Clinical Rules and Guidance

In this section, we review the following clinical rules and provide links to relevant online calculators and videos.

Head

• Canadian CT Head Injury/Trauma Rule

• New Orleans/Charity Head Trauma/Injury Rule

• NEXUS Criteria for Head Imaging

• PECARN Pediatric Head Injury/Trauma Algorithm

• NIH Stroke Scale/Score

Otorhinolaryngology (ENT)

• Centor Score (Modified/McIsaac) for Strep Pharyngitis

Neck

• NEXUS Criteria for C-Spine Imaging

• Canadian C-Spine Rule

Extremities

• Ottawa Knee Rule

• Ottawa Ankle Rule

• Wells Criteria for Deep-vein Thrombosis

Heart

• HEART Score for Major Cardiac Events

• San Francisco Syncope Rule

• Boston Syncope Rule

Lungs

• Wells Criteria for Pulmonary Embolism

• CURB-65 Score for Pneumonia Severity

Abdomen

• Alvarado Score for Acute Appendicitis

• Ranson Criteria for Pancreatitis Mortality

Clinical Rules

HEAD

Neuroimaging guidelines for head injury are designed to determine which patients do or do not require emergency head CT. These guidelines are derived from large retrospective and often prospective studies that may have different endpoints (e.g., “clinically significant” brain injury vs. any positive CT finding) and result in slightly different clinical criteria. In general, neuroimaging is recommended for any patient with a positive finding suggested by one of the following rules.

Canadian CT Head Injury/Trauma Rule

The Canadian CT head injury rule applies to patients with a Glasgow Coma Scale score (GCS) of 13-15 with loss of consciousness (LOC), amnesia to the head injury event, or confusion. In alcohol-intoxicated patients, the sensitivity has been reported to be 70% for “clinically important” brain injury. Exclusions include age <16 years, anticoagulation, or seizure after injury.

High-risk criteria (derived with endpoint of need for neurosurgical intervention):

If any of the following criteria are positive, obtain CT scan:

• GCS <15 within 2 hours after injury

• suspected open or depressed skull fracture

• any sign of basilar skull fracture (hemotympanum, raccoon eyes, Battle sign—mastoid ecchymosis, cerebrospinal fluid [CSF] otorrhea or rhinorrhea, cranial nerve abnormality)

• ≥2 episodes of vomiting

• age ≥65 years

Medium-risk criteria (in addition to the above, rules out “clinically important” brain injury):

If any of the following criteria are positive, obtain CT scan:

• amnesia retrograde to the event ≥30 minutes

• “dangerous” mechanism (e.g., pedestrian struck by motor vehicle, occupant ejected from motor vehicle, fall from >3 feet or >5 stairs, fall from more than 2 times patient’s height, and other events deemed dangerous by physician)

New Orleans/Charity Head Trauma/Injury Rule

These criteria are intended for use in patients with LOC who are neurologically normal (GCS=15 and normal brief neurological exam). If any of the following criteria are positive, consider CT:

• headache

• vomiting

• age >60 years

• alcohol or drug intoxication

• persistent anterograde amnesia (short-term memory deficits)

• visible trauma above the clavicle

• seizure

NEXUS Criteria for Head Imaging

The NEXUS criteria identify patients who could safely be excluded from imaging. Head CT is not required if none of the following are present:

Head CT is not required if none of the following are present:

• age ≥ 65 years

• evidence of significant skull fracture

• scalp hematoma

• neurologic deficit

• altered level of alertness

• abnormal behavior

• coagulopathy

• recurrent or forceful vomiting

PECARN Pediatric Head Injury/Trauma Algorithm

The Pediatric Emergency Care Applied Research Network (PECARN) clinical rule is for pediatric head trauma. Like the head rules described above, this validated algorithm guides decisions regarding the need for neuroimaging. Of note, physician experience and parental preference are important considerations for the intermediate-risk group and did factor into the ultimate results of the study.

(Reprinted from Identification of children at very low risk of clinically-important brain injuries after head trauma:a prospective cohort study. The Lancet 2009 Oct 3;374:1160, with permission from Elsevier.)

NIH Stroke Scale/Score

This scale was developed to quantify the severity of a stroke in the acute setting. Higher scores correlate with increased severity and worse clinical outcomes. Documentation of the scale is important for neurologists; however, it should not delay consultations, workup, or care. This scale is long and complicated. Instructions and details of the scale can be found here.

Although a score <4 generally is associated with good clinical outcome and functional independence, it should not preclude the need for imaging.

Otorhinolaryngology (ENT)

Centor Score (Modified/McIsaac) for Strep Pharyngitis

This score is for use only in patients with recent-onset (≤3 days) acute pharyngitis. It is used to predict which patients will have culture-confirmed streptococcal infections to minimize testing.

A score 0-1: no testing required

A score >1: test and treat according to result

Modified Centor Score criteria:

• age 3-14 years (+1)

• age 15-44 years (0)

• age ≥45 years (-1)

• exudate or swelling on tonsils (+1)

• tender/swollen anterior cervical lymph nodes (+1)

• fever >38°C, 100.4°F (+1)

• cough present (0)

• cough absent (+1)

Neck

NEXUS Criteria for C-Spine Imaging

These criteria were derived to identify patients who are eligible to be cleared clinically, without imaging. If no findings are present, risk of dangerous cervical spine fracture is very low.

If any of the following criteria are positive, obtain CT scan:

• altered level of consciousness

• intoxication

• distracting injury

• focal neurologic deficit

• midline cervical spinal tenderness to palpation

Canadian C-Spine Rule

The Canadian C-Spine Rule is a validated decision rule that can be used to safely rule out cervical-spine injury in alert, stable trauma patients without the need to obtain radiographic images. It can also be used for stable trauma patients. In contrast to NEXUS (described above), the rule can be used if a patient is alert and cooperative, regardless of blood alcohol content.

However, strict exclusion criteria include the following:

Canadian C-Spine Rule exclusion criteria:

• nontrauma patient

• GCS <15

• unstable vital signs

• age <16 years

• acute paralysis

• known vertebral disease

• previous C-spine surgery

(Source: The Canadian C-Spine Rule versus the NEXUS Low-Risk Criteria in Patients with Trauma. N Engl J Med 2003.)

Extremities

Ottawa Knee Rule

Knee imaging is not warranted in patients identified to be at low risk for fracture. This rule should be applied to all patients age ≥2 years with knee pain/tenderness in the trauma setting.

Patients who do not meet any of the following criteria do not need an x-ray. If one or more of the conditions are met, then imaging is recommended.

• age ≥55

• isolated tenderness of the patella (no other bony tenderness)

• tenderness at the fibular head

• unable to flex knee to 90°

• unable to bear weight both immediately and in emergency department (ED) (four steps, limping is okay)

Ottawa Ankle Rule

This rule was also developed to reduce the use of unnecessary radiographs. You can apply this rule for patients age ≥2 years to rule out clinically significant ankle and midfoot fractures after trauma without radiograph.

Patients who do not meet any of the following criteria noted in the following image do not need an ankle or foot radiograph. Those that fulfill either the foot or ankle criteria need an x-ray of the respective body part.

(Reprinted from Stiell IG et al. A study to develop clinical decision rules for the use of radiography in acute ankle injuries. Ann Emerg Med 21:384-90, 1992, with permission from Elsevier.)

Wells Criteria for Deep-vein Thrombosis

According to the Wells clinical decision rule, an ultrasound to rule out deep-vein thrombosis (DVT) is not necessary in patients deemed low risk with a negative D-dimer test result.

Interpretation of the Wells score:

A score of 0: DVT unlikely

• If the D dimer is negative, no further imaging is required.

• If the D dimer is positive, obtain an ultrasound.

• A negative ultrasound is sufficient to rule out DVT.

• If ultrasound is positive, consider treatment with anticoagulation.

A score of 1-2: moderate risk

• If high-sensitivity D dimer is negative, no further imaging is required.

• If the D dimer is positive, obtain an ultrasound.

• A negative ultrasound is sufficient to rule out DVT.

• If ultrasound is positive, consider treatment with anticoagulation.

A score of ≥3: likely DVT

• All patients require ultrasound and D-dimer test.

• If ultrasound is positive, treat with anticoagulation.

• If the D dimer is positive and ultrasound is negative, repeat ultrasound in 1 week.

• If the D dimer and ultrasound are negative, no further workup required.

Heart

HEART Score for Major Cardiac Events

Chest pain is a common complaint in the emergency department. This score predicts the 6-week risk of major cardiac events, thus helping clinicians determine appropriate disposition.

A score of 0-3: appropriate to discharge

A score of 4-6: admit to the hospital

A score of ≥7: candidates for early invasive measures

HEART Score criteria:

• slightly suspicious history (0)

• moderately suspicious history (+1)

• highly suspicious history (+2)

• normal electrocardiogram (ECG) (0)

• nonspecific repolarization disturbance in the ECG (+1)

• significant ST depression (+2)

• age <45 years (0)

• age 45 to 65 years (+1)

• age >65 years (+2)

• no known risk factors (0)

• one or two risk factors (+1)

• more than three risk factors or history of arteriosclerotic disease (+2)

• initial troponin within normal limit (0)

• initial troponin one or two times the normal limit (+1)

• initial troponin more than two times normal limit (+2)

San Francisco Syncope Rule

The San Francisco Syncope rule can be used to separate patients with syncope into high-risk and low-risk groups. The high-risk group is associated with serious adverse outcomes (e.g., death, myocardial infarction [MI], arrhythmia, pulmonary embolism [PE]) within 30 days. The rule has been studied in several different settings and countries. Some controversy exists about the sensitivity of this rule to predict a bad outcome, particularly in different geographic regions.

If the patient meets any of the following criteria, he/she cannot be considered low risk:

• history of congestive heart failure

• hematocrit <30%

• ECG abnormal (ECG changed, or any non-sinus rhythm on ECG or monitoring)

• symptoms of shortness of breath

• systolic BP <90 mm Hg at triage

Boston Syncope Rule

This rule predicts adverse events or need for critical interventions in patients who had syncope.

A patient with one of the risk factors should be admitted. If the patient does not have any of the risk factors, the patient can be safely discharged home. In one study, use of the Boston Syncope criteria reduced admissions by 11%. The OESIL Score for syncope estimates 12-month all-cause mortality in patients presenting with syncope

Lungs

Wells Criteria for Pulmonary Embolism

The Wells criteria for pulmonary embolism (PE) is used to determine the pretest probability of PE, which in turn influences the best next steps to rule out or rule in the diagnosis of PE.

The Wells score can be interpreted as follows:

• score <2: low risk for PE

• score 2-6: intermediate risk for PE

• score >6: high risk for PE

Low-Risk Wells Score: Patients who have a Wells score <2 are at low risk for PE (incidence, 1.3%) and are typically further risk stratified using the Pulmonary Embolism Rule-out Criteria (PERC):

• age <50 years

• heart rate <100 beats per minute

• oxyhemoglobin saturation ≥95%

• no hemoptysis

• no estrogen use

• no prior DVT or PE

• no unilateral leg swelling

• no surgery or trauma requiring hospitalization within the prior 4 weeks

If all eight of these criteria are met, then no further testing is needed. If any of the criteria are not met, then a D-dimer measurement can be helpful. A normal value can help rule out PE and obviate the need for imaging.

Intermediate-Risk Wells Score: In intermediate-risk patients (Wells score of 2-6; incidence of PE, 16.2%), a D-dimer level is indicated. If the D-dimer level is <0.5 µg/mL, further imaging is typically not needed. However, the full clinical picture should be taken into account for patients who fall into this group. Imaging to rule out PE may be appropriate for some intermediate-risk patients, regardless of D-dimer value. This may apply to older patients, those with cardiopulmonary compromise, those with a Wells score at the upper end of the intermediate range, and other patients where the clinical evaluation raises concern for PE beyond what is reflected in the Wells score.

High-Risk Wells Score: Imaging (usually CT angiography) should be obtained in all high-risk patients (Wells score >6; incidence of PE, 37.5%). There is no role for measuring a D-dimer level in these patients, as a normal D-dimer level does not adequately rule out PE.

The American College of Physicians recommends the following algorithm for evaluating patients with suspected PE using the different clinical guidelines.

CURB-65 Score for Pneumonia Severity

This clinical guideline was assigned to determine the disposition of the patient by estimating the mortality of community-acquired pneumonia.

A score of 0-1: outpatient care

A score of 2-3: inpatient or observation admission

A score of >3: inpatient admission with consideration for ICU for the score >4

CURB-65 Criteria

• Confusion (+1)

• blood Urea nitrogen (BUN) >19 mg/dL (+1)

• Respiratory rate ≥30 (+1)

• systolic BP <90 or diastolic BP ≤60 (+1)

• age ≥65 (+1)

Abdomen

Alvarado Score for Acute Appendicitis

The Alvarado Score is used to determine the likelihood of appendicitis in patients with suspected appendicitis.

A score ≤3: rules out appendicitis and generally does not warrant CT for diagnosis

A score of 4-6: indicates that CT will help differentiate the diagnosis

A score ≥7: highly suggestive of appendicitis and prudent to involve early surgical consultation

Alvarado Score criteria:

• right lower quadrant tenderness (+2)

• elevated temperature (37.3°C or 99.1°F) (+1)

• rebound tenderness (+1)

• migration of pain to the right lower quadrant (+1)

• anorexia (+1)

• nausea or vomiting (+1)

• leukocytosis >10,000 WBC/mm3 (+2)

• leukocyte left shift (+1)

Ranson Criteria for Pancreatitis Mortality

A Ranson score estimates mortality in patients with acute pancreatitis. It has two parts; as ED providers, you calculate the first part while the second part is not included.

A score ≤2: severe pancreatitis unlikely, low risk for mortality

A score ≥3: severe pancreatitis likely, consider ICU care

Ranson Score criteria:

• age >55 (+1)

• glucose >200 mg/dL(+1)

• WBC >16,000 mm³ (+1)

• AST >250 (+1)

• LDH >350 (+1)