A Critical Analysis of Rebound Tenderness in the Diagnosis of Appendictis

Abdominal pain is a common presentation within the accident and emergency department [A+E] and specialist nurses working in this environment need to be familiar and confident in dealing with this presentation (Hibberts and Bushell 2007, Pines, Pines, Hall, Hunter, Srinivasan and Ghaemmaghami 2005). Abdominal pain can be associated with a wide variety of surgical and nonsurgical conditions, with the most prevalent cause being acute appendicitis (Lin, Chen, Chung, Ho, and Lin, 2009). The diagnosis of appendicitis is formulated from subjective and objective data including a patient's history, abdominal examination, laboratory investigations and signs and symptoms. This assignment will critically analyse the clinical skill of testing for rebound tenderness and its relevance to diagnosing appendicitis in children.

The clinical diagnosis of acute appendicitis in children is difficult for many practitioners (Broek, Ende, Bijnen, Breslau and Alkmaar, 2004). Between the years 2008 and 2009 the number of patients presenting to A+E within the UK who were diagnosed with appendicitis was 44,244 (NHS Information Centre, 2009). This equates to almost 0.3% of all presentations in A+E over one year. Approximately 9,300 of this population were between the ages of 0 and 14 years old (NHS Information Centre, 2009). However up to 25% of these 9,300 children with suspected appendicitis have a normal appendix at operation (Smink, Finkelstein, Garcia-Pena, Shannon, Taylor, and Fishman, 2004). Furthermore, the 25% of paediatric negative appendectomies now result in considerable clinical and economic costs to the NHS (Koepsell, 2002). These substantial figures are one of the primary reasons for specifying this assignment on children. In addition, the scope of practice within A+E covers paediatrics for many adult qualified nurses and adult trained nurse practitioners. It is therefore imperative that the knowledge base for all A+E staff encompasses paediatrics at an advanced level as well (Cleaver, 2003).

The overall accuracy for the clinical examination in diagnosing acute appendicitis has been reported to be between 54% and 70% in children (Birkhahn, Briggs, Datillo, Van Deusen and Gaeta, 2006). In addition Whisker, Luke, Hendrickse, Bowley and Lander (2009) suggest that only 4% of children have a miss-diagnosis of appendicitis in specialist paediatric centres, compared to 20% in district general hospitals. Despite the uncertainty of the diagnosis and the cost of miss-diagnosis to the NHS, appendicitis requires urgent treatment (Williams, et al., 2009). This is due to the risk of perforation, which occurs in approximately one third of cases in children (Neilson, et al., 1990). Therefore the need for a good clinical assessment at first contact in A+E is needed to provide a correct management plan and reduce on costs for the NHS.

An abdominal examination should be performed where possible in a warm, well lit room with the patient well-draped and relaxed (Bickley, 2009). Initially the practitioner should undertake inspection, auscultation and percussion of the whole nine sections of the abdomen (Lippincott Williams and Wilkins, 2008). The final aspect of the abdominal examination should be palpation as this has the potential to be the most painful (Allan, 2008). Palpation is a process which should always be commenced away from the site of pain, as this will allow the patient to gain some reassurance from the practitioner and help them to relax (Bickley, 2009, Hibberts and Bushell, 2007). The practitioner should utilise the palmer surfaces of the fingers to identify any abnormal signs (Bickley, 2009).

More specific palpation techniques can help to diagnose appendicitis, such as rebound tenderness (Bickley, 2009). This is performed by pressing slowly and firmly to a specific area and then withdrawing them quickly (Bickley, 2009). Practitioners should observe the patient and ask if pain was worse on pressing or letting go (Hibberts and Bushell, 2007). However, Bickley (2009) suggests that if any of the previous examinations such as light or deep palpation are positive then this should not be undertaken as it will cause undue pain for the patient.

The whole process of abdominal examination in children follows the same system as in adults. However, the causes of abdominal pain in children are often different, encompassing a broad range of acute and chronic diseases (Bickley, 2009). Therefore it maybe pertinent to suggest that more emphasis should be placed special techniques such as checking for rebound tenderness rather than abdominal palpation and testing for rebound.

The initial discovery and accreditation of rebound tenderness (also known as Blumberg's sign) is credited to a German surgeon called Jacob Moritz Blumberg (1873 - 1955). Many articles make reference to Blumberg's sign; however there appears to be no relevant literature, research or evidence base to support this surgeon was the gentleman who discovered this sign (Mantzaris, Anastassopoulos, Adamopoulos and Gardikis, 2008).

A study undertaken by (Williams, et al., 2009) showed that out of 98 children who had acute appendicitis 91% had right lower quadrant tenderness on palpation however only 30% had rebound tenderness. Another study by Lin, Chen, Chung, Ho, and Lin (2009) also suggested that 43.4% of the 53 children examined with appendicitis had rebound tenderness. So both these studies suggest that positive rebound tenderness is an indication of an acute appendicitis in children and therefore cannot be ruled out of an initial differential diagnosis.

Golledge, Toms, Franklin, Scriven and Galland (1996) specifically evaluated the "cats eye symptom" (pain going over a bump in the road), the cough sign, right lower quadrant pain to percussion, rebound tenderness and guarding. The data from this evaluation suggested that rebound tenderness had a likelihood ratio of 7.4 compared to the other signs which had likelihood ratios of between 1.1 and 4.1. This data therefore suggests that rebound tenderness is a very useful sign in the diagnosis of acute appendicitis, but that the other signs and symptoms are not (Moyer, et al., 2001). Overall rebound tenderness is useful sign for diagnosing appendicitis when there is a high suspicion of appendicitis and is accompanied with other diagnostic indicators (Moyer, et al., 2001).

Another presentation to be considered in relation to abdominal pain and rebound tenderness is the duration of the pain experienced by the child. A study undertaken by O'shea, Bishop, Alario and Cooper (1988) involved 246 children from 13 to 18 years old who presented to the emergency department with a history of less than one week of abdominal pain. Results showed that the likelihood ratio of pain was greater when the child had the pain for more than 12 hours (Likelihood ratio: 1.3) compared to less than 12 hours (Likelihood ratio: 0.64). Later in the study pain duration was evaluated at less than 24 hours and more than 24 hours, with their likelihood ratios being 0.83 and 1.2 respectively. When compared to Andersson, et al. (1999) study of 502 patients aged 10 to 86 the greatest likelihood ratio was 1.7 at 7-12 hours after onset of pain. Based on both studies it is very difficult to see how duration of pain can lead to the diagnosis of appendicitis. Therefore, practitioners must not allow the duration of pain to prevent any further investigation into the diagnosis (Moyer, et al., 2001).

Another symptom which could possibly indicate the diagnosis of appendicitis is fever (Gwynn, 2001). Cardall, Glasser and Guss's (2004) study evaluated two hundred and ninety three people aged between 7 and 75 who presented to the emergency department with suspected appendicitis. Temperatures were classed at greater than 99oF or less than 99oF. The study showed that 27% of patients who's temperature was <99oF had a confirmed appendicitis compared to 37% of patients who had a temperature of >99oF. When the results were analysed in terms of specific temperature intervals, the highest likelihood ratio (3.18) was found in patients with temperatures greater than 102 °F. However, Bergeron's (2006) study on clinical judgement suggests there is no clinical value with temperature as there is minimal sensitivity and specificity in the diagnosis of appendicitis. Therefore, as with duration of pain duration and levels of WBCC, temperature as a single entity has little diagnostic utility in the diagnosis of appendicitis unless it is combined with other signs and symptoms such as rebound tenderness (Cardall, Glasser and Guss, 2004).

For many years laboratory tests such as white blood cell count (WBCC) leukocytes and C-reactive protein (CRP) have been used to support a diagnosis, but the considerable overlap with other inflammatory conditions accounts for the low specificity and positive predictive value of these tests (Stefanutti, Ghirardo and Gamba, 2007). Recent studies on adult patients who present with clinical signs and symptoms indicating acute appendicitis, show that appendicitis can be excluded if both leukocyte count and C-reactive protein value are normal (Gronroos, 2001). However, Stefanutti, Ghirardo and Gamba, (2007) suggest that only a few studies have been reported in paediatric patients and the role of WBCC and CRP in excluding acute appendicitis in children has not been confirmed. According to Andersson et al. (1999) children who present with signs and symptoms of appendicitis such as rebound tenderness and have a WBCC of < 8000 are at a low risk for acute appendicitis. Andersson et al. (1999) also suggests that a WBCC of between 8000 - 15000 does not significantly change the estimate of risk and a WBCC of >15000 only moderately increases the estimated risk of appendicitis. This therefore shows that only at the extremes of the WBCC does this diagnostic indicator appear useful (Moyer, et al., 2001). Therefore, contrary to adult patients, normal leukocyte count, WBCC and CRP value cannot effectively exclude acute appendicitis in children.

Another usual predictor of appendicitis is vomiting (Bergeron, Richer, Gharib and Giard, 1999). The study by Andersson et al. (1999) calculated the likelihood ratio for appendicitis in a patient with vomiting compared to one with no vomiting to be 1.8. In addition Reynolds and Jaffe (1992) study suggests that a combination of four predictors including; vomiting right lower quadrant pain, abdominal tenderness, and abdominal guarding. More specifically 97% of the 377 children studied who were diagnosed with appendicitis had two or more of these predictors. Therefore, a patient who presents to A+E with less than two of the above predictors is quite unlikely to have appendicitis.

Alvarado (1986) conducted a retrospective study of 305 patients hospitalised with abdominal pain suggestive of acute appendicitis. Signs, symptoms, and laboratory findings were analysed for specificity, sensitivity, predictive value, and joint probability. Their importance, according to their diagnostic weight, was determined as follows: localized tenderness in the right lower quadrant, leukocytosis, migration of pain, shift to the left, temperature elevation, nausea-vomiting, anorexia-acetone, and direct rebound pain (Alvarado, 1986). This scoring system shown below is deemed by many surgeons as an easy aid for supporting the diagnosis of acute appendicitis (Khan and Rehman, 2005).

A study undertaken by Baidya, Rodrigues, Rao and Khan (2007) investigated the diagnostic accuracy of Alvarado scoring system. The results showed that a score of >7 for an appendicitis was 88.2% correct in diagnosis. However, the diagnostic accuracy of an Alvarado score < 6 is only 16%. Khan and Rehman (2005) also studied the accuracy of the Alvarado scoring system and found that only 10 patients out of 64 had negative appendectomies. Khan and Rehman's (2005) positive predictive for their our study was (83.5%) and is comparable with other literature which reports 87.5%, 85.3%, 87.4% and 85.7% (Rehman and Burki 2003,. Kalan, Talbot, Cunliffe and Rich 1994., Malik, Khan and Waheed 2000., Owe, Williams, Stiff, Jenkinson and Rees 1992). These studies show that clinical scoring systems such as the Alvarado scoring system can be a cheap and quick tool to apply in emergency departments to rationalise acute appendicitis as one of the differential diagnosis (Khan and Rehman, 2005). Its application improves diagnostic accuracy and consequently reduces negative exploration and complication rates (e.g. perforation).

Despite recent advances in knowledge and diagnostic investigations, a population-based analysis in the United States found that the incidence of unnecessary appendectomy has not changed (Flum, Morris and Koepsell, 2001). Therefore to increase diagnostic accuracy, new modalities such as ultrasound scans have been introduced (Broek, Ende, Bijnen, Breslau and Alkmaar, 2004). Kaneko and Tsuda (2004) conducted a 10-year study using ultrasound scans to diagnose appendicitis in children and are convinced that ultrasound scans can identify inflamed appendices with 100% sensitivity and can also determine the severity as well. However Smink, Finkelstein, Garcia-Pena, Shannon, Taylor and Fishman (2004) suggest that the use of ultrasound has not decreased negative appendectomies as similar negative rates were present over a decade ago. Therefore on the basis of the available evidence, patients presenting to A+E with a strong clinical case of appendicitis should be referred direct to the surgeon without an ultrasound.

In addition to the use of ultrasound scanning the use of computed tomography (CT) has been recently studied and evaluated. There are currently two perspectives in the literature regarding the use of CT scan for the diagnosis of acute appendicitis: one supporting its routine use due to the decreased incidence of negative appendectomies, and the other one against its routine use due to the increased cost and delay in surgical management (Ceydel, Lavotshkin, Yu and Wise, 2006). In addition the benefits of imaging eliminating inpatient observation and unnecessary surgery must be weighed against the malignancy risk from radiation, as well as discomfort of rectal contrast administration (Smink, Finkelstein, Garcia-Pena, Shannon, Taylor and Fishman, 2004). Ceydel, Lavotshkin, Yu and Wise's (2006) retrospective study showed that the negative appendectomy rate was much less in patients who had CT scans (7.6%) compared to the non CT scan group (24%). Therefore clinicians within A+E use their clinical judgement and place emphasis on the importance of routine history and an accurate physical examination utilising CT scans for atypical cases of acute appendicitis (Gwynn, 2001).

Currently within the A+E department there is no specific pathway or tool for ruling in acute appendicitis in paediatrics. In addition Birkhahn, Briggs, Datillo, Van Deusen and Gaeta (2006) suggest that no major medical association or professional organisation currently endorses a standardised pathway for the evaluation of patients with suspected appendicitis. With up to 25 % of children having negative appendectomies it is therefore of clinical and financial value to consider the use of a scoring system to admit or discharge children who present with a possible acute appendicitis. Current systems are in place for other potential conditions such as myocardial infarctions, pancreatitis and pneumonia. These other systems have been audited locally and nationally and are currently working well within the trust, therefore the plans to introduce the Alvarado scoring system will be put forward in the next review of clinical practice meeting between nursing and medical staff.

To conclude, this assignment demonstrates that for an emergency department practitioner in a fast paced A+E setting, the accurate diagnosis of acute appendicitis remains a challenge for the paediatric age group. An accurate history and physical examination, which as highlighted can be challenge in younger patients plays an important role in the diagnosis of early acute appendicitis (Mallick, 2008). Physical clinical signs elicited upon examination provide the practitioner with a good insight to expected diagnosis. However, the usefulness of rebound tenderness as a single examination has minimal clinical value. The whole patient picture which encompasses an accurate history, clinical examination, laboratory investigations and possible diagnostic imaging is therefore vital to providing a correct diagnosis.

The use of clinical scoring systems like the Alvarado score can be a cheap and quick tool to apply in emergency departments to rule in acute appendicitis. This scoring system includes many aspects such as clinical history, rebound tenderness and laboratory investigations. This allows for observation and critical re-evaluation of the evolving clinical picture. Its application improves the overall diagnostic accuracy and consequently reduces negative appendectomies (Khan and Rehman, 2005). In clinical cases where the practitioner is unsure if the actual diagnosis is acute appendicitis other diagnostic imaging studies such as ultrasound and CT may be undertaken. This must only then be considered once a thorough clinical examination has not provided any indication for acute appendicitis and the benefits out way the risks.