A 10-day-old breastfed infant presents with poor weight gain, excessive crying, and the mother reports severe nipple pain and engorgement. On examination, the infant has a weak suck and milk transfer appears inadequate. Which investigation is most appropriate to objectively assess milk transfer and diagnose breastfeeding dysfunction?

Explanation

## Diagnosis of Inadequate Milk Transfer **Key Point:** Test weighing (weighing infant before and after a breastfeeding session) is the gold-standard, non-invasive investigation to quantify milk transfer and identify breastfeeding dysfunction. ### Why Test Weighing? Test weighing directly measures the volume of milk consumed by the infant during a single feed: - **Normal milk transfer:** 10–15 g (10–15 mL) per feeding in early lactation - **Inadequate transfer:** <5 g per feeding suggests poor latch, weak suck, or maternal supply issues - Performed using a calibrated electronic scale (accuracy ±2 g) - Non-invasive, repeatable, and provides immediate quantitative data ### Clinical Application 1. **Baseline assessment:** Identify if poor weight gain is due to inadequate intake or other causes (malabsorption, infection) 2. **Intervention monitoring:** Reassess after latch correction, nipple shield use, or supplementation 3. **Maternal reassurance:** Objective data helps mothers understand whether their milk supply is adequate **High-Yield:** Test weighing is the **first-line investigation** for suspected breastfeeding problems in the first 2 weeks of life when lactation is being established. ### Differential Approach to Breastfeeding Problems | Investigation | Indication | Limitation | |---|---|---| | **Test weighing** | Quantify milk transfer, assess latch effectiveness | Does not identify cause (latch vs. supply) | | Ultrasound of breast | Assess milk duct obstruction, abscess, structural abnormality | Not routinely used for milk transfer assessment | | Prolactin level | Evaluate hypogalactia (suspected hormonal cause) | Not indicated in early lactation; prolactin is normally elevated | | Urine specific gravity | Assess infant hydration status | Indirect measure; does not quantify milk intake | **Clinical Pearl:** A single test-weighing session showing <5 g transfer warrants immediate intervention (latch correction, hand expression, supplementation) to prevent dehydration and failure to thrive.