emDOCs Revamp: Appendicitis

Authors: Katey DG Osborne, MD (EM Attending Physician; Tacoma, WA), Rachel Bridwell, MD (EM Attending Physician; Tacoma, WA) // Reviewed by: Alex Koyfman, MD (@EMHighAK, EM Attending Physician, UTSW / Parkland Memorial Hospital) and Brit Long, MD (@long_brit, EM Attending Physician, San Antonio, TX)

Welcome to emDOCs revamp! This series provides evidence-based updates to previous posts so you can stay current with what you need to know.

An 18-year-old female presents to the ED for abdominal pain. The pain began the day prior in the “middle of her stomach,” but is now “lower to the right” and associated with rigors and anorexia. She denies new sexual partners, dysuria, or vaginal discharge, and her last menses was 1 week prior.

Triage Vital Signs: BP 109/69, HR 115, T 102.4°F Oral, RR 21, SpO2 99% on room air.

She appears uncomfortable but with no acute distress. Her abdomen is soft. She has tenderness to palpation at McBurney’s point, tenderness in the right lower quadrant when palpating the left; evidence of involuntary guarding.

What’s the likely diagnosis?

Answer: Appendicitis^1-21

Epidemiology / Clinical Presentation:

• Lifetime risk is estimated 8.6% for males and 6.7% for females^1,2
• Most prevalent in ages 10 -19 years old
• Most common non-obstetric surgical emergency in pregnancy
  • In comparison to other surgical conditions during pregnancy, appendicitis has increased risk for pre-term labor and fetal loss. Especially when associated with peritonitis. ³
• Classical presentation:
  • Early presentation with nonspecific symptoms – malaise, bowel irregularity, anorexia.
  • Initial visceral innervation causes vague, periumbilical discomfort with poor localization.⁴
  • Typical progression with movement to the right lower quadrant (RLQ) due to increased inflammation and peritoneal irritation.⁴
• Atypical presentations:
  • Up to 50% of patients may present atypically due to age or location of the appendix.
  • Retrocecal appendix: right flank or pelvic pain.⁴
  • Pregnancy: May present with right upper quadrant pain due to the uterine displacement.
    • Most common is still the RLQ in gravid patients ³
  • Elderly patients may have absence of fever or conclusive clinical findings of acute appendicitis with signs of peritonitis being more pronounced ⁵
• Low mortality rate of 0.04 – 0.21% in the general population
  • Risk factors for increased mortality include open surgery, complicated appendicitis, and increased frailty score (especially in the elderly) ⁵
• Missed diagnosis of appendicitis found in those who are age> 50, women, constipation plus abdominal pain (adults and children), and/or those with 2+ comorbidities⁶

Physical Exam:

• VS: fever, tachycardia, tachypnea, if hypotension is present, often a late sign and prognostically poor
  • In pediatric patients with undifferentiated abdominal pain, fever is most suggestive of acute appendicitis (LR + 3.4) ⁷
• Abdominal exam:

• • McBurney sign: Tenderness at the point 1/3 the distance from the right anterior superior iliac spine to the umbilicus
    • Sensitivity 50-94%; Specificity 75-86% ¹
  • Rovsing sign: Pain in the right lower quadrant when palpating the left lower quadrant
    • Sensitivity, 22-68%; Specificity 58-96% ¹
    • This maneuver is most suggestive of appendicitis in pediatric population. ⁷
  • Obturator sign: Right lower quadrant pain upon flexion and internal rotation of the right hip (pelvic appendix)
    • Sensitivity, 8%; Specificity 94% ¹
  • Psoas sign: right lower quadrant pain with passive extension of the right hip (retroperitoneal appendix)
    • Sensitivity, 13-42%; Specificity 58-96% ¹
  • Diffuse peritonitis: suggests appendiceal perforation with possible intraperitoneal contamination.

Evaluation:

• Labs:
  • CBC with differential:
    • >10,000 WBC/uL present in majority of patients ¹
    • 80% of patients have associated left shift in the leukocytosis differential
  • Urinalysis: leukocyte esterase and sterile pyuria are not unusual
    • e. – a positive UA does not refute the diagnosis.
  • B-HCG in age-appropriate female patients to rule out ectopic pregnancy
  • CMP and Lipase – to evaluate for alternative intra-abdominal etiologies
  • CRP – non-specific inflammatory marker that if > 10 mg/L is suggestive of appendicitis (LR+ 2.0)⁸
• Scoring Criteria:
  • Alvarado Score (fig. 1)
    • Developed by a surgeon prior to the advent of advance imaging to help decrease false positive appendectomies.
    • Can be used to help decide which patients with abdominal pain should be further evaluated with a CT Scan. ¹⁰
    • Cutoffs differ per study:
      • Coleman retrospective study, 2018:
        • Scores £ 2 in females and £ 1 in males were found to be safe to forgo CT ¹¹
      • McKay cohort study, 2007:
        • Scores £ 3 were low-risk and could forgo CT
        • Intermediate scores (4-6), CT is recommended ¹⁰
          • Sensitivity of 35.6% for acute appendicitis with these scores, compared to 90.4% for CT
    •  With a pretest probability of 60% in adults, meta-analysis performed by Ebell & Shinholser found an LR of 3.4 for a score ³ 7 and 0.3 for < 4. ¹²
    • Limitations of this scoring criteria:
      • Tends to overestimate acute appendicitis in women. ¹³
      • Does not include lab values –urinalysis, CRP which are seen in the RIPASA and Appendicitis Inflammatory Response Score (AIR)
      • Elevated scores can also be seen in those without appendicitis – such as pelvic inflammatory disease, tubo-ovarian abscess, diverticulitis, etc.

Fig 1: https://www.mdcalc.com/calc/617/alvarado-score-acute-appendicitis

• • Pediatric Appendicitis Score (PAS, fig. 2)
    • Similar to the Alvarado score but with more relevant to children with pain on coughing, jumping, or percussion.
    • Validated for use in children by multiple studies ^8,14
    • More recently, the Pediatric Appendicitis Risk Calculator (pARC) has been created for use in pediatric patients with concern for acute appendicitis and in one study was externally validated and found to outperform the PAS¹⁵

Fig 2: https://www.mdcalc.com/calc/3926/pediatric-appendicitis-score-pas

• Imaging:
  • Computed Tomography (CT) Abdomen and Pelvis is the study of choice per the American College of Radiology¹⁶
    • Sensitivity 96%, specificity 96% ¹
      • Lowest rates of indeterminant examinations
    • IV contrast is recommended to improve accuracy ¹⁶
      • Oral and rectal contrast are not recommended
    • Uncomplicated appendicitis CT findings:¹
      • Dilated appendix (³ 7 mm), appendiceal wall thickening, hyperenhancement, inflammatory stranding of the periappendiceal fat
    • Complicated appendicitis CT findings:
      • Evidence of perforation, presence of an extraluminal appendicolith, periappendicular/abdominal abscess formation, ileus, and /or diffuse peritonitis on exam.^1,5
      • Prevalence increases with age⁵
    • Approximately 40% of patients with appendicitis will have an appendicolith which in itself is associated with severe inflammation and increased risk of perforation. ¹
    • In the pregnant patient, ACOG guidelines state that CT should not be withheld if deemed necessary and/or more readily available than US or MRI¹⁷
  • Ultrasound is recommended as first line in pediatric and pregnant patients⁶
    • Sensitivity 85%, specificity 90% ¹
    • Findings of a non-compressible, aperistaltic, blind ending fluid-filled structure measured > 6 mm outer diameter.
      • Secondary signs can also be seen such as phlegmon, appendicolith, hyperemia (color doppler), and periappendiceal fluid. ¹⁸
    • Disadvantage is for potential non-visualization due to overlying bowel, sonographer experience, retrocecal appendix, body habitus or BMI > 25 ^1,6
    • With equivocal results (i.e. non-visualized or partially visualized appendix) and continued suspicion for appendicitis, advanced imaging with CT or MRI should be considered.

• • Magnetic Resonance Imaging (MRI) may be used in pregnant women and children (image 2)
    • Sensitivity 95%, specificity 92% ¹
    • Lower rates of non-visualization compared to US¹⁷
    • Use of gadolinium-based contrast is controversial during pregnancy, ACOG recommendation of noncontrast MRI¹⁷

• • Radiography (XR) is not indicated in work-up unless acutely concerned for perforation on initial evaluation
    • In those with constipation and abdominal pain, XR may lead to confirmation bias and early closure in evaluation leading to misdiagnosis for any age.⁶

Treatment:

• Fluid resuscitation, antipyretics, analgesics, antiemetics as appropriate.
• Patients should be made NPO.
• Administration of perioperative antibiotics:^1,4,19,20
  • Low-risk community acquired:
    • Piperacillin/tazobactam 3.375 g IV every 6 hrs
    • Ertapenem 1g IV every 24hrs
    • Ceftriaxone 2 g IV + Metronidazole 500 mg IV every 8 hrs
    • Ciprofloxacin 400 mg IV every 12 hrs + Metronidazole 500 mg IV every 8 hrs
      • Increasing resistance of E coli to fluoroquinolones, recommend reviewing local antibiogram
      • Use if patient has penicillin allergy
  •  High-risk community acquired:
    • Cefepime 2 g IV + Metronidazole 500 mg IV every 8 hrs
    • Piperacillin/tazobactam 4.5 g IV every 6 hrs
•  Conservative, Nonoperative Management:
  • Appropriate Candidates²:
    • Examination without peritonitis or sepsis/shock and imaging without perforation, large abscess/phlegmon, or mass.
    • Caution in including those with appendicoliths due to increased risk of treatment failure and higher risk for development of complicated appendicitis
    • Populations excluded from studies for conservative management include pregnant patients, immunocompromised patients, those with a history of inflammatory bowel disease (IBD), and severe sepsis secondary to appendicitis.
  • Shared decision making between consulting surgeon and the patient with uncomplicated appendicitis for management with antibiotics alone.
    • Associated with higher quality of life at 30 days in pediatric patients, fewer days of disability, and lower/similar risk of complications compared to surgery.²
    • Small risk of delayed cancer diagnosis or progression of disease in nonoperative management incidence of 0.9% of all appendectomy specimens²
      • Those > 40 years old should have a colonoscopy if opt for conservative management.²
  •  Appendectomy reserved for patients who do not respond to antibiotics or those with a recurrence of appendicitis. ²
    • One study found that appendectomy was later performed in 29% of patients in the conservative group ⁵
    • Patients with appendicoliths are less likely to respond to antibiotics alone and have higher rates of complication compared with surgical management and recurrence of appendicitis  41% with versus 25% without appendicolith⁵
  • Typically treated inpatient with broad spectrum antibiotics (gram negative and anaerobic coverage) and close follow-up²:
    • IV ceftriaxone plus metronidazole or IV ertapenem monotherapy ^1,2
    • Transition to oral fluoroquinolones plus metronidazole for 7-10 days
  • Disposition:
    • Patients have improvement / resolution of fever, pain, anorexia approximately 48 hours post the start of antibiotics.²
•  Surgical Treatment:
  • Management option in those with uncomplicated appendicitis and required in those with appendiceal perforation, peritonitis, and/or associated sepsis / hemodynamic instability.¹
    • Laparoscopic approach is the standard for adult appendicitis with fewer associated complications, lower post-operative mortality, and hospital length of stay as compared to the open approach ^1,5
      • Risk factors for post-operative complications include increased age, open surgery, and complicated appendicitis
      • Most common complication is surgical site infection^2,5,21
  •  Uncommon post-operative complication is the development stump appendicitis in an incompletely excised appendix²¹
    • In those with a prior appendectomy, keep this diagnosis on your differential if presenting with findings similar to typical appendicitis
•  Interventional Radiology in conjunction with delayed surgical intervention:
  • Initial percutaneous drainage of abscess(es) plus broad spectrum antibiotics may be considered for source control in stable patients with complicated, perforated appendicitis.²
  • Plan surgical intervention 4-6 weeks later as immediate surgery was found to have higher complication rates¹

Disposition:

• Admission to General Surgery team for IV antibiotics and surgical intervention.
• Transfer to facility with surgical capabilities.

Pearls:

• In the pregnant patient, ACOG guidelines state that CT should not be withheld if deemed necessary and/or more readily available than US or MRI
• Patients with uncomplicated appendicitis have more flexibility in management and may be considered for conservative, nonoperative therapy with antibiotics with 29% requiring future appendectomy.
• Unstable or septic patient with appendicitis should undergo emergent surgical intervention
• Use of scoring tools can help differentiate those who are low risk to having appendicitis and can forgo CT imaging.
• Consider stump appendicitis in the post-appendectomy patient with RLQ abdominal pain.

References:

1. Moris D, Paulson EK, Pappas TN. Diagnosis and Management of Acute Appendicitis in Adults: A Review. JAMA J Am Med Assoc. 2021;326(22):2299-2311. doi:10.1001/jama.2021.20502
2. Talan DA, Saverio SD. Treatment of Acute Uncomplicated Appendicitis. N Engl J Med. 2021;385(12):1116-1123. doi:10.1056/NEJMcp2107675
3. Cohen-Kerem R, Railton C, Oren D, Lishner M, Koren G. Pregnancy outcome following non-obstetric surgical intervention: [1]. Am J Surg. 2005;190(3):467. doi:10.1016/j.amjsurg.2005.03.033
4. DeKoning EP. Acute Appendicitis. In: Tintinalli JE, Ma OJ, Yealy DM, et al., eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 9th ed. McGraw-Hill Education; 2020. Accessed January 21, 2024. accessemergencymedicine.mhmedical.com/content.aspx?aid=1166533991
5. Lapsa S, Ozolins A, Strumfa I, Gardovskis J. Acute Appendicitis in the Elderly: A Literature Review on an Increasingly Frequent Surgical Problem. Geriatrics. 2021;6(3):93. doi:10.3390/geriatrics6030093
6. Mahajan P, Basu T, Pai CW, et al. Factors Associated With Potentially Missed Diagnosis of Appendicitis in the Emergency Department. JAMA Netw Open. 2020;3(3):e200612. doi:10.1001/jamanetworkopen.2020.0612
7. Benabbas R, Hanna M, Shah J, Sinert R. Diagnostic Accuracy of History, Physical Examination, Laboratory Tests, and Point-of-care Ultrasound for Pediatric Acute Appendicitis in the Emergency Department: A Systematic Review and Meta-analysis. Acad Emerg Med. 2017;24(5):523-551. doi:10.1111/acem.13181
8. Snyder MJ, Guthrie M, Cagle S. Acute Appendicitis: Efficient Diagnosis and Management. Am Fam Physician. 2018;98(1):25-33.
9. Wagner JM, McKinney WP, Carpenter JL. Does this patient have appendicitis? JAMA. 1996;276(19):1589-1594.
10. McKay R, Shepherd J. The use of the clinical scoring system by Alvarado in the decision to perform computed tomography for acute appendicitis in the ED. Am J Emerg Med. 2007;25(5):489-493. doi:10.1016/j.ajem.2006.08.020
11. Coleman JJ, Carr BW, Rogers T, et al. The Alvarado score should be used to reduce emergency department length of stay and radiation exposure in select patients with abdominal pain. J Trauma Acute Care Surg. 2018;84(6):946-950. doi:10.1097/TA.0000000000001885
12. Ebell MH, Shinholser J. What are the most clinically useful cutoffs for the Alvarado and Pediatric Appendicitis Scores? A systematic review. Ann Emerg Med. 2014;64(4):365-372.e2. doi:10.1016/j.annemergmed.2014.02.025
13. Ohle R, O’Reilly F, O’Brien KK, Fahey T, Dimitrov BD. The Alvarado score for predicting acute appendicitis: a systematic review. BMC Med. 2011;9(1):139. doi:10.1186/1741-7015-9-139
14. Mandeville K, Pottker T, Bulloch B, Liu J. Using appendicitis scores in the pediatric ED. Am J Emerg Med. 2011;29(9):972-977. doi:10.1016/j.ajem.2010.04.018
15. Cotton DM, Vinson DR, Vazquez-Benitez G, et al. Validation of the Pediatric Appendicitis Risk Calculator (pARC) in a Community Emergency Department Setting. Ann Emerg Med. 2019;74(4):471-480. doi:10.1016/j.annemergmed.2019.04.023
16. Kambadakone A, Santillan C, Fowler K, et al. ACR Appropriateness Criteria® Right Lower Quadrant Pain. American College of Radiology. Published 2022. Accessed February 25, 2024. https://acsearch.acr.org/docs/69357/Narrative/
17. Guidelines for Diagnostic Imaging During Pregnancy and Lactation. Committee Opinion no. 723. Am Coll Obstet Gynecol. 2017;130(4):e210-6.
18. Boyle MJ, Lin-Martore M, Graglia S. Point-of-care ultrasound in the assessment of appendicitis. Emerg Med J. 2023;40(7):528-531. doi:10.1136/emermed-2022-212433
19. Bradley A, Hutson M, Kyle J. Acute Appendicitis in Adults. US Pharm. 2019;44(12):HS2-HS9.
20. Mazuski JE, Tessier JM, May AK, et al. The Surgical Infection Society Revised Guidelines on the Management of Intra-Abdominal Infection. Surg Infect. 2017;18(1):1-76. doi:10.1089/sur.2016.261
21. Dahdaleh FS, Heidt D, Turaga KK. The Appendix. In: Brunicardi FC, Andersen DK, Billiar TR, et al., eds. Schwartz’s Principles of Surgery. 11th ed. McGraw-Hill Education; 2019. Accessed February 25, 2024. accesssurgery.mhmedical.com/content.aspx?aid=1164318395