Appendicitis (or epityphlitis) is a condition characterized by inflammation of the appendix. All cases require removal of the inflamed appendix, either by laparotomy or laparoscopy. Untreated, mortality is high, mainly because of peritonitis and shock. Reginald Fitz first described acute appendicitis in 1886, and it has been recognized as one of the most common causes of acute abdomen pain worldwide.
On the basis of experimental evidence, acute appendicitis seems to be the end result of a primary obstruction of the appendix lumen. Once this obstruction occurs the appendix subsequently becomes filled with mucus and swells, increasing pressures within the lumen and the walls of the appendix, resulting in thrombosis and occlusion of the small vessels, and stasis of lymphatic flow. Rarely, spontaneous recovery can occur at this point. As the former progresses, the appendix becomes ischemic and then necrotic. As bacteria begin to leak out through the dying walls, pus forms within and around the appendix (suppuration). The end result of this cascade is appendiceal rupture causing peritonitis, which may lead to septicemia and eventually death.
Among the causative agents, such as foreign bodies, trauma, intestinal worms, and lymphadenitis, the occurrence of an obstructing fecalith has attracted attention. The prevalence of fecaliths in patients with appendicitis is significantly higher in developed than in developing countries, and an appendiceal fecalith is commonly associated with complicated appendicitis. Also, fecal stasis and arrest may play a role, as demonstrated by a significantly lower number of bowel movements per week in patients with acute appendicitis compared with healthy controls. The occurrence of a fecalith in the appendix seems to be attributed to a right sided fecal retention reservoir in the colon and a prolonged transit time. From epidemiological data it has been stated that diverticular disease and adenomatous polyps were unknown and colon cancer exceedingly rare in communities exempt for appendicitis. Also, acute appendicitis has been shown to occur antecedent to cancer in the colon and rectum. Several studies offer evidence that a low fiber intake is involved in the pathogenesis of appendicitis. This is in accordance with the occurrence of a right sided fecal reservoir and that dietary fiber reduces transit time.
Atypical symptoms may include pain beginning and staying in the right iliac fossa, diarrhea and a more prolonged, smoldering course. If an inflamed appendix lies in contact with the bladder, there is frequency of micturition. With post-ileal appendix, marked retching may occur. Tenesmus or "downward urge" (the feeling that a bowel movement will relieve discomfort) is also experienced in some cases.
Other signs are:
Ultrasonography and Doppler sonography provide useful means to detect appendicitis, especially in children. In some cases (15% approximately), however, ultrasonography of the iliac fossa does not reveal any abnormalities despite the presence of appendicitis. This is especially true of early appendicitis before the appendix has become significantly distended and in adults where larger amounts of fat and bowel gas make actually seeing the appendix technically difficult. Despite these limitations, in experienced hands sonographic imaging can often distinguish between appendicitis and other diseases with very similar symptoms such as inflammation of lymph nodes near the appendix or pain originating from other pelvic organs such as the ovaries or fallopian tubes.
In places where it is readily available, CT scan has become the diagnostic test of choice, especially in adults whose diagnosis is not obvious on history and physical. (The use of CT in pregnant women and children is significantly limited, however, by concerns regarding radiation exposure.) A properly performed CT scan with modern equipment has a detection rate (sensitivity) of over 95% and a similar specificity. Signs of appendicitis on CT scan include lack of oral contrast (oral dye) in the appendix, direct visualization of appendiceal enlargement (greater than 6 mm in diameter on cross section), and appendiceal wall enhancement (IV dye). The inflammation caused by appendicitis in the surrounding peritoneal fat (so called "fat stranding") can also be observed on CT, providing a mechanism to detect early appendicitis and a clue that appendicitis may be present even when the appendix is not well seen. Thus, diagnosis of appendicitis by CT is made more difficult in very thin patients and in children, both of whom tend to lack significant fat within the abdomen. The utility of CT scanning is made clear, however, by the impact it has had on negative appendectomy rates. For example, use of CT for diagnosis of appendicitis in Boston, MA has decreased the chance of finding a normal appendix at surgery from 20% in the pre-CT era to only 3% according to data from the Massachusetts General Hospital.
According to a systematic review from UC-San Francisco comparing ultrasound vs. CT scan, CT scan is more accurate than ultrasound for the diagnosis of appendicitis in adults and adolescents. CT scan has a sensitivity of 94%, specificity of 95%, a positive likelihood ratio of 13.3 (CI, 9.9 to 17.9), and a negative likelihood ratio of 0.09 (CI, 0.07 to 0.12). Ultrasonography had an overall sensitivity of 86%, a specificity of 81%, a positive likelihood ratio of 5.8 (CI, 3.5 to 9.5), and a negative likelihood ratio of 0.19 (CI, 0.13 to 0.27).
Matrix metalloproteinase (MMP) levels can be used as biomarkers of increased risk of appendiceal rupture among patients with acute appendicitis according to a cohort study. MMP-1 was higher in gangrenous (p<0.05) and perforated appendicitis (p<0.01) compared with controls. MMP-9 was most abundantly expressed in inflamed appendix and reached a tenfold higher expression in all groups with appendicitis compared with controls (p<0.001).
A number of clinical and laboratory based scoring systems have been devised to assist diagnosis. The most widely used is Alvarado score.
|Migratory right iliac fossa pain||1 point|
|Nausea and vomiting||1 point|
|Right iliac fossa tenderness||2 points|
|Rebound tenderness||1 point|
|Shift to left (segmented neutrophils)||1 point|
|Total score||10 points|
A score of 7 or more is strongly predictive of acute appendicitis.
In patients with an equivocal score of 5-6, CT scan further reduces the rate of negative appendicectomy.
The surgical procedure for the removal of the appendix is called an appendicectomy (also known as an appendectomy). Often now the operation can be performed via a laparoscopic approach, or via three small incisions with a camera to visualize the area of interest in the abdomen. If the findings reveal suppurative appendicitis with complications such as rupture, abscess, adhesions, etc., conversion to open laparotomy may be necessary. An open laparotomy incision if required most often centers on the area of maximum tenderness, McBurney's point, in the right lower quadrant. A transverse or a gridiron diagonal incision is used most commonly.
In March 2008, an American woman had her appendix removed via her vagina, in a medical first.
According to a meta-analysis from the Cochrane Collaboration comparing laparoscopic and open procedures, laparoscopic procedures seem to have various advantages over the open procedure. Wound infections were less likely after laparoscopic appendicectomy than after open appendicectomy (odds ratio 0.45; CI 0.35 to 0.58), but the incidence of intraabdominal abscesses was increased (odds ratio 2.48; CI 1.45 to 4.21). The duration of surgery was 12 minutes (CI 7 to 16) longer for laparoscopic procedures. Pain on day 1 after surgery was reduced after laparoscopic procedures by 9 mm (CI 5 to 13 mm) on a 100 mm visual analogue scale. Hospital stay was shortened by 1.1 day (CI 0.6 to 1.5). Return to normal activity, work, and sport occurred earlier after laparoscopic procedures than after open procedures. While the operation costs of laparoscopic procedures were significantly higher, the costs outside hospital were reduced. Young female, obese, and employed patients seem to benefit from the laparoscopic procedure more than other groups.
There is debate whether emergent appendicectomy (within 6 hours of admission) reduces the risk of perforation or complication versus urgent appendicectomy (greater than 6 hours after admission). According to a retrospective case review study no significant differences in perforation rate among the two groups were noted (P=.397). Various complications (abscess formation, re-admission) showed no significant differences (P=0.667, 0.999). According to this study, beginning antibiotic therapy and delaying appendicectomy from the middle of the night to the next day does not significantly increase the risk of perforation or other complications. These findings may fit a theory that acute (typical) appendicitis and suppurative (atypical) appendicitis are two distinct disease processes. Findings at the time of surgery suggest that perforation occurs at the onset of symptoms in atypical cases.(1)
Surgery may last from 15 minutes in typical appendicitis in thin patients to several hours in complicated cases. Hospital lengths of stay usually range from overnight to a matter of days (rarely weeks in complicated cases.) The pain is not always constant; in some cases it can stop for a day and then come back.
The real possibility of life-threatening peritonitis is the reason why acute appendicitis warrants speedy evaluation and treatment. The patient may have to undergo a medical evacuation. Appendectomies have occasionally been performed in emergency conditions (i.e. outside of a proper hospital), when a timely medical evaluation was impossible.
Typical acute appendicitis responds quickly to appendectomy and occasionally will resolve spontaneously. If appendicitis resolves spontaneously, it remains controversial whether an elective interval appendectomy should be performed to prevent a recurrent episode of appendicitis. Atypical appendicitis (associated with suppurative appendicitis) is more difficult to diagnose and is more apt to be complicated even when operated early. In either condition prompt diagnosis and appendectomy yield the best results with full recovery in two to four weeks usually. Mortality and severe complications are unusual but do occur, especially if peritonitis persists and is untreated. Another entity known as appendicular lump is talked about quite often. It happens when appendix is not removed early during infection and omentum and intestine get adherent to it forming a palpable lump. During this period operation is risky unless there is pus formation evident by fever and toxicity or by USG. Medical management treats the condition.
An unusual complication of an appendectomy is "stump appendicitis": inflammation occurs in the remnant appendiceal stump left after a prior, incomplete appendectomy.
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