Which of the following terms best describes the pain associated with appendicitis?

Clinical Features

Appendicitis in children has an immensely broad spectrum of clinical presentation; <50% of cases have the classic presentation. The signs and symptoms in acute appendicitis can vary depending on the timing of presentation, patient age, the abdominal/pelvic location of the appendix, and most importantly, individual variability in the evolution of the disease process. Children early in the disease process can appear well and demonstrate mild symptoms, minimal findings on physical examination, and normal laboratory studies, while those with perforation and advanced peritonitis can demonstrate severe illness with bowel obstruction, renal failure, and septic shock. Most patients with appendicitis demonstrate an insidious onset of illness characterized by generalized nonspecific malaise or anorexia in the first 12 hr, and a steady, escalating progression in severity of signs and symptoms over 2-3 days with increasing abdominal pain, vomiting, fever, and tachycardia; perforation is common beyond 48 hr of illness. Thus, the opportunity for diagnosis before perforation in acute appendicitis in children is most often brief (48-72 hr) and a high percentage of patients are perforated at presentation.

Abdominal pain is consistently theprimary symptom in acute appendicitis; beginning shortly (hours) after the onset of illness. As with other visceral organs, there are no somatic pain fibers within the appendix; therefore, early appendiceal inflammation results in pain which is vague, poorly localized, unrelated to activity or position, often colicky, and periumbilical in location as a result of visceral inflammation from a distended appendix. Progression of the inflammatory process in the next 24 hr leads to involvement of the adjacent parietal peritoneal surfaces, resulting in somatic pain localized to the right lower quadrant (RLQ);thus, the classic description of periumbilical mid-abdominal pain migrating to the RLQ. The position of the appendix is a critical factor affecting interpretation of presenting signs and symptoms and accurate diagnosis. When the appendix is in a retrocecal or pelvic position, a slower progression of illness is typical and clinical presentation is likely to be delayed. Localized pain in the RLQ leads to spasm in the overlying abdominal wall muscles and now the pain is predictably exacerbated by movement. The child often describes marked discomfort with the bumpy car ride to the hospital, moves cautiously, and has difficulty getting onto the examining room stretcher. Nausea and vomiting occur in more than half the patients, and typicallyfollow the onset of abdominal pain by several hours. Anorexia is a classic and consistent finding in acute appendicitis, but occasionally affected patients are hungry. Diarrhea and urinary symptoms are also common, particularly in cases of PA when there is likely inflammation near the rectum and possible abscess in the pelvis. Painful voiding may not be from dysuria, but pressure transmitted to an inflamed peritoneum. As it progresses, appendicitis is often associated with adynamic ileus, leading to the complaint of constipation and possible misdiagnosis.

Introduction

Acute appendicitis (AA) is a very common disease and represents the most common cause of abdominal emergency. It is usually seen in the second and third decades of life, but can occur at any age.1 A male preponderance exists (ratio 1.4:1); the overall lifetime risk of developing AA is 8.6% for males and 6.7% for females.2

Although the etiology of AA is still poorly understood, the most common hypothesis refers to appendix obstruction followed by impairment of wall appendix barrier and subsequent wall perforation and/or abscess formation.1 However, some studies suggest that uncomplicated and complicated appendicitis are different entities that require a different treatment.3,4 This might explain why up to 20% of AA resolves spontaneously, as was observed 125 years ago by Fitz.5

Worldwide, the standard of care for AA is appendectomy, which is to date generally considered a routine and safe operation. Appendicitis can be notoriously difficult to diagnose, as its clinical presentation can be subtle, and the rate of unnecessary appendectomies is approximately 15%6,7; the routine use of ultrasonography (US) reduces this to 10%, and preoperative computer tomography (CT) further decreases it to 5–10%, but not to zero.8,9 Furthermore, most European surgeons do not routinely perform imaging studies as they trust the clinical diagnosis.10

Despite the fact that surgery represents the gold standard treatment of AA, several attempts have been made to investigate the role of antibiotic treatment. The conservative management of AA was considered a long time ago. In 1959, Coldrey reported on a five-year experience with 471 unselected patients who were non-operatively treated for AA, with low morbidity and mortality rates.11 In 1977, 425 unselected patients were treated by traditional Chinese medicine and antibiotic treatment and recurrent appendicitis was described in 7/100 patients.12

Since then the question has remained open.

Acute Appendicitis

Acute appendicitis is a ubiquitous problem, accounting for approximately 5% of all emergency department visits for patients under 65 years of age21 and 30% of acute surgical abdominal emergencies in patients under 50 years of age worldwide.22 Appendicitis accounted for 318,000 hospital admissions in the USA in 2006,23 and has an overall incidence of approximately 82 to 110/100,000 population in North America.24 The lifetime risk of appendicitis is 8.6% for males and 6.7% for females in Western countries,25 and may be twice this risk in Asia.26

Typically, acute appendicitis begins with prodromal symptoms of anorexia, nausea, and vague periumbilical pain. Within 6 to 8 hours, the pain migrates to the right lower quadrant and peritoneal signs develop. In uncomplicated appendicitis, a low-grade fever to 38°C and mild leukocytosis are usually present. A higher temperature and WBC count are associated with perforation and abscess formation. Common features of the history, physical examination, and WBC count in patients with appendicitis have been combined into a predictive tool known as theAlvarado score (Table 11.4).27 For men, a score of 4 or less accurately excludes appendicitis; the score is less useful in women and children.28 Atypical presentations of acute appendicitis, however, are common, and a diagnosis of acute appendicitis should not be rejected simply on the basis of the patient’s history and physical examination alone. An Appendicitis Inflammatory Response score has also been proposed.29 In children, mesenteric adenitis (or lymphadenitis) is frequently mistaken for acute appendicitis but is often preceded by a sore throat and is self-limited. Mesenteric adenitis may also be caused byYersinia enterocolitica (seeChapter 110).

Whereas plain abdominal films are not diagnostic and have little role in the diagnosis of acute appendicitis, CT has dramatically improved the accuracy of diagnosis in patients with acute appendicitis. An appendix diameter greater than 10 mm is generally considered diagnostic of appendicitis, although the normal range for the diameter of the appendix may extend to nearly 13 mm.30 Other CT signs of acute appendicitis include periappendiceal fat inflammation, presence of fluid in the RLQ, and failure of contrast dye to fill the appendix.31 The addition of CT has reduced the negative appendectomy rate to about 5%.32 Because CT entails radiation exposure,18 some authorities advocate avoiding CT in children and adolescents,33 in whom a higher degree of diagnostic uncertainty is tolerated in favor of lower radiation exposure (seeChapter 120). In this setting, US of the appendix has a sensitivity of 0.86 and specificity of 0.81 for detecting acute appendicitis.34 In a pregnant patient in whom radiation exposure is also a significant concern, MRI has become the imaging method of choice, with a sensitivity and specificity approaching those of CT.35

Clinical Management and Treatment

The treatment for acute appendicitis is appendectomy. Early acute appendicitis is generally managed with surgery and prophylactic antibiotics to minimize the risk of surgical site infection (SSI). If no perforation or focal peritonitis is encountered, there is generally no need for continuation of antibiotics after surgery, because the main infectious source has been removed—source control. For perforated appendicitis, appendectomy should be performed and systemic antibiotics continued for 5 to 7 days or until fever and leukocytosis have resolved. Escherichia coli and Bacteroides fragilis are the main organisms isolated in acute simple and perforated appendicitis. However, both anaerobic bacteria and other gram-negative organisms may be present, and polymicrobial infections are most common. The Surgical Infection Society (SIS) has recommended different single- and multiple-agent regimens based on the best available evidence, generally derived from randomized controlled trials. Single-agent regimens include cefoxitin, cefotetan, and ticarcillin-clavulanic acid; and multiple-agent therapies include a third-generation cephalosporin, monobactam, or aminoglycoside combined with antianaerobic coverage with agents such as metronidazole or clindamycin.

Delayed presentation, usually defined as presentation after 5 days or longer since onset of symptoms, is associated with abscess formation plus or minus phlegmon or diffuse peritonitis. Outcomes in these patients are worse than in those with early presentation. For these patients a CT scan is generally recommended. If a phlegmon is identified, the patient is admitted and treated with systemic antibiotics, bowel rest, and physiologic support. If the CT scan reveals an abscess, it should be drained via a percutaneous approach whenever feasible, and medical treatment as described previously should be initiated. Nonsurgical treatment has been reported to fail in approximately 7% to 10% of patients. Failure of medical treatment is defined as worsening abdominal pain, continuous fever, leukocytosis, and/or progression to focal or diffuse peritonitis. In these cases the patient should be taken promptly to the operating room for surgical management to include drainage and resection of the involved tissues, which often requires a cecectomy or hemicolectomy, and drain placement.

Management of nonperforated appendicitis with antibiotics alone (nonsurgical management) has been reported after initial experience in cases where surgical treatment was not available, such as in remote areas or isolated conditions (e.g., submarines). A recently published randomized controlled trial involving 252 male patients concluded that this nonsurgical strategy could be used in the setting of acute appendicitis. However, this approach is associated with adverse outcomes such as a high readmission rate (14% to 35%) and failure of medical treatment requiring surgery in the presence of more advanced disease. Because of these potential complications and the relatively benign course after appendectomy, early operative intervention with or without antibiotics (following previously outlined guidelines) is the treatment of choice whenever this strategy is available, and medical or antibiotic treatment alone should be reserved for well-selected patients in whom an operation may pose a greater risk or for those in whom surgical management is not immediately available.

For patients in whom appendectomy was not performed during the acute presentation, an interval appendectomy can follow 6 weeks to 3 months after the patient has recovered from the initial event. Although the need for this subsequent operation remains somewhat controversial, different studies have reported a high recurrence rate (10% to 30%), supporting strongly considering subsequent appendectomy. If an observant strategy is followed, subsequent studies must be completed to rule out neoplastic disease in selected individuals.

Lastly, there has been some debate regarding the best surgical approach for appendectomy: laparoscopic versus open. Results from multiple randomized controlled trials have been reported, and a recent review of the literature favored the laparoscopic approach because of better postoperative outcomes including lower rate of SSI, shorter length of stay, and faster return to work. Although the direct costs, operative time, and incidence of intraabdominal abscesses may be higher, the laparoscopic approach is currently the standard of care given the reported benefits after surgery.

Acute Appendicitis

Appendicitis is the most common cause for acute surgery in childhood. Between 30% and 40% of children do not present with the typical clinical presentation of appendicitis and, in particular, preschool patients often present with atypical features, more rapid progression and higher incidence of complications. Very young children often have a diagnostic delay and hence they have a higher risk of perforation at presentation. Consequently, imaging is often necessary to confirm, suggest or refute the clinical diagnosis and the use of imaging has dramatically reduced the false-positive appendectomy rates. Ultrasound should be the primary imaging investigation and performing a comprehensive ultrasound examination will make CT redundant in most cases. The ultrasound should be performed with a high-frequency linear transducer using a graded compression technique. The primary criteria of acute appendicitis are typically a tubular, blind-ending, non-compressible structure with maximal outer diameter over 6 mm. Other findings include wall hyperaemia or hypoperfusion (depending on the degree of inflammation/necrosis), surrounding hyperechoic mesenteric fat and the presence of an appendicolith (Fig. 71.17).

CT is rarely necessary but can be an important diagnostic tool in difficult cases where ultrasound is unable to clarify and the clinical situation enforces acute surgery. CT is also often performed when complicated periappendicular abscess formation is suspected. Note that the appendix may be retrocaecal and an inflamed retrocaecal appendix may cause subcapsular liver abscesses (Fig. 71.18).

Sonographic mimics of acute appendicitis may be acute salpingitis in teenage girls or terminal ileitis (see below) (Fig. 71.19).

ADDITIONAL DIAGNOSTIC TOOLS

Acute Appendicitis

Acute appendicitis is a common abdominal surgical problem in both immunocompromised and immunocompetent patients. The evaluation of an immunocompromised patient in whom acute appendicitis is suspected proceeds as it would for an immunocompetent patient. A high index of suspicion may help to avoid delays in diagnosis. The safety of emergency surgery for acute appendicitis in severely immunocompromised patients has been described with a mortality rate less than 10%.34,35 However, the pediatric surgical literature has reported success with nonoperative management of acute appendicitis in neutropenic patients that are otherwise stable.36 A similar approach with close observation and intravenous antibiotics may be possible in highly selected adult patients with severe neutropenia, early signs of acute appendicitis without any evidence of systemic sepsis, and in whom recovery of the neutropenia is anticipated during the following 24 to 48 hours, though several anecdotal reports show a good outcome with appendectomy.37 Few differences are observed in clinical findings and perioperative morbidity and mortality rates between non-HIV and HIV patients without AIDS.30

Abstract

Acute appendicitis is one of the most common causes of abdominal pain, with an incidence of approximately 8.5% in males and 6.7% in females; the mortality rate is approximately 0.5%. Although acute appendicitis can occur at any age, it most commonly occurs in the second or third decades. Conventional wisdom holds that acute appendicitis is the result of obstruction of the appendicular lumen with subsequent impairment of the wall leading to perforation and phlegmon formation. More recent thinking posits that mild uncomplicated appendicitis and severe complicated appendicitis are caused by different pathologic processes and are in fact two completely separate diseases requiring very different treatments.

The diagnosis is made on clinical grounds in many countries and appendectomy has remained the standard of care in the treatment of acute appendicitis for the last century. This is despite that approximately 15% of appendectomies yield a pathologically normal appendix and that appendectomy is not without morbidity and, rarely, mortality. The routine use of imaging, including ultrasound and computerized tomography as an adjunct to the clinical diagnosis of acute appendicitis, has decreased the number of “normal result” appendectomies to approximately 10%. Recent interest in the nonsurgical management of mild uncomplicated acute appendicitis is also impacting this statistic.

Abdominal pain is a common feature of acute appendicitis. Although the clinical presentation of the pain of acute appendicitis can be variable, its classic clinical presentation begins as mild periumbilical pain that becomes more severe and then migrates to the right lower quadrant at a point that is one third the distance from the anterior superior iliac spine and the umbilicus known as McBurney's point. The pain becomes more localized and constant with associated anorexia, nausea, vomiting, and fever. Constipation and diarrhea, as well as urinary tract symptoms, may also occur. Symptoms are usually present for less than 48 hours before the patient seeks medical attention.

CLINICAL FEATURES

Acute appendicitis is a disease of the young, most typically presenting in children and adolescents (5 to 15 years), although no age group is exempt.9, 10 A crude estimate of the incidence of acute appendicitis in the United States is 11 cases per 10,000 population.11 The pathogenesis of appendicitis is believed (although not by all) to reflect an initial insult to the mucosa resulting from luminal obstruction by a fecalith, a fragment of undigested food, or lymphoid hyperplasia, followed by bacterial infection that progressively spreads from the mucosa into the wall. However, the evidence for this is circumstantial at best, and some observers believe that acute appendicitis is instead a manifestation of a range of injuries encompassing hypersensitivity reactions, infections, and ischemic lesions. The potential causes of acute appendicitis have been summarized by Carr.11

Imaging methods to detect acute appendicitis have improved,12, 13 and laparoscopic appendectomy has emerged as a safe technique.14 About 70% of patients suspected of having appendicitis on clinical and imaging grounds prove to have acute appendicitis on resection.15, 16 Some observers believe that all appendices, even when grossly normal, should be removed during surgery for suspected acute appendicitis, as close to 20% of normal-appearing appendices may have acute inflammation on microscopic examination.15, 16 A possible exception is in those patients who might require urologic surgery in the future, as their appendices may prove useful as urinary conduits.17 Patients with appendicitis in the setting of HIV infection have similar clinical presentations, although sometimes with a less striking elevation in the peripheral white blood cell count. In one surgical series of appendicitis and HIV infection, delays before operation increased the likelihood of perforation.18

ACUTE APPENDICITIS

Acute appendicitis is a ubiquitous problem. In adult patients younger than 60 years, acute appendicitis accounts for 25% of admissions to the hospital from the emergency department for abdominal pain.20 The overall incidence of appendicitis is approximately 11/10,000 population, with a lifetime risk of 8.6% for men and 6.7% for women.21 Typically, acute appendicitis begins with prodromal symptoms of anorexia, nausea, and vague periumbilical pain. Within 6 to 8 hours, the pain migrates to the right lower quadrant and peritoneal signs develop. In uncomplicated appendicitis, a low-grade fever to 38°C and mild leukocytosis are usually present. A higher temperature and white blood cell count are associated with perforation and abscess formation. The mnemonic PANT can help the novice remember the classic progression of symptoms in appendicitis—pain followed by anorexia followed by nausea followed by temperature elevation. Uncommon presentations of acute appendicitis, however, are common, and the wary physician will not reject a diagnosis of acute appendicitis simply on the basis of the patient's history and physical examination alone. Whereas plain abdominal radiographs are not diagnostic and have little role in the diagnosis of acute appendicitis, CT has dramatically improved the accuracy of diagnosis in patients with acute appendicitis. The finding of an appendiceal diameter larger than 6 mm has positive and negative predictive values of 98%.22 Other CT signs of acute appendicitis include periappendiceal fat inflammation, presence of fluid in the right lower quadrant, and failure of contrast dye to fill the appendix23; these findings have lower degrees of specificity. Traditionally, an erroneous diagnosis of appendicitis, reflected by the finding of normal pathology at surgical exploration, was as high as 33%.24 The addition of CT has reduced the false-negative rate to approximately 6% for men and 10% for women.25 As noted earlier, CT does entail radiation exposure,18 and some authorities advocate avoiding CT in children and adolescents,26 in whom a higher degree of diagnostic uncertainty is tolerated in favor of lower radiation exposure (see Chapter 116).