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This entry was posted in Health Services and tagged APPENDICITIS on January 9, 2015 by sunnyliz

Acute appendicitis is acute inflammation and infection of the vermiform appendix, which is most commonly referred to simply as the appendix. The appendix is a blind-ending structure arising from the cecum. Acute appendicitis is one of the most common causes of abdominal pain and is the most frequent condition leading to emergent abdominal surgery in children. The appendix may be involved in other infectious, inflammatory, or chronic processes that can lead to appendectomy; however, this article focuses on acute appendicitis. Appendicitis and acute appendicitis are used interchangeably.

Common symptoms of acute appendicitis include abdominal pain, fever, and vomiting. The diagnosis of appendicitis can be difficult in children because the classic symptoms are often not present

A delay in the diagnosis of appendicitis is associated with rupture and associated complications, especially in young children. Improvements in rupture rates have been made with advanced radiologic imaging. Appendicitis is a clinical diagnosis with imaging used to confirm equivocal cases

The definitive treatment for appendicitis is appendectomy. Key to any evaluation and treatment plan are the following: relieve the patients pain and discomfort early and consistently; communicate with the patient and family about the plans; repeat the examination often; adjust the differential diagnosis as appropriate; and keep the patient for observation if a firm diagnosis is not made.

The most widely used antibiotic regimen is the combination of ampicillin, clindamycin (or metronidazole), and gentamicin.

The vermiform appendix is generally 5-10 cm in length. It arises from the cecum, which in most children is located in the right lower quadrant of the abdomen.

Although the base of the appendix is fixed to the cecum, the tip can be located in the pelvis, retrocecum, or extraperitoneum. Note that the anatomic position of the appendix determines the symptoms and the site of tenderness when the appendix becomes inflamed.

The appendix is lined by typical colonic epithelium. The submucosa contains lymphoid follicles, which are very few at birth. This number gradually increases to a peak of about 200 follicles at age 10-20 years and then subsequently declines. In persons older than 30 years, less than half that number is present, and the number continues to decrease throughout adulthood.

Acute appendicitis is due to obstruction of the blind ending appendix, resulting in a closed loop. In children, obstruction usually results from lymphoid hyperplasia of the submucosal follicles. The cause of this hyperplasia is controversial, but dehydration and viral infection have been proposed. Another common cause of obstruction of the appendix is a fecalith.

Rare causes include foreign bodies, parasitic infections (eg, nematodes), and inflammatory strictures.

Once the appendix becomes obstructed, bacteria trapped within the appendiceal lumen begin to multiply, and the appendix becomes distended. The increased intraluminal pressure obstructs venous drainage, and the appendix becomes congested and ischemic.

The combination of bacterial infection and ischemia produce inflammation, which progresses to necrosis and gangrene. When the appendix becomes gangrenous, it may perforate. The progression from obstruction to perforation usually takes place over 72 hours.

One study noted that appendiceal perforation is more common in children, specifically younger children, than in adults. A substantial risk of perforation within 24 hours of onset was noted (7.7%) and was found to increase with duration of symptoms. While perforation was directly related to the duration of symptoms before surgery, the risk was associated more with prehospital delay than with in-hospital delay.[1]

During the initial stage of appendicitis, the patient feels only periumbilical pain due to the T10 innervation of the appendix. As the inflammation worsens, an exudate forms on the appendiceal serosal surface. When the exudate touches the parietal peritoneum, a more intense and localized pain develops.

Perforation results in the release of inflammatory fluid and bacteria into the abdominal cavity. This further inflames the peritoneal surface, and peritonitis develops. The location and extent of peritonitis (diffuse or localized) depends on the degree to which the omentum and adjacent bowel loops can contain the spillage of luminal contents.

If the contents become walled off and form an abscess, the pain and tenderness may be localized to the abscess site. If the contents are not walled off and the fluid is able to travel throughout the peritoneum, the pain and tenderness become generalized.

Appendicitis is much more common in developed countries. Although the reason for this discrepancy is unknown, potential risk factors include a diet low in fiber and high in sugar, family history, and infection.

Appendicitis occurs in all age groups but is rare in infants. Appendicitis is most common in the second decade of life (age 10-19 y), occurring at a rate of 23.3 cases per 10,000 per year. Thereafter, the incidence continues to decline, although appendicitis occurs in adulthood and into old age

Generally, the prognosis is excellent. At the time of diagnosis, the rate of appendiceal perforation is 20-35%. The rate of perforation is 80-100% for children younger than 3 years, compared with 10-20% in children 10-17 years old. Children with ruptured appendicitis are at risk for intra-abdominal abscess formation and small bowel obstruction, and they can have a prolonged hospital stay (several weeks or more). The mortality rate for children with appendicitis is 0.1-1%.

Death from appendicitis is most common in neonates and infants for the following 2 reasons:

Appendicitis is rare in this age group; thus, unless the physician’s index of suspicion is high, appendicitis is often low on the list of suspected differential diagnoses.

Very young patients are unable to communicate the location and nature of their pain. Some neonates may not even become febrile. Often, the patient’s only symptom is irritability or inconsolability

The classic history of anorexia and vague periumbilical pain, followed by migration of pain to the right lower quadrant (RLQ) and onset of fever and vomiting, is observed in fewer than 60% of patients.[2] If the appendix perforates, an interval of pain relief is followed by development of generalized abdominal pain and peritonitis. Although some patients progress in the classical fashion, some patients deviate from the classic model. Atypical presentations are common in neurologically impaired and immunocompromised patients, as well as in children who are already on antibiotics for another illness.

In patients with a retrocecal appendix, who constitute 15% of cases, signs and symptoms may not localize to the RLQ but instead to the psoas muscle. In other patients, the tip of the appendix is deep in the pelvis, and the signs and symptoms localize to the rectum or bladder.

Certain features of a childs presentation may suggest a perforated appendix. A child younger than 6 years with symptoms for more than 48 hours is much more likely to have a perforated appendix. The child may have generalized abdominal pain and may have a temperature higher than 38°C.

A substantial risk of perforation within 24 hours of onset was noted (7.7%) in one study and was found to increase with duration of symptoms. While perforation was directly related to the duration of symptoms before surgery, the risk was associated more with prehospital delay than with in-hospital delay.[1]

All patients with appendicitis have abdominal pain, and many have anorexia; absence of both of these findings should place the diagnosis of appendicitis in question. A child who states that the ride to the hospital is painful when the vehicle hits bumps in the road may have peritoneal irritation.

Acute onset of severe pain is not typical of acute appendicitis but is seen with acute ischemic conditions such as volvulus, testicular torsion, ovarian torsion, or intussusception. If the pain is initially located in the right lower quadrant, severe constipation should be considered.

After a few hours, the pain migrates to the RLQ due to inflammation of the parietal peritoneum. This pain is more intense, continuous, and localized than the initial pain. This shift of pain rarely occurs in other abdominal conditions.

Atypical pain is common and occurs in 40-45% of patients. This includes children who initially have localized pain and those with no visceral symptoms. Pain on urination can be seen with pelvic appendicitis.

A unique feature of appendicitis is gradual onset of pain followed by vomiting. Vomiting first is more typical of gastroenteritis.

Generally, vomiting that occurs prior to pain is unusual. However, in patients with retrocecal appendices, particularly those that extend cephalad along the posterior surface of the right colon, inflammation of the appendix irritates the nearby duodenum, resulting in nausea and vomiting prior to the onset of RLQ pain.

Significant diarrhea is atypical in appendicitis, and the physician should consider other diagnoses, while not ruling out appendicitis. In patients with an appendix in a pelvic location, inflammation of the appendix occasionally results in an irritative stimulation of the rectum. These patients often report diarrhea. However, upon closer questioning, such patients usually describe frequent, small-volume, soft stools rather than true diarrhea.

Most children with appendicitis are afebrile or have a low-grade fever and characteristic flushing of their cheeks. Severe fever is not a common presenting feature unless perforation has occurred, and even then it may still be rare. According to one study, vomiting and fever are more frequent findings in children with appendicitis than in children with other causes of abdominal pain.

The physical examination findings in children may vary depending on age. Irritability may be the only sign of appendicitis in a neonate. Older children often seem uncomfortable or withdrawn. They may prefer to lie still because of peritoneal irritation. Teenaged patients often present in a classic or near-classic fashion.

Examination of the child requires skill, patience, and warm hands. Initial and continued observation of the child is of critical importance. An ill-appearing quiet child who is lying very still in bed, perhaps with the legs flexed, is much more a cause for concern than a child who is laughing, playing, and walking around the room.

The examination should be thorough and start with areas other than the abdomen. Because lower lobe pneumonia can cause abdominal findings, a history of such should be elicited and a thorough chest examination performed. It is also important to exclude urinary tract  (UTI) as a cause of abdominal pain.

Children vary in their ability to cooperate with the physical examination. It is important to tailor the physical examination to the childs age and developmental stage.

Patients’ general state and gait should be observed before interacting with them. The patient’s state of activity or withdrawal may lend information into their condition. A patient in obvious distress with abdominal pain gives the impression of an infectious process; however, other causes must be ruled out.

The findings on evaluation of the heart and lungs typically reflect the patient’s overall state more than they may suggest appendicitis. Patients are often dehydrated or in pain and may be tachycardic or tachypneic. Pediatric patients have great physiological reserves and may not show any general symptoms until they are very ill.

Full exposure of the abdomen is key. Before examining the abdomen, ask the child to point with one finger to the site of maximal pain. Begin palpation of the abdomen at a site distant to this, with the most tender area examined last. If the child is particularly anxious, palpation may be performed with a stethoscope.

Distracting questions concerning school and family members may be helpful to relieve anxiety during the examination. Observing the childs facial expressions during this questioning and palpating is critical.

Palpation of the abdomen should be performed with a gentle and light touch, searching for involuntary guarding of the rectus or oblique muscles. In early appendicitis, children may not have significant guarding or peritoneal signs. Younger children are much more likely to present with diffuse abdominal pain and peritonitis, perhaps because their omentum is not well developed and cannot contain the perforation.

Typically, maximal tenderness can be found at the McBurney point in the RLQ. A mass may be palpable in the RLQ if the appendix is perforated.

However, the appendix may lie in many positions. Patients with a medially positioned appendix may present with suprapubic tenderness. Patients with a laterally positioned appendix often have flank tenderness. Patients with a retrocecal appendix may not have any tenderness until appendicitis is advanced or the appendix perforates.

Presence of the Rovsing sign (pain in the RLQ in response to left-sided palpation or percussion) strongly suggests peritoneal irritation.

To assess for the psoas sign, place the child on the left side and hyperextend the right leg at the hip. A positive response suggests an inflammatory mass overlying the psoas muscle (retrocecal appendicitis).

Check for the obturator sign by internally rotating the flexed right thigh. A positive response suggests an inflammatory mass overlying the obturator space (pelvic appendicitis).

During the abdominal examination, try to avoid eliciting rebound tenderness. This is a painful practice and certainly destroys any trust that has been garnered during the examination. Peritonitis can be confirmed with gentle percussion over the right lower quadrant. Involuntary contraction of the abdominal wall musculature (involuntary guarding) and tenderness can be elicited with minimal stress or discomfort to the child.

Other methods can be used to establish that the patient has peritoneal irritation. Asking the patient to sit up in bed, cough, jump up and down, or bounce his or her pelvis off the bed while in the supine position may elicit pain in the presence of peritoneal irritation. Alternatively, other acceptable maneuvers are tapping the patients soles and shaking the stretcher. A child with advanced appendicitis typically prefers to lie still due to peritoneal irritation.

The digital rectal examination is often deferred but can be helpful in establishing the correct diagnosis, especially in sexually active adolescent girls. The patient should be told that the examination is uncomfortable but should not cause sharp pain. The caliber of the patients anus should be taken into consideration, and smaller digits should be used for examining younger patients.

The rectal examination is particularly important in the child with a pelvic appendix, in whom the findings on the abdominal examination for appendicitis may be equivocal and indicative of peritoneal irritation.

Objective information to ascertain includes impacted stool or an inflammatory mass. Right-sided tenderness of the rectum is the classic finding in patients with pelvic appendicitis or in those with pus that pools in the pelvis from an inflamed appendix elsewhere in the abdomen.

Patients who are able to communicate should be asked if they have tenderness in different areas of the rectum. The rectal examination in a young child may have to be completely objective because they may not be able to communicate variations in tenderness or may have general discomfort from the examination.

An external genitourinary (GU) examination is helpful to rule out testicular or scrotal tenderness in males and hematocolpos in pubertal girls.

A pelvic examination should be considered in sexually active adolescent girls to evaluate for tenderness (adnexal and/or cervical motion tenderness), masses, bleeding, or discharge.

Becker et al found that 44% of patients diagnosed with appendicitis presented with 6 or more of the following atypical features[3] :

Absence of maximal pain in the RLQ

Do not diagnose gastroenteritis rather than appendicitis unless the patient has nausea, vomiting, and diarrhea. Even with the presence of vomiting and diarrhea, consider the unusual presentations of retrocecal or pelvic appendicitis. Additionally, appendicitis can develop as a sequela of gastroenteritis associated with lymphoid hyperplasia.

Diagnose abdominal pain of unknown etiology in patients with nonspecific abdominal symptoms. Instruct patients to be reevaluated in 8-12 hours by their primary care physician or to return to the emergency department. Patients with equivocal examination findings should be admitted for observation for serial abdominal examinations or to undergo imaging with ultrasonography or abdominal CT scanning.

If constipation is diagnosed and treated with enemas and/or stool softeners with resolution of the signs and symptoms, inform the patient and family that recurrence of the abdominal pain in the future could be recurrent constipation or acute appendicitis and to seek medical advice.

Appendicitis should be considered in special patient populations, such as the immunocompromised and developmentally delayed. Appendicitis is rare in infants. If an infant has appendicitis, the diagnosis of Hirschsprung disease should also be considered.

Other problems to consider include the following:

The major differential diagnoses for acute appendiceal abscess or mass include Crohn disease and malignancy.

Making a timely diagnosis of appendicitis is a difficult challenge in children with abdominal pain. Laboratory findings may increase suspicion of appendicitis but are not diagnostic. The minimum laboratory workup for a patient with possible appendicitis includes a white blood cell (WBC) count with differential and urinalysis. Liver function tests and amylase and lipase assessments are helpful when the etiology is unclear.

Other studies, such as interleukin 6 and C-reactive protein (CRP) assays, have been advocated by some in the diagnosis of appendicitis. However, in multiple clinical series, these studies have not been shown to be of clear benefit and, for the most part, only add to the cost of the evaluation

The WBC count becomes elevated in approximately 70-90% of patients with acute appendicitis. However, the WBC count is elevated in many other abdominal conditions, as well. Furthermore, the WBC count is often within the reference range within the first 24 hours of symptoms. Elevation tends to occur only as the disease process progresses, and it is usually mild. Therefore, its predictive value is limited. Elevation of the neutrophil or band count can be seen without elevation of the total WBC count and may support the diagnosis of appendicitis.

If the WBCs exceed 15,000 cells/μL, the patient is more likely to have a perforation. However, one study found no difference in the WBC counts of children with simple appendicitis and those with perforated appendicitis. In the immunocompromised patient, a neutrophil count of less than 800 may suggest typhlitis.

Urinalysis is useful for detecting urinary tract disease, including infection and renal stones. However, irritation of the bladder or ureter by an inflamed appendix may result in a few urinary WBCs. The presence of 20 or more WBCs per high-power field (hpf) suggests a urinary tract infection.

Hematuria may be caused by renal stones, urinary tract infection, Henoch-Schonlein purpura, or hemolytic-uremic syndrome. However, small numbers of red blood cells (RBCs) can be found in as many as 20% of patients with appendicitis when an overlying phlegmon or abscess lies adjacent to the ureter. Typically, urinary RBCs are fewer than 20/hpf.

Normal urinalysis results have no diagnostic value for appendicitis. However, a grossly abnormal result may suggest an alternative cause of abdominal pain