What is the management and workup for a child with fever, diarrhea, vomiting, and a positive Fecal Occult Blood Test (FOBT) for 7 days?

Child with 7 Days of Fever, Diarrhea, Vomiting, and Positive FOBT

Immediate Assessment and Differential Diagnosis

This child requires urgent evaluation for bacterial dysentery, with stool culture indicated given the positive FOBT (bloody diarrhea) and prolonged symptoms. 1

The presence of blood in stool shifts the differential diagnosis toward invasive bacterial pathogens and requires specific workup beyond typical viral gastroenteritis. 1

Key Clinical Assessment Points

Assess hydration status immediately using these specific clinical markers 1:

• Mild dehydration (3-5% deficit): Increased thirst, slightly dry mucous membranes
• Moderate dehydration (6-9% deficit): Loss of skin turgor, skin tenting when pinched, dry mucous membranes
• Severe dehydration (≥10% deficit): Severe lethargy or altered consciousness, prolonged skin tenting (>2 seconds), cool/poorly perfused extremities, decreased capillary refill, rapid deep breathing (acidosis sign)

Obtain accurate body weight and compare to premorbid weight if available, as this is the most accurate assessment of fluid deficit. 1

Auscultate for bowel sounds before initiating oral therapy. 1

Critical Differential Diagnoses to Rule Out

Since fever, vomiting, and loose stools can indicate non-gastrointestinal illnesses, specifically evaluate for 1:

• Meningitis (check for neck stiffness, altered mental status, bulging fontanelle if infant)
• Bacterial sepsis (assess perfusion, capillary refill, mental status)
• Pneumonia (respiratory rate, work of breathing, lung auscultation)
• Otitis media (examine tympanic membranes)
• Urinary tract infection (particularly in febrile infants)

Primary Differential for Bloody Diarrhea

With positive FOBT, the most likely diagnoses include:

• Bacterial dysentery: Shigella, Salmonella, Campylobacter, enteroinvasive E. coli
• Hemolytic uremic syndrome (if associated with E. coli O157:H7)
• Inflammatory bowel disease (less likely with acute 7-day presentation)

Diagnostic Workup

Stool culture is specifically indicated for dysentery (bloody diarrhea) and should be obtained before initiating antimicrobial therapy. 1

Laboratory studies to obtain 1, 2:

• Stool culture (mandatory given positive FOBT)
• Serum electrolytes if clinical signs suggest abnormal sodium or potassium (severe dehydration, altered mental status, seizures)
• Complete blood count to assess for anemia from blood loss and leukocytosis suggesting bacterial infection
• Blood culture if sepsis is suspected

Routine laboratory studies are NOT needed for typical acute watery diarrhea in immunocompetent patients without blood. 1

Immediate Management

Rehydration Based on Severity

For mild dehydration (3-5% deficit) 1, 2:

• Oral rehydration solution (ORS) containing 50-90 mEq/L sodium
• Administer 50 mL/kg over 2-4 hours
• Use teaspoon, syringe, or medicine dropper initially with small volumes (5 mL every minute), gradually increasing as tolerated 2
• Reassess hydration status after 2-4 hours

For moderate dehydration (6-9% deficit) 1, 2:

• ORS at 100 mL/kg over 2-4 hours
• Same administration technique as mild dehydration
• Replace ongoing losses with 60-120 mL ORS for each diarrheal stool or vomiting episode 2

For severe dehydration (≥10% deficit, shock) 1, 3:

• Medical emergency requiring immediate IV rehydration
• Boluses of 20 mL/kg Ringer's lactate or normal saline until pulse, perfusion, and mental status normalize
• May require two IV lines or alternate access (venous cutdown, femoral vein, intraosseous)
• Transition to ORS for remaining deficit once consciousness returns

Managing Persistent Vomiting

Ondansetron may be administered to children >4 years to facilitate oral rehydration when vomiting is significant 3, 2:

• Dose: 8 mg sublingual every 4-6 hours for children over 4 years 2
• This facilitates ORS administration in children who would otherwise fail oral rehydration

Nasogastric ORS administration may be considered for patients unable to tolerate oral intake or refusing to drink adequately. 3

Nutritional Management

Resume age-appropriate diet immediately after rehydration 3, 2:

• Continue usual diet during illness
• Avoid foods high in simple sugars (soft drinks, undiluted apple juice) as they exacerbate diarrhea through osmotic effects 3
• Avoid high-fat foods 2
• Continue breastfeeding throughout the illness in infants 3

Early refeeding is recommended rather than fasting or restrictive diets. 3

Antimicrobial Therapy Considerations

Antimicrobial therapy should be considered given the bloody diarrhea, but await stool culture results unless the child appears toxic 3:

• Empiric antibiotics may be started if severe dysentery with systemic toxicity
• Tailor antibiotics once culture and sensitivities return
• Do NOT use antimicrobials routinely as viral agents predominate in most gastroenteritis 3

Medications to AVOID

Antimotility agents (loperamide) are absolutely contraindicated in children <18 years 3, 2:

• Risk of ileus, lethargy, and reported deaths (18 cases of severe abdominal distention with at least 6 deaths reported) 1
• Never use in bloody diarrhea regardless of age 3

Avoid adsorbents, antisecretory drugs, and toxin binders as they do not reduce diarrhea volume or duration and shift focus away from appropriate fluid and nutritional therapy. 3

Disposition and Follow-Up

Instruct parents to return immediately if 2:

• Child becomes irritable or lethargic
• Decreased urine output develops
• Intractable vomiting occurs
• Fever persists beyond 3-4 days
• Increased bleeding or abdominal distension

Follow up with primary care within 24-48 hours if symptoms persist. 2

Common Pitfalls to Avoid

Do not delay rehydration while awaiting diagnostic testing - initiate rehydration promptly. 3

Do not use sports drinks or apple juice as primary rehydration solutions for moderate to severe dehydration; low-osmolarity ORS formulations are preferred. 3

Do not unnecessarily restrict diet during or after rehydration. 3

Do not administer antimotility drugs to any child or in cases of bloody diarrhea. 3