APPENDICITIS Historical Perspective

In 1886, Reginald Fitz of Boston correctly identified the appendix as the primary cause of right lower quadrant inflammation. He coined the term appendicitis and recommended early surgical treatment of the disease. Richard Hall reported the first survival of a patient after removal of a perforated appendix, which launched focused attention on the surgical treatment of acute appendicitis. In 1889, Chester McBurney described characteristic migratory pain as well as localization of the pain along an oblique line from the anterior superior iliac spine to the umbilicus. McBurney described a right lower quadrant muscle-splitting incision for removal of the appendix in 1894. The mortality rate from appendicitis improved with the widespread use of broad-spectrum antibiotics in the 1940s. Recent advances have included improved preoperative diagnostic studies, interventional radiologic procedures to drain established periappendiceal abscesses, and the use of laparoscopy to confirm the diagnosis and exclude other causes of abdominal pain. Laparoscopic appendectomy was first reported by the gynecologist Kurt Semm in 1982 but has only gained widespread acceptance in recent years.

Pathophysiology

Obstruction of the lumen is believed to be the major cause of acute appendicitis.[2] This may be due to inspissated stool (fecalith or appendicolith), lymphoid hyperplasia, vegetable matter or seeds, parasites, or a neoplasm. The lumen of the appendix is small in relation to its length, and this configuration may predispose to closed-loop obstruction. Obstruction of the appendiceal lumen contributes to bacterial overgrowth, and continued secretion of mucus leads to intraluminal distention and increased wall pressure. Luminal distention produces the visceral pain sensation experienced by the patient as periumbilical pain. Subsequent impairment of lymphatic and venous drainage leads to mucosal ischemia. These findings in combination promote a localized inflammatory process that may progress to gangrene and perforation. Inflammation of the adjacent peritoneum gives rise to localized pain in the right lower quadrant. Although there is considerable variability, perforation typically occurs after at least 48 hours from the onset of symptoms and is accompanied by an abscess cavity walled-off by the small intestine and omentum. Rarely, free perforation of the appendix into the peritoneal cavity occurs that may be accompanied by peritonitis and septic shock and can be complicated by the subsequent formation of multiple intraperitoneal abscesses.

Bacteriology

The flora in the normal appendix is very similar to that in the colon, with a variety of facultative aerobic and anaerobic bacteria. The polymicrobial nature of perforated appendicitis is well established. Escherichia coli, Streptococcus viridans, and Bacteroides and Pseudomonas species are frequently isolated, and many other organisms may be cultured ( Table 49-1 ). Among patients with acute nonperforated appendicitis, cultures of peritoneal fluid are frequently negative and are of limited use. Among patients with perforated appendicitis, peritoneal fluid cultures are more likely to be positive, revealing colonic bacteria with predictable sensitivities.[3] Because it is rare that the findings alter the selection or duration of antibiotic use, some authors have challenged the traditional practice of obtaining cultures.

Diagnosis History

Appendicitis needs to be considered in the differential diagnosis of nearly every patient with acute abdominal pain. Early diagnosis remains the most important clinical goal in patients with suspected appendicitis and can be made primarily on the basis of the history and physical exam in most cases. The typical presentation begins with periumbilical pain (due to activation of visceral afferent neurons) followed by anorexia and nausea. The pain then localizes to the right lower quadrant as the inflammatory process progresses to involve the parietal peritoneum overlying the appendix. This classic pattern of migratory pain is the most reliable symptom of acute appendicitis.[5] A bout of vomiting may occur, in contrast to the repeated bouts of vomiting that typically accompany viral gastroenteritis or small bowel obstruction. Fever ensues, followed by the development of leukocytosis. These clinical features may vary. For example, not all patients become anorexic. Consequently, the feeling of hunger in an adult patient with suspected appendicitis should not necessarily deter one from surgical intervention. Occasional patients have urinary symptoms or microscopic hematuria, perhaps owing to inflammation of periappendiceal tissues adjacent to the ureter or bladder, and this may be misleading. Although most patients with appendicitis develop an adynamic ileus and absent bowel movements on the day of presentation, occasional patients may have diarrhea. Others may present with small bowel obstruction related to contiguous regional inflammation. Therefore, appendicitis needs to be considered as a possible cause of small bowel obstruction, especially among patients without prior abdominal surgery.

Physical Examination

Patients with acute appendicitis typically look ill and are lying still in bed. Low-grade fever is common (∼38°C). Examination of the abdomen usually reveals diminished bowel sounds and focal tenderness with voluntary guarding. The exact location of the tenderness is directly over the appendix, which is most commonly at McBurney's point (located one third of the distance along a line drawn from the anterior superior iliac spine to the umbilicus). The normal appendix is mobile, so it may become inflamed at any point on a 360-degree circle around the base of the cecum. Thus, the site of maximal pain and tenderness can vary. Peritoneal irritation can be elicited on physical examination by the findings of voluntary and involuntary guarding, percussion, or rebound tenderness. Any movement, including coughing (Dunphy's sign), may cause increased pain. Other findings may include pain in the right lower quadrant during palpation of the left lower quadrant (Rovsing's sign), pain on internal rotation of the hip (obturator sign, suggesting a pelvic appendix), and pain on extension of the right hip (iliopsoas sign, typical of a retrocecal appendix).

Rectal and pelvic examinations are most likely to be negative. However, if the appendix is located within the pelvis, tenderness on abdominal examination may be minimal, whereas anterior tenderness may be elicited during rectal examination as the pelvic peritoneum is manipulated. Pelvic examination with cervical motion may also produce tenderness in this setting.

If the appendix perforates, abdominal pain becomes intense and more diffuse, and abdominal muscular spasm increases, producing rigidity. The heart rate rises, with an elevation of temperature above 39°C. The patient may appear ill and require a brief period of fluid resuscitation and antibiotics before the induction of anesthesia. Occasionally, pain may improve somewhat after rupture of the appendix, although a true pain-free interval is uncommon.

Laboratory Studies

The white blood cell count is elevated with more than 75% neutrophils in most patients. A completely normal leukocyte count and differential is found in about 10% of patients with acute appendicitis. A high white blood cell count (>20,000/mL) suggests complicated appendicitis with either gangrene or perforation. A urinalysis can also be helpful in excluding pyelonephritis or nephrolithiasis. Minimal pyuria, frequently seen in elderly women, does not exclude appendicitis from the differential diagnosis because the ureter may be irritated adjacent to the inflamed appendix. Although microscopic hematuria is common in appendicitis, gross hematuria is uncommon and may indicate the presence of a kidney stone. Other blood tests are generally not helpful and are not indicated in the patient with suspected appendicitis.

Radiography

Although they are commonly obtained, the indiscriminate use of plain abdominal radiographs in the evaluation of patients with acute abdominal pain is unwarranted. In one study of 104 patients with acute onset of right lower quadrant pain, interpretation of plain x-rays changed the management of only 6 patients (6%), and in one case contributed to an unnecessary laparotomy.[6] A calcified appendicolith is visible on plain films in only 10% to 15% of patients with acute appendicitis; however, its presence strongly supports the diagnosis in a patient with abdominal pain. Plain abdominal films may be useful for the detection of ureteral calculi, small bowel obstruction, or perforated ulcer, but such conditions are rarely confused with appendicitis. Failure of the appendix to fill during a barium enema has been associated with appendicitis, but this finding lacks both sensitivity and specificity because up to 20% of normal appendices do not fill.

Among patients with abdominal pain, ultrasonography has a sensitivity of about 85% and a specificity of more than 90% for the diagnosis of acute appendicitis. Sonographic findings consistent with acute appendicitis include an appendix of 7 mm or more in anteroposterior diameter, a thick-walled, noncompressible luminal structure seen in cross section referred to as a target lesion, or the presence of an appendicolith ( Fig. 49-1 ). In more advanced cases, periappendiceal fluid or a mass may be found. Ultrasonography has the advantages of being a noninvasive modality requiring no patient preparation that also avoids exposure to ionizing radiation. For these reasons, it is commonly used in children and in pregnant patients with equivocal clinical findings suggestive of acute appendicitis. Disadvantages of ultrasonography include operator-dependent accuracy and difficulty interpreting the images by those other than the operator. Because performance of the study may require hands-on participation by the radiologist, ultrasonography may not be readily available at night or on weekends. Pelvic ultrasound can be especially useful in excluding pelvic pathology, such as tubo-ovarian abscess or ovarian torsion, that may mimic acute appendicitis.

Computed tomography (CT) is commonly used in the evaluation of adult patients with suspected acute appendicitis. Improved imaging techniques, including the use of 5-mm sections, have resulted in increased accuracy of CT scanning,[7] which has a sensitivity of about 90% and a specificity of 80% to 90% for the diagnosis of acute appendicitis among patients with abdominal pain. Controversy remains as to the importance of intravenous, oral gastrointestinal, and rectal contrast in improving diagnostic accuracy. In general, CT findings of appendicitis increase with the severity of the disease. Classic findings include a distended appendix greater than 7 mm in diameter and circumferential wall thickening, which may give the appearance of a halo or target ( Fig. 49-2 ). As inflammation progresses, one may see periappendiceal fat stranding, edema, peritoneal fluid, phlegmon, or a periappendiceal abscess. CT detects appendicoliths in about 50% of patients with appendicitis and also in a small percentage of people without appendicitis. Among patients with abdominal pain, the positive predictive value of the finding of an appendicolith on CT remains high at about 75%.

Should CT be used routinely in the diagnostic evaluation of patients with suspected appendicitis? In our opinion, no. In the setting of typical right lower quadrant pain and tenderness with signs of inflammation in a young patient, a CT scan is unnecessary, wastes valuable time, and exposes the patient to the risks for allergic contrast reaction, nephropathy, aspiration pneumonitis, and ionizing radiation. The latter carries increased risk in children in whom the rate of radiation-induced cancer has been estimated at 0.18% following an abdominal CT scan.[8] Moreover, a negative study may be misleading, particularly early in the inflammatory process. CT has proved most valuable among older patients in whom the differential diagnosis is lengthy, the clinical findings may be confusing, and appendectomy carries increased risk. [14] [15] Among patients with atypical symptoms, CT scan may reduce the negative appendectomy rate (i.e., the fraction of pathologically normal appendices that are removed). Selective use of CT scans seems most appropriate, and as always, the study needs to be obtained only in settings in which it has a significant potential to alter management.

The morbidity of perforated appendicitis far exceeds that of a negative appendectomy. Thus, the strategy has been to set a low enough threshold for removal of the appendix so as to minimize the cases of missed appendicitis. With increased use of CT scans, the frequency of negative explorations has declined in recent years without an accompanying rise in the number of perforations. A recent analysis of more than 75,000 patients in 1999 to 2000 revealed a negative appendectomy rate of 6% in men and 13.4% in women.[9]

Diagnostic Laparoscopy

Although most patients with appendicitis will be accurately diagnosed based on history, physical exam, laboratory studies, and if necessary, imaging techniques, there are a small number in whom the diagnosis remains elusive. For these patients, diagnostic laparoscopy can provide both a direct examination of the appendix and a survey of the abdominal cavity for other possible causes of pain. We use this technique primarily for women of childbearing age in whom preoperative pelvic ultrasound or CT scan fails to provide a diagnosis. Concerns about the possible adverse effects of a missed perforation and peritonitis on future fertility sometimes prompt earlier intervention in this patient population.

Differential Diagnoses

The differential diagnosis of appendicitis can include almost all causes of abdominal pain, as described in the classic treatise “Cope's Early Diagnosis of the Acute Abdomen.”[11] A useful rule is never to place appendicitis lower than second in the differential diagnosis of acute abdominal pain in a previously healthy person. The diagnosis of appendicitis is particularly difficult in the very young and in the elderly. It is in these groups that diagnosis is most often delayed and perforation occurs most frequently. Imaging studies are strongly considered here. Because of increasing concerns about radiation-induced cancers among children,[8] ultrasonography is the preferred initial imaging modality in this group. Ultrasonography was shown to change the disposition of 59% of children with abdominal pain that had already been evaluated by the surgical team.[12] For older patients, CT has the advantages of detection of the broader array of conditions, such as diverticulitis and malignancy, found in the differential diagnosis.

In infants, nonfocal findings such as lethargy, irritability, and anorexia may be present in the early stages, with vomiting, fever, and pain apparent as the disease progresses. Ultrasound is useful in the evaluation of appendicitis and other acute abdominal emergencies, such as pyloric stenosis, in infants.

In preschool-aged children, the differential diagnosis includes intussusception, Meckel's diverticulitis, and acute gastroenteritis. Intussusception may be distinguished by the colicky nature of the pain, with intervening pain-free periods, and the absence of peritonitis. Meckel's diverticulitis is relatively uncommon, but its presentation is similar to that of appendicitis with the exception that the pain and tenderness typically localize in the periumbilical region. Gastroenteritis can be difficult to distinguish from acute appendicitis in any age group. Typically, diarrhea and vomiting occur early and persistently in gastroenteritis, and focal abdominal tenderness and peritoneal signs are uncommon. However, it is advisable to discuss with parents of a child suspected of having gastroenteritis the importance of re-evaluation within 12 to 24 hours if the child develops worsening abdominal pain, or other signs of clinical deterioration, because misdiagnosed appendicitis remains high on the list of considerations.

In school-aged children, gastroenteritis often presents with abdominal pain and diarrhea without fever or leukocytosis. The most common mimicker of appendicitis in this population is mesenteric lymphadenitis, which may be caused by a wide variety of enteric infections.[13] Ultrasonography may be helpful in identifying enlarged lymph nodes in the region of the ileal mesentery in conjunction with thickening of the ileal wall and a normal appendix, in which case appendectomy may be avoided. It is important to bear in mind that enlarged mesenteric lymph nodes may also be the result of acute appendicitis. Inflammatory bowel disease is also considered in children, particularly if there is a history of recurrent episodes of abdominal pain. Constipation and functional pain are common in this age group. Although constipation may be associated with relatively severe pain, there are no peritoneal signs, fever, or leukocytosis, and the diagnosis is supported by a recent history of hard stools. Functional pain is usually somewhat milder, recurrent, and self-limited.

In adults, it is important to consider other regional inflammatory conditions, such as pyelonephritis, colitis, and diverticulitis. The pain and tenderness of pyelonephritis are typically located in the flank and are accompanied by high fever and white blood cell count as well as pyuria. Colitis is often accompanied by diarrhea, and the location of the pain typically outlines the trajectory of the colon. In Crohn's colitis, diarrhea is uncommon, but there is often a pattern of recurrent symptoms. The onset of right-sided diverticulitis is typically insidious, worsening over a period of days, and involves a larger area of the right lower abdomen than does appendicitis. CT scan is helpful in identifying the inflamed diverticula and enhancement of cecal wall thickening that accompanies this diagnosis.

The differential diagnosis for appendicitis among women in their childbearing years is broad and accounts for the higher incidence of false-positive diagnoses in this group. Pelvic pathology that may mimic acute appendicitis includes pelvic inflammatory disease (PID), tubo-ovarian abscess, ruptured ovarian cyst or ovarian torsion, and ectopic pregnancy, among others.[14] These conditions are typically distinguished from acute appendicitis by the absence of gastrointestinal symptoms. Pelvic ultrasound is especially helpful in these patients because of its high sensitivity and specificity for the diagnosis of pelvic pathology. If a normal appendix is also seen, appendicitis is unlikely.

Appendicitis is the most common nonobstetric surgical disease of the abdomen during pregnancy. Diagnosis may be difficult because symptoms of nausea, vomiting, and anorexia, as well as elevated white blood cell count, are common during pregnancy. Moreover, the location of tenderness varies with gestation. After the 5th month of gestation, the appendix is shifted superiorly above the iliac crest, and the appendiceal tip is rotated medially into the right upper quadrant by the gravid uterus. Ultrasound is helpful both in establishing the diagnosis and the location of the inflamed appendix. In cases in which ultrasound has been equivocal, magnetic resonance imaging (MRI) has been used successfully, thereby avoiding ionizing radiation exposure to the developing fetus. The main challenge is to recognize the possibility of appendicitis in pregnant patients and intervene promptly because peritonitis significantly increases the rate of fetal loss (2.6%-10.9% in one meta-analysis).[15] Laparoscopic appendectomy has been performed through the second trimester of pregnancy, although data are lacking comparing the safety of this approach to the open procedure.

Appendicitis in the elderly can be difficult to diagnose because many patients delay in seeking care and present atypically. Fever is uncommon, the white blood cell count may be normal, and many older patients with appendicitis do not experience right lower quadrant pain. About one half of older patients are incorrectly diagnosed at the time of admission, and these patients have a much higher rate of perforation at the time of surgery because of delays in operative intervention.[10] More than 50% of older patients have perforated appendicitis, compared with less than 20% for younger patients. Diverticulitis and bowel obstruction are common misdiagnoses in this patient population, and the differential diagnosis also includes malignancies of the gastrointestinal tract and reproductive system, perforated ulcers, and cholecystitis, among others. CT has become an invaluable tool in the evaluation of abdominal pain among older patients, and its use has shortened preoperative hospital delays.[10]

Diagnostic Algorithm

Patients in whom the diagnosis of appendicitis is being considered should have a surgical evaluation ( Fig. 49-3 ). Early involvement of the surgical team in the diagnostic evaluation of these patients may improve diagnostic accuracy and help to avoid expensive and unnecessary diagnostic studies.[16] Experienced clinicians accurately diagnose appendicitis based on a combination of history, physical exam, and laboratory studies about 80% of the time. We stratify patients based on their clinical findings starting with the extremes, which are easier to identify. Patients with a high probability of uncomplicated appendicitis undergo surgery. Patients suspected of having an appendiceal abscess undergo further imaging, typically ultrasonography for children or CT for adults. The next step in the evaluation of patients in whom the likelihood of appendicitis is believed to be low is determined by the probability and severity of alternate diagnoses under consideration. Many of these patients will be discharged with a planned follow-up visit or phone call the next day. Most older patients with abdominal pain undergo CT before discharge because of the high prevalence of surgical pathology in this patient population. The remaining patients are believed to have an intermediate probability of having appendicitis. Children and pregnant women in this category typically undergo abdominal ultrasonography. Women in their childbearing years may undergo pelvic ultrasonography or CT scan depending on the index of suspicion of pelvic pathology. Among patients that would otherwise be admitted to the hospital for observation, CT may reduce hospital costs by reducing length of stay. Following the completion of imaging studies, the patient is re-examined to determine whether pain and tenderness have localized to the right lower quadrant. If the diagnosis remains uncertain at this point, patients either undergo diagnostic laparoscopy, especially in fertile women, are admitted for observation and re-examination, or are discharged with follow-up the next day.

Treatment

Most patients with acute appendicitis are managed by prompt surgical removal of the appendix. A brief period of resuscitation is usually sufficient to ensure the safe induction of general anesthesia. Preoperative antibiotics cover aerobic and anaerobic colonic flora. For patients with nonperforated appendicitis, a single preoperative dose of antibiotics reduces postoperative wound infections and intra-abdominal abscess formation.[17] Postoperative oral antibiotics do not further reduce the incidence of infectious complications in these patients.[18] For patients with perforated or gangrenous appendicitis, we continue postoperative intravenous antibiotics until the patient is afebrile. [24] [25]

Several prospective randomized studies have compared laparoscopic and open appendectomy, and the overall differences in outcomes remain small. The percentage of appendectomies performed laparoscopically continues to increase.[21] Obese patients had less pain and shorter hospital stays after laparoscopic versus open appendectomy.[22] Patients with perforated appendicitis had lower rates of wound infections following laparoscopic removal of the appendix. [28] [29] Patients treated laparoscopically had improved quality-of-life scores 2 weeks after surgery[25] and lower readmission rates.[21] As compared with open appendectomy, the laparoscopic approach involves higher operating room costs, but these have been counterbalanced in some series by shorter lengths of stay.[21] For patients in whom the diagnosis remains uncertain after the preoperative evaluation, diagnostic laparoscopy is useful because it allows the surgeon to examine the remainder of the abdomen, including the pelvis, for abnormalities. Our practice is to perform appendectomies laparoscopically in fertile women, obese patients, and cases of diagnostic uncertainty; otherwise, the approach is determined by patient or surgeon preference.

Open appendectomy is usually easily performed through a transverse right lower quadrant incision (Davis-Rockey) or an oblique incision (McArthur-McBurney) ( Fig. 49-4 , inset). In cases with a large phlegmon or diagnostic uncertainty, a subumbilical midline incision may be used. For uncomplicated cases we prefer a transverse, muscle-splitting incision lateral to the rectus abdominis muscle over McBurney's point. Local anesthetic, administered before the incision, reduces postoperative pain.[26] After the peritoneum is entered, the inflamed appendix is identified by its firm consistency and delivered into the field. Particular attention is paid to gentle handling of the inflamed tissues to minimize the risk for rupture during the procedure. In difficult cases, enlarging the incision and working down the trajectory of the taeniae on the cecum will often facilitate localization and delivery of the appendix. The meso-appendix is divided between clamps and ties (see Fig. 49-4A ). The base of the appendix is skeletonized at its junction with the cecum. A heavy absorbable tie is placed around the base of the appendix, and the specimen is clamped and divided (see Fig. 49-4B ). An absorbable purse-string suture or Z stitch is placed into the cecal wall (see Fig. 49-4C ), and the appendiceal stump is inverted into a fold in the wall of the cecum (see Fig. 49-4D ). Simple ligation and inversion probably have equivalent outcomes. If the base of the appendix and adjacent cecum are extensively indurated, an ileocecal resection is performed. The wound is closed primarily in most cases because the wound infection rate is less than 5%.

Laparoscopic appendectomy offers the advantage of diagnostic laparoscopy combined with the potential for shorter recovery and incisions that are less conspicuous. If a CT scan was obtained preoperatively, it needs to be reviewed by the surgeon for useful information regarding the position of the appendix relative to the cecum. After injection of local anesthetic, we place a 10-mm port into the umbilicus, followed by a 5-mm port in the suprapubic midline region and a 5-mm port midway between the first 2 ports and to the left of the rectus abdominis muscle ( Fig. 49-5 , inset). The 5-mm, 30-degree scope is moved to the central port with the surgeon and assistant both on the patient's left. With the patient in Trendelenburg's position and rotated left-side down, we gently sweep the terminal ileum medially and follow the taeniae of the cecum caudad to locate the appendix, which is then elevated. The mesoappendix is divided using a 5-mm harmonic scalpel or Liga-Sure, or between clips, depending on the thickness of this tissue (see Fig. 49-5A ). We typically encircle the appendix with two heavy absorbable Endoloops cinched down at the base of the appendix and then place a third Endoloop about 1 cm distally and divide the appendix (see Fig. 49-5B and C ). In cases in which the base is indurated and friable, we use a 30-mm endoscopic stapler to divide the appendix. For most cases, however, the considerable added cost of the stapler is unwarranted. Any spillage of fluid is promptly aspirated, and similarly any identified appendicoliths are removed to prevent postoperative abscess formation. The appendix is placed into a specimen bag and removed with the port through the umbilical wound (see Fig. 49-5D ). Fascia at the 10-mm trocar site is closed, and all wounds are closed primarily.

Perforated Appendicitis

Patients with perforation of the appendix may be very ill and require several hours of fluid resuscitation before safe induction of general anesthesia. Broad-spectrum antibiotics directed against gut aerobes and anaerobes are initiated early in the evaluation and resuscitation phase. In children, a laparoscopic approach to the perforated appendix appears to reduce the incidence of postoperative wound infections and ileus and is associated with shorter hospital stays and lower costs.[27] Recent studies in adults suggest that patients successfully treated laparoscopically realize similar benefits, albeit with a higher risk for conversion to an open procedure than for patients with simple appendicitis. [33] [34] We usually begin with a diagnostic laparoscopy and use a rolled gauze to gently sweep adherent loops of small bowel away from the cecum, thereby exposing the appendix. Depending on the ease of completing that task, a decision is made whether or not to convert to an open appendectomy. Any pus encountered during the dissection is aspirated and sent for Gram stain and culture. Oozing from the severely inflamed retroperitoneum is easily controlled with argon beam coagulation, if available. The inflamed, indurated mesoappendix is divided using the LigaSure or harmonic scalpel. The taeniae of the cecum are followed onto the base of the appendix, and the stump is divided either between Endoloops or with a stapler, depending on the integrity of the tissues. When the mesoappendix is densely adherent to the cecum or retroperitoneum, it may be helpful to divide the stump of the appendix with the stapler before dividing the mesoappendix. The abdomen and pelvis are irrigated and the fluid aspirated. We leave a closed-suction drain in place only if a well-defined residual abscess cavity exists after reflection of the small bowel away from the appendiceal bed. Antibiotics may be altered, if necessary, based on the culture results and are continued until the patient is afebrile postoperatively.

Appendiceal Abscess

Patients who present late in the course of appendicitis with a mass and fever may benefit from a period of nonoperative management, which reduces complications and overall hospital stay [35] [36] ( Fig. 49-6 ). Imaging studies are useful both in confirming the diagnosis and in evaluating the size of any abscess present. Patients with large abscesses, greater than 4 to 6 cm in size, and especially those patients with abscess and high fever, benefit from abscess drainage. This may be accomplished via the transrectal or transvaginal route using ultrasound guidance if the abscess is suitably located,[32] or by a percutaneous image-guided approach. Those patients with smaller abscesses or phlegmon and who are not sick may be successfully managed initially with antibiotics alone. Patients who continue to have fever and leukocytosis after several days of nonoperative treatment are likely to require appendectomy during the same hospitalization, whereas those who improve promptly may be considered for interval appendectomy.[33]

After nonoperative treatment of suspected late appendicitis, adults undergo colonoscopy or barium enema because colon cancer is detected in about 5% of cases.[34] The risk for recurrent appendicitis is about 15% to 25% after nonoperative treatment and warrants consideration of interval appendectomy. We typically perform this procedure laparoscopically about 6 weeks after the initial bout of appendicitis. Interval appendectomy is associated with low morbidity and a short hospital stay. The procedure is routinely performed in children. The decision about whether to proceed with interval appendectomy for adult patients includes factors such as patient age, comorbid conditions, and prior abdominal surgery.

Chronic or Recurrent Appendicitis

A small number of patients report episodic bouts of right lower abdominal pain in the absence of an acute febrile illness. Some are found to have appendicoliths on CT[35] or sonographic evidence of an enlarged appendiceal diameter[36]; most of these will have both surgical and pathologic evidence of chronic inflammation of the appendix and relief of symptoms after appendectomy. These findings support the notion that appendicitis represents a spectrum of inflammatory changes that may, in rare cases, wax and wane.

The dilemma is more difficult when the report of pain is not accompanied by other clinical or radiographic findings. These patients fall into the category of those with chronic abdominal pain, and pathologically confirmed appendiceal inflammation is rarely found in these patients. We have sought evidence of appendiceal pathology before appendectomy for chronic pain using ultrasound, CT, or both, in combination with colonoscopy to exclude other causes of pain.

Normal-Appearing Appendix

If a normal-appearing appendix is identified at the time of surgery, should it be removed? This question has been raised again after the introduction of the laparoscopic approach; consensus is lacking on this point. Although it is difficult to know how many patients benefit from this practice, removal of the appendix adds little morbidity to the procedure. In some cases, pathologic abnormalities that were not apparent on visual inspection are identified. [42] [43] [44] Our practice is to remove the appendix and perform a thorough search for other causes of the patient's symptoms. We specifically examine the small intestine for Meckel's diverticulum and Crohn's disease, the mesentery for lymphadenopathy, and the pelvis for abscesses, ovarian torsion, and hernias.

Appendicitis in Elderly Patients

Older patients with appendicitis are more likely to delay seeking treatment, present with atypical findings, and have a higher rate of perforation at the time of presentation (see Differential Diagnoses, earlier). CT is widely used in older patients both to establish the diagnosis of appendicitis and to exclude neoplasms, diverticulitis, and other confounding conditions. Perforation and abscess formation are relatively common operative findings among older patients with appendicitis.[40] Elderly people have an increased incidence of cardiovascular, renal, and pulmonary complications after appendectomy. Analysis of a large administrative database showed that the laparoscopic approach was associated with a shorter hospitalization and a higher probability of discharge to home (rather than a skilled nursing facility) than open appendectomy for older patients with both perforated and nonperforated appendicitis.[41] Following risk adjustment among groups, the benefits of laparoscopic appendectomy appear to be more pronounced for older patients than for their younger counterparts.[42]

Treatment Algorithm

Our approach to the treatment of appendicitis is summarized in Figure 49-7 . Patients are considered to have so-called simple appendicitis if the duration of symptoms is less than 48 hours or imaging studies show the absence of a large abscess or phlegmon. These patients typically undergo appendectomy. For patients with an atypical or long history and those who present during the recovery phase, imaging studies are obtained. CT is typically selected for nonpregnant adults and ultrasound for pregnant women and children. Occasionally, these patients are found to have radiographic features of simple appendicitis and undergo appendectomy. More commonly, a phlegmon is found. An associated large abscess (>4-6 cm) is drained either percutaneously, if it is located in the iliac fossa, or transrectally, if it is in the lower pelvis. Patients who are systemically ill are treated with antibiotics and bowel rest and re-evaluated. If they do not improve, we perform an open appendectomy. Similarly, sick patients with a phlegmon or a small abscess are treated with antibiotics and bowel rest and re-evaluated for signs of improvement as described earlier. Some patients present during the recovery phase from the acute illness and may be managed as outpatients. Adults who are managed nonoperatively during their initial presentation undergo colonoscopy 2 to 4 weeks after their acute illness to exclude colitis or neoplasms. We typically remove the appendix in these patients 6 to 8 weeks after the initial presentation. The procedure is performed laparoscopically as an outpatient.

Outcomes

The mortality rate after appendectomy is less than 1%. The morbidity of perforated appendicitis is higher than that of nonperforated cases and is related to increased rates of wound infection, intra-abdominal abscess formation, increased hospital stay, and delayed return to full activity.

Surgical site infections are the most common complications seen after appendectomy. About 5% of patients with uncomplicated appendicitis develop wound infections after open appendectomy. Laparoscopic appendectomy is associated with a lower incidence of wound infections; this difference is magnified among groups of patients with perforated appendicitis (14% versus 26%).[43] Patients with a fever and leukocytosis and a normal-appearing wound after appendectomy undergo CT or ultrasonography to exclude an intra-abdominal abscess. Similarly, if pus emanates from a fascial opening during wound inspection, an imaging study is obtained to identify any undrained intra-abdominal fluid collections. In this situation, we place a percutaneous drain into the collection to divert the infected material away from the fascia and facilitate wound healing. For pelvic abscesses that are located in proximity to the rectum or vagina, we prefer ultrasound-guided transrectal or transvaginal drainage, thereby avoiding the discomfort of a percutaneous perineal drain.[32]

Small bowel obstruction occurs in less than 1% of patients after appendectomy for uncomplicated appendicitis and in 3% of patients with perforated appendicitis who are followed for 30 years.[44] About one half of these patients present with bowel obstruction during the first year.

The risk for infertility following appendectomy in childhood appears to be small.[45] A history of either simple or perforated appendicitis was sought in a large cohort of infertile patients and compared with the frequency of appendicitis in pregnant women; no significant differences were found.[46]

There are rare reports of appendicocutaneous or appendicovesical fistulas after appendectomy, typically for perforated appendicitis. Fistulas to the skin generally close after any local infection is treated. Fistulas to the bladder have been successfully diagnosed and treated laparoscopically in recent years.

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