Overview
Definition:
Food Protein-Induced Enterocolitis Syndrome (FPIES) is a non-IgE mediated gastrointestinal hypersensitivity reaction to ingested food proteins, primarily affecting infants and young children
It is characterized by delayed-onset, profuse vomiting, diarrhea, and lethargy, which can lead to dehydration, shock, and failure to thrive.
Epidemiology:
FPIES is estimated to affect 1 in 1000 to 1 in 7000 infants
The most common triggers are cow's milk protein and soy protein, followed by grains (rice, oats) and egg
Incidence is higher in infants introduced to formula early
It typically presents within the first year of life, with most cases resolving by 3 years of age.
Clinical Significance:
FPIES poses a diagnostic challenge due to its non-specific symptoms and delayed presentation, often mimicking other acute abdominal conditions in the emergency department
Accurate diagnosis and prompt management are crucial to prevent severe complications like hypovolemic shock and dehydration, and to guide appropriate long-term dietary avoidance and reintroduction strategies.
Clinical Presentation
Symptoms:
Acute onset of profuse, non-bilious vomiting typically occurring 1-3 hours after ingestion of the trigger food
Profuse watery diarrhea may follow several hours later
Lethargy, pallor, irritability, and abdominal distension are common
In severe cases, patients may develop hypotension, hypothermia, and circulatory collapse.
Signs:
Physical examination may reveal signs of dehydration (e.g., dry mucous membranes, decreased skin turgor, sunken fontanelles)
Vital signs may show tachycardia, hypotension, and hypothermia
Abdominal tenderness and distension may be present
Rectal examination may show mucus or blood-streaked stools.
Diagnostic Criteria:
Diagnosis is primarily clinical and relies on a history of characteristic symptoms following ingestion of a specific food, a symptom-free interval after the trigger is removed, and recurrence of symptoms upon re-challenge
Diagnostic criteria often include: 1
Characteristic gastrointestinal symptoms (vomiting, diarrhea)
2
Onset occurring 1-3 hours after ingestion of a trigger food
3
Resolution of symptoms within 24-48 hours of trigger removal
4
Recurrence of symptoms upon re-exposure to the trigger food.
Diagnostic Approach
History Taking:
A detailed dietary history is paramount
Inquire about the timing of symptom onset relative to feeding, the specific foods consumed, new food introductions, formula types, and any previous allergic reactions
Ask about vomiting characteristics (profuse, non-bilious), diarrhea (timing, consistency, presence of blood/mucus), and associated symptoms like lethargy and pallor
Obtain a family history of allergies.
Physical Examination:
Perform a thorough physical examination focusing on hydration status (mucous membranes, skin turgor, capillary refill, fontanelle depth), vital signs (BP, HR, RR, temperature), abdominal examination (distension, tenderness, bowel sounds), and general appearance (pallor, activity level).
Investigations:
In acute settings, investigations are aimed at assessing severity and ruling out other conditions
Complete blood count (CBC) may show hemoconcentration and leukocytosis
Electrolytes may reveal hyponatremia or hypernatremia, and metabolic acidosis
Liver function tests (LFTs) and renal function tests (RFTs) should be performed to assess organ involvement
Inflammatory markers like C-reactive protein (CRP) may be elevated
Stool studies may be needed to rule out infectious causes
Specific IgE testing for food allergens is typically negative in FPIES.
Differential Diagnosis:
Differential diagnoses include infectious gastroenteritis, surgical abdomen (intussusception, appendicitis), sepsis, milk-protein-induced enteropathy, eosinophilic gastroenteritis, and other food intolerances
Key differentiating features of FPIES include the delayed, reproducible pattern of vomiting and diarrhea following specific food ingestion, and the absence of IgE-mediated symptoms like urticaria or angioedema.
Management
Initial Management:
The cornerstone of ED management is fluid resuscitation for dehydration and shock
Intravenous (IV) fluids are essential for volume replacement
For mild dehydration, isotonic crystalloids like normal saline or Lactated Ringer's solution are used
For severe dehydration or shock, rapid IV fluid boluses of 20 mL/kg are administered
Monitor vital signs closely for improvement
If hypotension persists, consider vasopressors
Antiemetics can be considered if vomiting is severe and persistent, but their efficacy is limited.
Medical Management:
Once the acute episode resolves and the patient is stable, management focuses on identifying and avoiding the trigger food
For confirmed FPIES, strict avoidance of the offending protein is recommended
For infants, this means switching to a hypoallergenic formula (e.g., extensively hydrolyzed casein- or whey-based formula, or an amino acid-based formula)
The choice of formula should be guided by the severity of FPIES and the specific trigger
Reintroduction of the trigger food should be done under medical supervision, typically via an oral food challenge in a controlled setting after a period of avoidance.
Surgical Management:
Surgical intervention is generally not indicated for FPIES
The presentation can sometimes mimic surgical emergencies, necessitating careful evaluation to exclude conditions like intussusception or appendicitis
However, once FPIES is diagnosed, medical management is the primary approach.
Supportive Care:
Supportive care includes vigilant monitoring of hydration status and vital signs
Nutritional support is crucial for infants with FPIES, especially if multiple food triggers are identified, to ensure adequate growth and prevent failure to thrive
In rare, severe, or refractory cases, consultations with pediatric gastroenterologists and allergists are essential.
Complications
Early Complications:
The most significant early complication is hypovolemic shock due to severe dehydration from profuse vomiting and diarrhea
Other early complications include electrolyte imbalances (e.g., hyponatremia, hyperkalemia), hypoglycemia, and metabolic acidosis
Inadequate fluid resuscitation can lead to acute kidney injury.
Late Complications:
Chronic FPIES can lead to failure to thrive, poor growth, and nutritional deficiencies due to ongoing inflammation and malabsorption, or due to overly restrictive diets
Delayed diagnosis and management can contribute to significant parental anxiety and impact quality of life.
Prevention Strategies:
While primary prevention is not fully understood, strategies include appropriate timing of introduction of solid foods and hypoallergenic formulas in high-risk infants
Early recognition and diagnosis by healthcare providers in the ED and primary care setting can prevent severe complications and improve long-term outcomes.
Prognosis
Factors Affecting Prognosis:
Prognosis is generally good with proper diagnosis and management
Factors influencing prognosis include the severity of the acute episode, promptness of treatment, adherence to dietary avoidance, and the presence of comorbidities
Most children outgrow FPIES by the age of 3 years.
Outcomes:
With appropriate management, children typically experience resolution of symptoms, catch-up growth, and improved quality of life
Recurrence is possible if the trigger food is reintroduced without proper medical guidance
The long-term psychological impact on families can be mitigated by clear communication and support.
Follow Up:
Regular follow-up with a pediatrician, pediatric gastroenterologist, or allergist is recommended
This allows for monitoring of growth, assessment of nutritional status, and guidance on the safe reintroduction of trigger foods once tolerance is expected to have developed
Oral food challenges should be supervised by a healthcare professional.
Key Points
Exam Focus:
Remember the classic triad of FPIES: delayed vomiting (1-3 hrs post-ingestion), diarrhea (hours later), and lethargy, leading to dehydration
Suspect FPIES in infants presenting with acute gastroenteritis-like symptoms without a clear infectious etiology
Differentiate from IgE-mediated allergies (no urticaria/anaphylaxis)
ED plan focuses on aggressive IV fluid resuscitation.
Clinical Pearls:
The key is a detailed history of food intake and symptom timing
Always ask "What did the baby eat before this happened?" and "When did the vomiting start?"
In the ED, prioritize ABCs and IV fluids
A negative IgE test is common and does not rule out FPIES
Oral food challenges are the gold standard for diagnosis and are done under supervision.
Common Mistakes:
Misdiagnosing FPIES as infectious gastroenteritis or surgical abdomen, leading to delayed treatment and potential complications
Underestimating the severity of dehydration and shock
Relying solely on IgE testing for diagnosis
Delaying reintroduction of foods, leading to unnecessary dietary restrictions and nutritional concerns.