How do you assess rebound tenderness for appendicitis?

4 Psoas Sign

The inflamed appendix may lie against the right psoas muscle, causing the patient to shorten that muscle by drawing up the right knee. To elicit the psoas sign, the patient lies down on the left side and the clinician hyperextends the right hip. Painful hip extension is the positive response.7,11

5 Obturator Sign

The obturator sign is based on the same principle as the psoas sign, that stretching a pelvic muscle irritated by an inflamed appendix causes pain. To stretch the right obturator internus muscle and elicit the sign, the clinician flexes the patient’s right hip and knee and then internally rotates the right hip.7,11

1 Individual Findings [See EBM Box 52.2]

All of the findings in EBM Box 52.2 apply to patients with suspected appendicitis [indeed the most common cause of peritonitis in these studies was appendicitis]. Additional special tests that further increase the probability of appendicitis are McBurney point tenderness [LR = 3.4], positive Rovsing sign [LR = 2.3], and positive psoas sign [LR = 2]. The only special finding decreasing the probability of appendicitis [other than absence of right lower quadrant tenderness] is the absence of McBurney point tenderness [LR = 0.4].

McBurney point tenderness may have even greater accuracy if every patient’s appendix were precisely at the McBurney point, but radiologic investigation reveals that the normal appendix sometimes lies a short distance away.82 In one study of patients with acute abdominal pain, clinicians first located the patient’s appendix using handheld ultrasound equipment. Maximal pinpoint tenderness over this “sonographic McBurney point” had superior diagnostic accuracy for detecting appendicitis [sensitivity = 87%, specificity = 90%, positive LR = 8.4, negative LR = 0.1].83

In contrast to a long-held traditional teaching, giving analgesics to patients with acute abdominal pain does not change the accuracy of individual signs or reduce the clinician’s overall diagnostic accuracy.84

Rectal tenderness [see EBM Box 52.1] and the obturator sign [see EBM Box 52.2] were diagnostically unhelpful in these studies. Nonetheless, a rectal examination should still be performed to detect the rare patient [2% or less] with a pelvic abscess and rectal mass.39,41

Diagnostic Approach

Once a thorough history and physical examination have been completed, laboratory findings and integration of all data can help confirm the diagnosis. Laboratory tests should include a complete blood count, urinalysis, basic metabolic panel, and pregnancy test for all female patients of childbearing age. Leukocytosis ranging from 10,000 to 18,000 cells/mm3 and an elevated absolute neutrophil count are common in patients with simple early appendicitis. White blood cell counts greater than 18,0000 cells/mL3 correlate with perforated appendicitis or appendiceal abscess. A urinalysis helps to rule out a urinary tract infection because bacteriuria is not typically seen in patients with appendicitis. A basic metabolic panel may reveal electrolyte abnormalities derived from anorexia, vomiting, and secondary dehydration. A pregnancy test is important to rule out an ectopic pregnancy in all females of childbearing age.

The combination of findings derived from the history and physical examination and results from the initial laboratory tests can usually be enough to confirm the diagnosis or suspicion of acute appendicitis, particularly in the most common and typical cases. The most typical presentation will be a young adolescent male with a 1- to 2-day history of periumbilical pain radiating to the right lower quadrant with rebound positive or negative Rovsing sign and mild leukocytosis. More delayed presentations, 4 to 5 days from the beginning of pain, are characterized by the presence of fever, tachycardia, rebound, and positive Rovsing sign, and occasionally a right lower quadrant mass may be felt, suggesting the presence of an abscess or phlegmon. Less commonly, late presentations progress to diffuse peritonitis characterized by diffuse abdominal pain and a more severe systemic inflammatory response.

Other tools can be used to help confirm the diagnosis. Findings from history, physical examination, and laboratory tests can also be used to calculate the Alvarado score. This score is based on eight data points and was developed to help confirm the diagnosis of acute appendicitis using clinical and initial laboratory findings [Table 42-1]. Higher scores are directly associated with higher likelihood of appendicitis; scores lower than 5 are unlikely to represent appendicitis, whereas those higher than 6 or a score of 10 are considered consistent and highly consistent with appendicitis, respectively.

Special considerations should be given to the elderly, young children, and the pregnant. Both the elderly and children usually present later with longer duration of prehospital symptoms. In addition, findings in these populations are somewhat atypical. In older patients, periumbilical migratory pain is almost always absent, and pain located in the right lower quadrant is reported in only 80% of cases. The accuracy of the Alvarado score also declines in this population, with less than 50% of patients having scores higher than 7. This uncommon presentation is associated with more advanced disease, including higher rates of perforations and abscess formation, which in combination with more associated comorbidities result in worse overall outcomes, including longer lengths of stay and higher rates of postoperative complications and death. In children younger than 5 years old, the inability to give an accurate history often limits an earlier diagnosis, which can result in similar patterns of diagnosis, treatment, and outcomes as those observed in the elderly. In the pregnant patient, as the gravid uterus enlarges the appendix moves cephalad [Figure 42-3]. This is an important consideration that changes the location of pain as well as the surgical approach when the diagnosis is confirmed.

Finally, other differential diagnoses must be considered when evaluating patients with right lower quadrant abdominal pain, including urinary tract infections, diverticulitis, perforated ulcer, ectopic pregnancy, ruptured ovarian cyst, ovarian torsion, pelvic inflammatory disease, testicular torsion, inguinal hernia, Meckel's diverticulum, Crohn's enteritis, gastroenteritis, and complications derived from a colonic or small bowel tumor.

When using the described approach to work up patients with suspected acute appendicitis, a false-positive diagnosis can still be made. This results in negative appendectomy, which has been reported to occur in 15% of patients, as reported by both clinical and population-level analyses. The negative appendectomy rate is higher for females [22% versus 9% for males] and even higher for women of reproductive age [up to 26%]. A negative appendectomy rate of 10% to 15% is generally accepted, considering that a low threshold for operation can avoid the complications derived from delayed diagnosis including perforation, and this strategy is additionally supported by a low cost to the patient and the healthcare system.

A more thorough workup including the use of imaging studies [CT or ultrasound] has been advocated with the primary goal of improving the accuracy of the diagnosis. Two prospective studies have shown a decrease in the number of unnecessary admissions and appendectomies with CT. However, a longitudinal population-level study suggested that despite the introduction of ultrasound and CT scanning, the rates of negative appendectomies have remained unchanged over time, arguing against a routine use of these diagnostic strategies. Imaging studies should be considered selectively, when the diagnosis is unclear and in patients with higher risk of negative appendectomy. CT scan is the preferred diagnostic test, although ultrasound is a good alternative particularly in children and thin patients, as well as in pregnant women or women of childbearing age, to delineate uterine and/or ovarian pathology.

Physical Examination

Typical physical signs of acute appendicitis include localized tenderness in the right lower quadrant, muscle guarding, and rebound tenderness. Cutaneous hyperesthesia, right-sided pelvic tenderness on rectal examination, and the presence of a psoas or obturator sign occur less frequently and tend to be highly dependent on the examiner. Although often the temperature is normal, fever up to 38° C or higher may occur. In the usual case of acute, nonperforated appendicitis, higher fever occurs infrequently.

CLINICAL FEATURES

A detailed history and careful physical examination remain cornerstones of the diagnosis of acute appendicitis. Although no single item of the history, in isolation, allows the diagnosis to be made reliably, combination of the classic symptoms and the typical progression of symptoms coupled with right lower quadrant tenderness allows good diagnostic accuracy. In the classic presentation of acute appendicitis, patients first note vague, poorly localized epigastric or periumbilical discomfort, which typically is not severe and often is attributed to “gastric upset.” Patients commonly report feeling that a bowel movement should make the pain better, a sensation known as the downward urge.26

Diarrhea sometimes is seen early on with appendicitis, but this is not common. Within 4 to 12 hours of the onset of pain, most patients also note nausea, anorexia, vomiting, or some combination of these three symptoms. The nausea usually is mild to moderate, and most patients have only a few episodes of emesis. If vomiting is the major symptom, the diagnosis of appendicitis should be questioned. Likewise, emesis that occurs before the onset of pain should suggest other diagnoses.27 Many patients report a mild fever or chills; high fevers or significant rigors are uncommon. The patient's abdominal pain typically increases in intensity, and a characteristic shift in the pain to the right lower quadrant occurs over 12 to 24 hours. The character of the pain becomes achy and more localized. Localization of the pain to the right lower quadrant is a valuable finding when present and occurs in more than 80% of patients with appendicitis.27

On physical examination, most patients appear slightly ill. Tachycardia is uncommon with simple appendicitis, but it may be seen with complicated appendicitis. Most patients with simple appendicitis have a temperature less than 100.5°F; temperature greater than 100.5°F is most often associated with perforated or gangrenous appendicitis.17 Patients with appendicitis, like other patients with peritonitis, tend to lie still rather than move about. Right lower quadrant tenderness and rigidity, both voluntary and involuntary, are common findings. Localized right lower quadrant tenderness is an important finding when present, but its absence does not rule out appendicitis. A variety of methods exist to elicit localized right lower quadrant peritonitis, including the cough sign [the presence of point tenderness with a cough], percussion tenderness, and formal elicitation of rebound tenderness. Although all of these techniques are reasonably sensitive, one small study showed rebound tenderness to be the most accurate predictor of the localized peritonitis associated with appendicitis.28

Additional findings that may be helpful in diagnosing appendicitis include the psoas sign, the obturator sign, Rovsing's sign, and rectal tenderness. The psoas sign is sought by having a supine patient actively flex the right hip against resistance, or by the examiner flexing and extending the patient's right hip with the patient in the left lateral decubitus position. Pain with either of these maneuvers is thought to result from irritation of the underlying psoas muscle by an inflamed retroperitoneal appendix. The obturator sign is elicited by internally and externally rotating the flexed right hip. Pain is thought to arise when the inflamed pelvic appendix irritates the adjacent obturator internus muscle. Rovsing's sign is the finding of right lower quadrant pain during palpation of the left side of the abdomen or when left-sided rebound tenderness is elicited. All of these findings are valuable when present, but their absence does not exclude appendicitis.27

Appendicitis can be easy to diagnose when the presentation is typical, but a typical presentation is encountered in only 50% to 60% of cases. An atypical presentation of appendicitis occurs for a variety of reasons. The classic migration of periumbilical pain to the right lower quadrant is thought to occur when the parietal peritoneum in the right lower quadrant becomes irritated by the inflamed appendix. In cases of retrocecal or pelvic appendicitis, this site might not become irritated. Atypical presentations of appendicitis are particularly common in patients who are at the extremes of age, pregnant, or immunosuppressed, including those with acquired immunodeficiency syndrome [AIDS] and a low CD4 cell count.

Appendicitis in infants and young children remains a difficult diagnostic challenge because of difficulties in obtaining an accurate history. In young patients, the characteristic history of pain is difficult to elicit, and nonspecific findings of vomiting, lethargy, and irritability tend to predominate. Physical examination is difficult to perform because of poor patient cooperation and because localized right lower quadrant tenderness is found in less than 50% of patients.29 In addition, the characteristic laboratory findings often are not present. Leukopenia is as common as leukocytosis in young infants.30 As a result, errors in diagnosis are common, and the frequency of complicated appendicitis is as high as 40% to 70%.31

The diagnosis of appendicitis in elderly patients also may be a challenge. In the elderly, the classic pattern of pain migration, right lower quadrant tenderness, fever, and leukocytosis are observed in only 15% to 30% of cases.30,32 Older patients also tend to present to medical attention in a delayed time frame relative to younger patients. For all of these reasons, the complication and perforation rates can be as high as 63% in patients older than 50 years.33

The presentation of appendicitis during pregnancy also is associated with an atypical clinical presentation, particularly in the later stages of pregnancy. In one series, only 57% of pregnant women with appendicitis had the classic progression of pain.34 Nausea and vomiting tend to be more common in pregnant women with appendicitis, but they also are common occurrences during normal pregnancy. Fever and leukocytosis are less commonly seen in pregnant woman than in other patient groups, and the value of leukocytosis is obscured by the physiologic leukocytosis of pregnancy. Although right-sided abdominal pain and tenderness are found in more than 90% of pregnant women with appendicitis, pain is located in the right lower quadrant only 75% of the time.34

Immunocompromised patients in general, and patients with AIDS in particular, represent a challenging group in which to diagnose appendicitis. Abdominal pain is reported in 12% to 45% of AIDS patients with appendicitis. The range of diagnoses responsible for this pain is significantly greater than in patients without HIV and includes opportunistic infections and malignancies, although in most cases, the pain is related to a diagnosis not associated with HIV.35 Research suggests that appendicitis occurs more often in HIV-infected patients than in HIV-negative patients, with as much as a four-fold increase in incidence.36 Although patients with AIDS usually present with the classic symptoms of appendicitis, there often is a history of chronic abdominal pain. Diarrhea also is a more common presenting symptom of appendicitis in HIV-positive patients, and leukocytosis is relatively uncommon. Declining CD4 counts are associated with delays in presentation to medical attention and increased perforation rates.37 Despite the challenges of diagnosing appendicitis in patients with HIV, the surgical outcomes with appropriate treatment are quite good; the largest series to date had no mortalities and a 13% complication rate, which is comparable to outcomes in patients without HIV.37

Physical examination

As with most disease processes, much can be learned before the patient is touched. Children with appendicitis usually lie in bed with minimal movement. A squirming, screaming child rarely has appendicitis. An exception to this is the child with retrocecal appendicitis and subsequent irritation of the ureter presenting with pain similar to renal colic. Older children may limp or flex the trunk, whereas infants may flex the right leg over the abdomen. A recall of localized pain elicited by bumps in the road on the ride to the hospital is helpful.

Before starting palpation of the abdomen, it is useful to ask the child to point with one finger to the location of the abdominal pain. With the knees bent to relax the abdominal muscles, gentle palpation of the abdomen should begin at a point away from the location of perceived pain. Palpating the abdomen in an area remote from the site of pain may elicit tenderness in the right lower quadrant [Rovsing sign of referred pain], indicating peritoneal irritation. Younger children may be more cooperative if their hand or the stethoscope is used for palpation. The stethoscope can have several roles in the evaluation of a patient who potentially has appendicitis, the least important of which is auscultation. Although patients often have diminished or absent bowel sounds, this is not uniform and auscultation of the abdomen is of little benefit. However, auscultation of the chest to examine for lower respiratory infection is useful because right lower lobe pneumonia can mimic appendicitis. Cutaneous hyperesthesia, a sensation derived from the T10 to L1 nerve roots, is often an early although inconsistent sign of appendicitis. Lightly touching the patient with the stethoscope creates this uncomfortable sensation.

Localized tenderness is essential for diagnosis and is noted either on palpation or percussion. Tenderness can be mild and even masked by more generalized abdominal pain, especially during initial stages. The McBurney point is the most common location. Retrocecal appendicitis may be detected by tenderness midway between the twelfth rib and the posterior superior iliac spine. Pelvic appendicitis produces rectal tenderness. A child with malrotation will have localized tenderness that corresponds to the position of the exudative drainage from the inflamed appendix.

As the disease progresses to perforation, peritonitis ensues. The pattern of pain depends on the location of the appendix. Perforation may result in temporary relief of symptoms as the pain of the distended viscus is relieved. Initially, peritonitis is reflected as local muscular rigidity. This progresses from simple involuntary guarding to generalized rigidity of the abdomen. Other signs include rigidity of the psoas muscle [demonstrated by right hip extension or raising the straight leg against resistance] or of the obturator muscle [demonstrated by passive internal rotation of the right thigh], both of which indicate irritation of these muscles due to retrocecal appendicitis. Other tests of peritoneal inflammation such as rebound tenderness are seldom necessary for diagnosis and cause unnecessary discomfort.

The routine use of rectal examination in the diagnosis of appendicitis has recently been questioned.52–54 Pain during this examination is nonspecific for appendicitis. If other signs point to appendicitis, the rectal examination is unnecessary. However, it may be a helpful diagnostic maneuver in questionable cases such as when a pelvic appendix or abscess is suspected or when uterine or adnexal pathologic conditions are being considered.

If appendicitis is allowed to progress, two results are possible: [1] diffuse peritonitis and shock will occur or [2] the infection will become isolated and an abscess will form. Diffuse peritonitis is more common in infants, probably because of the absence of omental fat. Older children and teenagers are more likely to have an organized abscess. The physical examination in cases of an organized abscess reveals a boggy, tender mass over the abscess.

A frequently unreported but critical aspect of the evaluation is serial examinations done by the same person. The safety and efficacy of serial observation was first reported by White in 197555 and has since been reinforced by other studies. Surana56 reported a prospective study showing no increase in morbidity with appendectomy after active observation in a hospital compared with urgent appendectomy. When the diagnosis is unclear, serial abdominal examinations permit the physician to decrease the number of unnecessary laparotomies without increased risk to the patient.

1 What is the classic presentation of acute appendicitis?

Periumbilical pain that migrates to the right lower quadrant [RLQ] in a patient who is anorexic. Associated symptoms include: nausea, vomiting, and bowel changes.

2 What is the pathophysiology of appendicitis?

The appendix is susceptible to luminal obstruction, via lymphoid hyperplasia, a retained fecalith, tumor, foreign body, or kink. Any of these processes may result in lymphatic and venous obstruction that increases intraluminal pressure and causes distention of the appendiceal lumen. Consequently, an acute inflammatory response develops that leads to ischemia, bacterial overgrowth and eventually necrosis. Unless surgically removed, the gangrenous appendix will perforate, releasing the appendiceal contents into the peritoneal cavity. Subsequently a phlegmon, intraperitoneal abscess, or local peritonitis develops.

3 What is the mechanism of the periumblical pain?

The intestines are insensitive to touch or inflammation unless the enclosing peritoneum is involved. Epigastric pain results from a distended section of intestine. This pain is referred along midline.

4 Where is McBurney's point?

One third the distance between the anterosuperior iliac spine and the umbilicus.

5 What is McBurney's point?

The point of maximal tenderness in acute appendicitis. It results from local inflammation of the parietal peritoneum.

6 Was McBurney a cop from Boston?

Probably. Another McBurney was a surgeon from New York who, in collaboration with a surgeon named Fitz, coined the term appendicitis in classic papers published in 1886 and 1889.

7 What are the typical laboratory findings of a patient with appendicitis?

▪

White blood cell [WBC] count: 12,000 to 14,000

Negative urinalysis results [no WBCs]

Negative pregnancy test result

8 What layers does the surgeon encounter on exposing the appendix through a Rockey-Davis incision?

Skin, subcutaneous fat, aponeurosis of the external oblique muscle, internal oblique muscle, transversalis abdominus muscle, tranvsersalis fascia, and peritoneum.

9 Other possible signs in appendicitis include:

Rovsings sign: pain in the RLQ with palpation of the left lower quadrant [LLQ].

Dunphy's sign: increased pain with coughing [a cough jostles the inflamed peritoneum].

Psoas sign: pain on passive extension of the right thigh. It is present when the inflamed appendix is retrocecal and overlying the right psoas muscle.

Obturator sign: pain on passive internal rotation of the hip when the right knee is flexed. It is present when the inflamed appendix is in contact with the obturator internus muscle.

10 Who was Rockey-Davis?

Rockey-Davis was a pair of surgeons—A.E. Rockey and G.G. Davis—who developed RLQ transverse, muscle-splitting incisions that extend into the rectus sheath.

11 What is the blood supply to the appendix and right colon?

The ileocolic and right colic arteries, which come off the superior mesenteric artery.

12 Does surgery for appendicitis involve a risk of mortality?

No surgical procedure is devoid of risk.

Mortality rateNonperforated appendix