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Is interval appendectomy necessary after conservative treatment of appendiceal mass in children?

Three Part Question

In [children who have had successful conservative management of appendiceal mass] does [interval appendectomy compared to watchful waiting] improve [outcomes or cost-effectiveness.]

Clinical Scenario

A 5 year old boy was admitted to a rural New Zealand hospital with 10 day history of abdominal pain. The pain was localised to the RIF with guarding and examination revealed a palpable mass in the RIF. He had previously presented with a 1 day history of severe abdominal pain and fever and had been discharged the following day with a diagnosis of gastroenteritis. He was transferred to the tertiary hospital and a diagnosis was made on ultrasound scan of appendiceal mass with abscess. His condition was stable. He was commenced on conservative management and supportive care with intravenous (iv) antibiotics followed by a 2 week course of oral antibiotics. He responded well to conservative management and was scheduled for appendectomy after an interval of 6-8 weeks. You wonder whether it is necessary, now he is well, for him to have an appendectomy.

Search Strategy

TRIP online database
Medline online database 1950 – Oct 2007
TRIP database search: – "interval appendectomy" - 1 cost-effectiveness analysis and 1 randomised controlled trial

Medline searches:
Interval appendectomy AND appendiceal abscess – 11 papers, 2 relevant

interval appendectomy AND appendiceal mass, 18 papers, 5 relevant (1 duplicate); "appendiceal mass".tw, 52 papers, 7 relevant (1 duplicate); "interval appendectomy".tw, 82 papers, 9 relevant, including 1 review (2 duplicates).

Search Outcome

Overall there were 9 relevant papers; 1 was an RCT, 1 a cost-effectiveness analysis and cohort study combined, 6 other cohort studies of patients treated for appendiceal mass and 1 case series of two children who did not receive routine interval appendectomy. These papers were reviewed and are summarised in the table

Relevant Paper(s)

Author, date and country Patient group Study type (level of evidence) Outcomes Key results Study Weaknesses
Adalla SA.
27 patients of various ages with appendiceal massCohort study in which patients treated successfully with conservative treatment are not followed up with IARecurrence of appendicitis2/27 recurrences (8%) - at 2 and 3 months respectively.Follow up average of 15.5 months. Study population is not limited to children
Ein SH, Shandling B.
10 children (mean age 8.5) with appendiceal massCohort study of patients in a childrens hospital which routinely does not offer IA following conservative tx.Recurrence of appendicitis1/10 recurrences - 2 months following tx. The other 90% lived free of recurrence for the duration of follow upFollow up was between 6 months and 13 years
Puapong et al,
61 children treated conservatively for appendiceal massRetrospective cohort of patients aged 0–18 who underwent IARecurrence of appendicitis5/61 developed recurrence (8%). 80% of recurrences occur within 6 months and 100% within 3 years.Average follow-up 7.5 years (range 2 months–12 years)
Stevens et al,
46 patients with appendiceal massCohort study of patients treated with IA only for persistent symptoms or recurrence of appendicitisRecurrence of appendicitis17/46 underwent IA with the remaining 63% symptom free for the duration of follow-up. Average hospital stay was 9 days compared with 12 days in a routine IA cohort.Indication for IA in this study was not limited to recurrence of appendicitis. Study not limited to children
Karaca et al,
17 children (mean age 9.5) with appendiceal massCohort study in which patients treated successfully with conservative treatment are not followed up with IARecurrence of appendicitisNo recurrences of appendicitis (0/17)Follow up between 1 and 7 years
Price et al,
2 children with appendiceal mass, 8yo boy, 10yo girlCase report, both patients treated conservatively - one lost to follow up, one refused IARecurrence of appendicitis2/2 recurrences of appendicitis, 8 months and 2.5 years following tx respectively.Case report of single events, difficult to apply to a population. Low level of evidence.
Lai et al,
165 patients treated for appendiceal massRetrospective analysis of patients treated with "watchful waiting" following conservative treatment. The cost effectiveness of watchful waiting and treating recurrences was compared with calculated costs of routine IA.Cost effective analysis of IAWatchful waiting with appendectomy for those with recurrence is more cost effective than routine IAHospital costs not always generalisable. Follow up costs only captured for a period of 2-8 years maximum.
Kaminski et al,
1012 patients of various ages with appendiceal massRetrospective multicenter study of patients with appendicitis, 864 with appendiceal mass were treated conservatively without IARecurrence of appendicitis5% developed recurrence. Age is not related to recurrence.Average length of follow up 4 years
Kumar S, Jain S.
20 patients with appendiceal massRCT of 60 patients, comparing conservative treatment with IA, and conservative treatment aloneLong and short term outcome such as recurrence of appendicitis, incisional pain, hospital time2/20 recurrences (10%) in those managed conservatively. Short and long term outcomes following conservative treatment were superior to IA.Average follow up 33.5 months.


Emergency appendectomy in acute appendicitis is the management of choice in most cases and is preferentially performed before perforation of the appendix occurs. Recently it has been acknowledged that approximately 15% of children develop a complication following appendectomy (Wesson). However, where perforation and appendiceal mass have already developed, the complication rate from appendectomy is higher (Azzie). For this reason it is common to instead defer appendectomy in such cases and treat conservatively (non-surgical) with supportive care and antibiotics active against enteric flora (eg, cefuroxime, gentamicin and metronidazole). Non-surgical management usually requires that the patient has well localised tenderness over an appendix mass, is not overtly ill or deteriorating, and is without generalised peritonitis. Should the mass enlarge, clinical condition worsen or fevers continue after a few days of antibiotics, conservative management is considered to have failed and appendectomy is usually performed. Conservative management, when successful, restores normal appendix anatomy in the majority of patients (Mazziotti) and leaves the option for interval appendectomy (IA), often following a period of 6–8 weeks. There are many reports of the safety of this regimen. Histopathological studies have shown that following conservative treatment the appendix regains normal anatomy with a patent lumen in over 90% of cases (Histopathological studies have shown that following conservative treatment the appendix regains normal anatomy with a patent lumen in over 90% of cases (Mazziotti). However, this means that appendicitis may recur at a later stage and has led to the conclusion in many centres that IA is justifiable to avoid recurrence. In the past, IA has been recommended especially for adult populations as potentially serious underlying pathology such as malignancy may predispose to appendicitis (Gierup). Evidence regarding the need for IA following successful conservative management in the paediatric population is limited and summarised in the table. There is only one randomised controlled trial; other evidence has been obtained from cohort studies and case reports. One RCT compared outcomes between conservative management alone and IA. It concluded that long and short term outcomes (such as days off work, scar appearance, incisional pain) were superior in those managed non-surgically. Hospital stay was shortest in this group, and 90% of these patients had no further trouble from recurrence (Kumar). A recent review of the literature regarding the management of appendiceal mass in adults acknowledges that IA is the most common treatment in the UK. It concludes that following conservative treatment the recurrence of appendicitis is low and that current evidence no longer supports routine IA (Deakin). Other cohort studies of conservative management of appendiceal mass in the paediatric population reported that appendicitis recurs in around 8–10% of patients who have had successful treatment (Adalla, Ein, Karaca, Puapong). Where appendicitis returns, recurrence is often within the first few months following treatment. In a study with an average of 7.5 years of follow-up, all cases of recurrence had presented within 3 years and 80% within 6 months (Puapong). In one multicentre study including adults, the recurrence rate was as low as 5% and, most importantly, recurrence was not influenced by age (Kaminski). The major failing of these cohort studies is the length of follow-up. The maximum follow-up period quoted by Ein et al is 13 years. For a child, this means that prognosis in adulthood is unknown based on current knowledge. A recurrence rate of up to 10% may be viewed differently in different health care systems – it would be considered an acceptable rate in the United Kingdom and New Zealand but may be unacceptable in the USA. Where IA is performed, patients are exposed to a 15% complication risk (Wesson) in order to prevent a recurrence of appendicitis in only 5–10% of patients. It has been shown to be more cost effective to treat those recurrences as they occur with appendectomy (Lai). Treated with modern surgical techniques, antibiotics and anaesthesia, appendicitis is no longer a life threatening condition which must be avoided at all costs (Wesson).

Clinical Bottom Line

Appendicitis does not recur in most patients who have had successful conservative treatment for an appendiceal mass. (Grade B) The few cases of recurrence usually happen within months of initial presentation. (Grade B) Interval appendectomy is not necessary or cost effective for managing appendiceal mass. Rather, patients should be told that appendicitis may recur and encouraged to seek early medical attention so that an appendectomy can be carried out then. (Grade A)


  1. Adalla SA. Appendiceal mass: interval appendicectomy should not be the rule. Br J Clin Pract. 1996 Apr-May;50(3):168-9
  2. Ein SH, Shandling B. Is interval appendectomy necessary after rupture of an appendiceal mass? Journal Pediatric Surg 1996 Jun; 31(6):849-50
  3. Wesson DE. Treatment of appendicitis in children. UpToDate online 16.1, (accessed 1 April 2008).
  4. Azzie G, Salloum A, Beasley S, et al. The complication rate and outcomes of laparoscopic appendicectomy in children with perforated appendicitis. Pediatr Endosurg Innovative Techn 2004; 8 (1): 19–23.
  5. Mazziotti MV, Marley EF, Winthrop AL, et al. Histopathologic analysis of interval appendectomy specimens: support for the role of interval appendectomy. J Pediatric Surg 1997; 32: 806–9.
  6. Gierup J, Karpe B. Aspects on appendiceal abscess in children with special reference to delayed appendectomy. Acta Chir Scand 1975; 141 (8): 801–3.
  7. Deakin DE, Ahmed I. Interval appendicectomy after resolution of adult inflammatory appendix mass--is it necessary? Surgeon 2007; 5 (1): 45–50.
  8. Willemsen PJ, Hoorntje LE, Eddes EH, et al. The need for interval appendectomy after resolution of an appendiceal mass questioned. Dig Surg 2002; 19 (3): 221–2.
  9. Puapong D, Lee SL, Haigh PI, et al. Routine interval appendectomy in children is not indicated. J Pediatr Surg 2007; 42 (9): 1500–3.
  10. Stevens CT, de Vries JE. Interval appendectomy as indicated rather than as routine therapy: fewer operations and shorter hospital stays. Ned Tijdschr Geneeskd 2007; 151 (13): 739–41.
  11. Karaca I, Altintoprak Z, Karkiner A, Temir G, Mir E. The management of appendiceal mass in children: is interval appendectomy necessary? Surgery Today 2001; 31(8):675-7
  12. Price M R, Haase G M, Sartorelli K H, Meagher D P Jr. Recurrent appendicitis after initial conservative management of appendiceal abscess. Journal of Pediatric Surg 1996; 31(2):291-4
  13. Lai HW. Loong CC. Wu CW. Lui WY. Watchful waiting versus interval appendectomy for patients who recovered from acute appendicitis with tumor formation: a cost-effectiveness analysis. Journal of the Chinese Medical Association 2005 Sep. 68(9):431-4
  14. Kaminski A. Liu IL. Applebaum H. Lee SL. Haigh PI. Routine interval appendectomy is not justified after initial nonoperative treatment of acute appendicitis. Archives of Surgery. 2005 Sep; 140(9):897-901,
  15. Kumar S, Jain S. Treatment of appendiceal mass: prospective, randomized clinical trial. Indian J Gastroenterol 2004 Sep-Oct;23(5):165-7.