The sensitivity of US can be limited and can frequently be negative despite clinical or histological appendicitis.  However it is an important non-ionising tool to be used with other complimentary tests and has a role of narrowing the differential diagnosis.  There are various good articles published in the last few years that will provide some clarity of the challenges and limitations of ultrasound for acute appendicitis 

US is an excellent tool when performed with a skilled operator and should be a first line choice for imaging since no contrast or radiation is needed.  For children it is used extensively and should be used in adults more frequently

Thank you for your question. The negative predictive value of US is quite high, particularly in children where reducing potential exposure to radiation is more important than in adults.  As the previous answers state, US is a very useful first line imaging modality in clinically equivocal cases of suspected appendicitis, whilst there are some well documented limitations, in skilled hands it can help to safely reduce the incidence of negative appendectomy.

Thanks to all.

Yes I agree it should be the first investigation. But I have seen in my clinical practise that those patients where there is negative scan it isdifficult to convince the patients for surgery and they keep on smouldering and ultimately agony is prolonged. Since the appendix is 74% thimes retrocecal in position.then how can every patient be diagnosed with USG. Whatever we may call it ... Whether it is operator dependent or not... It delays the diagnosis.

In thin patients or less abdominal fat such as pediatrics, sometimes CT is more difficult to diagnose than ultrasound.

In limited ressources countries wher CT is not available all the time US still being a geat help for diagnosis of acut appendicitis. It is troue we can have some false negative results but for me nothing can't remplace

If clinical suspicion is there do USG. If patient still have features of appendicitis, and normal USG ,CT is warranted. CT is most sensitive.CT can rule out other causes of RIF pain e.g. ureteric calculus etc.

my submission is that a patient who is told that ur usg does not show any evidence for appendicitis is most of the times not ready for surgery and his agony is prolongrd. ct scan is the diagnostic investigation but it is not always available very where in a country like our, similarly it is cotly and above all people are not ready for further workup . due to this the people turn up in outpatient departments with recurrent pain and all the investigations are normal .

particularly for the children after detailed physical examination the first choice for diagnosis should be US. however, USG has Sensivity % 88 and Spesifity % 94 which are not be considered enough. every time gold standart is CT.

In the discussion of all the imaging choices no one has mentioned that surgery is being replaced successfully by conservative therapy with parenteral antibiotics with good outcomes.  In the correct clinical situation with fever, RLQ pain, white count and very high pretest probability of appendicitis then go directly to treatment and skip all imaging since the results will not effect management regardless of whether you see a true positive or suspect a false negative result.

Thanks Nicholas.

I do believe the diagnostic delay caused by the negative ultrasound report only makes the patients suffering worse and ultimately he may land up for surgery in a much worse situation than initially was

U/S is operator dependent.If the operator is experienced it gives adequate information about appendix on par with CT.

I agree ... But how to decide who is experienced or not. ? On top of that once a negative report of usg is given it is difficult to convince the patients otherwise... And a diagnostic delay thus increases morbidity.

A qualified radiologist is not always available in most of the peripheral hospitals in India. I personally believe that Acute Appendicitis is a clinical diagnosis to be supported only by lab investigations. In case of doubt in patients with sub-clinical/doubtful  signs should be observed and reexamined frequently keeping them on iv fluids/ NPO. Avoid analgesics during observation period which can mask the pain . Antibiotics should also be avoided during this period which in fact can subside the inflammation and a good number of these patients (about 25-30%)can present in future with recurrent appendicitis. USG usually diagnoses appendicitis in patients with clear cut clinical signs and always poses a query in cases of suspected diagnoses.

That's good answer

I agree that the diagnosis of acute Appendicitis is clinical supported by laboratory tests ( increase in white blood cells and C-reactive protein); but the ultrasound may be essential in the differential diagnosis in the case of the child with lymphadenitis and in case of the young woman in front of ovarian disease. The current spread of ultrasound technology, as well as handling of the ultrasound devices make the procedure fast and easy. But the clinical esamination remains the first guide in the choice of the surgeon.

Sure dr lambardi... All I want to say that ultrasound should not be used as diagnostic but as an adjunct t which helps to rule out the other possible differentials.

A positive sonological diagnosis of acute appendicitis by a trained sonologist should be taken seriously , in other doubtful cases believe on your clinical examination..besides Usg will rule out other differentials...

Dr. Chaudry,

       I have a very strong intuitive belief than you, also, have an insight into the pathogenesis and associated symptomatology hence, the clinical diagnostic points involved in the different stages of appendicitis: when to clinically  consider it early, spontaneously reversible, irreversible and ready to "rupture"( ergo: not antibiotic treatable anymore, which is nonsense anyway),  ruptured, etc.  Also, that you consider all the laboratory and technical tests as confirmatory or eliminative. That you are still too reticent, for whatever reason, to disclose your insight to your colleagues.  Am I correct?

       In surgical practice, I have define appendicitis as Irritative and Reactive. Both are potentially spontaneously reversible and the optimum timing for surgical intervention can be defined and attained. I  started  a treatise on this topic but have been unable to find an illustrator as yet. I am a computer moron so it will be too tedious and impossible for me t elucidate the topic in this format.  So, why not enlighten us. Regards and thanks.

In the present day practice most of the patients expect atleast an u/s scan in additon to clinical diagnosis in this part of the Globe.

As we know appendix is retrieval in about 72;!% of cases ... Then how can it be detected by ultrasound so confidently to be diagnostic. I believe it's an adjunct to rule out other diagnosis especially in children and female. Otherwise a good clinical sense should prevail.

I meant retro cecal

How can u call it gold standard when it has got so many flaws. Yes it could be the initial investigation but can't be called diagnostic.

Children and women of child-bearing age can be offered an ultrasound when they come with ?appendicitis. Any other group of patients, I don't see much of an advantage in doing an ultrasound. It is usually a clinical decision.

That's true sir.... It is to rule out other differentials but it is not diagnostic even in children and women

Dr. Chaudhary,  Are you just debunking Ultrasound use in Appendicitis, and I agree with you, or are you also trying to tell us there are other better methods to diagnose the different stages of acute appendicitis?  Please elucidate! 

In my part of the world where the CT scan is not available easily and where ever it is., It's costly , usg abdomen still remains the diagnostic method for acute appendicitis.m let of the times when the people are told about the absence of features of appendicitis on ultrasound they are very difficult to convince about the possibility of appendicitis. Such patients either refuse for surgery or never come to opd , only to end up becoming a chronic patient coming time and again to general opd with abdominal pain. Other patients have a prolonged hospital stay and ultimately end up in a surgery delayed. in last wo years I have operated upon about 150 patients of acute appendicitis where I have seen that in about 50% cases it delays the management and prolongs the hospital stay. In two patients even the CT scan missed the diagnosis . All I want to conclude is it can be used to rule out the other possible differentials especially in women and children but a negative ultrasound scan in a patient doesn't rule out acute appendicitis when clinically suspected.

My opinion:  Acute Appendicitis is a very common and simple disease with catastrophic consequences. It can spontaneously resolve without treatment.  It also can proceed to perforate and produce extreme morbidity and mortality. Appendectomy is a simple and curative procedure but we have to identify who deserves surgery to monitor and critique ourselves that we are not inflicting injury by operating unnecessarily. Discussions today hover around antibiotic treatment, how to accurately diagnose, and methods to do so. There is no one method to diagnose it until it is full blown and by that time you do not need a technological tool versus your clinical judgement to decide to operate. When it is spontaneously resolving the clinical signs improve, unless the patient is moribund and/or anergic, specially when the fibrosis and scarring outpaces the inflammatory event and successfully walls off the mural wound as it perforates and drains into the appendicial lumen, is expelled, and the appendix heals. 

Until  today, no one knows how to diagnose appendicitis enough to follow the stages of its evolution, and most importantly, how to  predict which one will  resolve and which one will proceed to rupture.  Until that moment is attained, it is best to operate when  rebound tenderness appears because it means that the appendicial serosa is about to be breached!  With the technological  tools, the timing of its use is crucial. Examples: The WBC may be normal or low if taken early, on the anergic, older patient, etc. The ultrasound which depend on reflexivity may be normal even if there is microscopic appendicitis, and by the same token, the CTScan performed may be normal lon an evolving appendicitis which ruptures five hours later.  Your clinical wisdom is your best tool.  "Per scientiam, Ad sapientiam". 

Thank u

it depends on sensitivity of ultrasound machine and expertise of operator,but its almost 87%

Accuracy of ultrasonography in the diagnosis of acute appendicitis in adult patients: review of the literature

Fabio Pinto, 1 Antonio Pinto,2 Anna Russo,3 Francesco Coppolino,4 Renata Bracale,5 Paolo Fonio,6 Luca Macarini,7and Melchiorre Giganti8

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Abstract

Background

Ultrasound is a widely used technique in the diagnosis of acute appendicitis; nevertheless, its utilization still remains controversial.

Methods

The accuracy of the Ultrasound technique in the diagnosis of acute appendicitis in the adult patient, as shown in the literature, was searched for.

Results

The gold standard for the diagnosis of appendicitis still remains pathologic confirmation after appendectomy. In the published literature, graded-compression Ultrasound has shown an extremely variable diagnostic accuracy in the diagnosis of acute appendicitis (sensitivity range from 44% to 100%; specificity range from 47% to 99% ). This is due to many reasons, including lack of operator skill, increased bowel gas content, obesity, anatomic variants, and limitations to explore patients with previuos laparotomies.

Conclusions

Graded-compression Ultrasound still remains our first-line method in patients referred with clinically suspected acute appendicitis: nevertheless, due to variable diagnostic accuracy, individual skill is requested not only to perform a successful exam, but also in order to triage those equivocal cases that, subsequently, will have to undergo assessment by means of Computed Tomography.

Keywords: Acute appendicitis, Ultrasound, Abdomen (US), Abdominal Pain

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Background

Appendicitis represents one of the most common causes of abdominal pain of adult patients referred to the emergency department. More than 250,000 cases of appendicitis are diagnosed in the United States each year, and appendectomy is the most frequent emergent surgery performed worldwide [1,2]. Despite its prevalence, the diagnosis of appendicitis can be elusive and fraught with pitfalls because of the absence of a pathognomonic sign or symptom, the poor predictive value of associated laboratory testing, and its varied presentation diagnosis [3-5]. The rate of unnecessary laparotomies is still high: to balance an acceptable positive laparotomy rate with minimal delayed or missed diagnoses, the clinician must take into account all the available historical and physical findings, laboratory data, and appropriate imaging method. In fact, following significant advances in accuracy, imaging is an important part of the modern work-up of appendicitis, that remains a high-risk disease for delayed or missed diagnosis in the emergency department [6,7].

Among imaging methods currently used in the clinical practice, Ultrasound (US) is a valuable tool. It was first introduced by Puylaert in 1986, who described the "graded compression" technique apt to better visualize the inflamed appendix [8]; by using the graded compression technique, a linear high-frequency transducer is placed on the right lower quadrant and pressure is applied gradually while imaging, displacing overlying gas-filled loops of bowel. Moreover, this noninvasive option is repeatable, avoids the exposure to nonionizing radiation and can be less expensive as compared to Computed Tomography (CT) costs. At US, findings suggestive of appendicitis include, a thickened wall, a noncompressible lumen, outer appendiceal diameter greater than 6 mm, absence of gas in the lumen, appendicoliths, echogenic inflammatory periappendiceal fat change, and increased blood flow in the appendiceal wall . If compared to other diagnostic tests, US is inferior to CT as to sensitivity; due to its low negative predictive value for appendicitis, it may not be as useful for excluding appendicitis. More recently, color and power Doppler examination of the appendix have proven to be a useful adjunct to improve the sensitivity by demonstrating increased flow in an inflamed appendix [9,10].

Indeed, US is not accepted worldwide to rule out an acutely inflamed appendix: the quality of the ultrasound examination improves with operator experience and skill. Accordingly, the purpose of this study was to investigate the diagnostic accuracy of the US method in the diagnosis of acute appendicitis of the adult patient as in the literature reported [11,12].

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Results and discussion

Although US is frequently used to diagnose acute appendicitis, the accuracy of this imaging test remains unclear because of a great variability in the reported performance. An evidence-based review of the role of graded compression US for the diagnosis of appendicitis was performed by Terasawa and coworkers [13]: they found that 14 studies of graded compression US could meet their inclusion criteria: Ultrasonography showed an overall sensitivity of 0.86 and a specificity of 0.81, a positive predictive value of 84%, and a negative predictive value of 85%.

In Korea, a large meta-analysis on the role of graded compression US in the diagnosis of acute appendicitis was carried out a few years ago, including 22 articles [14]. The overall sensitivity and specificity were 86.7% and 90.0%, respectively. In particular, their study suggested that US could be useful for the diagnosis of acute appendicitis, especially when patients were younger age, male, and highly clinical suggestive.

In other published series, overall sensitivity of US in adult and adolescent patients was 86%, specificity 81% , the positive predictive value of graded compression US was 84% (range from 46% to 95%), and the negative predictive value of graded compression US was 85% (range from 60% to 97). While the range of reported accuracy (82% to 96%) for US in children has been acceptable, the sensitivity (44% to 100%) and the specificity (47% to 99%) have varied considerably; also, the visualization rates vary widely in the published literature, from a low of 22% to a high of 98% [14]. Several factors might be taken into account as the causes of these variations. First, because US is an operator-dependent technique, with a steep learning curve, individual skill may be an important factor to determine an extremely variable diagnostic accuracy of appendicitis [15]. Moreover, difficulties to scan populations of fertile age females may be related to the broad and frequent overlap of the symptoms for acute abdominal conditions [16-20]. In obese patients, as well in individuals who underwent previous laparotomy, adequate compression of the right lower quadrant, according to the graded compression technique, cannot be always obtained. Variability in the appendiceal location is a well known cause for clinical misdiagnosis, and a false negative US diagnosis may occur, for example, in case of a retrocecal location of the appendix, not appropriately visualized. Indeed, most of the false-negative diagnoses at US result from non-visualization of the appendix or from inflammation limited to the appendiceal tip [15-17]. While positive ultrasound findings have a relatively high positive-predictive value, identification of a normal appendix is sometimes difficult. Excellent results have been achieved at select centers, with nonvisualization of the appendix being reported to have a negative-predictive value of 90% [21]. Such results require a great deal of skill and experience; in fact, in many centers nonvisualization of the appendix is considered equivocal.

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Conclusions

Imaging is necessary in adult patients referred with clinically suspected acute appendicitis: in fact, there is wide agreement that the outcome of acute appendicitis is best with early diagnosis. Graded-compression US remains our first-line method in the evaluation of patients referred with clinically suspected acute appendicitis. It can be performed at any time, regardless of specific patient's preparation. Nevertheless, due to variable diagnostic accuracy, individual skill is requested not only to perform a successful exam, but also to triage those equivocal cases that, subsequently, will have to undergo Computed Tomography assessment [22,23].

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Competing interests

All the authors declare that they have no competing interests.

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Declarations

This article has been published as part of Critical Ultrasound Journal Volume 5 Supplement 1, 2013: Topics in emergency abdominal ultrasonography. The full contents of the supplement are available online at http://www.criticalultrasoundjournal.com/supplements/5/S1. Publication of this supplement has been funded by the University of Molise, University of Siena, University of Cagliari, University of Ferrara and University of Turin.

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References

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 https://www.ncbi.nlm.nih.gov/pubmed/17447365

Acute appendicitis (AA) is a common abdominal emergency with a lifetime prevalence of about 7 %. As the clinical diagnosis of AA remains a challenge to emergency physicians and surgeons, imaging modalities have gained major importance in the diagnostic work-up of patients with suspected AA in order to keep both the negative appendectomy rate and the perforation rate low.

http://www.ultrasoundpaedia.com/normal-appendix/

Technique

1. Patient position: supine.

a. Tip: Have the patient bend their knees in order to relax the abdominal wall musculature for ease of compressibility.

b. Tip: Provide pain medication prior to scanning.

2. Probe: Either the high frequency linear probe or the curvilinear probe (if increased depth is required) can be used to detect the appendix.

a. Tip: When using the linear probe, choose the probe with the larger/wider footprint, which will allow better visualization of the regional anatomy. 

3. Technique: Place the probe in the right upper quadrant over the ascending colon with the probe indicator toward the patient’s right. Sliding inferiorly down to the right lower quadrant will reveal the cecum/terminal ileum and ultimately the appendix. Alternatively, the probe may be placed directly over the point of maximal tenderness, as indicated by the patient. 

Graded compression is applied to image the bowel; firm pressure is applied to bring the abdominal wall in contact with the psoas muscle every 1cm.

a. Tip: In the right lower quadrant, identify the psoas muscle and the transverse iliac vessels. Once found, the appendix usually lies just anterior to those structures. 

4. Appendix Anatomy: The appendix is a blind-ending tubular structure that normally will demonstrate peristalsis, is 6mm in diameter, noncompressible, and lacks peristalsis. Click Here for Video. There are several secondary signs of appendicitis that may be appreciated on ultrasound. A hyperechoic appendicolith within the lumen may be seen with posterior shadowing. Increased vascularity of the appendiceal wall may be appreciated as hyperemia with color flow Doppler, often referred to as the “ring of fire” on short axis. Finally, periappendiceal fluid collections may be seen suggesting edema or perforation.

https://books.google.com.pk/books?id=w9eZCwAAQBAJ&pg=PA166&lpg=PA166&dq=ultrasound+guided+pleural+brush+biopsy&source=bl&ots=Odmm_oTIjd&sig=0e7PabA4N202c47M30v9xCeUsKI&hl=en&sa=X&ved=0ahUKEwjam_Xp3NvTAhUBPRQKHbisD3QQ6AEITTAH#v=onepage&q=ultrasound%20guided%20pleural%20brush%20biopsy&f=false

http://emedicine.medscape.com/article/1894279-overview?pa=grPyT8tS0mxABFY%2BG%2B%2BhxN6acbh5xEKaG9yItnuKHXH3rpY9MeeU8JCB%2BQ4ob%2BfHHantmkUso3vmYIrXSBczDnum7wC6L3C41M8%2BukeCQMU%3D