Why we do what we do: Ultrasound for appendicitis

Why we do what we do has returned – this time focusing on the use of ultrasound in appendicitis, which has become the test de rigeur these days in most Pediatric Emergency Departments. I won’t belabor the point on how important it is to correctly diagnose appendicitis. It peaks between ages 9-12, and can lead to perforation within 36-72 hours. Missed appendicitis is also one of the biggest causes of filed malpractice claims.

How is it typically performed?

The most common technique is called graded compression. A linear probe is placed over the point of maximal tenderness and the bowel contents are pushed out of the way. Landmarks sought include the iliac vessels and posts muscle – to which the appendix is anterior.

A normal appendix is <6mm in diameter, compressible and peristalses. The wall is generally <2 mm thick. An enlarged, non compressible appendix may also have increased flow on Doppler. Secondary signs of appendix include free fluid, a phlegmon or abscess, thickening of the mesentery and inflamed fat. If more than one of these are present the sensitivity of the ultrasound is increased. In experienced hands the appendix is seen up to 80% of the time. Pediatric Emergency Medicine and Emergency Medicine physicians can be taught to do it, with reported sensitivity in the 60-80% range after a single didactic session.

What are the possible results?

  • Normal appendix seen
  • Abnormal appendix seen
  • Appendix not visualized, no secondary signs of appendicitis
  • Appendix not visualized, one or more secondary signs of appendicitis

How good is it?

It turns out that it varies, but in general ultrasound, when performed by an experienced monographer is pretty darn good. Not CT good, but, given the lack of radiation exposure good enough to consider the first line in pediatric imaging for acute appendicitis. In general the longer the duration of pain (see Bachur et al), or the more experienced the sonographer – the more accurate the results.

The overall sensitivity 74-100%

The overall specificity 88-99%

Let’s take a look at some of the evidence in detail:

Ultrasonography and limited computed tomography in the diagnosis and management of appendicitis in children.
Garcia Peña et al. JAMA. 1999

Prospective cohort of 139 children, 108 of which had an equivocal ultrasound and then got a CT. This protocol was 94% sensitive, 94% specific and had a PPV of 90% and NPV of 97%. A negative ultrasonography result did not change the surgeons’ clinical confidence level in excluding appendicitis (P= 0.06), while, as expected a negative CT did (P<0.001).

Accuracy of noncompressive sonography of children with appendicitis according to the potential positions of the appendix
Baldisserotto et al. Am J Roentgenol. 2000

This study investigated both noncompressive and compressive techniques and saw had a sensitivity 98.5%, specificity of 98.2%, PPV 98% and NPV 98.7%.

The impact of ultrasound examinations on the management of children with suspected appendicitis: a 3-year analysis.
Dilley et al. J Pediatr Surg, 2001

The authors reviewed over 1,000 pathology reports and noted that of the 84% that actually had appendicitis 58% had received an ultrasound. Overall there was an 89% sensitivity, 95% specificity, 86% PPV, 96% NPV.

Performance of ultrasound in the diagnosis of appendicitis in children in a multicenter cohort
Mittal et al., Acad Emerg Med, 2013

A secondary analysis of a multicenter cohort from PEMCRC Of 2,625 patients with abdominal pain. 965 (36.8%) had an US – with 72.5% (95% CI = 58.8% to 86.3%) sensitivity and a 97.0% (95% CI = 96.2% to 97.9%) specificity. This takes into account both definitive and inconclusive ultrasounds.

When the appendix was clearly visualized – (48.6% of cases) – the sensitivity was 97.9% (95% CI = 95.2% to 99.9%), and the specificity was 91.7% (95% CI = 86.7% to 96.7%).

What does it mean if the appendix isn’t seen?

Recall those secondary signs mentioned above? Well, there is some evidence to suggest that they are of value even if the appendix is not seen. Estey et al in Pediatric Emergency Care in 2013 conducted a retrospective case review of 662 consecutive children with  suspected appendicitis. The appendix was not visualized in 38% (241). The additional findings considered included;

  • Free fluid
  • Phlegmon
  • Pericecal inflammatory fat changes
  • Any free fluids with prominent lymph nodes

Per the authors the odds of appy “increases from 0.56 to 0.64 to 2.3 and 17.5, respectively, when there were 2 and 3 ultrasonographic inflammatory markers identified.”

Weirsma et al in 2009 noted that in their population hyper echoic mesenteric fat was the most common secondary sign. They also noted that the NPV of not visualizing the appendix, but also have no secondary signs was close to 100%. The two studies noted above were somewhat limited by number of subjects.

The most complete study on this topic comes from Ross et al, from Academic Emergency Medicine in 2014. The authors retrospectively reviewed 968 children that had an ultrasound. The appendix was seen in less than half (45.7%, 442). 60% of those in which the appendix was not visualized were discharged home. Clinically well appearing (low suspicion patients, non-concerning exam) that were discharged home rarely had happy (0.3%). Of those discharged home based on clinical findings after incompletely visualized appendices, only 1/311 ended up having appendicitis. Ultimately 15.6% of children with incompletely visualized appendices had pathology-confirmed appendicitis – many had secondary signs.

Does anything decrease the accuracy?

It is also important to note that body habitus (BMI ≥ 85th percentile) and low pretest probability (you don’t think it was likely to be an appy to begin with) were associated with high rates of inaccurate results (interestingly more false positives!).

So, I should go with ultrasound first?

Yup, in most cases yes. Here are some specific scenarios:

  • In highly suspicious patients with a clinical diagnosis of appendicitis (teenage males) consider consulting the surgeon directly
  • If the appendix is seen and is normal, you have ruled it out.
  • Conversely, an ultrasound consistent with appendicitis means the surgeon should get a call post haste.
  • If the appendix is not visualized, but there are no secondary signs of appendicitis you have about a 1/25 chance of this patient actually ending up with appendicitis. This is probably lower in patients with a non-concerning exam – but then why are you imaging in the first place? In very suspicious cases consider a consult to surgery and/or a contrast CT scan, or even MRI – this is the so-called staged approach. Ross et al in 2014 (see above) found that the success rate of serial ultrasounds was 21% – thus, consider another imaging modality if the ultrasound was non-diagnostic.
  • If the appendix is not visualized, but the patient has one or more secondary signs of appendicitis call the surgeon. Many patients will go to the OR, others will get admitted for serial exams, and others will get a contrast CT. The important thing is not to discharge these kids home.

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Absolute and relative contraindications for ketamine use in the Pediatric Emergency Department

Another informative post by Lauren Riney, one of the excellent Pediatric Emergency Medicine Fellows at Cincinnati Children’s Hospital Medical Center.


When is ketamine ABSOLUTELY contraindicated?

  • Age younger than 3 months (primarily for risk of airway complications)
  • Schizophrenia (studies show this condition may be exacerbated with ketamine administration)

The list of relative contraindications is much longer:

  • Anything that may increase the risk of laryngospasm (major procedures stimulating the posterior pharynx, active pulmonary infection such as URI, active pulmonary disease such has asthma)
  • Anything that could be detrimental with enhanced sympathomimetic effect (porphyria, thyroid disease, HTN, heart failure, cardiovascular disease)
  • History of airway instability, tracheal surgery, tracheal stenosis
  • Increased ICP or intraocular pressure (CNS masses, hydrocephalus, glaucoma, or acute globe injury). Of note, head trauma is NOT a relative contraindication to ketamine. Newer evidence suggests that the cerebral vasodilatory effect may be cerebroprotective and the increases in pressure are minimal with normal ventilation.

The clinical practice guidelines for ED ketamine sedation, a 2011 update, is a great resource

Also, remember, dosing needs are more likely to increase with decreasing age!

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A dissociative state of mind: Talking to parents about ketamine

This post was contributed by Lauren Riney, one of the excellent Pediatric Emergency Medicine Fellows at Cincinnati Children’s Hospital Medical Center.

So you’ve got another procedural sedation to do in the pediatric emergency department. If your ED is anything like ours, your options for sedation include ketamine, ketamine, and, well, more ketamine.

The pharmacology of ketamine is totally different from any other sedative. It works by dissociating the CNS from outside stimuli causing a cataleptic trancelike state. This amazing medication does not blunt the respiratory drive nor cause hypotension, and at the same time allows for effective sedation, amnesia, and analgesia. It is almost too good to be true!

The dissociation induced by ketamine does not follow the progression of increasing depth of sedation followed by cardiorespiratory depression. Patients either are or are not dissociated; there is no increased depth response to increase in dose.

So what exactly is dissociative sedation? And what should you be telling parents about this type of sedation? For starters, the patient will be in a trancelike state of mind where they do not respond to stimuli but the eyes may remain open, they may make noises, and they may move their extremities. Nystagmus is common and muscular clonus may be seen. The patient will have substantial or complete analgesia as well as total amnesia all while maintaining their respiratory drive and cardiovascular stability.

You should include parents and family members (older children) in the sedation process. For example, have the family talk with the patient to think of topics for dreaming during sedation, which has been shown to decrease recovery reactions. Just before induction, I often have the patient think about a recent trip they went on: describe what they saw, how they felt, who went with them, and their favorite part. The more calm and relaxed the patient is during induction with ketamine, the more likely their recovery will be pleasant.

The clinical practice guidelines for ED ketamine sedation, a 2011 update, is a great resource

Also, remember, dosing needs are more likely to increase with decreasing age!

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About saving time in the ED

I have delved into similar topics before, but I wanted to highlight something I read on Academic Life in Emergency Medicine this weekend. They have been running a series entitled “How I work smarter” that features leaders in the field talking about various aspects of their careers. This weekend’s entry from Dr. Rick Body contained a powerful bit of advice in response to the question, What is your best time saving tip in the ED?

In all honesty, my best time saving tip is to forget about time when you’re seeing patients. That seems counter-intuitive. As a junior, I always wanted to be fast so that patients wouldn’t have to wait so long. From the start of every consultation I was conscious that the clock was ticking and I really tried to direct and focus what was happening. Nowadays, I realise how badly mistaken I was. Those first few moments after you make initial contact with a patient are crucial to help them to relax, to trust you and to open up about what’s really troubling them. Listen to your patient without interrupting. Make good eye contact. Allowing brief moments of silence gives them opportunities to realise you’re listening, to tell you things they otherwise wouldn’t, to appreciate that they don’t need to exaggerate their symptoms to get you to take them seriously. Ultimately, by really understanding what’s going on you get to an accurate diagnosis faster.

I couldn’t have said it better myself. Read more at Academic Life in Emergency Medicine.

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Fracture Fridays: FOOSH (re-post)

The case

A preschooler was riding his big sister’s “girl” bike, crashed it and landed on his outstretched hand. A true FOOSH if you will (fell on outstretched hand). His mom brought him to the ED because he was having trouble holding his iPad with the injured arm. An X-Ray is obtained.


The Diagnosis

This is a buckle or torus fracture which is actually one type of greenstick fracture. The bones of young children are more plastic, and the bone deforms without breaking completely. As you can see in the image above there is a ‘buckling’ of the bone more so towards the dorsal side. Neurovascular injuries in association with this type of fracture are extremely rare.


The management of buckle fractures consists of splinting or casting, and then just letting the darn thing heal, which in will in about a month. generally there is less soft tissue swelling than with other injuries, so a short arm cast would be a viable option. You could also just as easily place a splint. Though a volar splint is great for nondisplaced nonangulated forearm fractures, in a child of this age a sugartong splint would assure that it is better immobilized and protected until definitive casting. For pain most children require acetaminophen or ibuprofen alone. Pain that is out of proportion to what you’d expect should prompt the search for other injuries.

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Listen to the new PEM Currents podcast: An interview with bronchiolitis guru Todd Florin

I’m delighted to share the latest PEM Currents podcast! I recently sat down with Todd Florin, one of the faculty physicians at Cincinnati Children’s Hospital Medical Center and talked about bronchiolitis, delving into the controversies around the use of hypertonic saline, albuterol and more. Todd also recommended that all of my listeners check out the current AAP Bronchiolitis Guideline, which I’ve linked here. AAP Bronchiolitis Guideline

You can listen to the podcast via the streaming media player right here, or download at iTunes.


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