Screening for Breast Cancer During Pregnancy

Being diagnosed with breast cancer during pregnancy is rare. One in every 3,000 people is diagnosed with breast cancer while pregnant. Not all lumps are breast cancer, but if you find a lump on your breast, it’s vital to let your doctor know right away. Don’t wait until you give birth to have your doctor check the lump.

Screening mammograms are not typically performed during pregnancy unless there are signs and symptoms of breast cancer. But breast cancer signs and symptoms can be tricky to detect during pregnancy. Breasts swell and become tender as milk ducts grow and stretch to prepare for breastfeeding. Swelling can make it difficult for you to detect small lumps and for your doctor to diagnose breast cancer.

If you are pregnant and have a high breast cancer risk or any signs of breast cancer that worry you, your doctor might recommend a mammogram. Mammograms are considered fairly safe to have during pregnancy since the process requires only a small amount of radiation. The radiation is focused on the breast, so most of it doesn’t reach other parts of the body. For extra protection, the lower part of the belly is covered with a lead shield to block any radiation.

Ultrasounds don’t require radiation, so doctors consider them a safe way of checking breast lumps during pregnancy. An ultrasound can confirm whether a lump is a cyst filled with fluid or a solid mass that may or may not be cancerous. Ultrasounds are less accurate in distinguishing whether solid lumps are or aren’t breast cancer. If an ultrasound confirms there is a solid mass in the breast, the next step is typically a mammogram.

Breast MRIs don’t require radiation. But in most cases, this imaging technique uses a contrast material called gadolinium that is injected into the blood so doctors can get useful images. Because gadolinium can cross the placenta, doctors don’t usually recommend breast MRIs during pregnancy. 

Still, some doctors may recommend a breast MRI for a lump that looks cancerous on a mammogram even if you are pregnant. It’s possible to have a breast MRI without the contrast material, so you may want to ask your doctor if having a breast MRI without the contrast material is an option for you.

PET scans, bone scans, and CT scans are more likely to expose a fetus to radiation, so doctors don’t order these imaging tests when screening for breast cancer during pregnancy.

If an imaging test is inconclusive or raises concerns that a breast lump might be cancerous, doctors usually remove a small piece of breast tissue from the suspicious area. This procedure is called a biopsy.

The most common type of breast biopsy is called a core needle biopsy, usually performed as an outpatient procedure. After numbing the area with a local anesthetic, the doctor uses a hollow needle to remove a piece of breast tissue. Since local anesthesia poses little risk to the fetus, doctors consider it safe to perform core needle biopsies during pregnancy. Doctors also consider core needle biopsies to be safe for women who are breastfeeding.

Doctors may recommend a surgical biopsy if the results of a core needle biopsy aren’t clear. Also called an excisional biopsy, this surgical procedure often requires general anesthesia — with a small risk to the fetus. The doctor then removes a larger piece of breast tissue or even sometimes the entire lump through a small cut (or incision).

The risk of infection is higher with surgical biopsies because it is more involved. There is also the possibility of breast milk leaking into the affected area. But doctors can drain the milk with the same type of hollow needle used in a core needle biopsy (called fine needle aspiration).