Ultrasound: Abdomen

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Background

  • New techniques and findings on ultrasound of the abdomen can decrease time to diagnosis and patient/family satisfaction
  • Ultrasound in not limited to FAST or aortic exams but can be used for appy’s, SBOs, and intussusception

Appendicitis

  • Bedside ultrasound can be helpful in ruling in the diagnosis
  • EDUS in adults has a Sn of 0.68 and Sp of 0.98[1]
  • EDUS in pediatric has a Sn of 0.85 and Sp of 0.93[2]

Indications

  • Classically symptoms include periumbilical pain traveling to the RLQ pain, followed by nausea, anorexia, and vomiting

Images

Instructions

  • Use linear probe (curvilinear in more obese patients)
  • Scan RLQ from ASIS to right iliac artery to identify a tubular structure
    • Scanning over the point of maximal tenderness can be helpful
  • The appendix typically appears anterior to the psoas muscle and iliac vessels
  • Once identified, evaluate if the tube is compressible in the transverse view

Evaluation

  • Accepted criteria for diagnosis includes[3]:
    • Noncompressible
    • Blind-ending tubular structure in the longitudinal axis
    • Measures >6 mm in diameter from outer wall to outer wall
    • Lacks peristalsis
  • Other attributes can add to identification:
    • Target-like appearance in the transverse axis
    • Abdominal free fluid
    • Wall edema
    • Identification of fecalith

Small Bowel Obstruction

  • EDUS had a Sn of 0.91 and Sp of 0.84 for SBO (compared to 0.02 and 0.67 respectively for Abd Xray)[4]

Indications

  • Patients with crampy abdominal pain, paroxysms, and nausea/vomiting

Images

Instructions

  • Use curvilinear/phased array probe (linear probe can be used in very thin patients)
  • Scan the entire abdomen using "lawn-mower" technique of horizontal tracks (or other systematic method)
    • Scanning over dependent areas yields the most success
  • Identify dilated loops of bowel

Evaluation

  • SBO criteria include:
    • Dilated loops of bowel >2.5cm
    • Bidirectional peristalsis
  • Additional findings include:
    • "Keyboard" sign which are finger-like projections that represent plicae circulares
    • Bowel wall edema
    • Intraabdominal free fluid
    • Sonographic transition point

Intussusception

  • With minimal training, ED providers have a Sn of 0.85 and Sp 0.97[6]

Indications

  • Classically a child from 3-36 mos with colicy pain, palpable mass on the right, and current jelly stool

Images

Instructions

  • Use linear probe
  • Scan from the cecum in the RLQ towards the RUQ
    • Scanning over a palpable mass if felt can be helpful
  • Identified the characteristic findings

Evaluation

  • Longitudinal view shows a dilated intussuscipiens containing the intussusceptum
    • This forms three parallel hypoechoic layers separated by hyperechoic zones
  • Pseudokidney sign can be seen if mesentery is only on one side of the bowel
  • Short axis shows a target sign of three parallel hypoechoic areas separated by hyperechoic zones

External Links

See Also

References

  1. Mallin M, et al. Diagnosis of appendicitis by bedside ultrasound in the ED. The American Journal of Emergency Medicine. 2014. 33(3):430 – 432.
  2. Sivitz A, et al. Evaluation of Acute Appendicitis by Pediatric Emergency Physician Sonography. Annals of Emergency Medicine. 2014. 64(4):358–364.
  3. Fox JC, et al. Prospective evaluation of emergency physician performed bedside ultrasound to detect acute appendicitis. Eur. J. Emerg. Med. 2008; 15(2):80-5.
  4. Jang TB, et al. Bedside ultrasonography for the detection of small bowel obstruction in the emergency department. J Emerg Med. 2011. 28(8):676-678.
  5. http://www.thepocusatlas.com/bowel/
  6. Riera A, et al. Diagnosis of intussusception by physician novice sonographers in the emergency department. Ann Emerg Med. 2012; 60(3):264–268.