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 leads to the inflammation of the appendix, obstruction of the blood vessels supplying it, and finally infection.
• Once these blood vessels are obstructed, appendiceal tissue starts to die and leak out its cellular components.
• 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 thrombosis and occlusion and stasis of blood and lymphatic flow..
• The stasis favours the bacterial growth leading to the formation of abscess if left untreated.

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.

Causes

Natural gut flora which includes gram negative and anaerobic bacteria play a major role in the development of appendicular abscess

Aerobic bacteria	Anaerobes bacteria
Enterococcus Escherichia coli Klebsiella pneumoniae Pseudomonas aeruginosa Staphylococcus aureus Proteus	Bacteroides fragilis Clostridium perfringens

Differential diagnosis

Diseases	Clinical features					Diagnosis		Specific findings
	Symptoms				Signs	Laboratory fingdings	Radiological findings
	Fever	Abdominal pain	Nausea vomiting	Diarrhea
Psoas abscess	✔	Dull RLQ pain radiating to hip and thigh	✔	✘	Positive Psoas sign	↑ WBC ↑ ESR ↑ BUN	CT: A large peripherally enhancing collection seen in the psoas muscle	Associated with IV drug abuse and HIV Staphylococcus Aureus is the most common pathogen involved
Cellulitis	✔	✘	✘	✘	Involved site is red, hot, swollen, and tender	↑ WBC ↑ ESR ↑ BUN	Ultrasonographic-guided aspiration of pus is both gold standard for diagnostic and therapeutic In early cellulitis: Diffuse increase in the thickening and echogenicity of the subcutaneous tissue Late cellulitis: Accumulation of fluid in the subcutaneous tissue	Severe infection is indicated by Lymphangitic spread (red lines streaking away from the area of infection) Circumferential cellulitis Pain out of propotion
Crohn's disease	✔	RLQ continuous localized pain	✔	Bloody	Fullness or a discrete mass may be appreciated, typically in the right lower quadrant of the abdomen Extra intestinal manifestations are present	[ASCA]) are found in Crohn disease	CT scan shows intra-abdominal abscess. Transmural ulcerations are seen on colonoscopy	Endoscopic visualization and biopsy are essential in the diagnosis
Gastroenteritis	✔	Diffuse crampy intermittent abdominal pain	✔	Bloody/ watery	Rebound tenderness, rash	Antilisteriolysin O (ALLO) is positive for bacterial gastroenteritis Culture media used to isolate bacteria. In most cases of viral gastroenteritis,lab tests are not indicated.		No specific test
Primary peritonitis	✔	Abrupt diffuse abdominal pain	✔	Bloody/watery	Abdominal distension, rebound tenderness	Peritoneal fluid shows >500/microliter count and >25% polymorphonuclear leukocytosis.	X-ray abdomen identifies free air under the diaphragm CT demonstrates abscess or fluid in abdomen,	History of advanced cirrhosis or nephrosis Peritoneal fluid analysis confirms the diagnosis
Pyelonephritis	✔	Flank pain radiating to inguinal region	✔	✘	CVA tenderness	Urine microscopy and culture confirm presence of bacteria.	CT demonstrates round swollen kidneys with hypo-dense appearance Abscesses may or may not be seen	CVA tenderness H/o UTI
Ovarian torsion	✘	Sudden sharp pain	✔	✘	Unilateral, tender adnexal mass		Ultrasonography shows ovarian cyst and decreased blood flow	Ultrasound is gold standard in diagnosing
Testicular torsion	✘	Sudden sharp pain	✔	✘	Swollen, tender, high-riding testis with abnormal transverse lie Loss of the cremasteric reflex	Normal Blood test Normal Urine analysis	Absent or decreased blood flow in the affected testicle Hypervascularity with a low resistance flow pattern (after partial torsion-detorsion)	Testicular torsion is a clinical diagnosis.  Testicular Workup for Ischemia and Suspected Torsion (TWIST) is employed for determination of risk for torsion
Pelvic inflammatory disease	✔	Bilateral lower quadrant pain	✔	✘	Purulent discharge from cervical os. Cervical motion tenderness	Abundant white blood cells (WBCs) on saline microscopy of vaginal secretions Laboratory evidence of cervical infection with N gonorrhoeae or C trachomatis(via culture or DNA probe)	Transvaginal ultrasonographic scanning or magnetic resonance imaging (MRI) shows thickened, fluid-filled tubes with or without free pelvic fluid or tubo-ovarian abscess (TOA).	Laparoscopy helps in confirmation of the diagnosis
Ruptured ectopic pregnancy	✔	Diffuse abdominal pain	✔	✘	Unilateral or bilateral abdominal tenderness Abdominal rigidity, guarding On pelvic examination, the uterus may be slightly enlarged and soft, and cervical motion tenderness	HCG hormone level is high in serum and in urine	Ultrasound reveals presence of mass in fallopian tubes.	Triad of amenorrhea, abdominal pain and vaginal bleeding SIgns of hypotension directs towards ruptured ectopic pregnancy Transvaginal ultrasound with BHCG levels are the gold standard for diagnosis

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

Natural history

• The symptoms of appendicular abscess typically develop when the inflamed appendix gets complicated due to decreased blood flow.
• Without treatment, the patient will likely develop symptoms of diffuse abdominal pain, which is different from typical appendicitis pain, starting centrally (in the periumbilical region) before localizing to the right iliac fossa in the right lower quadrant of the abdomen.
• They will also experience loss of appetite, diarrhea, High gradefever, nauseua, and vomiting.
• During the final stage of the untreated disease process, the appendix will rupture, and this may eventually lead to death if peritonitis develops.

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 if the abscess is ruptured and associated with hemorrhage.
• Tachypnea.

Skin

• Diaphoresis
• Pallor
• Cold extremities.

Abdomen

• The abdominal wall is very sensitive to mild palpation.
• Rebound tenderness (it cannot be elicited in most of the patients due to abscess formation)
• 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

Lab findings that are not specific but include

• Leukocytosis with a shift to the left along with elevation of ESR and CRP

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 fluid levels.
• 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 along with IV fluids followed by surgery which includes interval laparoscopic 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:

• When patients present 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.

Complications

Complications that may develop after the interval appendectomy include

• Adhesions
• Wound infection
• Fistula

Prognosis

• Most patients with appendicitis recover quickly with surgical treatment (laparoscopic appendectomy), 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 acute appendicitis responds quickly to appendectomy and occasionally will resolve spontaneously.
  • If appendicitis resolves spontaneously, it remains controversial whether an elective interval appendectomy should be performed to prevent a recurrent episode of appendicitis.
• Atypical appendicitis (associated with suppurative appendicitis) is more difficult to diagnose and is more apt to be complicated, even when operated on early.
  • In either condition, prompt diagnosis and 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 of appendicitis, especially if peritonitis develops and is left untreated.