A negative rule helps only after the child is already judged genuinely low risk.
A positive PERC-PEDS result means only that the rule cannot end the work-up; it neither diagnoses pulmonary embolism nor mandates computed tomography.
An adolescent with pleuritic chest pain and mild dyspnoea can move rapidly from concern about pulmonary embolism to blood tests and computed tomography. Unnecessary testing brings radiation and contrast exposure, while the residual risk of missed venous thromboembolism still has to be considered. The paediatric pulmonary embolism rule-out tool PERC-PEDS offers a route out of the work-up, but only for a narrowly defined low-risk group.
Where PERC-PEDS belongs
The study enrolled children aged 4–17 years when pulmonary embolism testing was ordered or strongly considered. The rule comes after a clinician estimates the pre-test probability at below 15%. It is not a screening checklist for every child with chest pain, cough or breathlessness.
With complete rule data, PERC-PEDS had 99.6% sensitivity, a 99.9% negative predictive value and a negative likelihood ratio of 0.02. It was negative in about 18% of children, with a false-negative rate of 0.1%. Those figures describe performance inside the intended sequence.
When investigators removed the requirement for a clinician-estimated probability below 15%, sensitivity fell to 91.3% and the false-negative rate rose to 2.1%. Its upper confidence limit exceeded the study’s prespecified safety threshold. Clinical judgement is part of safe rule use, rather than an optional step before the criteria are applied.
What each result permits
If every criterion is negative in a carefully selected low-risk child, the study supports stopping the pulmonary embolism evaluation without D-dimer or pulmonary vascular imaging. Alternative causes still need assessment. The small residual risk should be explained and clear return precautions provided.
Any positive criterion means only that PERC-PEDS cannot end the work-up. It does not diagnose pulmonary embolism or mandate computed tomography pulmonary angiography. The clinician should reassess the overall probability and then decide whether D-dimer or imaging is appropriate.
D-dimer used alone was less convincing. At 500 ng/mL fibrinogen-equivalent units, sensitivity was 89.8%. A sequential PERC-PEDS-then-D-dimer approach ruled out venous thromboembolism in 54.3% of the cohort and was estimated to reduce computed tomography pulmonary angiography by about 20%, but this pathway was not prospectively mandated and still requires impact testing.
Only 36.6% of participants underwent pulmonary vascular imaging. Record review, outside-record checks and 45-day follow-up covered the remainder, creating verification bias despite independent adjudication. Younger children, hospitalised patients, pregnancy, current anticoagulation and non-academic or rural settings were also underrepresented.
A genuinely low-risk child with a negative PERC-PEDS assessment may avoid further pulmonary embolism testing. One positive item returns the decision to clinical assessment; it is not a shortcut to computed tomography. Documenting the pre-test probability matters as much as recording the individual criteria.
Cardiac surgery for infective endocarditis requires early team referral, timely optimisation and decisive perioperative troubleshooting. Key issues include molecular testing of operative valve tissue, antithrombin-related heparin resistance, vasoplegia and low cardiac output after bypass.
Outer-shell electrons explain how covalent, ionic and hydrogen bonds form in biological molecules. Water polarity then connects basic chemistry with electrolyte dissolution, osmosis, membrane electrical activity, fat solubility and reversible DNA strand pairing.
The paediatric pulmonary embolism rule-out tool PERC-PEDS may support ending testing in carefully selected children aged 4–17 years once clinical pre-test probability is below 15% and every criterion is negative. A positive result or negative D-dimer alone cannot settle the diagnosis.
Loud snoring, witnessed apnoeas, daytime sleepiness and difficult-to-control hypertension increase suspicion for obstructive sleep apnoea, but comorbidity determines the right test. Home testing suits uncomplicated high-probability cases; negative results with persistent suspicion or concern for central apnoea, hypoventilation, heart failure, opioid use or neuromuscular disease need laboratory assessment.
Document why the clinical pre-test probability of pulmonary embolism is below 15% before applying PERC-PEDS. Record every criterion explicitly. When the result is positive, reassess the overall probability before deciding whether D-dimer or pulmonary vascular imaging is appropriate.
An otherwise stable 15-year-old with pleuritic chest pain has a clinician-estimated pulmonary embolism probability below 15%. Every PERC-PEDS criterion is negative. What should happen to the pulmonary embolism work-up?
It can stop without D-dimer or pulmonary vascular imaging. Continue assessing alternative causes, explain the small residual risk and provide clear return precautions.
Antibiotics are started before adequate cultures in a patient undergoing valve surgery for suspected infective endocarditis. Blood cultures remain negative and infected valve tissue is excised. Which investigation offers the best remaining opportunity to identify the organism?
Request urgent 16S ribosomal RNA polymerase chain reaction with sequencing on the operative tissue. Bacterial genetic material may remain detectable after antibiotics prevent growth in blood cultures.
A nerve cell changes its membrane potential as sodium and potassium cross the cell membrane. What carries the electrical signal in this biological system?
Charged ions moving across the membrane alter the electrical difference between its two sides. This differs from electron flow through a metal wire.
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