Appendicitis: Epidemiology, Evaluation, and Controversy in Management

Abstract

Appendicitis is the most common acute general surgical emergency. As no investigation is accurate, the diagnosis has to rely on clinical symptoms and signs or clinical scoring systems and as a result, frequently misdiagnosed. Blockage of the appendiceal lumen by faecolith is assumed to be the mechanism in many cases. Surgery for appendicitis only evolved when the mortality associated with perforated appendicitis was high. The fact that only few patients progressed to potentially lethal complications provided the argument for conservative antibiotic treatment. The indications for operative (surgery), non-operative (antibiotics), or both in management are discussed. Laparoscopic appendicectomy has become the gold standard of treatment but non-operative management with antibiotics may suffice in selected cases with uncomplicated appendicitis. The controversy in the management of the appendix mass/abscess between an expedient appendicectomy, or a combination of conservative management and interval appendicectomy is discussed. The novel minimally invasive techniques including natural orifice transluminal endoscopic surgery (NOTES) are evolving but for the limitations, cost, availability, and technical expertise required.

1. Introduction

Appendicitis is the most common intra-abdominal emergency. The presentation of acute appendicitis is varied, ranging from subclinical and self-resolving to overwhelming sepsis and death. Typically, patients who develop appendicitis in isolated settings (e.g., on ships, submarines, saturation dives, or in remote areas) are treated conservatively with antibiotics, and, in most cases, appendicitis is resolved without surgery [1, 2, 3, 4, 5, 6]. Surgery for the acute abdomen caused by appendicitis only evolved when the mortality associated with perforated appendicitis was found to be significant (>5%). The mortality was associated with the age of the patient and delayed diagnosis resulting in perforated appendicitis [1]. Conservative treatment with later drainage of any abscess had been the standard and diffuse peritonitis was usually fatal. The fact that only few patients progressed to potentially lethal complications provided the argument for conservative antibiotic treatment. Although it is clearly advantageous to spare patients from unnecessary surgery, the morbidity and mortality from failing to diagnose appendicitis until perforation has occurred are greater than that associated with the removal of a normal appendix [2, 3, 4]. Thus, early surgery for all patients with suspected appendicitis became the definitive method of preventing severe peritoneal sepsis. However, recent studies particularly during the coronavirus-19 (COVID-19) lockdown have re-iterated the fact that although there is a 20% risk of recurrent attacks, simple appendicitis may be treated with antibiotics only [3, 5]. This may explain the decreased incidence of acute appendicitis during the COVID-19 pandemic following antibiotic treatment for right iliac fossa pain, but the high incidence of complicated appendicitis due to the “stay at home” message [5]. Advances in interventional radiological techniques for peritonitis have also significantly reduced the morbidity and mortality of physiologically severe complicated abdominal infections including appendix abscesses [7].

2. Prevalence

Appendicitis is a global disease. The incidence of appendicitis is 7–12% in the population of the USA and Europe, and, stable in most western countries [8]. Data from newly industrialized countries are sparse but suggest appendicitis is rising rapidly, although it is still lower than the reported incidence amongst patients in the developed world [8, 9, 10]. Appendicitis trends in South Africa are consistent with those in developing regions [9]. The lifetime risk of developing acute appendicitis requiring surgery is ~7% which is maximal in childhood and declines steadily with increasing age as the lymphoid tissue and vascularity atrophy [1, 2, 8]. Acute appendicitis can occur at any age but it is rare in infants because of their larger appendiceal ostium. The incidence rises rapidly in children above the age of 5 years and reaches a peak in teenagehood with a median age of 10–11 years [2, 11]. The disease is not uncommon in the elderly and can occur in extreme old age. Some authors have reported a sex difference in the younger age group (15–25 years) where it may be twice as common amongst males. However, it is not surprising that women continue to have a higher appendicectomy rate with 30% revealing normal appendices because of various gynecological conditions mimicking appendicitis [12, 13]. There is still considerable discussion about the reasons why the appendix should so commonly become infected. The fact that its lumen is open to feces and pathogenic organisms of the colon must play an important role, but the main factor that has been implicated is blockage of the lumen by faecolith, by hypertrophy of lymphoid follicles, or by fibrous stricture. This is made more likely by its narrow lumen. Abnormalities of its shape or position (such as occurs, for example, when a short appendicular artery holds the organ up retro-ileally may predispose to infection because of kinking causing obstruction [2]. As long as 1896, it was reported that “iliac phlegmons” were less common in the southern states of America than in the north, and the blacks in northern states had a lower incidence of the disease than whites. This did not appear to be due to genetic factors because when American blacks began moving to the north of the USA in large numbers an increasing incidence of appendicitis occurred. Diet appears to be an important factor in the etiology of infection. In Western countries, 16% of the population undergoes appendicectomy but in Africa and Asia with a high roughage diet, the prevalence is much lower [14]. Burkitt described an increase in disease in Africa associated with the adoption of a Western diet [14]. Walker et al. reported the prevalence of appendicitis in South African students from different racial backgrounds and ascribed the higher incidence to a lower intake of dietary fiber. They also found a marked difference in different social groups. In one study, they reported an annual rate of appendicitis of 7.8 cases per 1000 population of privileged white students eating a typical Western diet, but only 1.8 cases per 1000 in an underprivileged group of white students on a high-fiber diet [15]. The fact that increasing the dietary fiber in modern Western society can reduce the incidence of appendicitis, is demonstrated by the substantial fall over the last 30 years in Western countries. The prevalence has been more or less stable since the year 2000, at 151 per 100,000 person years within Western Europe and assumed to be secondary to improved living standards and general hygiene [8]. Most deaths occur in the elderly because of rapid progression to gangrene, delayed diagnosis, and peritoneal sepsis compounding coincidental cardiovascular, respiratory, or renal pathology [1, 2, 16].

3. Anatomy and pathology

The appendix is a blind-ending hollow muscular tube that arises as a diverticulum from the cecum at the confluence of the taeniae coli. It is thus the beginning of the colon and the structure of its wall comprising serosal, muscular, submucosal, and mucosal layers is not different from the cecum. However, the lumen of the appendix is irregular and narrow due to abundant lymphoid follicles, interspersed with a few mucus-secreting glands in the submucosa. The lymphatic channels in the submucosa tend to run in a longitudinal direction. There is a profuse blood supply via one or two appendicular arteries arising from the ileocolic artery. The arteries run in the mesoappendix, but they are closely applied to the wall distally, and secondary thrombosis is common. The lymphoid tissue and vascularity atrophy with age. In 15–20% of individuals, the appendix is extraperitoneal in a retrocecal position in 64% requiring a retrograde approach in resection. In 80–85%, the position is variable, depending on the length and mobility of the appendix and cecum (preileal 1%, postileal 0.5%, subcecal 2%, and pelvic 32%) although may show variations with different populations [17, 18]. In pregnancy, the enlarging uterus progressively displaces the appendix up into the right hypochondrium [17]. The organ probably has a little function but some authors have suggested that the numerous follicles may indicate that it has important immunological activity in the gut, at least during the first three decades of life when the lymphoid tissue is such a prominent future. This may also suggest a biological cause to the association of appendicectomy with an increased risk of Crohn’s disease and, the appendix protecting against ulcerative colitis [19, 20]. Although blockage of the appendiceal lumen is assumed to be the mechanism in many cases of appendicitis, the underlying causative pathology is not always clear, and frequently misunderstood [21]. Inflammation of the appendix is initiated by obstruction of the lumen secondary to swelling of the lymphoid tissue in the wall in response to viral infection or to mechanical obstruction by a faecolith (from a low-fiber diet) in the lumen. Extrinsic compression, inflamed, obstructed, or perforated appendix can occur in a hernia (Amyand’s hernia) and previous inflammation may result in fibrotic stricture of the wall. Occasionally, the obstruction may result in a mucocele [22, 23]. Tumors usually present as acute appendicitis or as a mucocele of the appendix caused by obstruction. Less commonly the tumor may present as an abdominal mass causing pain or obstruction. Neoplasms of the appendix and adjacent cecum also cause obstructive appendicitis. Benign neoplasms (leiomyoma, fibroma, neuroma, neurofibroma, and ganglioneuroma) have been recorded but the most common tumor is the carcinoid which occurs in 1% of appendicectomies. Other malignant tumors are uncommon but adenocarcinomas, malignant mucocele, and a variety of sarcoma have been described. A blockage has been observed by parasitic worms and the enlargement of lymphoid aggregates within the appendix wall in Burkitt’s (Non-Hodgkin’s) lymphoma [24, 25]. Being an extranodal lymphoid organ, it could be the only initial indication of lymphoma or an underlying pathology and, an important reason for routine histological examination of a resected appendix [26]. Acute appendicitis is the commonest indication for surgery in HIV/AIDS and the opportunistic cytomegalovirus (CMV) has been isolated from appendix specimens in these patients raising the possibility that CMV may be causative or a co-factor [27, 28, 29]. It may also be due to the obstructing lymphadenopathy from the atypical mycobacterium avium intracellular (MAI) or lymphoma or the immune reconstitution syndrome with the highly active antiretroviral treatment (HAART). These are associated with a high level of immunosuppression and operative mortality. Thus, the importance of liaison with the HIV/AIDS physician in management [30, 31]. The pathology of acute appendicitis is classically described as suppurative, gangrenous, or perforated. The acute inflammation of the appendix ranges from trivial catarrhal inflammation with a complete spontaneous resolution by host defenses, to fatal suppurative necrosis with perforation, abscess formation, or generalized peritonitis. The appendicular artery is a single-end artery closely applied to the wall distally, and secondary thrombosis is common giving rise to gangrene which explains the short progressive history (3–5 days) and the poorer prognosis with the atherosclerosis of the aged. Typically, there is a full-thickness inflammation of the appendix wall, and as the disease progresses hemorrhagic ulceration and necrosis of the wall indicate gangrenous appendicitis and subsequent perforation may be associated with localized peri-appendiceal abscess or generalized peritonitis. The bacteria flora of the appendix comprises the anaerobic and aerobic organisms typical of the large bowel. Luminal obstruction and stercoral ulceration, due to a large faecolith, promote invasive infection, and inflammatory endarteritis. Faecoliths are present in 30–40% of resected appendices, and gangrene is twice as common (75–80%) in these appendices compared to those containing no faecolith [23]. Stump appendicitis is a rare delayed complication of appendicectomy with time intervals ranging from 2 months to 51 years and, is under-reported in the literature [32, 33].

4. Natural history

If appendicitis is untreated, progression of the disease depends on the interplay of several factors (Table 1). Progression from intramural inflammation through luminal obstruction to gangrene and perforation is not inevitable. Inflammation follows a variable pattern that may be aborted or delayed by host defenses at any time [34]. Children less than 3 years of age have an 80% perforation rate because of delay in diagnosis and host defenses including the omentum are not fully developed [11, 35]. Appendicitis has a more rapid course in the elderly because atherosclerosis, gangrene, and perforation are common [36]. The perforation rate of 25% in patients with a history of pain of less than 24 hours is not much lower than 35% rate of perforation in patients with a history of over 48 hours [37]. An alternative outcome is that the appendix becomes surrounded by a mass of omentum which walls the inflammatory process and prevents inflammation from spreading to the abdominal cavity (appendix mass) yet resolution of the condition is delayed. If the appendix becomes walled off by omentum but has perforated, an abscess will develop localized to the peri-appendiceal region in the right paracolic gutter or the subcecal area of the pelvis. There is no evidence to indicate the proportion of patients likely to develop diffuse sepsis, because antibiotic treatment alters the pattern of disease by replacing the risks of perforation with the lesser risk associated with surgery [22, 23, 37, 38].

Systemic	Local
Extremes of age; Coincidental systemic disease (e.g., rheumatoid arthritis, morbid obesity); Immunosuppression (e.g., as a result of HIV/AIDS, corticosteroids, chemotherapy)	Site of appendix; Speed of development of inflammation; Presence of faecolith; Vascular impairment; Mobility of omentum (less in children)

Table 1.

Factors determining progression of inflammation in appendicitis.

5. Investigations

There are no special investigations to confirm appendicitis. As no test is accurate, the diagnosis has to rely on clinical symptoms and signs. The Alvarado score was designed more than two decades ago as a diagnostic score using the clinical features of acute appendicitis for subsequent clinical management [39]. The appropriateness of its routine clinical use is still unclear (Table 2). A recent meta-analysis showed its positive role in “ruling out” appendicitis but not in “ruling in” the diagnosis without surgical assessment and further diagnostic testing. It is inconsistent in children and over-predicts the probability of acute appendicitis in women [40]. Alvarado scoring may be valuable in low-resource or primary care centers where imaging is not an option [38]. The adult appendicitis score (ASS) that stratifies patients into three groups (high, intermediate, and low) and thus selective imaging is reliable and renders a low negative appendicectomy rate [41]. It is fast and accurate in categorizing patients with suspected appendicitis, takes into account gender, duration of symptoms, and age, and roughly halves the need for diagnostic imaging (Table 3). A right iliac fossa pain treatment (RIFT) study group observational study on behalf of the West Midlands Research Collaborative [42] demonstrated that in clinical practice the adult appendicitis score (AAS) can be used more reliably than the Alvarado and the Raja Isteri Pengiran Anak Saleha appendicitis (RIPAS) scoring systems. The Appendicitis Inflammatory Response (AIR) scoring system showed a direct relationship with the phase of acute appendicitis in immigrant patients, but the introduction of the adult appendicitis score (AAS) reduced the negative appendicectomy rate [43, 44]. Tests should serve as adjuncts to clinical diagnosis and may help exclude alternative diagnoses, especially in female or the elderly. A white cell count is usually elevated but a normal white cell count does not exclude appendicitis [39, 40, 41]. The appendicolith, a radio-opaque concretion located within the appendix, which is deemed to be the most specific finding of appendicitis on plain radiographs is visualized in only 5–15% of patients with appendicitis [45]. Ultrasonography (US) in expert hands is perhaps the most useful investigation. It has a high specificity (94%), high predictive value, noninvasive, and identifies alternative pathology but of low sensitivity (88%) in early appendicitis [46]. Although computed tomography (CT) scan is superior to US scan and allows for alternative causes of abdominal pain to be diagnosed, the risk of radiation-induced malignancy (21/100,000 patients) renders it not of particular use in pediatric patients. It is expensive and has a low sensitivity (72%) in early and perforated appendicitis [47, 48]. An appendix “triple test” (a combination of negative diagnostic imaging a normal white cell count and normal C-reactive protein can improve diagnostic accuracy significantly without an unacceptable rise in the rates of perforation/gangrenous appendicitis [49, 50]. Laparoscopy is essentially an operation rather than an investigation. Although, usually restricted to young women with equivocal signs many studies have now demonstrated that laparoscopy significantly improves surgical decision-making in patients with acute abdominal pain [12, 13, 36, 38]. The continuing development of ultrasound techniques and laparoscopic surgery have demonstrated that the proportion of normal appendices removed (20%) is unacceptably high [13].

Symptoms	Migration; Anorexia-acetone; Nausea-vomiting	1; 1; 1
Signs	Tenderness in right lower quadrant; Rebound pain; Elevation of temperature	2; 1; 1
Laboratory	Leukocytosis; Shift to the left	2; 1
Total Score		10

Table 2.

Alvarado scoring system.

A score of 5 or 6 = acute appendicitis; 7–8 = probable appendicitis; 9–10 = very probable appendicitis.

Symptoms and findings		Score
Pain in RLQ; Pain relocation; RLQ tenderness; Guarding	Mild; Moderate or severe	2; 2; 3/1^*; 2; 4
Laboratory tests; Blood leukocyte count (×10^9); Proportion of neutrophils; CRP (mg/l), symptoms <24 h; CRP (mg/l), symptoms >24 h	≥7.2 and <10.9; >10.9 and <14.0; ≥14.0; ≥62 and <75; ≥75 and <83; ≥83; ≥4 and <11; ≥11 and <25; ≥25 and <83; ≥83; ≥12 and <53; ≥53 and <152; ≥152	1; 2; 3; 2; 3; 4; 2; 3; 5; 1; 2; 2; 1

Table 3.

Adult Appendicitis Score.

6. Controversy in management

It is not possible to practice fully the ideal management of early diagnosis and surgery for the acute abdomen, thus reducing morbidity and mortality to zero because patients and the disease are variable [16, 51]. Because infection, inadequate perfusion, and a persistent inflammatory state are the most important factors for the development of multiple organ failure it seems logical that initial therapeutic efforts should be directed at their early treatment or prevention (early goal-directed therapy) with intravenous fluids, antibiotics, and analgesia [52, 53]. The risk of portal pyemia from septic emboli is also decreased. It is important to recognize the features of the acute abdomen which would indicate the need for resuscitation in the high dependency or intensive care unit [49, 54].

6.1 Operative or non-operative or both?

Since the incidental removal of an inflamed appendix through a groin incision for a scrotal hernia by Amyand in 1735 and, the first appendicectomy for appendicitis by the French surgeon Mesteivier in 1759, open appendicectomy through a standard right iliac fossa (modified McBurney’s gridiron/Lanz) incision at the earliest possible time after the onset of symptoms is the standard treatment of choice. Diffuse peritonitis, which has been diagnosed preoperatively, should be dealt with by formal laparotomy, to allow thorough peritoneal toilet and lavage [1, 21, 37, 38]. Modern techniques with equal efficacy but with minimal postoperative pain, decrease negative appendicectomy rate, decrease surgical site infection, and early return to normal activities include conventional laparoscopic appendicectomy, a single incision (port) laparoscopic appendicectomy, and transluminal (Natural orifice transluminal endoscopic surgery—NOTES) appendicectomy via a trans gastric, colonic, or vaginal approach [55, 56]. NOTES have the advantage of markedly decreasing surgical site infection, hernias, and postoperative pain [55]. Care should be taken during laparoscopy by insisting upon using disposable ports with a vestibular flange to prevent splash back, and by deflating the abdomen prior to port withdrawal because any aerosol emanating from the port entry wound may harbor HIV or COVID-19 [56]. In addition, the cost and technical expertise required in these novel techniques including the numerous limitations of NOTES should be taken into consideration. Recent guidelines stipulate that appendicectomy should be performed laparoscopically unless this is contraindicated [1, 4]. Although conventional laparoscopic appendicectomy has become the gold standard, these innovations are unlikely to render formal open appendicectomy obsolete [53]. In 2012, in the UK, one-third of patients underwent open appendicectomy [57]. Open appendicectomy provides all the valuable skills of abdominal incision, dissection, resection, and abdominal wall closure required by a trainee surgeon. The skills will be useful following conversion of laparoscopic to open surgery [58]. However, unlike laparoscopic surgery, open procedures typically commit the surgeon to proceed to appendicectomy even if the appendix is macroscopically normal on visualization. Thus, the increased take-up of laparoscopy would hypothetically decrease the negative appendicectomy rate [1, 59, 60]. The results of the surgical treatment of appendicitis have improved dramatically during the past decades because of the introduction of more effective antibiotics against both aerobes and anaerobic organisms if peritonitis develops. Prophylactic use of antibiotics (short course i/v metronidazole) perioperatively halved the incidence of surgical site infection with important clinical and economic consequences [61, 62, 63]. A single peri-operative dose of antibiotic is sufficient for low-risk cases, but a therapeutic 3-day course is necessary when peritonitis is present.

The role of antibiotic treatment in early non-perforated appendicitis using broad-spectrum i/v ceftriaxone and i/v metronidazole for anaerobes is well known. There is a reasonable body of evidence to support non-operative treatment of appendicitis predating the COVID-19 pandemic [64, 65, 66, 67, 68, 69, 70]. There is evidence of low failure rates and minimal recurrence especially in 5–16 year olds [3, 13]. This has been reinforced by papers from the early stages of the COVID-19 pandemic [71, 72, 73, 74] that suggested a reasonable alternative option in the right carefully selected patient but with greater reliance on imaging [71, 72]. However, during the pandemic, there was a higher incidence of complicated appendicitis in patients who underwent appendicectomy when compared to those in the prior year which mostly must have been due to the “stay at home” message [73, 74]. Antibiotics, as definitive therapy may be acting in synergy with the host defense mechanisms and thus be most useful in the acute catarrhal phase of appendicitis which usually spontaneously resolves [2, 3]. It would avoid the complications of open appendicectomy and the generally 10% negative appendicectomy rates. Recent trials have shown that antibiotic treatment is a safe first-line approach in CT-confirmed uncomplicated appendicitis (non-gangrenous nor perforated) [71, 72]. Salminen et al. demonstrated in 257 patients between 16 and 60 years old in Finland that using i/v ertepanem for 3 days followed by 7 days oral levofloxacin and metronidazole 75% required no surgery in 1 year and, there was no progression to complicated disease. The recurrence rate was 27% (1 year), 34% (2 years), 35% (3 years), 37% (4 years), and 39% (5 years) [65]. Thus, even with long-term follow-up, the initial treatment with antibiotics is still a safe alternative approach to appendicectomy. The use of antibiotics can also convert acute appendicitis into a semi-elective procedure and avoid the stress of emergency surgery [75, 76, 77]. This was demonstrated in the lock-down period during the COVID-19 pandemic which allowed time to obtain the COVID-19 test result [71, 72, 73, 74]. It may also exclude COVID-19 as the cause of the abdominal symptoms which is an important differential diagnosis of appendicitis [73]. A much recent study in Amsterdam showed about half of the average population preferred antibiotics over surgical treatment of uncomplicated appendicitis and were willing to accept a high recurrence risk to avoid surgery initially [78]. This is similarly reproduced in the USA [79]. It is important to note that the effects of widespread antibiotics such as drug resistance and opportunistic infections both in the individual patient and the population at large are poorly considered in the literature [80, 81].

There is controversy in the management of the appendix mass/abscess. Some authors believe that the condition is best managed conservatively as the risk of perforation has passed and the removal of the appendix at this late stage can be difficult. Patients with a mass that does not diminish within a short time should be submitted to full intestinal investigations. In older patients, a diagnosis of carcinoma of the cecum, which has obstructed the appendix, must be considered and excluded by a CT scan or colonoscopy [36]. However, conservative management of an appendix mass risks a 30% recurrence of acute inflammation [2, 37, 38]. Sub-acute obstruction may occur and the appendix mass may be confused with a cecal carcinoma in the elderly, Crohn’s disease, ileocecal tuberculosis, or an ovarian tumor. Appendix abscess characterized by swinging pyrexia, tachycardia, undulating mass, and being systemically unwell is best treated by surgical intervention through a standard right iliac fossa incision. Residual necrotic appendix is usually found and resected. Tissues and organs adjacent to the abscess cavity will be friable and should be handled with care. Thus, for a palpable mass presenting pre-operatively the differentiation of a phlegmonous mass from an abscess is not a practical problem because surgery is the correct management for both. In addition, a mass is often detected only after the patient has been anesthesized and paralyzed. Such a policy renders any debate on interval appendicectomy redundant [1, 37, 38]. The operation which may be an appendicectomy, an ileocecal resection, or a hemicolectomy if indicated during the first admission is expeditious and safe, provided steps are taken to minimize postoperative sepsis. The serious consequences of missing a carcinoma in the elderly patient or other pathological lesions such as Crohn’s disease, ileocecal tuberculosis, and schistosomiasis are abolished [37, 38, 82]. The controversies with conservative antibiotherapy and drainage of appendix abscess include the optimal timing of the interval appendicectomy which is usually 6–12 weeks [75, 76, 77]. There are reports of recurrent appendicitis and increased neoplasms within that interval. Re-operation is associated with a significant incidence of postoperative complications and most patients are not treated by operation unless they develop further trouble. There is no evidence of benefit of lavage over suction alone for postoperative infective complications [83] and the insertion of a drain in the abscess cavity is controversial. Infact, there is a significantly longer operative time and a higher postoperative complication rate (SSI/intra-abdominal abscess) in the irrigation group than in the suction-only group after laparoscopic appendicectomy for uncomplicated appendicitis [84]. Peritoneal and wound drains are of no use. Delayed or non-closure of the skin is not necessary. Apart from the problem of the drain type (open vs. close), the size of the abscess cavity (small vs. large), and the removal time (early vs. late), abdominal drains may cause more problems than they solve. The adhesions that occur in the healing process of the stump or general peritoneal cavity will attract the peritoneal drain (foreign body), prevent adhesions to vascular structures, and physically damage the small bowel or stump causing an enterocutaneous fistula [85, 86]. Drains can mislead the surgeon as they easily get blocked. They are portals for the entry of exogenous bacteria causing surgical site and wound infection [85]. Large bore drains are useful in sepsis following inadequate peritoneal lavage in generalized peritonitis or residual sepsis but should be placed in the appropriate dependent areas of the abdominal cavity such as the paracolic gutters, pelvis away from the intestine [51]. Postoperative peritoneal sepsis may be diffuse and result in intestinal obstruction or a localized, usually pelvic, abscess requiring protracted convalescence. Both complications are the result of poor surgical technique. Untreated pockets of infected peritoneal fluid and failure to remove faecoliths cause postoperative sepsis. If obstruction and sepsis persist, reoperation is indicated. Leakage from the stump of the appendix is an uncommon but serious complication as it causes high pressure, large output fecal fistula which will require an ileocecal resection or a right hemi-colectomy [87]. Although pelvic abscesses could be drained via the rectum, other well-defined abscesses should be drained percutaneously under radiological or ultrasonic guidance followed by a microbiologically guided therapeutic course of antibiotics for 2 weeks [7, 51]. Ruptured appendicitis has been implicated in causing scarring, which can lead to infertility and/or ectopic pregnancy. Appendicectomy is not associated with future infertility in women from scarring, but with an increased risk of ectopic pregnancy [88]. Although, a nationwide cohort study in Finland in 2021 showed no association between complicated appendicitis on the risk of later in vitro fertilization treatment requirement and ectopic pregnancy [89] the argument or early laparoscopic appendicectomy in childbearing age to diagnose and treat appendicitis or complicated salpingitis is still favored over non-operative management.

6.2 The appendix is normal at operation

The terminal 60 cm of the ileum must be delivered to exclude a Meckel’s diverticulum, terminal ileitis, and mesenteric adenitis. If the base of the appendix and cecum are healthy, the appendix is removed when ileitis is present. Biopsy and culture of inflamed nodes aid a diagnosis of Yersinia infection. The right ovary and tube must be visualized and the extension of the incision, a head down tilt and adequate retraction may be required. Occasionally, fluid leaking from a perforated peptic ulcer down the right paracolic gutter produces clinical findings resembling those of acute appendicitis. A classical appendicectomy incision would reveal bile-staining free peritoneal fluid and a second upper abdominal incision is usually required. Purulent fluid tracking down the right paracolic gutter may also suggest acute cholecystitis. If the clinical diagnosis is equivocal despite investigations, it is best to begin with a low midline incision which could be extended if there is evidence of a perforated peptic ulcer [37, 38]. Prophylactic appendicectomy during the course of another procedure may be justifiable only in young individuals in whom there is a significant risk of appendicitis, but not appropriate in elderly patients [4, 35].

6.3 Tumor is found in the appendix

This will usually be a carcinoid tumor and appendicectomy is the adequate treatment if the tumor is less than 2 cm in diameter. If larger, right hemicolectomy is necessary. Less commonly a tumor may present as an abdominal mass causing pain or obstruction. Whatever histological variant is found, metastases are rare and the development of a carcinoid syndrome is very uncommon. A mucoid carcinoma confined to the appendix may be indistinguishable from a mucocele, but in either cases rupture must be avoided because of peritoneal dissemination resulting in subsequent myxoma peritonei. Occasionally, a tumor may be found unexpectedly during a laparotomy for some other condition [24, 90].

6.4 Chronic appendicitis or “the grumbling appendix”

Patients with true relapsing or chronic appendicitis are rare (1.5% of all cases of acute appendicitis), and often it is difficult to diagnose as the symptoms may be atypical and short-lived. It is thought to be secondary to partial and transient obstruction of the appendix [91, 92]. Although not considered a surgical emergency, it is often a missed diagnosis with complications such as perforation or abscess formation. In the genuine case of chronic appendicitis, the macroscopic appearance of the appendix is abnormal, and thus the diagnosis is best established by laparoscopy, following which the appendix is removed [92, 93]. Minor frequent episodes of right iliac fossa pain “the grumbling appendix” can be caused by threadworms in the appendix [25] or by some conditions other than the appendix. Chronic pain with evidence of organic disease (weight loss, elevated erythrocyte sedimentation rate (ESR) is usually due to Crohn’s disease at any age or cecal carcinoma in the elderly or lymphoma or tuberculosis in endemic areas [82]. Pain without signs or abnormal investigations is likely to be due to irritable bowel syndrome, but small bowel studies are still warranted if pain persists, to exclude more unusual causes. If the patient goes on to complain of recurrent episodes of abdominal pain, anorexia, and general malaise and shows tenderness over the appendix, then it is right to advise a planned (elective) appendicectomy [92, 94].

7. Conclusions

Acute appendicitis is one of a relatively dwindling number of conditions in which a decision to operate may be based solely on clinical findings. Laparoscopic appendicectomy is becoming the gold standard of treatment but non-operative management with antibiotics may suffice in selected cases with uncomplicated appendicitis. The advantages of the innovations in minimally invasive and endoscopic surgery are unlikely to render formal open appendicectomy obsolete. The controversy in the management of the appendix mass/abscess remains.

Conflict of interests

None.

Funding

The author has no sponsor for this research.

Ethical approval

The research did not involve patients directly. Thus there was no need for ethical approval.

Consent

None required.