Appendicitis
Rennier A. Martinez
Accounts for about one-third of childhood admissions for abdominal pain1
Peak incidence during adolescence2
Diagnosis is difficult especially in younger children
Definite diagnosis only in 50% to 70% of cases3
Variable diagnostic algorithms depend on physician and institutional factors
Appendectomy is still the treatment of choice; however, in select patients nonoperative management can be attempted
RELEVANT ANATOMY
Location:
Intraperitoneal (95%)
Pelvis (30%) and Retrocecal (65%)
Retroperitoneal (5%)
Size: average 8 cm and 5 to 10 mm wide
Blood supply: appendiceal branch of ileocolic artery (lies behind ileum)
Base of the appendix arises from confluence of the 3 taeniae coli (useful landmark to find appendix)4
McBurney point: most common location of the appendix; one-third of the distance from the anterior superior iliac spine to the umbilicus (Figure 21.1)
ETIOLOGY AND EPIDEMIOLOGY
Appendicitis is due to obstruction of the appendiceal lumen leading to vascular congestion, ischemic necrosis, and subsequent infection2,4
Other causes include lymphoid hyperplasia, carcinoid or other tumors, foreign bodies, and parasites5
Pathophysiology:4
Obstruction of appendiceal lumen → distention due to accumulating mucus
Distention activates T-10 visceral nerve fibers referring to periumbilical region
As pressure increases, lymphatic, venous, and, later, arterial flow are compromised; thus, ischemia ensues
Localized inflammation activates somatic parietal peritoneum pain fibers causing pain in right lower quadrant (RLQ)
Localized abscess or peritonitis occurs late in the process (>24-36 h)
Diffuse peritonitis is more common in young children and infants owing to proportionally smaller omentum that is less able to contain advancing inflammatory process (Figure 21.2)
Rare in children <2 years of age
Children <5 years of age more likely to present with perforation2
 Figure 21.1 Location of appendicitis on a female child. McBurney point is indicated as a dot on the center of a dashed line drawn between the anterior spine of ilium and the navel. (Reprinted with permission from Nath JL. Using Medical Terminology. 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins/Wolters Kluwer Health; 2012.) |
 Figure 21.2 Common causes of peritonitis. (Reprinted with permission from Timby BK, Smith NE. Introductory Medical-Surgical Nursing. 12th ed. Philadelphia, PA: Wolters Kluwer; 2018.) |
CLINICAL PRESENTATION
Appendicitis can affect any age group; however, it is extremely rare in neonates and infants.
Classic presentation: a child with periumbilical pain that over past 12 hours has migrated to RLQ with associated nausea, anorexia, low-grade fever, and leukocytosis.
This presentation however is not very common especially in younger children.
Pain in the RLQ is the most common symptom.
Midabdominal pain migrating to RLQ, and fever increases probability of appendicitis.6
Fever, if not present, decreases probability of appendicitis by two-thirds.6
Anatomic variability of appendix (ie, retrocecal, pelvic) is common and can alter presentation.
Children often lie in bed with minimal movement.
A squirming, screaming child rarely has appendicitis.4
Exception is the retrocecal appendicitis inflaming the ureter and causing renal colic-type symptoms.
Older children will often limp or flex trunk.
Referred testicular pain or urinary frequency is often seen in the cases of pelvic appendicitis because of inflammation of the ureter.4
Anorexia is another classic presenting symptom. Emesis is mild, and diarrhea may be due to ileocecal inflammation.
Severe GI symptoms before onset of pain usually indicate another diagnosis other than appendicitis.5
Low-grade fever with temperature <38.6°C is the norm in nonperforated appendicitis.
Higher temperature suggests severe inflammation or perforation.
Differential Diagnosis
Acute appendicitis can mimic any intra-abdominal process.
Have to keep in mind other inflammatory, infectious, vascular, congenital, and genitourinary conditions including the following:
Gastroenteritis, Crohn disease, mesenteric adenitis (ie, Campylobacter, viruses), pancreatitis, peptic ulcer, cholelithaisis, cholecystitis, Meckel diverticulitis, constipation, intussusception, ovarian torsion, ovarian cysts, pelvic inflammatory disease, renal stones, pyelonephritis, cystitis, etc.5
Systemic disorders that may present with acute abdominal pain include porphyria, sickle cell disease, diabetic ketoacidosis, measles, and parasitic infections.
DIAGNOSIS
Physical Examination
Principal means of diagnosis is history and physical examination.
It decreases number of unnecessary laparotomies without increased risk to the patient.
Signs during physical examination depend on the time course of the disease as well as anatomic location of the appendix.5
Initially tenderness is mild and vague over RLQ.
As the parietal peritoneum becomes irritated, tenderness becomes localized over McBurney point.
Retrocecal appendicitis may cause pain midway between 12th rib and posterior superior iliac spine.
Pelvic appendicitis produces rectal tenderness, testicular pain, or urinary frequency by causing inflammation to surrounding tissues.4
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