Pregnancy and Lactation Breast Imaging
Radiation Safety in Pregnancy — Mammography
- Risk to fetus is NEGLIGIBLE
- Fetal dose from conventional mammogram: 0.001–0.01 mGy (orders of magnitude below estimated thresholds)
- Breast receives ~3 mGy per mammogram (essentially negligible to the fetus)
- Potential for fetal harm: requires ≥ 500 mGy to abdomen/uterus
- ACR: fetal doses up to 100 mGy are likely “too subtle to be clinically detectable” regardless of gestational age
- Fetal doses from mammography are of no clinical concern
Board Pearl
Mammography is NOT contraindicated during pregnancy. The fetal dose is orders of magnitude below harmful thresholds. Mammography is recommended during pregnancy when indicated.
Mammography Screening Recommendations — Pregnant and Lactating
| Risk Profile | Age | Pregnancy | Lactation |
|---|---|---|---|
| High risk | ≥ 25 y | Recommended | Recommended |
| Intermediate risk | < 30 y | Not recommended | Recommended |
| Intermediate risk | ≥ 30 y | Recommended | Recommended |
| Average risk | < 40 y | Not recommended | Not recommended |
| Average risk | ≥ 40 y | Recommended | Recommended |
Supplemental Ultrasound (Pregnant and Lactating)
| Risk Profile | Age | Pregnancy | Lactation |
|---|---|---|---|
| High risk | Any | Can be considered | Can be considered |
| Intermediate risk | Any | Can be considered | Can be considered |
| Average risk | < 40 y | Not recommended | Not recommended |
| Average risk | ≥ 40 y | Can be considered | Can be considered |
MRI and Gadolinium in Pregnancy
MRI Without Contrast
- Generally safe during pregnancy
- MRI recommended for lactating patients if galactography needed
Gadolinium Contrast — ACR Recommendation: Avoid
- ACR recommends against the use of dynamic contrast-enhanced MRI (DCE-MRI) in pregnant women regardless of risk profile
- Rationale:
- Animal studies show fetal malformation and death with repeated supraclinical doses
- Chelated gadolinium is known to cross the placenta in measurable quantities
- May theoretically dissociate to free, nonchelated gadolinium (neurotoxic)
- Although several small retrospective studies determined no adverse fetal effects
Gadolinium and Breastfeeding
- ACR does NOT recommend discontinuation of breastfeeding after gadolinium administration
- Gadolinium excretion via breast milk: 0.0004% of the maternal dose (negligible)
- Breastfeeding can be continued after gadolinium contrast administration
Sentinel Node Biopsy in Pregnancy
- Sulfur colloid: safe to use in pregnant patients
- Blue dye (vital blue dye): NOT safe in pregnant patients (unknown fetal effects — don’t use)
Bloody Nipple Discharge in Pregnancy
- “Rusty pipe syndrome”: most common physiologic cause
- Occurs during 3rd trimester when physiologic changes are most pronounced
- Due to physiologic epithelial remodeling and increased vascularity → microtrauma
- Spontaneous bloody secretion not associated with underlying lesion usually involves more than one duct
- Evaluation algorithm:
- If bloody secretion NOT from single duct → follow clinically if imaging reassuring
- If limited to a single duct → pathologic entity suspected
- Galactography in pregnant patients
- MRI in lactating patients
- US: retroareolar ultrasound evaluation should be first-line modality in pregnant women with nipple discharge
- False bloody secretions may result from nipple trauma from breastfeeding
Breast Lesions in Pregnancy — Timeline
The imaging overlap of benign entities varies by timing relative to childbirth:
| Entity | Predominant Timing |
|---|---|
| Pregnancy-associated breast cancer (PABC) | Any time (most malignant features) |
| Hypertrophic fibroadenoma | Pre-conception through lactation |
| Puerperal mastitis | Near childbirth, through 6 months lactation |
| Lactating adenoma | Near childbirth, through 12 months lactation |
| Galactocele | Childbirth through 18 months post |
| Granulomatous mastitis | After cessation of breastfeeding (most benign features) |
Board Pearl
PABC has the most malignant imaging features and can occur at any point. Granulomatous mastitis can be difficult to distinguish from PABC — occurs after cessation of breastfeeding with relatively more benign imaging features.
Pediatric and Adolescent Breast Masses > 5 cm
Differential for large breast masses (> 5 cm) in children/adolescents:
- Giant juvenile fibroadenoma: rare, 0.5% of all FAs, greater stromal component than normal FA
- Benign phyllodes tumor: looks like FA, oval, circumscribed, can have internal cystic components
- Malignant phyllodes: more irregular, non-circumscribed margins; most common primary malignant breast mass in adolescents; 3% mortality rate; 10% recur after wide local excision; can get mets (rare)
- PASH: looks like a circumscribed huge mass; proliferation of stromal cells; wide local excision, can recur
- Juvenile papillomatosis: firm mobile mass at periphery of breast; older adolescents; can be ill-defined; multiple small cysts in fibrous stroma; papillary epithelial hyperplasia; > 50% have strong family history; 5–15% have concurrent breast cancer
- Invasive secretory carcinoma
Management of Masses > 5 cm in Children
- See surgeon either way (decide CNB vs. surgical excision)