Ultrasound for the Win! 3-year-old with abdominal pain #US4TW

A 3-year-old Hispanic female with no significant past medical or surgical history presents to the Emergency Department with her mother for a 3 day history of crampy abdominal pain, intermittent bloody diarrhea and fever. There has been no recent travel, admissions, or antibiotic use. Her older sister reports similar symptoms, which have resolved. The patient saw her pediatrician the day prior, who recommended supportive care including oral rehydration.

This Ultrasound For The Win!” (#US4TW) Case Series focuses on a real clinical cases where point-of-care ultrasound changed the management of a patient’s care or aided in the diagnosis.

Learning Objectives

1. Compile a differential diagnosis for pediatric abdominal pain.
2. Discuss the role point-of-care ultrasound (POCUS) plays in differentiating various etiologies of pediatric abdominal pain.
3. Discuss the epidemiology, presentation, diagnosis (including common sonographic findings), and management of intussusception.

Vitals

• P 124 bpm
• RR 24 breaths/min
• O2 98% room air
• T 36.8 C

Differential Diagnosis

• Appendicitis
• Clostridium difficile
• Constipation
• Gastroenteritis
• Hemolytic uremic syndrome
• Henoch-Schönlein purpura
• Intussusception
• Meckel’s diverticulum
• Mesenteric lymphadenitis
• Obstruction
• Peritonitis
• Volvulus

On physical examination, the patient is afebrile and nontoxic appearing but visibly uncomfortable. Her abdomen is mildly distended and diffusely tender without peritoneal findings. Genitourinary exam is unremarkable. A severe diaper rash is present on her buttocks, but no stool was noted initially.

A point-of-care ultrasound (POCUS) is performed at the bedside:

Point-of-Care Ultrasound

Ultrasound is the diagnostic imaging modality of choice in diagnosing intussusception in pediatric patients. While a curvilinear probe is required in adult patients, a linear probe is often ideal in the pediatric population.

Sonographic findings of intussusception include:

• A target or pseudokidney sign (Figures 1-2),^​1​ which has a reported sensitivity of 98–100%,^​1,2​ specificity of 88–100%,^1-2 and negative predictive value of 100%^​3​

High-risk findings (which may predict failure of enema)^​1​ include:

• Peritoneal fluid between the bowel walls (Figure 2)
• Lack of blood flow of the bowel wall with Color Doppler
• Intraperitoneal free air (see a prior #US4TW case)
• Involvement of the mesentery (Figure 2)

Diagnosis & Case Conclusion

The patient was diagnosed with intussusception on point-of-care ultrasound and transferred to the local children’s hospital for successful treatment with an air enema. Notably, the patient had currant jelly stools while at the children’s hospital. (Figure 4).

The patient had an uneventful hospital course and was discharged home without complications.

Discussion

Definition

• Intussusception is defined as the telescoping of proximal bowel (the “intussusceptum”) into an adjacent distal bowel segment (the “intussuscipiens”)^​4​

Epidemiology

• Male:female ratio is 3-8:1
• 2/3 of cases <1 year old^​1​
  • Leading cause of small bowel obstruction (SBO) in children
• 5% of cases occur in adults^​4​
  • 1-5% of adult SBO cases
  • 8-20% of adult cases are benign without lead point

Presentation

• Classic triad: Colicky abdominal pain, vomiting, and bloody stools
  • Only present in 10-25% of patients^​1,5​
  • Currant jelly stools are rare

• Nonspecific findings:
  • Severe, intermittent colicky abdominal pain
  • Non-bilious to bilious emesis
  • Constipation
  • Abdominal distention
  • Bloody stools (PPV 80%)^​5​
  • RUQ abdominal mass (PPV 94%)^​5​

Etiology

1. Idiopathic – most common (7-20%)^​4​
   • Ileo-colic
   • Ileo-cecal
   • Often viral (i.e. adenovirus) in pediatric cases
   • 80-90% of pediatric cases benign^​4​

2. Entero-enteral (jejuno-jejunal, jejuno-ileal, ileo-ileal)
   • Small bowel only
   • Henoch-Schönlein purpura
   • Cystic fibrosis

3. Colo-colic
   • Large bowel only
   • Malignant etiology more likely (2/3 of cases)

4. Pathologic lead points^​1,4​
   • Meckel’s diverticulum
   • Polyp
   • Cyst
   • Malignancy (most common cause in adults)
   • Stricture
   • Inflammatory bowel disease
   • Adhesions

5. Post-gastric bypass surgery in adult patients

Diagnosis

• Initial diagnosis missed in 40-50% of cases
• Ultrasound is the diagnostic imaging modality of choice
• CT scan^​4​
  • Sensitivity: 53-100%
  • More beneficial in adults
    • 90% of cases have pathologic lead points
    • Identifies etiology
  • Limitations: radiation, contrast, and transportation out of ED
• X-ray
  • No role for x-rays because of poor sensitivities^​1,6​

Treatment

• Fluid resuscitation
• Surgical consultation on ALL patients
• Pneumatic or hydrostatic enema is preferred modality in pediatric patients^​1​
  • Risk of perforation: 1%
  • Recurrence rate: 10%
• Surgery for adults (and some pediatric cases)^​1​
  • Recurrence rate: 1%

Complications

• Perforation
• Ischemia
• Obstruction

Take Home Points

• Intussusception is an often missed diagnosis, but should remain high on your differential diagnosis for pediatric patients presenting with abdominal pain, and for adult patients with a history of gastric bypass surgery.
• The symptoms of intussusception are often non-specific. The classic triad of colicky abdominal pain, vomiting, and bloody stools is present in <25% of patients with intussusception. The presence of currant jelly stools is a rare finding.
• Ultrasound is the diagnostic imaging modality of choice for pediatric patients, and sonographic findings may include a “target sign” or “pseudokidney sign”.
• Sonographic findings suggesting high risk patients include the presence of free air, peritoneal fluid between the bowel walls, lack of blood flow in bowel wall, and involvement of the mesentery.

To learn more about pediatric point-of-care ultrasound, take the free ALiEMU course on intussusception point-of-care ultrasonography for certificate credit.

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