Management of acute appendicitis
Acute appendicitis (AA) is not, as has long been assumed, a linear inflammation of the appendix possibly ending in perforation, peritonitis with subsequent sepsis, and even death, if no medical intervention is undertaken. Rather, AA is a much more heterogeneous and complex disorder.
There is a distinction between uncomplicated appendicitis (UA; inflammatory thickening of the appendix) and complicated appendicitis (CA), which is present in about 20% of cases and is defined by the occurrence of gangrene or perforation of the appendix or a periappendiceal abscess. In most cases, however, they are no longer understood as two successive stages of the same disease, but rather as two distinct entities of this disease [1]. This finding is based on epidemiological data, according to which the incidence of both entities develops independently 2,3].
Diagnostic work-up
In addition to the medical history, a clinical examination including the various signs of appendicitis (McBurney, Lanz, Blumberg, Rovsing, Psoas) and a lab panel are mandatory [4]. A common complaint in patients with a history of AA is pain migrating from the epigastrium to the right lower quadrant [5].
Leukocytosis and elevated CRP levels are nonspecific parameters of inflammation [6]. If two or more parameters are confirmed, the presence of AA is more likely; if all parameters are missing, this diagnosis is unlikely [7]. Procalcitonin has no relevant place in routine diagnostic work-up; however, high procalcitonin levels in combination with high CRP levels correlate with complicated appendicitis [8,9].
While elevated temperature and fever are nonspecific symptoms, they correlate with advanced AA, and therefore temperature should be measured routinely [6]. According to a meta-analysis, digital rectal examination is not mandatory [10].
Urinalysis (strip test) and pregnancy testing in young women of childbearing age should be performed regularly [4].
Appendicitis scores
Various scores have been developed to better assess the likelihood of AA being present: Alvarado (MANTRELS)-Score, Appendicitis Inflammatory Response (AIR oder Andersson) score, Pediatric Appendicitis Score (PAS), Raja Isteri Pengiran Anak Saleha Appendicitis (RIPASA) score, and Adult Appendicitis Score (AAI) [11-14]. These may facilitate decision making [15] but are rarely used in routine clinical practice in Germany.
Diagnostic imaging
Ultrasonography (specificity 71-94%, sensitivity 81-98%) can reliably confirm AA with appropriate expertise, but it is not reliable enough to rule it out with certainty [16, 17, 18]. Abdominal computed tomography (CT) (sensitivity 76-100%, specificity 83-100%) is superior to ultrasonography for ruling out or confirming the diagnosis of AA [16]. However, radiation exposure should not be underestimated, especially in children, adolescents, and pregnancy [11]. Here, MRI (sensitivity 97%, specificity 95%) with its lack of radiation exposure offers a safe alternative to CT [16].
In the United States, imaging in suspected appendicitis is performed in more than 80% of patients (usually CT), whereas imaging is not performed in approximately 1/3 of European patients and in approximately 3/4 of Australian patients [15]. The Dutch guidelines regard imaging as indispensable in the diagnosis of appendicitis [19].
Surgical treatment of appendicitis
At present, there is no German guideline for the treatment of appendicitis. There are the „Guidelines for Laparoscopic Appendectomy“ by the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES). More recent guidelines have been published by the European Association of Endoscopic Surgery in a consensus conference (EAES) and by the World Society of Emergency Surgery (WSES) [11, 16, 20]. There is widespread agreement in the guidelines recommending laparoscopic appendectomy as first-line treatment.
Laparoscopic appendectomy has been reported to result in an increased rate of intraabdominal abscess, particularly in complicated appendicitis, while the open technique reportedly suffers from higher rates of wound infection and transit disorders [21, 22, 23].
In AA, perioperative administration of broad-spectrum antibiotics (single-shot) reduces the incidence of wound infection and abscess formation. In UA, postoperative continuation of antibiotics is not advised; in CA they should be continued for 3 to 5 days, considering the clinical situation and lab results [11].
Timing of surgery in acute appendicitis
When imaging suspects UA, appendectomy can be deferred for 12-24 hours without increasing morbidity after prompt initiation of antibiotics. Patients ≥ 65 years of age or with comorbidities, should undergo surgery ≤ 12 hours from the time of diagnosis. Appendectomy ≥ 48 hours is associated with a higher rate of surgical infection [11, 24, 25, 25a, 25b].
In CA with phlegmon or abscess, the current literature does not permit a definite recommendation on the timing of surgery. The urgency here depends on the severity of the clinical findings and comorbidities. In perforated appendicitis with free air, there is undoubtedly an urgent indication for surgery [26].
Nonsurgical treatment of uncomplicated appendicitis
Primary non-surgical management of UA, most often confirmed by CT, with antibiotics is effective in approximately 86% of patients. If conservative treatment fails (14% of cases with persistent or even progressive symptoms), prompt appendectomy should be performed [27]. Patients primarily responding to antibiotics may be spared appendectomy in nearly 80% of cases in the first year, although at least 22.5% experience recurrent appendicitis during the first year [28]. In a study with a 5-year follow-up, the incidence of recurrent appendicitis was 27% in the first year, 34% after 2 years, 35.5% after 4 years, and 39% after 5 years [29]. A 2019 review indicated that as many as 37% of patients initially treated conservatively required appendectomy within one year [29a]. A meta-analysis published in 2019 found no statistically relevant increase in the rate of perforation in imaging-confirmed UA managed non-surgically, although the efficacy of surgical treatment of AA is higher [28, 30].
Management of complicated appendicitis
At present, there is no internationally standardized evidence-based protocol for CA management.
There are some retrospective studies and meta-analyses showing low morbidity for non-surgical or interventional management in CA versus urgent/emergent appendectomy [31,32]. In contrast, other studies have shown the benefit of surgical therapy in CA [33, 34, 35]. A 2019 meta-analysis contrasted two groups of patients: laparoscopic (appendectomy or lavage with drainage) and conservative (antibiotics only or antibiotics with interventional drainage). The laparoscopic group reported higher rates of uncomplicated courses, shorter LOS in hospital, and lower incidence of recurrent or residual abscess. Thus, the meta-analysis clearly favored laparoscopic management in CA [34].
Laparoscopic interval appendectomy 4 to 6 months after CA should be reserved for selected patients (e.g., with persistent symptoms) because these patients suffer from a higher conversion rate, significantly more intraoperative complications, and intra-abdominal infections compared with urgent/emergent appendectomy [36, 37].
Even though conservative management is becoming more important, various publications indicate that the current data are inadequate to justify departure from the primary surgical approach in acute appendicitis [38-41]. The main criticism is the lack of randomized placebo-controlled blind trials to resolve long-term outcomes with regard to adverse effects of conservative treatment.