**Introduction**
Failure to thrive can be a symptom of a more pervasive medical diagnosis such as nutritional neglect; however, it may also be the result of an underlying condition. As such, when a medical provider is confronted with a child with poor weight gain, a thorough medical history, including feeding history, and exam should be completed to evaluate for all causes of failure to thrive.
**Case Presentation**
A 6-month-old female dichorionic diamniotic twin born via c-section at 38 weeks presented to the local children's advocacy center with child protective services for an evaluation of failure to thrive. Previous medical and social history included multiple missed appointments and poor weight gain following 100 grams of weight loss over 2 months, among other social concerns, prompting a CPS referral. Newborn screening, including the critical congenital heart defects screen, was normal. At the time of presentation, the infant's diet consisted of 4-6 ounces of formula every 4 hours, rice cereal, and baby foods. Notably, the other twin was healthy. Upon physical exam, the infant was found to be significantly tachypneic with retractions, head bobbing, and non-palpable femoral pulses. Respiratory distress led to admission to the local children's hospital where oxygen was started. Physical exam revealed a SpO2 of 100%, gallop, weak 1+ brachial and femoral pulses bilaterally with brachio-femoral delay. Tachypnea continued with difficulty feeding. An RPP was positive for Rhino/Enterovirus and Adenovirus. Initial chest x-ray showed cardiomegaly and bilateral perihilar pulmonary infiltrates prompting a consult to pediatric cardiology. An echocardiogram demonstrated severe dilation of the left atrium, severe dilatation and moderate hypertrophy of the left ventricle with severely decreased systolic function, bicuspid aortic valve, and severe coarctation of the aorta. The infant was transferred to the PICU due to cardiogenic shock where intubation, alprostadil and milrinone were initiated after stabilization. The infant was then transported to another facility where extended end-to-end anastomosis and PDA ligation was completed. Regular follow-up with pediatric cardiology was initiated.
**Discussion**
Failure to thrive can be multifactorial in etiology. While most cases of failure to thrive are driven by an inorganic cause including improper mixing of infant formulas, feeding refusal, or parental neglect, this case reinforces the importance of keeping a broad differential. Additionally, the literature indicates the most common lesion to be missed during CCHD screen is coarctation of the aorta. This case highlights the crucial need for thorough physical exams, broad differential, and detailed documentation.
