Appendicitis, Emergency Medicine

Basics

Description

Most common abdominal emergency
Acute obstruction of appendiceal lumen results in distension followed by organ ischemia, bacterial overgrowth, and eventual perforation of the viscus
Pain migration:
- Periumbilical pain: Appendiceal distension stimulates stretch receptors, which relay pain via visceral afferent pain fibers to 10th thoracic ganglion.
- RLQ pain: As inflammation extends to surrounding tissues, pain occurs owing to stimulation of parietal nerve fibers and localizes to position of appendix.

28-57% misdiagnosis in patients <12 yr (nearly 100% in patients <2 yr)
70-90% perforation rate in children <4 yr
Perforation correlates strongly with delayed diagnosis.

Decreased inflammatory response
3 times more likely to have perforation owing to anatomic changes
Diagnosis often delayed owing to atypical presentations

Slightly higher rate in 2nd trimester compared to 1st/3rd/postpartum periods
Increased perforation rate (25-40%), highest in 3rd trimester
RLQ pain remains the most common symptom
7-10% fetal loss, up to 24% in perforated appendicitis

Etiology

Luminal obstruction of appendix
Appendiceal lumen becomes distended, inhibiting lymphatic and venous drainage.
Bacterial invasion of wall, with edema and blockage of arterial blood flow
Perforation and spillage of contents into peritoneal cavity, causing peritonitis (usually 24-36 hr from onset)
May wall off and form abscess
Gram-negative rods and anaerobic organisms predominate

Diagnosis

Signs and Symptoms

History

Abdominal pain: Primary symptom:
- Normal location:
  - RLQ pain
  - 35% of patients have appendix located within 5 cm of "normal" location.
- Retrocecal appendix (28-68%):
  - Back pain
  - Flank pain
  - Testicular pain
- Pelvic appendix (27-53%):
  - Suprapubic pain
  - Urinary or rectal symptoms
- Long appendix (<0.2%):
  - Inflamed tip may cause pain in RUQ or LLQ.
  - Anorexia
  - Vomiting
Change in bowel habits: Diarrhea (33%), constipation (9-33%)
Classic presentation (<75% adults):
- Initially periumbilical pain
- Followed by anorexia (1st symptom in 95%) and nausea
- Localizes to RLQ (1-12 hr after onset)
- Finally, vomiting with fever

Presentations often nonspecific and difficult to localize (<50% have classic presentation)
Anorexia, vomiting, and diarrhea more common (half-eaten meal hours before complaints of pain may more accurately indicate duration of symptoms)
Observe child before exam for subtle indicators of local inflammation:
- Limping gait
- Hesitation to move or climb
- Flexed right hip

Physical Exam

Vital signs:
- Often normal
- Fever: Normal to mild elevation (<1 °F) initially, increases with perforation
Abdominal exam:
- Tenderness at McBurney point (1/3 of distance from right anterior iliac spine to umbilicus)
- Guarding:
  - Voluntary guarding early owing to muscular resistance to palpation
  - Involuntary guarding (rigidity) later as inflammation progresses and perforation occurs
- Rebound:
  - Pain with any rapid movement of peritoneum (e.g., bumping stretcher)
- Specific signs (less useful in pediatrics):
  - Rovsing sign: Pain in RLQ when palpating LLQ
  - Psoas sign: Increased pain on extension of right hip with patient lying on her or his left side, owing to inflamed appendix touching iliopsoas muscle.
  - Obturator sign: Pain with passive internal rotation and flexion of right hip
Rectal exam:
- Limited value: May localize tenderness/mass
Pelvic exam:
- Important to differentiate gynecologic disease
- Vaginal discharge and/or adnexal tenderness or mass suggests gynecologic disease.
- Cervical motion tenderness when present suggests PID, but can be seen in up to 25% of women with appendicitis
Patient position:
- Supine or decubitus with legs (particularly the right) drawn up
- Prefer not to move
Shuffling gait-known as "appy walk"

Almost all children have generalized abdominal tenderness with some rigidity.

Enlarging uterus displaces appendix upward and laterally.
Hyperemesis gravidarum and other nonsurgical causes of vomiting should not cause abdominal tenderness.

Typical signs of peritonitis may be absent in elderly.

Essential Workup

Suggestive history and physical exam sufficient to establish preoperative diagnosis and warrant surgical consultation
Tests listed below may be used to assist in diagnosis
Atypical cases: Repeat serial exams in conjunction with some of the tests listed below is effective, with decreased rates of negative appendectomies and no increase in rates of perforation

Diagnosis Tests & Interpretation

Lab

CBC:
- WBC >10,000, with left shift (80%)
- Normal WBC does not exclude diagnosis
C-reactive protein:
- Overall sensitivity 62%, specificity 66%
- May not be elevated early (<12 hr)
- Increased sensitivity with serial measurements
Urinalysis:
- Generally normal
- Mild pyuria, bacteriuria, or hematuria (25-30%)
- Pyuria present if inflamed appendix lies near ureter or bladder
Pregnancy test for females of child-bearing age

Imaging

Unnecessary when diagnosis is clear
Most helpful in female patients of child-bearing age where diagnosis is often unclear
Abdominal radiographs-not recommended
US: Sensitivity 86-90%; specificity 92-95%:
- Noncompressible appendix 6 mm anteroposterior (AP) diameter
- Presence of appendicolith
- Periappendiceal fluid/mass
- Limited by obesity, bowel gas, retrocecal appendix, and operator
- Negative study of limited use
CT: Sensitivity 91-100%; specificity 94-97%:
- Highest yield using oral and rectal contrast with focused appendiceal technique (5 mm cuts from 3 cm above cecum extending distally 12-15 cm)
- Fat stranding (100%)
- Appendix 6 mm in diameter (93%)
- Focal cecal apical thickening
- Defines appendiceal masses (phlegmon vs. abscess)
- Best study for finding alternative diagnoses
- Nonvisualized appendix does not rule out appendicitis
MRI: Sensitivity 97-100%, specificity 92-94%:
- Appendix 7 mm in diameter
- Periappendiceal fat stranding
- Advantages: Lack of ionizing radiation, excellent safety profile of gadolinium contrast agents
- Disadvantages: High cost, limited availability, lengthy exam, lack of radiologist familiarity in appendicitis
- No gadolinium in early pregnancy (class C drug)

American College of Radiology recommends US followed by CT as needed for suspected appendicitis
Diagnostic Procedures/Surgery

Laparoscopy:
- Diagnostic and therapeutic use
- Gross pathology may be absent with positive microscopic findings
Open appendectomy
Percutaneous drainage

Differential Diagnosis

Gastroenteritis
Meckel diverticulum
Epiploic appendicitis
Crohns disease
Diverticulitis
Volvulus
Abdominal aortic aneurysm
Intestinal obstruction
UTI
Pyelonephritis
PID
Ectopic pregnancy
Ovarian cyst/torsion
Tubo-ovarian abscess
Endometriosis
Renal stone
Testicular torsion
Mesenteric adenitis
Henoch-Sch ¶nlein purpura
Diabetic ketoacidosis
Streptococcal pharyngitis (children)
Biliary disease

Treatment

Initial Stabilization/Therapy

Airway, breathing, and circulation management (ABCs)
Fluid resuscitation with LR or 0.9% NS

Ed Treatment/Procedures

IV fluids, correct electrolyte abnormalities
Immediate surgical consult for convincing history and physical exam:
- Laparoscopic versus open technique
- Negative appendectomy rate of 10% in males and 20% in females
- Percutaneous drainage, IV antibiotics, bowel rest and possible interval appendectomy in 6-8 wk in appendiceal abscesses
Perioperative antibiotics
NPO
Order CT if palpable mass is present in RLQ to define phlegmon versus abscess
If diagnosis is uncertain, send serial labs, observe, and repeat exams (6-10% negative appendectomy rate with observation protocols)
Analgesics:
- Administration of analgesics, including narcotics, does not adversely affect abdominal exam or mask pathology

Medication

Ampicillin/sulbactam: 3 g (peds: 100-200 mg ampicillin/kg/24 h) IV q6h
Cefoxitin: 2 g (peds: 80-100 mg/kg/24 h) IV q6h
Ceftriaxone: 1 g (peds: 50-100 mg/kg) IV q24h
Ciprofloxacin: 400 mg (peds: 20-40 mg/kg) IV q12h
Ertapenem: 1 g IM/IV q24h
Metronidazole: 500 mg (peds: 30-50 mg/kg/24 h) IV q8-12h
Morphine sulfate: 3-5 mg (peds: 0.1-0.2 mg/kg per dose q2-q4h) IV, every 15 min titrated to effect
Piperacillin/tazobactam: 3.375 g (peds: 150-300 mg/kg/d if <6 mo; 240-400 mg/kg/d if >6 mo) IV q6h

Follow-Up

Disposition

Admission Criteria

Surgical intervention of acute appendicitis
Observation or further diagnostic workup if diagnosis is uncertain

Discharge Criteria
Patients with abdominal pain thought not to be appendicitis may be discharged if they meet the following criteria:

Resolved or resolving symptoms
Minimal or no abdominal tenderness
No lab/radiologic abnormalities
Able to tolerate PO intake
Adequate social support and able to return if symptoms worsen

Followup Recommendations

24-48 hr recheck for patients discharged from the ED with abdominal pain of unclear etiology

Pearls and Pitfalls

Pediatric and geriatric patients present atypically and have increased perforation rates
Imaging is not required in a classic presentation of acute appendicitis
Appendicitis cannot be ruled out on any imaging modality if the appendix is not visualized

Additional Reading

Basaran A, Basaran M. Diagnosis of acute appendicitis during pregnancy: A systematic review. Obstet Gynecol Surv. 2009;64(7):481-488.
Hennelly KE, Bachur R. Appendicitis update. Curr Opin Pediatr. 2011;23:281-285.
Long SS, Long C, Lai H, et al. Imaging strategies for the right lower quadrant pain in pregnancy. AJR Am J Roentgenol. 2011;196:4-12.
Singh A, Danrad R, Hahn PF, et al. MR imaging of the acute abdomen and pelvis: Acute appendicitis and beyond. Radiographics. 2007;27:1419-1431.

Codes

ICD9

540.1 Acute appendicitis with peritoneal abscess
540.9 Acute appendicitis without mention of peritonitis
541 Appendicitis, unqualified
540.0 Acute appendicitis with generalized peritonitis
540 Acute appendicitis
542 Other appendicitis

ICD10

K35.3 Acute appendicitis with localized peritonitis
K35.80 Unspecified acute appendicitis
K37 Unspecified appendicitis
K35.89 Other acute appendicitis
K35.2 Acute appendicitis with generalized peritonitis
K35.8 Other and unspecified acute appendicitis
K35 Acute appendicitis
K36 Other appendicitis

SNOMED

74400008 Appendicitis (disorder)
85189001 Acute appendicitis (disorder)
266439004 Acute appendicitis with appendix abscess (disorder)
286967008 Acute perforated appendicitis
51036000 Acute appendicitis with peritoneal abscess (disorder)
9124008 Subacute appendicitis (disorder)

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