for hospitalization for children in the United States, and there's a huge variation in the care that's delivered to children,"   "Often the care of children is not evidence based and result in both over- and undertreatment of children and less than ideal outcomes.”

It is interesting that they do not recommend x-rays.  When you take an x-ray the cloudy area that one sees is called pneumonia but in fact is just “congestion”.  It is mucous.  The mucous can be sterile as in allergies and asthma, it can be viral with a chest cold, or bacterial as with bronchitis or pneumonia.  The x-ray does not tell you which but is reported “pneumonia”.  Then the doctor faced with a x-ray report of pneumonia has to treat it as if it is bacterial pneumonia so that he does not “miss” pneumonia and get sued if the patient later comes in the secondary bacterial pneumonia after the chest cold.  We have discussed in previous articles about the chest viral cold with fever and cough at the beginning is usually viral and a recurrence of fever and lethargy after the fifth day is secondary bacterial infection.  That is when we need to see the patient.  But many people are treated for pneumonia who have a viral chest cold or allergy.  Everyone who is coughing and goes into the walk-in emergency clinics gets a chest x-ray and many get treated for their “pneumonia”.  I don’t take a lot of x-rays for this reason.  It does not affect your medical decision that much.

While we are talking about false diagnosis with tests, let’s talk about strep tests.  10% of strep cultures and rapid tests are negative when there actually is strep throat.  And 5% of the population carries strep around in their throat all year.  They are carriers. So you can have a strep throat and a negative test and not get treated.  Then you can have a viral/allergy sore throat and positive test and get treated for a strep that has been in there all year and had nothing to do with the sore throat.  That is why your friend says their child had a strep throat and did not even run fever.  Or the doctor started antibiotics for “strep throat” and the patient was not well in a few days so they changed antibiotics.  There are no strep resistant to Amoxicillin.  When they changed antibiotics then the viral sore throat finally went away and it seems like it was from the changing of the antibiotic.

Also think of Urinary tract infections.  Most girls below 5 yrs. old who have burning do not have an infection but just irritation.  There is what is called asymptomatic bactiuria.  There are bacteria in many females bladder and it is in there all year.  It does not harm them and does not need to be treated.  But the child gets irritation from a bubble bath and the culture comes out “positive”.  Those may have been bacteria that were in there all month.  They still get treated to be on the safe side. (no bubbles and use Dove soap in the bath.)

What I am saying is that it is not exact and gets confusing as to what is real or not.  A lot of clinical judgment, experience, and common sense goes a long way. 

Roger Knapp MD