(1)
Introduction
The appendix is a true diverticulum of
the cecum, its base originating at the confluence of the teania coli.
The appendix is relatively large at birth and progressively decreases
in size until age 5 years. Its position with regard to the cecum can
be variable and this explains its many potential presentations when
inflammation occurs. Variable presentations are also common in the
extremes of age.
(2)
Pathophysiology
By definition, the pathologic finding in
acute appendicitis is mucosal disruption with invasive infection and
inflammation. The invasive organisms, consistent with normal stool
flora, include E. Coli, Klebsiella, and Enterobacter. The inciting
event is thought to be luminal obstruction, most commonly from a
fecalith (40 percent of perforated appendicitis) or lymphoid
hyperplasia (most commonly in children). However, not all luminal
obstructions cause acute appendicitis and certainly not all acute
appendicitis is caused by obstruction. Following obstruction the
appendix continues to secrete into a closed lumen causing increased
luminal pressures with eventual venous congestion and infarction along
the watershed region. Eventual perforation is preceded by mucosal
ulceration and transmural necrosis. Abscess formation or peritonitis
may ensue.
(3)
Presentation
(a) Differences
in sex and age at presentation will alter the initial clinical
scenario. Children less than 5 years of age and adults over the age of
50 will typically present later in the disease process and frequently
with vague signs and symptoms.
(b) With
acute appendicitis, vague epigastric and periumbilical pain presents
early and is described as a dull ache. This pain is regulated by
autonomic visceral pain fibers. Nearly 95 percent of patients will
experience a pain similar to this described. Anorexia is present in
90 percent of patient’s at this stage. In fact, if a person is hungry
upon history taking, the diagnosis of acute appendicitis must be
questioned. Approximately 4 to 6 hours after initial onset of illness
the inflammation extends, activating the somatic pain fibers and
localizing the pain to the region of the appendix. This is most
commonly in the right lower quadrant at McBurney's point; however,
the variability of anatomic locations of the appendix (retrocecal,
etc.) may cause the pain to be localized in almost any region. A
good history is the most helpful tool in making a diagnosis.
(c) Acute
appendicitis is known as the great imitator and can cause right upper
quadrant pain, perineal and rectal fullness and pain, and a collection
of other presentations. Acute appendicitis should be in the
differential diagnosis for anyone presenting with acute abdominal
pain.
(d) Once
the pain localizes, it is common to find the patient very still with
voluntary guarding. Cutaneous hyperesthesia is present over the point
of maximal tenderness and pain. A low-grade temperature is now very
common (38
°C)
and now a low-grade leukocytosis is also commonly present (WBC of
12,000 to 16,000). A WBC greater than 18,000 is not generally seen at
this point of the process and should suggest another possible
diagnosis. Certainly after perforation a high WBC is not uncommon.
Progression will lead to perforation and either abscess formation with
the associated signs and symptoms.
(e) Other
signs on examination include right lower quadrant pain with palpation
in the left lower quadrant (Rovsing's sign), obturator internus (obturator
sign), and psoas sensitivity (psoas sign). These are indicative of
peritoneal inflammation. Increased pain upon coughing (Dunphy's sign)
is less consistent. Patients with symptoms present for over 48 hours
are unlikely to have acute appendicitis, as this process will
typically take less than 24 hours to manifest.
(4)
Differential Diagnosis
(a) As
stated earlier, the female patient not uncommonly presents with signs
and symptoms consistent with acute appendicitis, however up to 40
percent of young women explored for appendicitis had a negative
surgical exploration of the appendix. Salpingitis, ruptured ovarian
follicle, and ectopic pregnancy must be considered as the diagnosis
with the appropriate work-up initiated. Surgical exploration is,
however, warranted if any question remains regarding possible acute
appendicitis.
(b) Mesenteric
lymphadenitis and associated viral gastroenteritis are the most common
diagnoses found when acute appendicitis is ruled out. The symptom
complex and progression as well as a careful history and physical
examination will provide diagnostic clues. Very rarely will a patient
with acute appendicitis first present with diarrhea and high fevers.
This is more suggestive of a viral complex with gastroenteritis as the
primary diagnosis.
(c) Other
considerations in the differential diagnosis of abdominal pain
resembling acute appendicitis include:
-
Gastroenteritis (viral or bacterial)
-
Acute regional ileitis ( crohn’s
disease )
-
Ureteral colic
-
Salpingitis
-
Ruptured ovarian follicle
-
Ovarian torsion
-
Ectopic pregnancy
-
Diverticulitis
-
Perforated ulcer
-
Cholecystitis
-
Perforated neoplasm
-
Urinary tract infection
(5)
Treatment
(a) Appendectomy
is the correct treatment for most patients with acute appendicitis.
Patients presenting late in their disease progression with either a
periumbilical phlegmon or abscess may initially respond to
non-operative antibiotic therapy. Surgery should be performed only
by qualified surgeons. The initial treatment of appendicitis can
be intravenous antibiotics, bed rest, NPO, and semiurgent or urgent
medical evacuation.
(b) Ultimately
those patients treated non-operatively should undergo interval
appendectomy 6 to 8 weeks after their episode of appendicitis. This
form of treatment may be the only course available for the active duty
member stationed at a remote site where surgical consultation is not
readily available. In this instance the patient should receive
intravenous fluid therapy, be kept NPO, and receive broad-spectrum
antibiotics covering the common gastrointestinal flora, specifically
gram (-) rods and anaerobes. A good combination is Unasyn 3.0 grams
IV every 6 hours and Flagyl 500mg IV every 6 hours. A broad-spectrum
cephalosporin such as cefotan is also acceptable. Whenever possible,
surgical consultation should always the first choice. The typical
recovery from a non-complicated appendectomy is10-14 days. Active
duty members whose job requires physical activity should be withheld
from activity for approximately 4 weeks.
Submitted by CAPT
William Liston, MC, USN, Head, Department of Surgery, Naval Medical
Center Portsmouth, Portsmouth, Virginia (1999).
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