A 1-month-old boy is brought to the office for evaluation of blood-streaked stools. The patient was born at full term via spontaneous vaginal delivery and has been breastfed exclusively. The mother says he usually has 5 yellow, seedy stools daily, but over the past 3 days they have become loose and streaked with blood and mucus. The infant nurses every 2-3 hours but spits up a small amount of breast milk with every feed. The mother recently completed a course of antibiotics for mastitis but otherwise takes no daily medications and has a regular diet. The patient's weight, length, and head circumference have been tracking along the 40th percentile. Vital signs are normal. The infant appears well. The abdomen is soft and nontender. No fissures are noted on anal examination. A fecal occult blood test is positive. Which of the following is the most likely cause of this patient's condition?

Question

A 1-month-old boy is brought to the office for evaluation of blood-streaked stools.  The patient was born at full term via spontaneous vaginal delivery and has been breastfed exclusively.  The mother says he usually has 5 yellow, seedy stools daily, but over the past 3 days they have become loose and streaked with blood and mucus.  The infant nurses every 2-3 hours but spits up a small amount of breast milk with every feed.  The mother recently completed a course of antibiotics for mastitis but otherwise takes no daily medications and has a regular diet.  The patient's weight, length, and head circumference have been tracking along the 40th percentile.  Vital signs are normal.  The infant appears well.  The abdomen is soft and nontender.  No fissures are noted on anal examination.  A fecal occult blood test is positive.  Which of the following is the most likely cause of this patient's condition?

Quizplus · Accepted Answer

11ec25c8_d67b_89bb_bc81_454fd685dc85_MD0003_00 This patient most likely has food protein-induced allergic proctocolitis (FPIAP), a common condition of early infancy. FPIAP is a non-IgE-mediated reaction that usually occurs in response to proteins in cow's milk (eg, casein, whey), such as those in standard formula. Because breast milk contains proteins derived from the maternal diet, FPIAP can also occur in breastfed infants. Disease onset is insidious, and symptoms often do not arise until weeks (most commonly at age 1-4 weeks) to months (up to age 6 months) after first exposure to the food allergen. The typical presentation involves a well-appearing infant with painless bloody stools that may also be loose and mucus streaked. Symptoms suggestive of a different diagnosis include failure to thrive, profuse diarrhea, and forceful vomiting; this patient's spit-up likely results from physiologic gastroesophageal reflux. FPIAP is a clinical diagnosis and is confirmed when bleeding ceases after the trigger protein is removed from the diet. The prognosis is excellent, and patients usually can tolerate products containing the offending protein (eg, milk, yogurt) by age 1. (Choice A) Although antibiotics, a risk factor for Clostridioides (formerly Clostridium) difficile colitis, may be transmitted through breast milk, C difficile infection is rare in infants, who lack the intestinal receptors to the toxin until approximately age 2. Moreover, other infectious symptoms (eg, fever, profuse diarrhea) would be expected. (Choice C) Intussusception occurs in infants and toddlers age 6-36 months. It presents with lethargy, vomiting, and episodic, crampy pain/irritability as one bowel segment telescopes into another. Hematochezia is a late sign and indicates bowel ischemia. This infant's age and lack of irritability make intussusception unlikely. Intussusception (Choice D) Lactose intolerance, typically diagnosed in older children and adults, is a nonimmunologic reaction to carbohydrate components of cow's milk due to lactase deficiency. Symptoms include crampy abdominal pain, bloating, flatulence, and nonbloody diarrhea. (Choice E) Malrotation with midgut volvulus can cause bloody stools due to intestinal ischemia. However, affected neonates are ill appearing with bilious emesis and poor appetite. Malrotation with midgut volvulus (Choice F) Although Meckel diverticulum classically manifests in older children as painless hematochezia due to ectopic gastric tissue, bleeding in patients age <6 months is exceedingly rare and typically is associated with complications (eg, obstruction, perforation, intussusception). Ill appearance and irritability due to pain would be typical in these cases and are not seen here. Meckel diverticulum Educational objective: Food protein-induced allergic proctocolitis is a common, benign reaction to proteins (eg, cow's milk) in breast milk or formula. Presentation involves a well-appearing infant with painless, bloody stools. References: Food protein-induced enterocolitis syndrome and allergic proctocolitis. (http://www.ncbi.nlm.nih.gov/pubmed/25976434) Non-IgE-mediated gastrointestinal food allergy. (http://www.ncbi.nlm.nih.gov/pubmed/25956013)

A 1-Month-Old Boy Is Brought to the Office for Evaluation