Interval appendectomy in adults: A necessary evil?

The management of appendiceal mass remains a matter of major controversy in the current literature. Currently, initial nonoperative management followed by interval appendectomy is favored over immediate appendicectomy. However, the necessity of doing an interval appendectomy has been questioned - is it a necessary evil? The present review revisits the above controversy, evaluates the current literature, assesses the need for interval appendectomy in adults, and provides recommendations.

INTRODUCTION

Acute appendicitis is a clinical diagnosis. Its etiology is unknown but is believed to be multifactorial, with all of the following playing a part: inadequate dietary fiber,[1] familial factors,[2] and luminal obstruction from fecalith impaction or lymphoid hyperplasia, and other processes[34] such as parasitic infestation. The lifetime risk for acute appendicitis is 8.6% and 6.7% for men and women, respectively, in US.[5] Appendectomy is the treatment of choice for acute appendicitis and remains the most commonly performed abdominal emergency surgery. Epidemiologically, acute appendicitis accounts for over 1 million patient-days of admission in the US.[5] Most patients present early in the disease process; however, in 2%–6% of patients diagnosis is made when an appendiceal mass is discovered on preoperative imaging.[67]

The appendiceal mass (tumor formation after appendicitis) is the end result of a walled-off appendiceal perforation. Pathologically, it may range from phlegmon to abscess.[7] The former is an inflammatory tumor consisting of the inflamed appendix, its adjacent viscera, and the greater omentum, whilst the later is a pus-containing appendiceal mass.[7] The management of appendiceal mass has been a matter of major controversy for decades. There are three schools of thought regarding the correct management: (a) immediate appendicectomy prior to initial inflammatory mass resolution;[8-10] (b) initial conservative treatment followed by interval appendectomy;[11-13] and (c) an entirely conservative approach, without any appendectomy.[14-16] The initial conservative management of appendiceal mass entails hospital admission, bowel rest, broad-spectrum antibiotics, hydration, and percutaneous drainage of the abscess until the resolution of the mass. Currently, the initial conservative, nonoperative management for appendiceal mass is favored by most surgeons.[13-16] However, for the past decade the million dollar question has been: what next after conservative management of appendiceal mass? The classical or traditional answer to this question is ‘interval appendectomy,’[11-13] but this approach has been questioned in the literature.[715-22] Advocates of interval appendectomy believe recurrence of appendicitis is very high during the waiting period and, besides, appendectomy will provide a definite diagnosis and also rule out any underlying malignancy masquerading as a phlegmon or appendiceal mass.[12132223] The antagonists of interval appendectomy argue that the rate of recurrent acute appendicitis is low (6–20%)[24-26] but that the complications of surgery for acute recurrent appendicitis is not low, with reported rates ranging from 3.4–17%.[131927] The present review revisits the above controversy, evaluates the current literature, assesses the need for interval appendectomy, and provides recommendations.

INTERVAL APPENDECTOMY: NECESSARY?

Initial conservative management of an appendiceal mass, as advocated by Ochsner,[28] is widely accepted among surgeons; however, interval appendectomy is still practiced due to the claimed risk of recurrent acute appendicitis and the need to establish a definite diagnosis and to rule out an underlying malignancy.[122930] In a retrospective review of 46 patients who underwent interval appendectomy after initial successful nonoperative management of appendiceal mass, 16% had a normal or obliterated appendix on final pathology.[31] However, 44%, 15%, 4%, and 4% of these interval appendectomies revealed acute appendicitis, chronic appendicitis, inflammatory bowel disease, and mucinous cyst adenoma, respectively.[31] Although only 9% (four patients) developed recurrent abdominal pain after the initial successful nonoperative management, the authors recommended interval appendectomy as it would allow evaluation for a clinically significant disease process and help avoid recurrence.

In another retrospective series of 73 patients (mean age of 41 years), 5 patients underwent interval appendectomy 6–8 weeks from initial presentation. There was one postoperative complication of wound infection and one case showed the presence of a mucocele on final pathology.[12] Although the sample size was too small for any definitive conclusion, the authors felt that interval appendectomy was beneficial. Besides, a recent survey (with a high response rate) of 90 practicing general surgeons in England revealed that 53% still performed routine interval appendectomy at 6–12 weeks mainly due to fear of recurrent appendicitis[32] 13% of the surgeons did so because of concerns about presence of malignancy.[32] Yamini et al, have reported that interval appendectomy is safe, with a complication rate of only 10% and without need for prolonged hospitalization (mean length of hospital stay: 1.4 days).[33]

INTERVAL APPENDECTOMY: EVIL?

Traditionally, after successful nonoperative management of an appendiceal mass, interval appendectomy is performed either semi-electively or electively. This management approach is still preached today but has been questioned by a growing amount of evidence.[715-2230] Tekin et al, prospectively followed 94 patients (mean age 46.4 years) for 3 years after they were conservatively managed for appendiceal mass.[21] The mean reported incidence of recurrent appendicitis was 14.6% (13-patients).[21] The majority of the recurrences occurred in the first 6 months (9 patients; 10.1%) but the rate decreased to 2.2% at 1 year. The authors concluded that routine appendectomy after initial successful nonoperative management is not justified.

Similarly, in a retrospective review of 165 patients (mean age: 53.6 years) managed conservatively after initial presentation with appendiceal mass, the reported recurrence rate for acute appendicitis was 25.5%, with the risk of recurrence being highest during the first 6 months (83.3%).[22] However, if interval appendectomy was performed 6 and 12 weeks after discharge, less than 16% and 10% of recurrent appendicitis could be prevented with this approach. Moreover, routine interval appendectomy benefited less than 20% of the patients in this study and therefore the authors did not recommend interval appendectomy.[22] However, it is noteworthy that in five (3.03%) patients the histological specimen revealed colon cancer.

A recent prospective nonrandomized study of 51 patients (mean age: 31.75 years) who had initial successful conservative treatment of appendiceal mass revealed a recurrence rate of 17.6% (nine patients) for acute appendicitis, with 44.4% (four patients) of these recurrences occurring within 6 weeks, 22.2% (two patients) between 6–12 weeks, and 33.3% (three patients) after 12 weeks.[34] Interval appendectomy therefore prevents 10.6% and 6.7% of cases of recurrent appendicitis if performed at 6 and 12 weeks, respectively; the 1 year recurrence rate was also low (1.9%).[34] These data argue against interval appendectomy.

Willemsem et al, based on their retrospective review of 233 appendectomies done after successful initial conservative management of appendiceal mass, suggested that routine interval appendectomy was unnecessary.[19] Thirty percent of the appendectomies showed a normal appendix without signs of previous inflammation. The recurrence rate was low (2%) but the complication rate due to interval appendectomy was high (18%).[19] In a recent large retrospective cohort study involving 1012 patients (58% men; 48% of subjects in the age range of 20–49 years) who presented with appendiceal mass and underwent initial successful conservative management, no interval appendectomy was performed in 864 (85%) patients.[28] The recurrence rate was 5% (39 patients) after a mean follow-up of 4 years. The mean length of hospital stay was 4 days for those who did not undergo interval appendectomy as compared to 6 days for patients who underwent interval appendectomy. The authors concluded that routine interval appendectomy was not justified.

The only randomized prospective study done in this decade involved 60 patients with appendiceal mass, and the data from that study showed that conservative management without interval appendectomy is safe. The recurrence rate was low (10% after a mean follow-up of 33.4 months) and, moreover, recurrent acute appendicitis could be successfully managed with appendectomy.[35]

DISCUSSION

Although the surgical treatment of appendicitis is widely accepted, controversy still exists regarding the management of appendiceal mass. Current literature supports an initial conservative approach but whether routine interval appendectomy should be done is still a matter of debate. On the one hand, it is generally believed that recurrence of acute appendicitis is very high during the waiting period but, on the other hand, appendectomy can provide a definite diagnosis and identify malignancy masquerading as a phlegmon.[122930]

The reported rate of recurrence of acute appendicitis ranges from 6–25.5%, with the majority of recurrences occurring during the first 6 months.[2224-26] The 1-year recurrence rate is also low (1.9–2.2%).[192132] The prospective series of Youseff et al, showed that interval appendectomy performed at 6 weeks and 12 weeks will prevent 10.6% and 6.7% of recurrent appendicitis, respectively.[34] That means 89.4% and 93.3% of patients respectively had unnecessary appendectomy.[34] This is similar to the less than 20% of patients benefiting from interval appendectomy in the series reported by Lai et al,[22] Moreover, there is no increased morbidity associated with appendectomy when done in recurrent cases.[34] However, even though current evidence does not support such practice, 53% of surgeons in England still perform routine interval appendectomy at 6–12 weeks, mainly due to the fear of recurrent appendicitis.[32]

Another important reason for doing an interval appendectomy after successful nonoperative management of appendiceal mass is the need to make a definite diagnosis and to rule out malignancy. Mucinous cystadenoma was noted in one out of five pathology specimens after interval appendectomy.[12] Similarly, one adenocarcinoma was detected from 38 interval appendectomies in another series.[18] In a series of 46 interval appendectomies, two patients had mucinous cystadenoma and another two had inflammatory bowel disease on final pathology.[31] Recently, a retrospective study by Lai et al, reported 2% neoplasm and 8% mucinous changes among 70 interval appendectomies and 10% neoplasm and 5% mucinous changes for those who underwent appendectomies after recurrence (20 patients).[22] This greater incidence of new pathology on the final appendectomies is not high enough to support the use of interval appendectomy but, at the same time, it is also not low enough when one takes into consideration the consequences of misdiagnosing an underlying malignancy. As expected, more than 50% of all interval appendectomies showed chronic and acute appendicitis, which does not encourage routine interval appendectomy after successful nonsurgical treatment. Therefore, it would be prudent to do an evaluation of the colon with colonoscopy or barium enema to detect any underlying disease in high-risk patients after a successful initial nonoperative approach.[202230] Moreover, for extracolonic lesions and Crohn disease virtual colonoscopy, CT scan, and ultrasound are more useful investigational tools after conservative management of appendiceal mass.[20] In effect, colonoscopy augmented by CT scan is a good modality for excluding cecal pathology in high-risk patients.[36]

Interval appendectomy is also not without morbidity. The reported complication rate ranges from 12% to 23%.[1316181924] The complications include sepsis, bowel perforation, small bowel ileus, fistulas, and various wound infections as reported by Willemsen et al. in their retrospective review of 233 interval appendectomies after successful initial conservative management of appendiceal mass.[19] Eriksson et al, reported an 18% complication rate for interval appendectomy in their series, which was similar to the rate in patients treated with immediate appendectomy for appendiceal mass[18] – ‘an outdated practice.’ The practice of interval appendectomy therefore need serious reconsideration in view of the high complication rates and the low probability of new findings on final pathology. Tables 1–3 summarize some of the key literature (since 1990) on the current controversy about the necessity for interval appendectomy.

Table 1

Studies with evidence against interval appendectomy (1996–2010)

Table 3

Studies evaluating the necessity of interval appendectomy

As far as cost-effectiveness is concerned, interval appendectomy after conservative management of appendiceal mass was not economical according to a large single-institution retrospective analysis involving 165 patients followed for 5-years.[37] According to the study, there is 38% cost reduction during follow-up if appendectomy is performed only after recurrence of acute appendicitis as compared to routine interval appendectomy in all patients with appendiceal mass.[37] Kaminski et al, also showed that the median length of hospital stay for patients admitted due to recurrent appendicitis was shorter than that for those admitted for interval appendectomy and hence the former approach was more cost-effective.[28] This is similar to the report by Kumar et al., in which hospital stay was shorter and time spent away from work less for patients managed entirely nonoperatively until they developed recurrent appendicitis.[35]

CONCLUSION

Appendiceal mass should be managed nonoperatively at the initial presentation. Interval appendectomy is not indicated after successful nonoperative management. The recurrence rate of acute appendicitis is low and appendectomy can be safely performed at that time. The risk of missing the diagnosis of an underlying malignancy is also low but we recommend additional evaluation with colonoscopy or barium enema in patient over 40 years. In addition, nonoperative management has a cost advantage over routine interval appendectomy after initial successful conservative management.

Disclaimer

The views expressed in this review article are those of the author and do not reflect the official policy of the Department of the Navy (DON), Department of Defense (DOD), or US Government.[39]

Table 2

Studies that support interval appendectomy (1996–2010)