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Holzheimer RG, Mannick JA, editors. Surgical Treatment: Evidence-Based and Problem-Oriented. Munich: Zuckschwerdt; 2001.

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Surgical Treatment: Evidence-Based and Problem-Oriented.

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Appendicitis

, M.D., Ph.D.

Department of Surgery, University Hospital, Linköping, Sweden

Introduction

The treatment of acute appendicitis was non-operative up till a hundred years ago then it turned totally surgical in less than 20 years. Appendectomies per 100,000 population peaked at mid century and has since steadily declined in western countries. It seems that surgeons are returning to the core of knowledge about appendicitis held in the late 1800s. The mortality was relatively low as most appendicitis resolves spontaneously but there was a significant recurrence of the appendicitis. The surgical pioneers of appendectomy feared that the operative mortality exceeded that of conservative treatment at the time and hence they avoided the acute operation. They were familiar with and feared the recurrence and therefore did interval appendectomy to prevent the relapse. When emergency appendectomy exploded in the first years of the last century the mortality in appendicitis did not decline. Indeed, vital statistics from Sweden show that the death rate from appendicitis in the population was unchanged or higher at least up till 1930 (1).

Increasing the diagnostic accuracy

Especially the number of negative appendectomy but also operations for simple appendicitis are declining while the operations for gangrene and perforation remain stable (2). The diagnostic accuracy is therefore increasing. Negative appendectomy of 30% was thought acceptable but it is now possible to reach a diagnostic accuracy in excess of 90% for men while that of women is less good. Appendicitis is more common in men for unknown reasons but the incidence of appendectomy is nearly identical in men and women. This is not explained by misdiagnosis of gynecologic disease but is better explained by the larger number of women that seek attention for pain of the right lower quadrant (3). Each such patient has a certain chance of being subjected to an appendectomy.

The inclination to operate patients with suspected appendicitis is strongly influenced by traditions and believes that are very difficult to treat in an evidence-based manner. The beliefs are:

1.

all appendicitis need an operation,

2.

all appendicitis progress to gangrene, and

3.

immediate operation will prevent gangrene and perforation.

When such perceptions make up the foundation of clinical praxis and the quality of care is measured by the delay of the operation or proportion of perforation it is very difficult to challenge these perceptions. Neither of them will be subjected to scientific test as they are part of the foundation according to which appendicitis is managed. However, there is indirect evidence to suggest that all three perceptions are wrong.

The most impressive evidence is perhaps the results of two randomized clinical trials of non-operative treatment of appendicitis (4). The larger trial is as yet unpublished. Patients with clear clinical signs of acute appendicitis (excluding obvious perforation) were randomized to operation or antibiotic treatment. In this trial the diagnostic accuracy in the operated arm was 94% and hence a similar number of true appendicitis in the antibiotic arm. 90% of the antibiotic cases resolved without an operation (Eriksson, Karolinska, Stockholm, personal communication). The trial immediately refutes the perception that all acute appendicitis need an operation but also the perception that all appendicitis progress to worse forms.

How true is it that an immediate operation prevents perforated appendicitis? There is no random clinical trial that examines this fundament of the management. From population studies which show the incidence of perforations per 100,000 population it is remarkable how independent perforations are to the total incidence of appendectomy. In one study (years 1970–1989) the incidence of appendectomy fell by 29% from 256 to 182 per 100,000 population but the perforations were stable at 21 per 100,000 population (2). The results are similar in several other studies that are population based. An interpretation, among others, is that surgeons will operate all with perforation but whether they operate many or few with suspected appendicitis is of no consequence, and therefore surgeons probably are unable to influence the perforations. Another interpretation is that only a minority of all appendicitis will go on to perforation. For this small subgroup surgical behavior is unimportant and does not reflect in population statistics. All that counts is that the perforations are operated when they are diagnosed.

Clinical diagnosis of appendicitis

Appendicitis is peritonitis and shows the common signs which are abdominal tenderness and systemic inflammation. The disease history obtained from the patient provides only the time frame and progression of the episode. The surgeon must integrate the information from history, abdominal examination and laboratory tests of acute inflammation to reach the diagnosis (5, 6). The basic boundaries are disease progression over 8 to 48 hours, with distinct tenderness of the right lower quadrant associated with rebound tenderness, and increased temperature, leukocytosis with left shift and increased concentration of C-reactive protein. Outside such boundaries the chance that it is appendicitis is progressively reduced. For instance, it is uncommon that abdominal tenderness without systemic inflammation is appendicitis.

Every surgeon will be able to relate appendicitis that had an atypical presentation where the traditional diagnostic signs were minimal or absent. It cannot be denied but it begs the question if patients with minimal responses need an operation.

Clinical diagnosis supported by scoring methods

The many well-recognized diagnostic items from history, physical examination and laboratory tests lend themselves to statistical modeling to aid the clinician about the diagnosis. Several such scores have been compared and validated in another hospital. In general, none of the scores has been acclaimed as they tend to perform worse than clinical judgement alone in the test situation (7, 8). A possible explanation is that the scores depend on local interpretation of the contributing factors which are not sufficiently objective; e.g. the presence and degree of rebound tenderness (9). The score can therefore only be used in conjunction with clinical judgement but then provide a structured evaluation that may be an educational aid for the young surgeon.

Ultrasonographic diagnosis of appendicitis

This diagnostic aid has been tried extensively with very differing results. In the hands of a dedicated radiologist US may have similar, or better, accuracy than clinical diagnosis alone (10, 11). When used by surgeons as part of their clinical evaluation of the patient the results are disappointing (12, 13). Apart from being dependent on the investigator there are other limitations of the technique. In particular it is difficult to exclude appendicitis as the normal appendix may be hard to visualize especially in obese patients. Unless substantial improvement of the technique becomes available US will remain a marginal investigation for use in patients under observation.

Computed tomography diagnosis of appendicitis

The appendix is nearly always visible with a helical CT scan. It is claimed that an enlarged appendix with periappendiceal fat stranding is present in 93% of patients with appendicitis but there are additional signs of appendicitis (14). Both the sensitivity and the specificity can be higher than for the clinical diagnosis. In a recent study of 100 consecutive patients with suspected appendicitis reviewed in the emergency department before being admitted to hospital the diagnostic accuracy was 98% when checked against histology in the 59 operated patients and follow-up in those not operated. It was claimed that unnecessary operations could have been avoided, but also hospital admission for observation could be avoided based on the results of the CT scan (15). In addition a number of other diagnoses were established. In a following study some of these claims were supported in that the negative appendectomy rate was reduced from 20% to 7% and to only 3% in those who had had a CT before the operation (16).

It seems quite clear that the CT scan can provide a diagnostic accuracy in excess of the best clinical diagnosis. The diagnosis can be established without observation. Its potential is therefore to change clinical management by reducing negative appendectomy to a minimum and to shorten or eliminate observation for possible appendicitis. Several independent studies that confirm the accuracy will be needed.

Specific components of the appendectomy

Appendectomy is one of the most commonly performed operations with about 7% of the population having that operation. It should be an operation where every detail has been examined in prospective clinical trials but it is not. Of an overwhelming number of scientific reports on appendicitis (more than 5500 entries in the Medline) only a few are about randomized trials. We should have firm knowledge about such things as antibiotic treatment (initiation, route and duration), wound management (incision and closure) and excision of the appendix (stump closure and drains). It seems that much of the surgical technique evolved from traditions and later knowledge has been engaged in simplification. For example, multiple drains with or without continuous irrigation are not used for perforated appendicitis any longer but it must have made sense at the time. Even the single passive drain for a periappendiceal abscess is thought inappropriate by most surgeons today. So, when speaking about evidence here it must be viewed against strong traditions that are continuously changing regardless of real scientific evidence. When such evidence is available its penetration is often slow. Further, it must be accepted that the underlying conditions have changed so what seemed reasonable at one time is no longer appropriate. For instance, wounds used to be infected in the range of 30–50% in perforating appendicitis. Infection is much less frequent now for reasons that patient care and surgical technique are different.

Antibiotic prophylaxis and therapy

The appendectomy ranges from clean-contaminated to contaminated and dirty surgery. There can be no antibiotic regimen that is universally appropriate. The antibiotic or a combination should be suitable for emergency intestinal surgery. It should be instituted before skin incision. The duration should be according to the operative findings, meaning single dose in normal appendix or simple inflammation. For gangrene without abscess studies show that 1 or 2 days are adequate while the perforated appendix may require prolonged treatment over several days (17, 18). There is no indication for treatment beyond the time in hospital although this has not been properly examined.

Primary closure of the wound or delayed

The established treatment of war wounds with delayed primary closure (DPC) was introduced as an effective means of avoiding postoperative wound infection. Several case series in appendicitis supported its use. There are only two prospective randomized trials but none demonstrated a benefit (19, 20). In a recent structured review of primary closure and DPC for gangrenous and perforating appendicitis no superiority of DPC was found (21). This result was based on 2532 patients reported in 27 studies. The wound infection rate was 4.6% and 4.7% for the two principles of wound treatment. All these patients had had antibiotic treatment instituted prior to the operation.

The appendix stump

It is traditional to bury the appendix stump into the base of the caecum. It can be done single, with one purse string suture, or double. The origin of this practice is probably very old and may be a correlate to the inversion of an anastomosis, which is unnecessary as shown by everted stapled anastomosis. There are several case series which show that invagination of the appendix stump is unnecessary. There are also at least four prospective randomized trials comparing simple ligation with invagination. The largest of these trials included 735 operations equally randomized between ligation alone and stump invagination (22). All the results go in the same direction: it is simpler and quicker with just ligation. Additional benefits are no deformity of the caecum and possibly lower infection rate.

There is also an obscure practice of coagulation of the mucosa of the stump with diathermy, believed to prevent infection. When laparoscopic appendectomy made burial of the stump impractical some surgeons instead chose to coagulate the stump. There are no trials of this practice but from theoretical considerations it must be very wrong. The coagulation is more likely to destroy tissue than the bacteria that rather thrive on the dead tissue.

Laparoscopic appendectomy

For once there are several dozens of trials available from which repetitive information can be extracted. The largest and most recent of the prospective randomized trials included 523 patients (23). It showed that the operation time for laparoscopy was longer (+ 25 minutes) but patients had less pain and recovered quicker (- 1 week). There was no statistical difference for hospital stay or sick leave. The latter reflect administrative decision that may not be affected by the operative method.

There are at least six structured reviews (meta-analysis) which included information from up to 28 prospective trials (2429). There is universal finding of the longer operation time, but most also establish less pain and shorter recovery. Hospital stay is slightly shorter and wound infections are fewer. The conversion rate was about 10% in the studies. Information that was not systematically analyzed includes the number of laparoscopic surgeons available, whether the same surgeons did all the open and laparoscopic operations, and the missed inclusions and exclusions. The cost for laparoscopy has also not been systematically studied.

There is overwhelming evidence of some gains with laparoscopy but its limitation has not been given the same attention. Hence it remains a policy decision to balance the gains against a more expensive and more difficult method that cannot manage all cases of appendicitis. It is this reviewers impression that laparoscopy for appendicitis is currently loosing that trial in favor of the open operation. The penetration of laparoscopic appendectomy varies widely from one hospital to another but the overall penetration is probably no more than around 15% for western countries.

Comments

Considering the evidence available it is reasonable that new foundations are laid for the treatment of suspected appendicitis. Its essence would be to find out in new trials what proportion of those with appendicitis that need an operation. The equivalent of the cost of the unnecessary operations avoided will pay for much better diagnostic work-up to increase both the diagnostic accuracy and the adequacy of an operation. Because the helical CT scan promises real change in this respect it is now important that this means of diagnosis is further investigated.

Laparoscopic diagnosis has been proposed with claims that if there is appendicitis it can be removed simultaneously. However it is not the appendectomy that is the issue but the unnecessary operation. Unless the laparoscopic diagnosis can be obtained on the awake patient at a price comparable with a CT scan there seems to be little place for it.

Laparoscopic appendectomy is sufficiently investigated. Under the current principles of treatment for appendicitis, it is an administrative decision whether laparoscopy should be pressed further.

There should be simple ligation of the appendix stump in the future, primary closure of the wound, and no drain. Antibiotic treatment should be of short duration, usually single dose unless there is perforation and abscess.

References

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2.
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20.
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21.
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23.
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24.
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Copyright © 2001, W. Zuckschwerdt Verlag GmbH.
Bookshelf ID: NBK6987

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