Appendicitis

Appendicitis

1. Historical Aspects
• in the 1500s, a severe inflammation of the cecal region was known as ‘perityphlitis’
• first successful appendectomy was performed in 1735
• in 1886, Reginald Fitz accurately described the clinical history, physical findings, and pathology of acute appendicitis and advocated early appendectomy as the appropriate treatment
• in 1889, McBurney reported on the importance of early operative intervention and described the point of maximal tenderness (one-third of the distance between the anterior superior iliac spine and the umbilicus)


2. Embryology and Anatomy
• arises from the cecum during the 8th week of gestation
• base of the appendix comes to lie medially near the ileocecal valve and is constant in location
• tip of the appendix may be found in many different positions (pelvic, retrocecal (60%), retroperitoneal)
• 3 taenia coli converge at the junction of the cecum and the appendix and can be a very useful landmark to find the appendix
• has a separate mesoappendix with an artery and vein that are branches of the ileocolic vessels
• lymphatic drainage follows the ileocolic artery and drains into the mesenteric nodes


3. Function
• immunologic organ and is a component of the gut-associated lymphoid tissue (GALT) system
• amount of lymphoid tissue peaks at puberty, stays steady for the next decade, and then decreases with age
• may serve as a reservoir of ‘good’ intestinal bacteria, and may aid in recolonization and maintenance of normal colonic flora


4. Incidence
• roughly parallels that of lymphoid development and peaks in the teen years
• more males than females (1.3:1)
• lifetime risk is 6% to 7%
• number of cases appears to be declining, for unclear reasons


5. Pathophysiology
• luminal obstruction is the prime cause (fecalith, lymphoid hypertrophy, inspissated barium, seeds, tumors)
• normal mucous production rapidly leads to distention of the obstructed appendix
• as intraluminal pressure rises, capillaries and venules become occluded; eventually arteriolar pressure can be exceeded, which leads to ischemia, infarction and perforation
• bacteria also multiply rapidly in the obstructed appendix and as mucosal blood supply becomes impaired, bacteria are able to invade into the appendiceal wall, leading to transmural inflammation


6. Clinical Manifestations and Diagnosis
1. Symptoms
• anorexia is nearly always present and is often the first symptom
• appendiceal distention stimulates visceral afferent pain fibers, which produces a dull, vague pain in the periumbilical region
• appendiceal distention may also stimulate peristalsis, so that abdominal cramping or an episode of diarrhea may also occur
• as the inflammatory process progresses and involves the serosa and parietal peritoneum, the pain becomes sharp and localizes to the right lower quadrant (somatic pain)
• most patients (75%) will have one or two episodes of vomiting, which usually occurs after the development of pain


2. Signs
• physical findings are determined by the anatomic position of the appendix as well as whether it has ruptured


1. Vital Signs
• temperature is rarely elevated more than 1° C in uncomplicated cases
• pulse is often normal unless rupture has occurred


2. Position
• usually supine with thighs drawn up


3. Physical Exam
• point tenderness is the principal physical finding
• point of maximal tenderness will vary depending on the location of the appendix
• extension of the hip (psoas sign) will elicit pain if the appendix lies on the psoas muscle
• flexion and internal rotation of the thigh (obturator sign) will elicit pain if the appendix lies in the pelvis adjacent to the obturator internus muscle
• rectal examination is invaluable in diagnosing a pelvic appendicitis
• Rovsing’s sign – pain referred to the RLQ when the LLQ is palpated – also indicates the site of peritoneal inflammation


3. Lab Tests
1. WBC Count
• most patients will have a WBC count between 10,000 and 18,000
• most patients with a WBC count < 10,000 will have a left shift
• however, it is possible to have acute appendicitis with a normal WBC count and differential
• nonsurgical problems such as gastroenteritis and ruptured ovarian cysts may also present with an elevated WBC


2. Urinalysis
• used to rule out a urinary source for the inflammation
• a few WBCs or RBCs may be present if the inflamed appendix overlies the ureter or bladder
• however, many WBCs, RBCs, or bacteria implicates the urinary tract


3. Pregnancy Test
• mandatory in menstruating women


4. Radiographic Studies
• not necessary in straight-forward cases (young males)


1. Plain Films
• most useful in ruling out other diagnoses
• fecaliths are not commonly seen, but their presence is highly suggestive of appendicitis
• pneumoperitoneum is not seen in perforated appendicitis



2. Ultrasound
• appendix is identified as a blind-ending, non-peristaltic bowel loop originating from the cecum
• scan is considered positive if a non-compressible appendix 6 mm in diameter or greater is seen
• an easily compressible appendix 5 mm or less in diameter excludes appendicitis
• study is inconclusive if the appendix cannot be visualized
• results are very user dependent
• advantages include speed, no ionizing radiation, low cost
• used most often in pediatric and pregnant patients (to avoid radiation)
• most studies report sensitivities and specificities of 80% to 90%



3. CT Scan
• more sensitive and specific than ultrasound, but is more expensive and uses ionizing radiation
• useful in patients in whom physical examination is impossible or misleading (neurologically impaired, immunosuppressed, morbidly obese)
• also helpful when an abscess is suspected to ascertain the feasibility of percutaneous drainage
• classic findings include an enlarged appendix (>6 mm) with surrounding inflammation (stranding)
• early appendicitis may not have CT findings



4. MRI
• useful in pregnant patients (no contrast)
• sensitivity and specificity approaches 100%
• disadvantages include cost and limited availability after hours



7. Differential Diagnosis
1. Mesenteric Adenitis
• disease most commonly confused with acute appendicitis in children
• an upper respiratory infection is usually present or has just subsided


2. Gastroenteritis
• nausea, vomiting, and diarrhea are usually much more prominent than in typical appendicitis
• abdominal pain is often cramping in nature


3. Acute Ileitis
• cannot be distinguished from appendicitis on clinic grounds
• need to distinguish acute ileitis from Crohn’s disease at operation
• if the cecum is not involved, then an appendectomy is indicated


4. Pyelonephritis
• may mimic a retrocecal appendicitis
• high fever, chills, right CVA tenderness, and many WBCs and bacteria in the urine usually differentiates the two conditions


5. Ureteral Stone
• pain is usually extremely severe and often referred to the labia or scrotum
• hematuria may be present; WBC count usually normal


6. Pelvic Inflammatory Disease
• may mimic appendicitis if it is confined to the right tube
• pain and tenderness is usually lower
• may have exquisite cervical motion tenderness
• purulent vaginal discharge is often present


7. Other Gynecologic Disorders
• ruptured follicle, ruptured or twisted ovarian cyst, endometriosis, and ruptured ectopic pregnancy may all mimic acute appendicitis
• women between the ages of 15 and 45 historically have had the highest incidence of negative appendectomies (32% to 45%)


8. Special Presentations
1. Appendicitis in the Young
• diagnosis is often delayed because of the inability of the child to give an accurate history, and the frequency of gastrointestinal complaints in this age group
• 20% incidence of ruptured appendices in the pediatric age group; children under 8 have twice the perforation rate as older children
• appendicitis is very uncommon in children < 2 years old


2. Appendicitis in the elderly
• morbidity and mortality rates of appendicitis are significantly increased in this population
• failure to consider the diagnosis, a more rapid progression to perforation, and coexisting disease are all significant factors in this increased complication rate
• symptoms are often subtler and less typical than in younger patients
• CT scanning is important to rule out other pathologies that can mimic appendicitis (diverticulitis, colon cancer)


3. Appendicitis during Pregnancy
• most common nonobstetric emergency (1 in 1500 pregnancies)
• equal distribution in all 3 trimesters
• as gestation progresses, the appendix becomes displaced laterally and superiorly, making the diagnosis more difficult
• leukocytosis during pregnancy is physiologic, making lab evaluation less helpful
• US is usually the first diagnostic test; if inconclusive, then MRI, or rarely, CT scan can be used
• accurate diagnosis is crucial: negative appendectomy has a 4% fetal loss rate; uncomplicated appendicitis has a 2% fetal loss rate; complicated appendicitis has a 6% fetal loss rate
• perforation is the factor most strongly associated with both maternal and fetal death
• diagnosis and surgical intervention should be rapid in the pregnant patient suspected of appendicitis
• controversial whether laparoscopic appendectomy has a higher fetal loss rate than open appendectomy


9. Surgical Management
1. Simple (Nonperforated) Appendicitis
1. Operative Management
• safe, effective, and definitive treatment for appendicitis
• majority of surgeons and surgical societies consider appendectomy to be the standard or care
• the timing of the surgery remains controversial, but multiple studies have not shown an increased perforation rate with a short in-hospital delay of 12 – 24 hours
• a single preoperative dose of an antibiotic that covers colon flora is usually adequate
• for patients on aspirin and/or Plavix, surgery does not need to be delayed


1. Open Appendectomy
• done through a Rocky-Davis (transverse) or McBurney (oblique) right lower incision
• incision should be made over the point of maximal tenderness or a mass
• once the appendix is located, it must be delivered into the wound
• the mesoappendix is divided serially between clamps and ligated
• the base of the appendix is doubly ligated with absorbable suture
• it is traditional but not necessary to invert the appendiceal stump, unless the viability of the appendix at the ligature site is questionable


2. Laparoscopic Appendectomy
• safe and effective
• now the most common approach
• associated with improved cosmesis and a quicker return to normal activity
• lower incidence of wound infections, less pain, and shorter hospital stays
• higher incidence of intra-abdominal abscesses and longer operative times
• obese patients particularly benefit since they require larger incisions during open appendectomy
• conversion rate is ~ 10%


2. Nonoperative Management
• some trials support antibiotic therapy alone for treatment of uncomplicated appendicitis
• 10% of patients will not respond to antibiotics and will require appendectomy during the initial admission
• an additional 30% will develop recurrent appendicitis during the first year and require surgery
• in older patients, there is also a concern about missed neoplasms
• at present, appendectomy should still be considered the standard treatment


2. Perforated Appendicitis
• occurs in up to 20% of patients with acute appendicitis
• may present with free perforation, an abscess, or with a phlegmon
• most patients treated nonoperatively initially will require an interval appendectomy


1. Free Perforation
• patients may present with sepsis and generalized peritonitis
• hemodynamically unstable patients will require preoperative resuscitation
• once stabilized, patients will require an emergency laparotomy
• drains are not necessary unless a discrete abscess cavity is present


2. Appendiceal Abscess
• many patients will initially be managed with a CT-guided abscess drainage and then interval appendectomy 6 – 8 weeks later
• however, it is also reasonable to proceed with immediate appendectomy with operative abscess drainage



3. Appendiceal Phlegmon
• patients should initially be treated with antibiotics
• immediate operation is associated with injury to surrounding structures from dense adhesions and inflammation
• patients who do not respond to nonoperative management will require rescue appendectomy (20%)



4. Interval Appendectomy
• typically performed 6 – 8 weeks after hospital discharge
• the incidence of appendiceal neoplasms is much higher in interval appendectomy specimens (10% - 29%) than in routine appendectomy specimens (~1%)
• interval appendectomy will also prevent episodes of recurrent appendicitis


3. Management of the Normal Appendix
• with modern preoperative imaging, the negative appendectomy rate in the U.S. is 6%
• a noninflamed appendix should be removed at appendectomy because it removes appendicitis from the differential diagnosis if the RLQ pain recurs
• the cecum, terminal ileum and mesentery should be inspected for acute and chronic inflammatory changes
• the distal 3 feet of ileum should be inspected for an inflamed Meckel’s diverticulum
• in women the uterus and both ovaries and tubes should be inspected
• if no pathology is found in the lower abdomen, then upper abdominal problems such as acute cholecystitis or perforated peptic ulcer must be ruled out


10. Complications
1. Mortality
• mortality rate of unruptured appendicitis is 0.06%; mortality rate of ruptured appendicitis is 3% overall and 15% in the elderly
• death usually results from uncontrolled gram-negative sepsis


2. Morbidity
• wound infection is common and is treated by opening the wound
• intraabdominal or pelvic abscesses may be treated by percutaneous drainage or transrectal drainage