Appendicitis

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Chapter 42

Appendicitis

Veronica F. Sullins and Steven L. Lee

Appendicitis is one of the most common surgical emergencies in children. Over 70,000 cases are seen in the USA each year.1,2 The lifetime risk of appendicitis is 9% in boys and 7% in girls. Unfortunately, there is a lack of general consensus regarding its diagnosis and management.³

Pathophysiology

The spectrum of appendicitis ranges from simple inflammation to gross perforation. This concept was initially described by van Zwalenberg in 1905 and confirmed in an experimental model by Wangensteen in 1939.4,5 Obstruction of the lumen can occur from multiple causes including fecal material (fecalith), lymphoid hyperplasia, foreign body, or parasites. Fecaliths are present in roughly 20% of children with acute appendicitis and 30–40% of children with perforated appendicitis.^6,7 Fecaliths and appendicitis are more common in developed countries with low-fiber diets compared to developing countries with high-fiber diets.⁸ Hyperplasia of the lymphoid tissue near the base of the appendix is also a common cause of appendiceal obstruction in children. Interestingly, the incidence of appendicitis closely resembles the amount of appendiceal lymphoid follicles present.⁹ Organisms such as Yersenia, Salmonella, and Shigella can cause a local or generalized reaction of the lymphoid tissue leading to obstruction. In similar fashion, parasitic infestations from Entamoeba, Strongyloides, Enterobius, Schistosoma, or Ascaris species and viral infections such as mumps virus, coxsackie virus B, cytomegalovirus, and adenovirus can lead to luminal obstruction secondary to lymphoid hyperplasia.^10–18 In children with cystic fibrosis, obstruction may be due to abnormal production of mucus leading to painful distention with or without inflammation.¹⁹ Appendicitis in neonates is rare and warrants evaluation for cystic fibrosis and Hirschsprung disease.²⁰ It is difficult to distinguish neonatal appendicitis from necrotizing enterocolitis confined to the appendix.²¹

Following obstruction, the appendix becomes distended from the accumulation of mucus and proliferation of bacteria. As intraluminal pressure increases, lymphatic and venous drainage are impaired resulting in local edema. A further increase in pressure will limit arterial inflow, thus jeopardizing tissue integrity and ultimately leading to tissue necrosis and perforation. Although the natural history of untreated appendicitis is usually perforation and abscess, not all patients will progress in this fashion. Resolution of untreated appendicitis has been described and may be the mechanism behind the clinical phenomenon of relapsing or chronic appendicitis.22,23

Historically, appendicitis has been considered a somewhat time-sensitive condition such that a significant delay in treatment may lead to an increased risk of perforation. It is for this reason that young children have a higher appendiceal perforation rate compared to older children.²⁴ Younger children have less ability to understand or articulate their developing symptoms. As a result, perforation rates have been reported to be as high as 82% in children younger than 5 years and nearly 100% in 1-year olds.²⁵

Age is not the only factor accounting for delays in treatment and therefore higher perforation rates. One of the biggest concerns contributing to this delay is the lack of access to health care. It follows that patients with poor access to health care will have higher perforation rates. Indeed, children with no insurance or public insurance have higher rates of appendiceal perforation compared to children with private insurance.26–29 Minorities also have higher perforation rates compared to whites.^26–29 Encouragingly, settings in which patients have equal access to health care or a well-established primary care network eliminate these racial, ethnic, and socioeconomic differences.^30,31

Clinical Presentation

The clinical presentation of appendicitis closely correlates with the pathophysiology of the disease process. The most common initial symptom is vague abdominal pain. This pain is due to activation of the visceral pain fibers from distention of the appendix following obstruction. Pain is vague, nonspecific, and commonly located in the periumbilical region as with distention of all midgut derivatives. As the appendiceal distention progresses, symptoms of nausea, vomiting, diarrhea, and anorexia often follow. The appearance of these symptoms prior to the onset of pain makes the diagnosis of appendicitis less likely. Intermittent, crampy pain is also less commonly associated with appendicitis.

Fever, tachycardia, and leukocytosis develop as a consequence of systemic inflammatory mediators released by ischemic tissues, white blood cells, and bacteria. The inflamed appendix then irritates the overlying peritoneum, typically by direct contact. This leads to focal peritonitis and localized right lower quadrant pain. This process explains the typical migrating pain from the umbilicus to the right lower quadrant. Any movement of the peritoneum will lead to an exacerbation of the pain. Thus, children will often demonstrate voluntary guarding of the right lower quadrant during the exam. Furthermore, children will usually resist walking and jumping due to the increased pain associated with such movement.

The most common finding on physical examination is focal tenderness in the right lower quadrant. Typically in children, only gentle pressure is required to elicit wincing, moving, or guarding. Applying pressure to a stethoscope while listening to the abdomen is a subtle way to palpate the abdomen in frightened children in whom it is difficult to obtain an accurate exam. Narcotic analgesics improve the comfort level of the patient, but do not alter the inflammatory process. Thus, tenderness will persist in patients receiving narcotics. Attempts to illicit rebound tenderness in children are uncomfortable, inaccurate, and should be avoided. An easier and more accurate method for determining the degree of peritoneal irritation is to ask the patient to walk or jump. Palpating a mass is difficult and often impossible due to the level of discomfort and guarding. Masses are more easily detected after induction of anesthesia. It is important to remember that localized tenderness is dependent on peritoneal irritation. Therefore, obesity, a retrocecal appendix, or an appendix that is walled off by omentum, mesentery, or small bowel may not be associated with localized tenderness, making the diagnosis more challenging.

Laboratory studies often show a mild leukocytosis. A markedly elevated leukocyte count suggests perforation or another diagnosis. Patients with appendicitis will have higher leukocyte counts compared to patients without appendicitis.³² However a broad range of sensitivity (52–96%) exists, which limits the usefulness of this laboratory value alone. A left-shifted differential count may be a better diagnostic indicator, but a wide range in sensitivity (39–96%) also can lead to misinterpretation.^33–35 Other inflammatory markers including C-reactive protein (CRP), procalcitonin, and D-lactate have also been investigated. Of these markers, only CRP has been shown to be useful. A value greater than 3 mg/dL has been associated with the definitive diagnosis of appendicitis when compared to children with abdominal pain from a different etiology.³² The combination of elevated leukocyte count and CRP level has the highest correlation of definitively diagnosing appendicitis.^32,36 Although normal values of both leukocyte count and CRP make the diagnosis of appendicitis less likely, the clinical signs and symptoms should be carefully considered as appendicitis cannot be excluded based on normal laboratory values. A urine analysis is typically obtained and is usually free of bacteria, but a few or moderate number of red or white blood cells may be found as the inflammatory process of the appendix may locally affect the bladder or ureter.

The typical presentation of appendicitis as described previously is found in roughly 50% of patients.³⁷ Children with appendicitis often present with wide deviations from this classic picture making for a challenging diagnosis. In patients with an atypical presentation of appendicitis, clinical scoring systems have been used to aid in making the diagnosis.^38,39 Accuracy of these scoring systems has been inconsistent which limits their usefulness over clinical judgment.^40–42 They have, however been shown to decrease the use of computed tomography (CT) scans.⁴³ Recent studies have stratified patients into risk categories based on history, physical examination, and laboratory studies to determine which patients should have surgical consultation (high risk), additional imaging studies (medium risk), or be discharged (low risk).^38–42 This is the most applicable use of a scoring system or clinical pathway at the present time.

Imaging Studies

Misdiagnosing appendicitis can lead to significant delays in treatment. Children are often diagnosed with gastroenteritis and parents are reassured that their child will improve, which may delay them from seeking further care. Epidemiologic data have shown the risk of a missed diagnosis in children to be higher in hospitals with a volume of less than one pediatric appendectomy per week.⁴⁴ Historically, negative appendectomy rates of 10% to 20% were not only considered appropriate but advisable to minimize the number of patients with a missed diagnosis and to decrease perforation rates. Some authors have questioned this philosophy, citing the risk and expense of an avoidable operation.⁴⁵ Appropriate use of diagnostic imaging can minimize both the negative appendectomy and perforation rates. Currently, the negative appendectomy rate from high-volume children’s hospitals is 3–4%.^46–48 Despite the increased use of imaging studies, correctly diagnosing children less than 5 years of age continues to be challenging with negative appendectomy rates ranging from 13–17%.⁴⁸

Plain radiography can show fecaliths in 10–20% of patients and can contribute to the diagnosis if the history and physical exam findings are consistent. Other helpful findings on plain films include lumbar scoliosis and obliteration of the psoas shadow. In general, plain films may be more useful to evaluate for other disease processes when the suspicion for appendicitis is low.

Ultrasonography (US) offers the advantages of being an efficient bedside technique that is noninvasive, requires no contrast, and emits no radiation. Thus, ultrasound should be the first imaging study utilized in patients with atypical presentations of appendicitis. Common ultrasound findings include a fluid-filled, noncompressible appendix, a diameter greater than 6 mm (Fig. 42-1), appendicolith, periappendiceal or pericecal fluid, and increased periappendiceal echogenicity caused by inflammation.^49,50 Most studies demonstrate a sensitivity greater than 85% and specificity greater than 90%.^51,52 However, ultrasound is operator dependent and results of published studies may not be similar to results obtained in many clinical settings. Patient factors such as bowel gas pattern, obesity, and guarding or movement can affect the accuracy. False-positive results may be due to a large appendix or another tubular structure being mistaken for the appendix. When a normal appendix is identified, it is a reliable study to rule out appendicitis. Unfortunately, only 10–50% of children with normal appendices can be identified.^52–54 When a normal appendix is not seen, there is still a risk of appendicitis despite an otherwise normal ultrasound study.⁵⁵ Graded compression ultrasound places pressure on the transducer to displace bowel loops and identify the appendix. The pressure is felt adequate if the psoas muscle and the iliac vessels are identified, which assure the range of view is posterior to the appendix. Furthermore, data from a large series employing upward graded compression, posterior manual compression, left oblique lateral decubitus position, and a low frequency convex transducer demonstrated that nearly all appendices could be identified with over 98% accuracy for correctly diagnosing appendicitis.⁵⁶ Contrast-enhanced power Doppler ultrasound imaging demonstrated similar accuracy in a small study.⁵⁷

FIGURE 42-1 This longitudinal view of an ultrasound in a patient with acute appendicitis shows an enlarged appendix measuring 11 mm. in diameter.

When ultrasound is unable to exclude or confirm appendicitis, additional imaging or observation with serial examinations is warranted. In order to avoid hospitalization for observation, many physicians obtain a CT scan. The findings of an enlarged appendix (>6 mm), appendiceal wall thickening (>1 mm), periappendiceal fat stranding, and appendiceal wall enhancement are useful diagnostic criteria (Fig. 42-2).^58,59 For the most part, the sensitivity and specificity of CT are around 95%.^60–66 These values are significantly lower in diagnosing perforated appendicitis.⁶⁷ The perceived improved diagnostic accuracy of CT has led to a dramatic increase in the number of CT scans performed in children even though there is not good evidence that supports its routine use for the diagnosis of appendicitis.^68–71

FIGURE 42-2 These three CT scans show differing presentations for appendicitis. (A) The appendix (arrow) is enlarged and has a thickened wall. There are no inflammatory changes such as periappendiceal fat stranding seen on this study. (B) The appendix (arrow) is enlarged and there is free fluid and inflammatory changes medially indicating likely perforation. (C) The patient presented with a one week history of pain and the appendix has perforated with the development of two abscesses (asterisks). In addition, a fecalith is seen medially (dotted arrow). This patient was initially managed nonoperatively with drainage of the abscesses and intravenous antibiotics. She underwent laparoscopic interval appendectomy 10 weeks following the initial admission.

There are, however, several concerns with CT. Some protocols require a delay in the emergency department for contrast administration, and younger children may require sedation. Recently, the ease of rapid helical CT has led to an estimated 200% increase in pediatric CT scans, significantly increasing radiation exposure in young patients.⁷² This has become a growing concern because although no direct connection between CT scan and malignancy has been made, lifetime radiation exposure has been linked to an increased risk of malignancy.⁷³ It has been estimated that a complete abdominal CT scan is equivalent to 25.7 months of natural background radiation exposure.⁷⁴ Developing tissues are more sensitive to the effects of radiation as evidenced by an increased risk of radiation-induced malignancy in patients exposed at a younger age.^73,75 The risk of a fatal radiation-induced malignancy is estimated at 0.18% for a 1-year-old child. In other words, one death due to malignancy would result from an abdominal CT scan done on 555 1-year-old patients, whereas about twice as many 15-year-olds would need to be scanned to equal that risk. Although this estimate seems significant, it represents only a 0.35% increase in overall risk compared to the risk of cancer mortality with natural background radiation.⁷⁶ Use of a staged imaging protocol, performing CT scan only if ultrasound findings are equivocal, has shown a reduction in the number of CT scans performed and therefore overall radiation exposure without sacrificing diagnostic sensitivity and specificity.⁷⁷ In addition, international guidelines on radiation protection have implemented the ALARA principle (as low as reasonably achievable), thus decreasing radiation exposure in children by 30-50%.^72,75,77 Although the overall increase in risk may be miniscule, it is important to attempt to limit radiation exposure when evaluating children with acute appendicitis.

Magnetic resonance imaging (MRI) is an intriguing nonradiation alternative to CT and is extremely accurate in diagnosing appendicitis.⁷⁸ The current version of this technology makes it impractical for widespread application, but future generations of scanners could allow it to be the preferred diagnostic imaging modality.

Differential Diagnosis

Acute appendicitis can mimic virtually any intra-abdominal process and should be high on the differential diagnosis in children with abdominal pain.⁷⁹ Causes of acute right lower quadrant pain that are often indistinguishable from appendicitis include tubo-ovarian pathologic processes, Crohn disease, mesenteric adenitis, cecal diverticulitis, Meckel diverticulitis, constipation, viral gastroenteritis, and regional bacterial enteritis (Yersinia and Campylobacter in particular). Lower abdominal pain or vague nonfocal pain can result from a urinary tract infection, kidney stone, ureteropelvic junction obstruction, uterine pathologic process, right lower lobe pneumonia, sigmoid diverticulitis, cholecystitis, pancreatitis, gastroenteritis, vasculitis, bowel obstruction, and malignancy (lymphoma). The most common diagnosis made in the presence of missed appendicitis is reported to be gastroenteritis.⁸⁰ Although many of these conditions may seem easily distinguishable, they each possess a spectrum of presentation that overlaps with appendicitis.

Treatment

The treatment of appendicitis begins with intravenous fluids and broad-spectrum antibiotics to provide coverage of enteric organisms. Management after initiating antimicrobial therapy depends on the severity of inflammation and the discussion must therefore be separated into uncomplicated (nonperforated) and complicated (perforated appendicitis). This distinction, however, is not always clear. Diagnostic imaging may help but cannot accurately diagnose perforation and many patients will not undergo preoperative imaging.⁶¹ Even intraoperative assessment showed high rates of discordance when compared to histologic evaluation of gangrenous and/or ruptured appendicitis.⁸¹ Surgeons polled with photographs showed extreme incongruence on which patients had perforation,⁸² and a survey of American Pediatric Surgical Association members revealed that most surgeons base their practice patterns on individual preferences.³ For this reason, the literature focusing on perforated appendicitis must be viewed with caution.

In reality, appendicitis presents as a spectrum of disease and it is important to distinguish which patients are at higher risk of complications. The data comparing outcomes of nonperforated versus perforated appendicitis is extensive, but most studies fail to use a strict definition of perforation. One prospective study showed that defining perforation as a visible hole in the appendix or a fecalith in the abdomen effectively identified those with greater risk of developing intra-abdominal abscesses (Fig. 42-3).⁸³ In addition, outcomes in gangrenous appendicitis are similar to acute appendicitis and many patients may actually be over-treated.⁸⁴ Thus, in the following discussion, the management of uncomplicated appendicitis will include acute, suppurative, and gangrenous appendicitis whereas complicated appendicitis will be synonymous with perforated appendicitis.

FIGURE 42-3 These two images depict the definition of perforation used in a prospective randomized trial.¹⁰³ This definition of either (A) a hole in the appendix (arrow) or (B) stool in the abdomen was subsequently validated.⁸³ An objective definition of perforation allows surgeons to compare outcomes data more accurately about perforated appendicitis.

Uncomplicated Appendicitis

After intravenous fluids and administration of broad-spectrum antibiotics, the current standard of care for uncomplicated appendicitis is appendectomy. Prophylactic antimicrobial agents should be given for 24 hours or less. In fact, a single preoperative dose of antibiotics has shown to decrease the risk of wound infection and abscess.85,86 Following appendectomy, patients are typically discharged within 24 hours. Additional postoperative antibiotics for acute appendicitis are not necessary or recommended.^85,87 However, it may be reasonable to administer additional antibiotics for patients with suppurative or gangrenous appendicitis during the first 24 hours after appendectomy or longer based on the patient’s clinical status.

Recent data in adults suggests that administration of antibiotics without appendectomy may be sufficient to treat uncomplicated appendicitis. Multiple prospective randomized trials in adults have demonstrated similar outcomes from acute appendicitis treated with antibiotics alone with success rates ranging from 44% to 85%.88–92 Adults managed nonoperatively demonstrated fewer complications and less pain, although recurrence rates were high, ranging from 14% to 37%.⁹³ There have been no prospective, randomized trials in children comparing antibiotics alone to appendectomy. Regardless of treatment modality, once antibiotics have been initiated, appendectomy is no longer considered to be an emergency and may even be considered somewhat elective.88,89,93–98 Until there is enough prospective randomized data in pediatric patients proving the efficacy of primary antibiotic treatment, appendectomy remains the standard of care for uncomplicated appendicitis. However, the need for operation may not be as urgent as previously thought.

Complicated Appendicitis

Patients with perforated appendicitis should receive postoperative antibiotics until clinical resolution has occurred. The antibiotic regimen employed for perforated appendicitis has traditionally been triple antibiotic therapy (ampicillin, gentamicin, and clindamycin or metronidazole). However recently there has been a shift towards more simple antibiotic regimens. Single agent therapy with piperacillin/tazobactam or cefotaxime, or double agent therapy with ceftriaxone and metronidazole, has been shown to be as efficacious as triple antibiotic therapy but is more cost effective.99–103 Several authors have highlighted a decrease in antibiotic expense with once daily dosing of ceftriaxone compared with multi-dose monotherapeutic agents. In addition, a prospective randomized study confirmed that single daily dosing of ceftriaxone and metronidazole is equal to and more cost effective than traditional triple antibiotic therapy in the treatment of perforated appendicitis.¹⁰³ Therefore, current best evidence suggests once-a-day dosing with ceftriaxone at 50 mg/kg/day and metronidazole at 30 mg/kg/day provides the simplest and least expensive regimen.

Although the length of antibiotic course for perforated appendicitis is not yet standardized, current findings from multiple systematic reviews recommend continuation of antibiotics until resolution of clinical symptoms.85,102 This includes normalization of leukocyte count and differential, full return of gastrointestinal function, resolution of fever, and normalization of physical exam. In addition, if the duration of intravenous antibiotic therapy is less than 5 days, patients can be discharged safely on oral antibiotics to complete a 7-day course.¹⁰⁴ A patient who is clinically well by postoperative day three is unlikely to develop an abscess.¹⁰⁵ However, if a patient’s clinical symptoms have not resolved, it should raise the suspicion of an intra-abdominal abscess and intravenous antibiotics should be continued.

After initial intravenous fluid administration and antibiotics, the management of complicated appendicitis can be separated into nonoperative and operative treatment. Choice of treatment depends on identification of patients at high risk for treatment failure. It is also important to consider that many patients will not be diagnosed with perforated appendicitis preoperatively. Risk factors for failure of nonoperative management include greater than 15% band forms on the white blood cell differential count, disease that extends beyond the right lower quadrant, absence of a well-defined abscess, or presence of an appendicolith on imaging.106–108 Conversely, a large meta-analysis comparing appendectomy versus conservative treatment for complicated appendicitis as defined by abscess or phlegmon on presentation demonstrated higher rates of overall complications, wound infections, and intra-abdominal abscesses in those who had immediate appendectomy.¹⁰⁹

The concept of managing complicated appendicitis with antibiotics alone is to decrease the significant local and regional inflammation that may make an immediate operation very difficult and potentially more dangerous. Once treated, most surgeons will perform interval appendectomy after six to ten weeks. However, some advocate that the interval appendectomy is not necessary as recurrence rates are low, ranging from 8–14%.110,111 One problem with these studies is the relatively short length of follow-up. A recent systematic review found a 20.5% overall risk of recurrent appendicitis with a range of 0–42%. However, nearly all studies were retrospective and thus only included patients specifically selected for nonoperative management.¹¹² Some studies showed high rates of pathologic findings in interval appendectomy specimens.^113,114 Although there is a lack of long-term data to accurately predict the rates of recurrence in both adults and children, some studies suggest that most recurrences will occur within three years and the majority within one to six months.^110–112 For these reasons, most pediatric surgeons perform interval appendectomy in patients with complicated appendicitis who were initially managed nonoperatively.³

The majority of patients who present with a well-formed abscess on initial imaging are managed nonoperatively (see Fig. 42-2C). Historically, immediate appendectomy in this patient population was difficult, required a larger incision, and had a high morbidity. Primary treatment of the abscess with antibiotics alone, or antibiotics and percutaneous drainage with or without drain placement for larger fluid collections, is a widely accepted treatment strategy. Interval appendectomy is then performed after the inflammation has subsided.^3,115–119 Although treatment with percutaneous drainage and interval appendectomy has inherent risk of complications, success rates have been reported to be as high as 88%.¹⁰⁷ A recent pilot randomized trial comparing initial laparoscopic appendectomy versus antibiotics, percutaneous drainage and subsequent interval laparoscopic appendectomy in patients presenting with perforated appendicitis and abscess demonstrated no difference in the rate of recurrent abscess, length of hospital stay, or hospital charges.¹²⁰ Patients undergoing immediate appendectomy had longer operations and a longer time to return of bowel function. Alternately, patients who had interval appendectomies had more CT scans. Quality of life surveys at presentation, 2 weeks, and 12 weeks in both groups from this study showed that families experience significant parenting distress related to disruption in the child’s quality of life until the appendectomy is performed.¹²¹

The majority of patients with complicated appendicitis can be safely managed with appendectomy. Specifically, patients with a phlegmonous mass, appendicolith, or absence of a well-formed abscess on imaging have a higher risk of failure of nonoperative management.107,122 These patients can safely and reliably undergo immediate laparoscopic appendectomy.^123,124 In patients with perforated appendicitis without abscess, a recent prospective randomized trial demonstrated lower rates of adverse events, shorter length of hospitalization, and earlier return to normal activity with early appendectomy.¹²² In addition, mean total hospital charges and resource use were significantly higher in patients undergoing interval appendectomy, likely due to the increased number of adverse events.¹²⁵

The choice of nonoperative versus operative treatment depends on the preoperative diagnosis of perforation. As mentioned previously, it is difficult to interpret data on perforated appendicitis because a strict definition of perforation has not uniformly been used. Currently, patients are initially managed operatively or nonoperatively based on disease severity and surgeon preference. Although evidence suggests that the majority of patients can safely undergo early appendectomy, the optimal management of complicated appendicitis still remains unclear.

Operative Technique

First described in 1893 by McBurney, the traditional method of appendectomy was a muscle-splitting, right lower quadrant incision.¹²⁶ The cecum is delivered through the incision, the mesoappendix is divided, and the appendix is ligated at its base. In the laparoscopic approach, both surgeon and first assistant stand on the patient’s left facing a video monitor positioned on the right (Fig. 42-4A).¹²⁷ The patient is positioned supine on the operating table, and the abdomen is prepped widely. After insertion of a 10–12 mm umbilical cannula, pneumoperitoneum is established. Two 5 mm ports are then placed, one in the left lower quadrant and one in the left suprapubic area (Fig 42-4B). A 5 mm 30° or 45° telescope is introduced through the left lower quadrant port, and the other two ports are the working ports. This allows effective triangulation of instruments to maximize utility in a small space, a core principle of endoscopic surgery. Diagnostic laparoscopy is initially performed. If present, abscesses are opened and purulent fluid is aspirated from the pelvis, perihepatic space and paracolic gutters. The appendix is located by following the taenia of the cecum inferiorly. After grasping the appendix and retracting it inferiorly, a window is created in the mesoappendix close to the cecum. The endoscopic stapler is inserted through the 12 mm umbilical cannula and used to divide the appendix and mesoappendix (Fig. 42-5). The appendix is usually divided first, followed by division of the mesoappendix. On occasion, however, it may be more expedient to ligate the mesoappendix first. If the appendix can be delivered through the cannula, an endoscopic bag is not used. However, if the appendix is too large for the cannula, an endoscopic bag is employed to avoid dragging the appendix through the umbilical incision. Drains are not routinely utilized for advanced disease.

FIGURE 42-4 (A) Port positions for a laparoscopic appendectomy. Typically three cannulas are used, with the endoscopic stapler introduced through the 12 mm umbilical port. The appendix is removed through this site as well. (B) Postoperative appearance.

FIGURE 42-5 (A) Initially, a window is made in the mesoappendix. (B) Usually, the appendix is ligated and divided with the stapler first, followed by ligation/division of the mesoappendix.

Since the introduction of laparoscopic appendectomy 25 years ago, there has been an abundance of data comparing open and endoscopic techniques. Initial advantages of the open approach seemed to be a shorter length of operation and fewer postoperative intra-abdominal abscesses.128–130 However, as expected, there were higher rates of wound infections, presumably due to contamination of the incision when delivering an infected appendix through the wound (Fig. 42-6). Advantages of the laparoscopic approach are multiple. It allows better visualization of the entire abdomen, which is especially beneficial in obese patients who would otherwise require a larger incision, and fertile females who may have other intra-abdominal pathology.^131–133 Laparoscopy also allows lysis of interloop abscesses and aspiration of purulent fluid, and it facilitates dissection in obese patients in whom open appendectomy would be challenging. Use of laparoscopy has been associated with a higher negative appendectomy rate.¹³⁴ However, this discrepancy may be explained by the increased use of diagnostic laparoscopy in patients whose diagnosis is not clear, specifically teenage females who may have gynecologic findings. Open appendectomy may be easier in younger patients due to lack of space in the peritoneal cavity relative to the size of the laparoscopic instruments.

FIGURE 42-6 This child underwent open appendectomy through a right lower abdominal incision and developed a wound infection which is being treated. The significant reduction in the incidence of wound infections is one of the benefits of the laparoscopic approach, especially for perforated appendicitis.

The use of laparoscopy has increased from about 20% in 1998 to 70% in 2007.135–137 In the past decade, there have been multiple prospective randomized trials, large retrospective studies, and meta-analyses comparing outcomes in open versus the laparoscopic approach. While early studies found increased operating times for laparoscopy, more recent studies have shown no difference in length of operation.^138–142 A few studies actually demonstrated shorter operating times with laparoscopy.^139–140 Laparoscopic appendectomy is also associated with shorter hospitalization, fewer postoperative outpatient visits, decreased time off work, and earlier return to routine activity.134–136,138,142–144 One study suggested increased inpatient costs but lower outpatient costs for the laparoscopic approach, while a large national database review found increased costs in uncomplicated appendicitis but similar costs for complicated appendicitis.^137,142 A prospective randomized double-blind study demonstrated that patients who underwent laparoscopic appendectomy had an improved quality of life at two weeks.¹⁴⁵

Overall complication rates are less than 3% for uncomplicated appendicitis and 16% to 18% for complicated appendicitis with many studies showing the same if not lower rates after laparoscopy.131,135,137,138,144 One of the more common complications following appendectomy is an intra-abdominal abscess. Rates of postoperative abscess are estimated to be less than 1% in uncomplicated appendicitis and 1–15% in complicated appendicitis. However, in many of these studies, there is not uniform definition of perforation. When a uniform definition is used, rates as high as 20% have been reported.^{83,105,120,137} One group found an increase in abscess rate from 19% to 46% when comparing non-obese to obese patients.¹⁴⁶ A decade ago, a few groups reported a higher incidence of postoperative abscesses in patients who had a laparoscopic appendectomy.^128–130 However, there is now an abundance of level 1, 2, and 3 evidence showing no difference in rates of intra-abdominal abscesses.^{136–138,144,147–155} In fact, the most recent national database review evaluated 212,958 pediatric patients and found a higher rate of postoperative abscess in patients who underwent open appendectomy for both uncomplicated and complicated appendicitis.¹³⁷ This discrepancy may be due to increasing surgeon experience with laparoscopy, more advanced endoscopic equipment, or possibly using an endobag for removal of the perforated appendix.¹⁵⁶

Regardless of whether laparoscopic or open appendectomy is performed, culture of the fluid has not been shown to be helpful at the time of the initial operation.157,158 One study demonstrated that children whose antibiotic treatment was based on the cultures did somewhat worse than those whose fluid was not cultured.¹⁵⁸ Peritoneal lavage with either saline or antibiotic solution has also not been shown to decrease the incidence of abdominal abscesses.¹⁵⁹ Similarly, the use of drains has not proved useful except in cases of walled-off abscess cavities.^160,161

With respect to wound infections, this complication occurs in less than 1% of patients with uncomplicated appendicitis. In contrast, patients with complicated appendicitis may have up to 16% incidence of wound infection.¹⁴⁴ Most recent studies have found that laparoscopy has a lower rate of surgical site infections.^{24,135–138,143,144} The use of laparoscopy has also demonstrated a nearly fourfold decrease in postoperative bowel obstructions.^162,163 Other less common postoperative complications include urinary tract infection and pneumonia.

The concept that higher complication rates accompany the laparoscopic approach is outdated. It is now widely accepted that laparoscopic appendectomy should be the procedure of choice in both uncomplicated and complicated appendicitis, except in centers without laparoscopic experience.

Recently, the use of single-site laparoscopic surgical techniques have been reported.164–171 In single-incision laparoscopic appendectomy (SILA), a single transumbilical incision is made and a 5 mm or 12 mm port is placed. One or two additional ports are placed through the same incision using multi-port devices or separate fascial incisions. Subsequent dissection and appendectomy are identical to the traditional three-port procedure. Advantages of this technique are thought to be shorter length of hospitalization, better cosmesis, and lower hospital costs. Technically the procedure can be more challenging as close approximation of instruments limits range of motion and narrows the visual field.¹⁷² Theoretically a larger fascial incision may result in increased postoperative pain and higher rates of incisional hernias although preliminary evidence is limited. Hybrid procedures such as laparoscopic-assisted single-port appendectomy (SPA) and transumbilical laparoscopic-assisted appendectomy (TULAA) are other described techniques that combine a laparoscopic single-incision approach for dissection followed by extracorporeal removal of the appendix through the umbilicus as in the traditional open procedure (Fig. 42-7). Early retrospective reviews have shown no difference in postoperative complication rates and similar or even decreased hospital costs when compared to open and other laparoscopic techniques.^167,168,170 A recent prospective randomized trial comparing single site to traditional three-port appendectomy in patients with nonperforated appendicitis demonstrated no difference in postoperative wound infection or abscess rates, length of hospital stay, or hospital charges.¹⁶⁴ This particular study found a longer operative time (in minutes) for the single-incision approach, but this was not clinically relevant.