This is commonest abdominal surgery emergency
Surgical anatomy
The vermiform appendix can lie in a variety of positions. The relative frequency of the more usual positions occupied by the organ is:
retro cecal 74%
pelvic 21%
post ileal 5%
pre ileal 1%
para ileal 2%
sub cecal 1-5%

if the cecum doesn’t migrate during the development to its normal positions in the right lower quadrant of the abdomen, the appendix can be found near the gall bladder. Very occasionally the cecum and the appendix are situates in the left iliac fossa or in the left hypochondrium. This can cause difficulties of diagnosis if an attack of appendicitis develops in a malpositioned appendix.
The appendix varies considerably in length and circumference. The average length is between 7.5 & 10 cm the lumen , which should admit a matchstick is irregular. 
The mesoappendix which springs from the lower surface of the mesentery is subject to great variations.(what is meso appendix and whr is cecum??) mesoappendix is the mesentery that adjoins to the appendix; cecum is the first part of the colon, after ileum and the ileocecal junction
The appendicular artery is a branch of the lower division of the ileocolic artery. It is an “end artery” and thrombosis of this artery as a result of appendicitis causes necrosis of the appendix ( gangrenous appendicitis ).
Lymphatic vessels : four , six, or more lymphatic channels travels the mesoappendix to empty into ileocecal lymph nodes.
The submucous contains numerous lymphatic follicles. This profusion of lymph tissues has promoted the description of “abdominal tonsil” for the appendix and draws attention to this feature as relevant to the causes of appendicitis.
The visceral layers of the peritoneum envelop the appendix completely except for the narrow line of attachment of the mesoappendix.
Three taenia coli join together at the base of the appendix.
Clinical features
The vast majority of patients with acute appendicitis present with marked localized pain and tenderness in the right iliac fossa .
Typically the pain commences as a central peri-umbilical colic which shifts after approximately 6 hours to the right iliac fossa or more accurately to the site of the inflamed appendix; thus if the appendix id in the pelvic position the pain may then become suprapubic or if it is in the high retrocolic position ,, the symptoms may become localized in the right loin.
Occasionally the tip of the inflamed appendix extends over to the left iliac fossa and pain may be localized there. 
The central abdominal pain is visceral in origin.
The shift of pain is dur to involvement of the sensitive parietal peritoneum by the inflammatory process
Typically the pain is aggravated by movement and the patient prefers to lie still with the knees flexed/
Nausea and vomiting are usually present and follow the onset of pain
Murphy described as a diagnositic sequence” central pain, the vomiting ; then moves to right iliac fossa. 
Anorexia is almost invariable
Constipation is usual, but occasionally diarrhea may occur particularly where the ileum is irritated by the inflamed appendix in the retroileal position
There may be a history of previous milder attacks of similar pain.
With perforation of appendix this is followed by more severe and more generalized pain with profuse vomiting as general peritonitis develops.


Treatment:
If the diagnosis is made at an early stage in the attack and particularly in the absence of a localized mass, all agree that the appendix should be removed urgently.
The treatment of acute appendicitis is appendicectomy except under the following circumstances:
the patient is moribund with advanced peritonitis; here the only hope is to improve his condition by drip and suction, abc, and blood transfusion.
the attack has already resolved; in such a case, the appendicectomy can be advised as a elective procedure, but there is no immediate emergency.
an appendix mass has formed without evidence of general peritonitis (see below)
where circumstances make operation difficult or impossible (ex: at sea)
here, reliance must be placed on conservative regime and the hope that resolution or local abscess will form rather than on one’s surgical skill with a razor blade and a bent spoon.
One should avoid using such statements as “conservative treatment is employed after 48-hours”. Nature does not on anytime relationships.

Appendicectomy:
When the diagnosis is certain, the grid-iron incision is the best one to be employed.
When diagnosis is in doubt the lower right paramedian incision is preferable because it gives good access to the pelvic organs in the female and if necessary it can be readily extended to deal with a perforated duodenal ulcer or other unexpected intra abdominal pathology.

the grid-iron incision:
an adequate incision is made at the right iliac fossa at right angles to a line joining the anterior superior iliac spine to the umbilicus; its center being at the Mc Burney’s point.
the external oblique is incised in the length of incision
the fibers of the internal oblique and the transverses abdominis are separated, and after suitable retraction the peritoneum is opened.

2.    the paramedian incision:
is a vertical incision lying parallel to and 1.25 to 2.5 cm to the right of the middle line. It commences 2.5 cm below the level of the umbilicus and ends just above the pubis
the anterior rectus sheath is incised in the line of the incision and the rectus muscle is retracted laterally 
branches of the inferior epigastric vessels may require ligation
the transversalis fascia and the peritoneum is incised together

3.    Rutherford Morison’s incision:
It is useful if the appendix is para- or retro- caecal and fixed. It is essentially an oblique muscle cutting incision with its lower end over Mc Burney’s point and extending obliquely upwards and laterally as necessary. All layers are divided in the line of incision

The caecum is withdrawn; once the appendix has been delivered the caecum is grasped by an assistant. The base of the mesoappendix is clamped in a hemostat, tied , and severed.
The appendix now completely freed is crushed near its junction with the caecum in a hemostat, which is removed and reapplied just distal to the crushed portion.
A catgut ligature is tied around the crushed portion of the caecum.
An atraumatic catgut purse-string suture is inserted into the cecum about 1.25 cm from the base. The string  passes through the muscle coat, especially picking up taenia coli. It is left untied until the appendix has been amputated with a scapel below the hemostat.
The stump is invaginated while the purse-string suture is tied , thus burying the appendix stump.
It is better not to attempt invagination. the stump of the appendix should be ligated and the cut surface touched with the diathermy in attempt to reduce infection.

4.    Retrograde appendicectomy:
When the appendix is retrocecal and adherent. We have to divide the base of the organ between hemostats. The organ is removed from base to tip.

Drainage of peritoneal cavity
Adequate peritoneal toilet has been done. If there is considerable purulent fluid in the retrocecal space or the pelvic, or if there is persistent oozing, it is wise to bring out the penrose or silastic drain through a separate stab incision.

Drainage of the parietes:
This is indicated if there is any soiling of the wound, especially in obese and in children
The rule is : if in doubt drain, and especially the parietes

by col3neg

published Date 2017-03-23