APPENDIX
Anatomy
Appendix becomes first visible in the 8th week of embryological development as a
protuberance from the terminal portion of the cecum. During both ante-natal &post-natal
development, the cecal growth rate exceeds that of the appendix displacing the appendix
medially towards the ileo-cecal valve(so that the appendix becoming retro-cecal).The
relationship of the base of the appendix to the cecum remains constant but the tip can be
found in different positions.{74%retrocecal, 21%pelvic, 2%paracecal, 1.5%subcecal, 1%preileal, 0.5%post-ileal}
Sometimes the cecum doesn't migrate into the Rt. Lower quadrent,as a consequence the
appendix can be found in near the gall bladder. In cases of gut malrotation,the cecum(&so
the appendix) will be found in the Lt. lower quadrent.
The different locations account for difficulties in reaching diagnosis of acute appendicitis.
The longitudinal muscle layer of the large bowel (tenia coli)converge &meet at the base of
the appendix forming the appedicular outer longitudinal muscular layer. Following the tenia
coli(especially the anterior one) help in finding the base of appendix during surgery.
The appendix is supplied by the appendicular artery which arises from the lower division of
ileocecal artery, passes behind the terminal ileum till enters the mesoappendix just distal to
appendicular base. Mostly, the appendicular artery is an end artery.Venous blood reaches
the portal system via superior mesenteric vein.
Lymphatics drain into the ileocecal lymph nodes .
The mesoappendix is part of mesentery of terminal ileum, it's transparent in young children
allowing easy visualization of blood vessels,but with advancing age the mesentery becomes
fat-laden obscuring blood vessels.
The appendix varies greatly in size, averaging 7.5_10 cm in length.
The wall consists of mucosa,submucosa,muscularis& serosa.
Mucosa is columnar-celled, thrown into folds& crypts.At the bases of the latter, lie the
argentaffin cells(from which originate carcinoid tumour).The submucosa contains lymphatic
follicles(the number of which varies with age).
For many years the appendix has been regarded as a vestigial functionless organ. But now
it's well-recognized that the appendix has immunologic function (being part of the GALT)
participating in secretion of immunoglobulin(especially IgA).Despite that,this function isn't
essential &appendicectomy doesn't lead to immunocompromise.
Incidence:
Appendectomy for acute appendicitis is the most frequently performed urgent abdominal
operation.
Acute appendicitis is relatively rare in infants but becomes increasingly common in
childhood & early adult life, reaching a peak in the teens &early 20s;then the incidence
decreases.
Prior to puberty,incidence is equal among males &females; after that male:female ratio
increases. But the male predominance declines with advancing age.
The percentage of misdiagnosis of appendicitis is significantly higher among females than
males & in women the highest rate of negative appendectomies was in elderly ones.
Etiology & pathophysiology:
Luminal obstruction is the dominant causal factor in acute appendicitis. The causes of
obstruction are: fecoliths, lymphoid tissue hypertrophy ,tumours, inspissated barium from
previous x-ray studies, vegetable & fruit seeds & intestinal parasites.the frequency of
obstruction rises with the severity of the inflammatory process(i.e,fecoliths are found in
40% of cases of simple acute appendicitis,65% of cases of gangrenous appendicitis without
perforation & about 90% in cases of gangrenous appendicitis with perforation.
When proximal appendicular lumen is obstructed & normal secretion continues by the
mucosa ,the appendix distends.Distension is also caused by multiplication of the already
present bacteria.This distention stimulates the visceral afferent nerves, producing a
vague,diffuse pain in the in the umbilicus or lower epigastrium. Also it produces reflex
nausea &vomiting.
As intra-luminal pressure rises venous return is impaired while arterial flow continues
leading to congestion ;inflammation soon extends to the serosa & adjacent parietal
peritoneum producing the characteristic shift in pain to Rt. lower quadrant.
With progression of the condition,arterial inflow is impaired & mucosa ulcerates allowing
bacterial invasion to the submucosa &muscularis propria leading to acute appendicitis.
Sometimes,the inflammation resolves spontaneously but only apparently as recurrence is
common. Subsidence of inflammation may leave the organ distended with mucus_ a
mucocele.
Further impairment of blood supply leads to ischemic necrosis of the appendix and
subsequent perforation(usually just beyond obstruction point at the anti-mesenteric
border). Gangrenous appendicitis+/- perforation.
Perforation may occur into the general peritoneal cavity leading to generalized peritonitis Or
the greater omentum & bowel loops adhere to the inflamed appendix localizing the
inflammatory process leading to appendicular mass or abscess.
Certain factors promote perforation,including:
Extremes of age.
Immunosuppresion.
Diabetes mellitus.
Fecolith obstruction.
Pelvic appendix.
Previous abdominal surgery.
Clinical features:
Symptoms
•
Abdominal pain: the cardinal symptom.
Classically, the pain is initially vague centered in the umbilicus or lower epigastrium,
moderately severe, steady with intermittent cramps.after a period of time(usually 4-6 hours)
the pain localizes to the Rt. Lower quadrant.
This classic visceral-somatic pain sequence is present in only 50% of cases. Atypically,the
pain may start in the Rt. Lower quadrant & remains there. Sometimes,the pain maybe only
in the mid-abdomen.
Different locations of the appendix also accounts for different presentation. i.e,retro-cecal
appendix may present with flank or backache,pelvic appendix may cause suprapubic pain,
post-ileal appendix may cause testicular pain from irritation of spermatic artery &ureter.
•
Anorexia: nearly always accompanies appendicitis(diagnosis should be questioned if
anorexia is absent .)
•
Vomiting: despite that about 75% of patients with appendicitis vomit,it's neither
prominent nor prolonged (most of them vomit once or twice.)
*The pattern of bowel function is of little diagnostic value. Most of the patients would give a
history of constipation prior to the onset of abdominal pain & many feel that defecation
would relieve their abdominal pain.But diarrhea with tenesmus occur in other patients
especially those with pelvic appendix .
The sequence of symptom appearance has a great diagnostic significance: In 95% of
patients, anorexia is the first symptom, followed by abdominal pain & the latter is followed
by vomiting (if vomiting occurs). If vomiting precedes the onset of pain, diagnosis of
appendicitis should be questioned.
Signs :
The cardinal signs of appendicitis are low grade-pyrexia, localized lower abdominal
tenderness, muscle guarding ,rebound tenderness.
Temperature: is normal in the beginning of illness, but may rise thereafter.the elevation
rarely exceed 1 C° with a corresponding rise in pulse rate. Greater changes in temperature
indicates that a complication has occurred or the another diagnosis should be considered.
Abdominal signs:
The patients prefer to lie still with the thighs(especially the Rt. one) drawn up because any
motion would increase the pain & if asked to move they do slowly & cautiously.
There may be limitation in abdominal movement with respiration.
The patient points by a finger that the pain started at the umbilicus, then shifted to the Rt.
Lower quadrant(pointing sign.)
There is Rt. Lower quadrant tenderness maximum at the McBurney's point(Junction of the
medial 2/3 & lateral 1/3 of an imaginary line between anterior superior iliac spine &the
umbilicus). Rebound tenderness is also found at this point .
Asking the patient to cough,will produce pain in the Rt.lower quadrant(cough sign.)
When pressure is exerted in the Lt.lower quadrant, tenderness might be felt in the Rt.lower
quadrant(Rovsing's sign). Refered rebound tenderness may also be found.
Cutaneous hyperesthesia in the area supplied by T10,T11,T12 spinal nerves on the Rt.side
may be found early in the disease before other signs become evident.
Early in the disease course, muscular resistance to palpation is voluntary(i.e,guarding) but as
peritoneal irritation progresses a true reflex rigidity develops.
Variations in locations of appendix may alter the encountered physical signs:
Retro-cecal appendix may have maximum tenderness in the Rt.flank.
In pelvic appendix,abdominal signs may be less or even absent.However, per-rectal
examination provokes suprapubic pain & local rectal tenderness. In addition,Psoas
&Obturator signs may be positive. Psoas sign is demonstrated by lying the patient in the
Lt.lateral position &the examiner slowly extends the Rt.hip thereby stretching iliopsoas
muscle;such movement produces Rt.lower quadrant pain if the inflamed lies near the
muscle.Similarly, Obturator test is regarded positive if suprapubic pain occure when the
flexed Rt.hip is passively internally rotated.
Named physical signs in appendicitis
Blumberg's sign Rebound tenderness in the Rt. lower quadrant
Dunphy's sign Cough sign
Cope's test/sign Psoas & Obturator signs
Markle's sign
Pain in the Rt.lower quadrant on dropping from standing on toes to heels
Ten Horn sign Abdominal pain caused by gentle traction on the Rt.spermatic cord
Bassler's sign
Aaron's sign
Referred pain felt in the epigastrium upon continuous pressure over
McBurney's point_ chronic appendicitis?
Investigations
Laboratory
WBC count ranging from 11,000_18,000/mm3 is usually present in patients with acute
uncomplicated appendicitis & is often accompanied by polymorph predominance. Counts
higher than 18,000/mm3 raises the possibility of perforation.
Urinalysis is useful in differentiating appendicitis from urinary infection. Patients with more
than 30 RBC/HPF. in a specimen of voided urine should be suspected of having urinary tract
disease as is the presence of bacteria; however pyuria some RBCs & minimal albuminuria
may present in the urine of patient with appendicitis if the inflamed appendix lying close to
the ureter (retrocecal appendix.)
The finding of anemia in elderly patients with features of appendicitis should raise the
suspicion for cecal cancer.
Women of childbearing age,with lower abdominal pain should be submitted for pregnancy
test.
Plain abdominal x_rays
Not indicated routinely in acute appendicitis.the following may be seen in acute
appendicitis:
Fecolith, localized ileus in the Rt. Lower quadrant ,loss of peritoneal fat stripping.
**N.B The accidental finding of a fecolith on a plain abdominal x_ray is an indication for
elective appendicectomy.
Ultrasonograghy(U/S)
Sensitivity 82%,specificity 96%
The appendix is visualized & the pain is assessed as gradually increasing pressure is placed
on the the area of the appendix with U/S probe.False negative results are associated with
failure to visualize the appendix.U/S is examiner dependent.the study is less beneficial in
obese patients and in the presence of plenty of bowel gas.
Features of abnormal appendix:
•
tubular non-compressible structure ≥ 6 mm diameter
•
presence of an appendicolith.
CT scan
Sensitivity 90%,specificity85%.
Features of abnormal appendix:
•
The wall appear circumferentially-thickened
•
Fluid-filled
•
Periappendicular inflammation along with fat stranding, fluid collection, phlegmon
formation.
**N.B Barium enema is no longer in use in the diagnosis of appendicitis,but was used prior
to advent of U/S or CT scan.