From the Guidelines
To order a culture swab for nipple discharge, you should order it as a "Nipple Discharge Culture" or "Breast Discharge Culture" under the patient's current medical record, specifying that it's for breast/nipple discharge to ensure the laboratory processes it appropriately. When placing the order, it's essential to document whether discharge can be expressed during the examination, and if present, note its color, consistency, and whether it's unilateral or bilateral, as these characteristics help determine the underlying cause 1. According to the acr appropriateness criteria® evaluation of nipple discharge: 2022 update, breast imaging may be considered if the discharge appears pathologic or persists despite negative culture results, with breast US being usually appropriate as the initial imaging of pathologic discharge in adult female patients younger than 30 years of age 1. The sample should be collected by gently expressing discharge from the nipple onto the sterile swab, which can help identify any bacterial pathogens that might be causing the discharge, particularly if there are signs of infection such as redness, pain, or purulent discharge.
Key Considerations
- The patient's age and sex should be considered when determining the appropriate imaging modality, with breast US being the preferred initial imaging modality for adult female patients younger than 30 years of age 1.
- The characteristics of the discharge, such as color, consistency, and laterality, can help determine the underlying cause, with physiologic discharge typically being bilateral and milky or clear, and pathologic discharge often being unilateral, spontaneous, and may be bloody or purulent.
- Additional workup, including breast imaging, may be necessary if the discharge appears pathologic or persists despite negative culture results, with mammography being the first-line imaging modality for evaluation of pathologic nipple discharge in male and female patients over 40 years of age 1.
Ordering the Culture Swab
- Specify that the culture swab is for breast/nipple discharge to ensure the laboratory processes it appropriately.
- Document the patient's symptoms, including the presence or absence of discharge, and its characteristics.
- Consider additional workup, including breast imaging, if the discharge appears pathologic or persists despite negative culture results.
From the Research
Nipple Discharge Evaluation
To determine if a culture swab is necessary for a 19-year-old with uncertain nipple discharge, consider the following:
- The patient's symptoms and medical history should be evaluated to determine if the discharge is physiologic or pathologic 2, 3.
- Physiologic nipple discharge is typically caused by hyperprolactinemia due to medications, pituitary tumors, or endocrine disorders, and does not require a culture swab 2.
- Pathologic nipple discharge, on the other hand, may require further evaluation, including imaging studies such as mammography, ultrasound, or MRI 4, 5, 6.
Culture Swab Ordering
If a culture swab is deemed necessary, it should be ordered under the following conditions:
- The patient has a suspicious radiologic lesion or pathologic nipple discharge 2, 5.
- The patient's symptoms and medical history suggest an underlying infection or malignancy 3, 6.
- The culture swab is part of a comprehensive evaluation and management strategy, including clinical examination, imaging studies, and possibly ductoscopy or breast MRI 4, 6.
Key Considerations
- The majority of nipple discharge cases have a benign etiology, and a thorough history and physical exam can help rule out underlying malignancy 3, 4.
- Imaging studies, such as mammography and ultrasound, are widely available and can be used for initial work-up 4, 5.
- MRI has become an important tool in the evaluation process of nipple discharge, with high sensitivity and specificity 5, 6.