Sandbox:Aditya

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Farwa Haideri [2] Aditya Ganti M.B.B.S. [3]

Synonyms and keywords:

Overview

An appendicular abscess is unusual and rare entity and a life threatening complication of acute appendicitis. It is seen in 2-7% of population presenting with appendicitis.

Historical Perspective

• During the late 1600s, Lorenz Heister was the first surgeon to perform post-mortem sections of appendicitis and gave an unequivocal description of a perforated appendix and abscess.
• Fitz described and diagnosed appendicitis in 1886 for the first time.
• McBurney performed an appendectomy in 1894 for the first time..

Classification

No known classification of appendicular abscess exists.

Pathophysiology

• Obstruction of the tubular space inside the appendix is the main inciting event , this initial problem is compounded into a cascade of events that lead to the inflammation of the appendix, the obstruction of the blood vessels supplying it, and infection.
• Once these blood vessels are obstructed, appendiceal tissue starts to die and leak out its cellular components leading to inflammation of the appendix .
• This leads to an increase in endo-luminal and intramural pressure, which can result in an occlusion of the venules in the appendiceal wall resulting in filling with mucus and distends.
• This increase in pressure leads to thrombosis and occlusion of the small vessels, and stasis of lymphatic flow.
• The stasis along with decreased blood flow favours the bacterial growth leading to the formation of abscess if left medically unattended.

Transmission

• The abscesses usually contain a mixture of aerobic and anaerobic bacteria from the gastrointestinal tract.

Duration

• The risk of perforation or abscess formation is negligible within the first 12 h of untreated symptoms, but then increases to 8.0% within the first 24 h.

Microscopic findings

• A focally necrotic appendiceal debris is seen in the mucosal wall. Intravascular fibrin is seen in medium-sized blood vessels.
• Clusters of neutrophils are seen on the serosal aspect.

Epidemiology and Demographics

The lifetime risk of appendicitis is 8.6 % for males and 6.7 % for females; however, the risk of undergoing appendectomy is much lower for males than for females (12 vs. 23 %) and it occurs most often between the ages of 10 and 30, with a male:female ratio of approximately 1.4:1.

Screening

According to the Guidelines by the Surgical Infection Society and the Infectious Diseases Society of America there is insufficient evidence to recommend routine screening for appendicular abscess.

Natural History, Complications, and Prognosis

Complications

Complications that can develop as a result of the untreated appendicular abscess include:

• Septicemia
• Rupture
• Peritonitis
• Hemorrhage
• Death

Prognosis

• Most patients with appendicular abscess recover quickly with drain and iv antibiotics, but complications can occur if treatment is delayed or if peritonitis occurs.
• Recovery time depends on age, condition, complications, and other aspects in the patient's history (including amount of alcohol consumption).
• It usually takes between 10 and 28 days to recover completely.
• For young children (around 10 years old), recovery takes three weeks.
• Typical Abscess responds quickly to antibiotics and percutaneous drain and resolves spontaneously.
• If abscess resolves, interval appendectomy should be performed 2-3 months after to prevent a recurrent episodes.
• Atypical presentation (associated with suppurative) is more difficult to diagnose and is more apt to be complicated, even when operated on early.
• In either condition, prompt diagnosis and treatment with interval appendectomy yield the best results with full recovery usually occurring in two to four weeks.
• Mortality and severe complications are unusual but do occur in some cases, especially if peritonitis develops and is left untreated.

Diagnosis

History

The key to an efficient and accurate diagnosis is a detailed and thorough history. The following information should be obtained:

• Onset, location, radiation, and duration of pain
• Aggravating or relieving factors
• Severity of pain (constant or intermittent)
• Characteristics of the pain
• History of the pain
• Association with nausea, vomiting, anorexia, or diarrhea
• Time of last bowel movement and
• Recent use of analgesics, narcotics, or antibiotics.

Symptoms

Symptoms of appendicular abscess include that of appendicitis with late presentation and can overlap. Typical symptoms of appendicitis may or may not be present but patient presents with

• Fever >38.5 C
• Generalized abdominal pain
• Vomiting
• Prolonged diarrhea
• There is a possibility of micturition if an inflamed appendix lies in contact with the bladder.
• Tenesmus (the feeling that a bowel movement will relieve discomfort) can be experienced.

Physical Examination

Physical examinations mostly focus on abdominal findings. The patient may appear in pain with a fever and mild tachycardia. Even minimal pressure on the abdomen can elicit a marked response from the patient due to pain.

Vitals

• Fever
• Tachycardia
• Hypotension
• Tachypnea
  • Breathing patterns may be altered by patient to compensate for abdominal pain.

Skin

• Diaphoresis
• Pallor

Abdomen

• The abdominal wall is very sensitive to mild palpation.
• Rebound tenderness (it cannot be elicited in most of the patients with abscess)
• Abdominal guarding
• Rovsing's sign Deep palpation of the left iliac fossa may cause pain in the right iliac fossa.
• Psoas sign Occasionally, an inflamed appendix lies on the psoas muscle and the patient will lie with the right hip flexed for pain relief.
• Obturator sign If an inflamed appendix is in contact with the obturator internus, spasm of the muscle can be demonstrated by flexing and internally rotating the hip.This maneuver will cause pain in the hypogastrium.
• A digital rectal examination elicits tenderness in the rectovesical pouch in special cases of appendicitis.
• In case of a retrocaecal appendix even deep pressure in the right lower quadrant may fail to elicit tenderness.
• If the appendix lies entirely within the pelvis, there is usually complete absence of abdominal rigidity.

Laboratory findings

Leukocytosis with a shift to the left in the segmented neutrophils is the most common electrolyte and biomarker indicators of appendicular abscess. Other inflammatory markers like ESR and CRP are also elevated but are not specific to abscess.

X-Ray

• Plain abdominal radiography is not the most useful tool in making a diagnosis of appendicular abscess.
• Plain abdominal films may be useful for the detection of ureteral calculi, small bowel obstruction, or perforated ulcer, but these conditions are rarely confused with appendicitis precursor of abscess.
• An opaque fecalith can be identified in the right lower quadrant in less than 5% of persons being evaluated for appendicitis.

Ultrasound

• Ultrasound is the first investigation advised to evaluate a suspected appendicular pathology.
• Findings of an appendicular abscess include:
• Fluid collection (hypoechoic) in the appendicular region which may be well circumscribed and rounded or ill-defined and irregular in appearance appendix may be visualised within the mass.

CT

• CT is significantly more sensitive than US for the diagnosis of appendicitis, but that US should be considered in children
• Fluid collection is seen in the appendicular region with or without air within. Many times an appendicolith may be visualized.

Treatment

No universal standard treatment exists for appendicitis complicated by abscess. The preferred treatment includes non-operative management such as drainage and broad spectrum IV antibiotics followed by interval appendectomy. It has proved to have a high success rates up to 97% and low incidences of complications.

Medical Therapy

Antibiotics should be started immediately once the diagnosis of abscess is made. Preoperative antibiotics have been associated with lower rates of wound and intra-abdominal infections.

Empiric therapy

Monotherapy with a beta-lactam/beta-lactamase inhibitor:

• Preferred regimen (1):Ampicillin-sulbactam 3 g IV q6h
• Preferred regimen (2):Ticarcillin-clavulanate 3 g IV q4h
• Preferred regimen (3):Piperacillin-tazobactam 3 g or 4.5 g IV q6h

Combination third generation cephalosporins PLUS metronidazole

• Preferred regimen (1): Ceftriaxone 1 g IV q24h AND Metronidazole 500 mg IV q8h OR 1500 mg q24h.
• Preferred regimen (2): Cefazolin 1–2 g IV q8h AND Metronidazole 500 mg IV q8–12 h OR 1500 mg q24h
• Preferred regimen (3): Cefuroxime 1.5 g IV q8h AND Metronidazole 500 mg IV q8–12 h OR 1500 mg q24h
• Preferred regimen (4): Cefotaxime 1–2 g IV q6–8 h AND Metronidazole 500 mg IV q8–12 h OR 1500 mg q24h

Alternative empiric regimens

Combination fluoroquinolone PLUS metronidazole:

• Preferred regimen (1): Ciprofloxacin 400 mg IV q12h AND Metronidazole 500 mg IV q8–12 h OR 1500 mg q24h
• Preferred regimen (2): Levofloxacin 750 mg IV q24h AND Metronidazole 500 mg IV q8–12 h OR 1500 mg q24h

Monotherapy with a carbapenem

• Preferred regimen (1): Imipenem-cilastatin 500 mg IV q6h OR 1 g q8h
• Preferred regimen (2): Meropenem 1 g IV q8h
• Preferred regimen (3): Doripenem 500 mg IV q8h
• Preferred regimen (4): Ertapenem 1 g IV q24h

Duration

The duration of treatment with intravenous antibiotics ranges from 5 to 10 days, until fever resolves, white blood cell count normalizes, and bowel function returns.

Surgery

Emergency appendectomy

Indications:

• In patients with life-threatening signs of peritonitis
• large appendiceal abscess,
• In patients with an extraluminal appendicolith.

Percutaneous drainage

• Percutaneous drainage can be performed under USG or CT guidance, using either the Seldinger or trocar technique.
• USG is limited if the abscess is small, obscured by other structures, or if precise placement is required because of nearby vessels or organs. In these cases, CT is the optimal imaging modality.<ref>
• When an abscess is deep in the pelvis, depending on the specific location of the fluid collection, access may be obtained via transgluteal, transvaginal, or transrectal approaches.
• If the fluid collection is sterile, a transgluteal approach is preferred because it allows for sterile technique.<REF>
• Depending on the location of abscess,patient is placed in prone or supine position on the CT table
• Localization scan using CT allows in selecting a safe window of access into the collection.
• A coaxial micropuncture introducer set is advanced into the abscess under CT guidance.
• An Amplatz guidewire is advanced through the sheath and coiled within the abscess.
• After serial dilatation of the tract with a dilator, an pigtail drain is advanced over the guidewire and deployed.

Interval Appendectomy

Following drain and antibiotics an interval appendectomy is recommended for patients six to eight weeks, it is done to :

• Prevent recurrence of appendicitis.
• Exclude neoplasms (such as carcinoid, adenocarcinoma, mucinous cystadenoma, and cystadenocarcinomas)

Complications of interval appendectomy

• Fever
• Infection (sepsis)
• Pelvic abscess
• Aspiration pneumonia

Late complication

• Abdominal adhesions
• Fecal fistula