Fig. 20.1
Appendiceal tip position can widely vary. Here the most frequent positions in which it is possible to find the appendix are illustrated. (a) Ascending into the retrocecal recess (65 %). (b) Descending into the iliac fossa (31 %). (c) Transverse retrocecal position (about 2.5 %). (d) Ascending paracecal, preileal position (1 %). (e) Ascending paracecal, retroileal position (about 0.5 %)
Fig. 20.2
Variations of appendicular artery. (a) Origin of the appendicular artery from an “ileal branch” of ileocolic artery (35 %). (b) Origin of the appendicular artery from ileocolic artery immediately before it divides into its terminal branches (28 %). (c) Origin of the appendicular artery from anterior cecal artery (20 %)
We cannot forget that a child is an evolving person. Some anatomic features of appendix can change during development and correlate with incidence and presentation of appendicitis. For example, the appendix is funnel shaped during the first year of life making it difficult to be obstructed. The omentum is underdeveloped in younger children making easier a rapid diffusion of intra-abdominal infections. This feature could explain the quick clinical evolution and worsening of acute appendicitis in younger patients.
Furthermore, the appendiceal epithelium contains lymphoid follicle that may obstruct the lumen. These structures reach their maximal size during adolescence correlating with the peak incidence of acute appendicitis [9].
20.4 Pathophysiology
Obstruction of the appendiceal lumen is the first pathogenetic moment [9, 10]. Fecal material, foreign bodies, hypertrophic lymph node, bands, and torsion can be the causes. As a consequence the patient feels colic pain poorly localized in the periumbilical region.
The lack of physiologic washout of the lumen causes distension of the lumen, wall thickness, and bacterial overgrowth. Mucosal barrier is overwhelmed, leading to bacterial invasion of the wall, inflammation, ischemia, gangrene, and eventually perforation [9, 10].
Involved microorganisms belong to the normal bacterial flora, both aerobic and anaerobic: E. coli, Peptostreptococcus sp., Bacteroides Fragilis, and Pseudomonas sp. [11].
Inflammation of the wall finally involves appendiceal peritoneum leading to localized tenderness on abdominal evaluation.
Risk of perforation increases with time passed from the onset of symptoms, being rare during the first 12 h and occurring more likely after 72 h.
Intra-abdominal dissemination of the infection is prevented by omentum and intestinal loops, which migrate in the involved site confining the disease. If this barrier is insufficient, as it happens in small children, bacteria rapidly spread in the abdominal cavity leading to a diffuse peritonitis.
20.5 Clinical Manifestation
The clinical presentation of acute appendicitis classically includes the following symptoms [9]:
Anorexia
Periumbilical pain at the onset
Migration of pain in the lower right quadrant (commonly in the first 24 h)
Vomiting (after the pain onset)
Fever, commonly mild
Right lower tenderness
Signs of peritoneal irritation
This classical pattern is less common in pediatric age: specific findings could be difficult to elicit; typical symptoms are not always present and may vary with age.
20.5.1 Newborns
Appendicitis in neonates is a rare condition, often correlated with quite high mortality (28 %), principally due to challenging diagnosis [12, 13]. Symptoms orient toward abdominal disease but are often aspecific: abdominal distension and tenderness, decrease in feeding intake, vomiting, lethargy or irritability, and temperature instability [12].
20.5.2 Children Younger Than 5 Years
Appendicitis is uncommon in pre-scholar age. In the history, there are aspecific findings such as fever, vomiting, diffuse abdominal pain with tenderness, and rebound. Diarrhea is quite common and makes difficult to differentiate appendicitis from gastroenteritis. Difficulty with or refusal to ambulate may also be present and due to right hip pain [14].
20.5.3 Children Between 6 and 12 Years of Age
Appendicitis is common in this age. Clinical findings belong to the typical ones: fever, early periumbilical pain and subsequent migration to the lower right quadrant with localized tenderness and rebound, anorexia, vomiting, pain with percussion, hopping, or coughing [15]. Diarrhea and dysuria may also be present and reflect low peritoneum irritation.
20.5.4 Adolescent
Clinical findings are those of the adulthood. The onset of pain typically occurs before vomiting, being a sensitive indicator for acute appendicitis. In pubertal girls, attention must be paid to gynecologic conditions that may have similar clinical presentation.
20.6 Diagnosis
The diagnosis of appendicitis is made clinically and should be suspected in all children with abdominal pain and tenderness on physical examination.
20.6.1 History
The history is characterized by the recent onset of pain, initially periumbilical or diffuse, which subsequently migrates into the right iliac fossa where it remains dull and constant or gets progressively worse. The child with acute appendicitis usually refuses food and complains nausea or has vomiting, also repeated. Patients usually prefer to lie still with one or both hips flexed. Abdominal movements during breath are reduced due to peritoneal irritation. Limp or difficulty with ambulation may be present.
20.6.2 Abdominal Evaluation
Local tenderness in the right lower quadrant and in particular in the McBurney’s point is the most reliable clinical sign of abdominal appendicitis and is called McBurney’s sign.
Many are the historically described points where it’s possible to evoke pain and appreciate tenderness on palpation (Fig. 20.3).
Fig. 20.3
(a) McBurney’s point: a point that lies one-third of distance laterally on a line drawn from the umbilicus to the right anterior superior iliac spine. (b) Morris’ point: a point an inch and a half from the umbilicus in a line drawn from the navel to the right anterior superior spine of the ilium. (c) Munro’s point: a point at the right edge of the rectus abdominis muscle, between the umbilicus and the anterior superior spine of the ilium. (d) Lanz point: it is situated on a line connecting the two anterior superior iliac spines one-third of the distance from the right spine. (e) Clado point: a point at the right edge of the rectus abdominis muscle on a line connecting the two anterior superior iliac spines. (f) Jalaguier point: it is located in the middle of the line connecting the right anterior superior iliac spine and the pubic tubercle
Peritoneal irritation makes it possible to elicit pain during particular maneuvers [9]:
Blumberg sign or rebound tenderness: increased pain with release of manual pressure in the right iliac fossa
Rovsing sign: pain in the right lower quadrant during palpation of the left side by cecal distension
Obturator sign: pain on flexion and internal rotation of the right hip caused by a pelvic appendix which irritates the obturator internus muscle
Iliopsoas sign: pain on extension of the right hip caused by a retrocecal appendicitis.
Rotter sign: pain during rectal exploration caused by endopelvic appendicitis
20.6.3 Laboratory Testing
The value of the laboratory tests is limited to detect a bacterial infection. The information received by them must necessarily be integrated with clinical data.
Classically, the following tests are the most useful:
White blood cell count (WBC)
Absolute neutrophil count (ANC)
C-reactive protein (CRP)
WBC and ANC are elevated in 96 % of patients with acute appendicitis, and WBC values <9000/ml are associated with acute appendicitis in less than 10 % of patients with this suspected diagnosis [6, 16].
Elevated CRP is less sensitive in the first 24 h from the onset of symptoms, but is more sensitive than WBC in patients with symptoms for 24–48 h [17].
When WBC and CRP are elevated, specificity for appendicitis reaches 90 %, but sensitivity remains low (40 %) [18].
Further test may help the differential diagnosis:
Urinalysis: to exclude urinary tract infections
Liver transaminases and bilirubin: to exclude cholestasis and cholecystitis
Lipase and amylase: to exclude acute pancreatitis
Electrolytes: to investigate and eventually correct imbalances
20.6.4 Risk Estimation
History, physical examination, and laboratory results are used from several scores to estimate risk of appendicitis. Alvarado score is the most known in adult patients but does not have adequate accuracy in children.
Pediatric appendicitis score (PAS) (Table 20.1) [19] achieves acceptable diagnostic accuracy and may guide decision-making. PAS is a ten-item score that permits risk stratification.
Table 20.1
Pediatric appendicitis score (PAS)
Items | Score |
|---|---|
Anorexia | 1 |
Nausea or vomiting | 1 |
Migration of pain | 1 |
Fever >38° | 1 |
Pain with cough, percussion, or hopping | 2 |
Right lower quadrant tenderness | 2 |
WBC >di 10,000/ml | 1 |
ANC >di 7500/ml | 1 |
Total | 10 |
PAS ≤2 or 3 suggests a low risk for appendicitis (0–2 %) and suggests to discharge the patient as long as the caretakers (properly instructed regarding signs of appendicitis) note a persistent pain or onset of additional symptoms that require a further evaluation.
PAS ≥7 or 8 indicates a high risk for appendicitis (78–96 %). In clinical practice, these patients undergo surgical consult and appendectomy in most of the cases preceded or not by imaging evaluation.
20.6.5 Imaging
20.6.5.1 Ultrasonography (US)
US is the first-line imaging tool in children with atypical or equivocal clinical findings for appendicitis. It is available in most of the centers and allows to investigate alternative diagnosis such as ovarian torsion or cyst, cholecystitis or cholelithiasis, urinary tract dilatations, and abdominal masses. In our practice, all girls with suspected diagnosis of appendicitis undergo US to exclude gynecologic anomalies.
Unfortunately, diagnostic accuracy depends upon experience and skills of the sonographer. Therefore, a negative US in the case of persistent symptoms is not sufficient to exclude appendicitis, and the examination may be made difficult by pain and anxiety or in the case of overweight children.
Despite this, the following findings may support the diagnosis of appendicitis:
Diameter >6 mm
Wall thickness of the appendix >2 mm
Noncompressible tubular structure in the right lower quadrant
Intraluminal fecalith
Thickening of the mesentery
Localized tenderness with graded compression
Free fluid in the lower right quadrant
Localized collection in the lower right quadrant (abscess)
In case of persistent symptoms and equivocal findings on US, the patient should undergo serial evaluations (both clinical and instrumental), till the clinical features become clearer. In the case of progressive clinical worsening with no clear diagnosis, second-level imaging investigation can be done [25].
20.6.5.2 Computed Tomography (CT) and Magnetic Resonance Imaging (MRI)
CT has high specificity and sensitivity for the diagnosis of acute appendicitis (94–100 % and 93–100 %, respectively) [26, 27].
Despite this, CT does not appear to reduce the negative appendectomy rate (NAR). The only exception is in children younger than 5 years of age where CT significantly reduces NAR [28]. If CT is performed, it should be a contrast-enhanced CT with intravenous contrast.
CT has the disadvantage of ionizing radiation exposure. In centers with adequate experience in interpreting MRI and rapid availability, it may be preferable to CT because of similar diagnostic accuracy without radiation exposure.
20.6.5.3 Plain Abdominal Radiographs
Abdominal X-ray has a poor value in diagnosis of appendicitis. It may reveal a fecalith and signs of obstruction or perforation or may exclude alternative diagnosis such as a basilar pneumonia.
20.6.6 Differential Diagnosis
Acute appendicitis in children often presents with atypical symptoms; moreover, many diseases can mimic appendicitis. The principal diseases involved in differential diagnosis are summarized in Table 20.2.
Table 20.2
Differential diagnosis
Disease | Clinical and instrumental findings |
|---|---|
Emergent surgical diagnoses | |
Bowel obstruction | Previous surgery |
Bilious vomiting | |
Abdominal X-ray: distended loops, air-fluid levels, pneumoperitoneum | |
Intestinal malrotation | Signs of bowel obstruction (see above) |
Upper digestive tract X-ray: duodenal compression | |
US: abnormal position of major intestinal vessels | |
Intussusception | Intermittent episodic abdominal pain with vomiting |
Blood in the stool | |
Palpable sausage-shaped mass in right quadrants | |
US: target image
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