Skip to Content
Tricia Merrigan

Tricia Merrigan, MD, FACS

Breast Surgery
4.9 / 5 (Based on 135 Ratings) Learn More

“It’s important for me to develop a relationship with each patient. I take time to help her understand what’s happening and hope she feels like she’s involved in the process, comfortable with her treatment and included at all times.“

Office Information

About Me

If you or a loved one receives a breast cancer diagnosis, count on Tricia Merrigan, MD, FACS, for experienced and specialized breast surgery. Dr. Merrigan is a fellowship-trained and board-certified breast surgeon at Avera Medical Group Comprehensive Breast Care in Sioux Falls, SD.

Innovative Breast Cancer Surgical Procedures

Providing an effective breast cancer surgery is Dr. Merrigan’s first priority. She also strives to give women the best cosmetic result possible. She achieves this through specialized training in surgical procedures such as:

  • Electron-based intraoperative radiation therapy (IORT) – Includes radiation during surgery which may eliminate the need for additional radiation or shorten the course of radiation
  • Oncoplasty – Combines techniques for removing cancer along with plastic surgery methods to improve the appearance of breasts
  • Lumpectomy – Conserves the breasts while providing the same recurrence prevention as mastectomy
  • Nipple-sparing mastectomy – Preserves the nipple and skin of the breast for future reconstruction
  • Hidden Scar™ – Removes the tumor and a slight amount of surrounding tissue through a small incision

Dr. Merrigan is the first surgeon in South Dakota, Minnesota, Nebraska and North Dakota to receive Hidden Scar™ certification. "I’m dedicated to this approach," she says. "It takes a little extra effort and time to avoid making scars on the breast so that they heal nicely, but is well worth it for my patients."

She also helped lead a project to bring Provista™ Videssa Breast to Avera. This simple blood test, along with imaging, offers women the latest in breast cancer screening and detection.

Compassionate, Holistic Care for Women

"I really believe in our mission – caring for the patient as a whole," she adds. "Treating breast cancer at Avera is all about providing a team approach to care for the whole patient. It’s all about doing what’s best for each patient."

Active Lifestyle

In her free time, Dr. Merrigan likes to play games, go camping and enjoy the outdoors with her family. She also enjoys riding and showing horses.



University of South Dakota Sanford School of Medicine, Vermillion


General Surgery; Iowa Methodist Medical Center, Des Moines


Breast Surgery Oncology; Akron General Medical Center, Accredited by the Society of Surgical Oncology


American Board of Surgery


September 13, 2019
Dr Merrigan is a great doctor and has always treated us very well. I couldn't have asked for a better breast surgeon!
September 10, 2019
Wonderful experience! Staff and Dr Merrigan are terrific!
August 20, 2019
Always pleasant. The staff greets you with a smile and exchange pleasantries when you arrive. Also acknowledge when you leave-very friendly!
August 07, 2019
Friendly staff
July 28, 2019
Dr. Merrigan and her staff have always been wonderful and willing to answer all my questions.
July 26, 2019
Dr Merrigan and her staff were friendly and courteous throughout the visit.
July 20, 2019
I can't find one negative comment about any person or procedure I have encountered at Avera during my entire journey through cancer diagnosis, treatment or after-care. Avera is the best!!!
July 18, 2019
always satisfied
July 16, 2019
Always super helpful and friendly staff!! Love DR Merrigan!!
July 16, 2019
I finished my first appointment ahead of schedule and they made an effort to get me in ahead of my scheduled time.
July 10, 2019
Dr. Merrigan and everyone here are totally amazing!
June 28, 2019
Avera is very to have such a great provider as Tricia Merrigan.
June 25, 2019
Dr. Merrigan takes all the time needed to talk and I appreciate that.
June 13, 2019
I have come to Dr. Merrigan for a number of years. I appreciate her calm demeanor and knowledge. She has always helped me make good decisions about my care. Her staff is always pleasant and cheerful. I feel welcomed by all
June 11, 2019
Dr Merrigan was my angel She found the cancer others didn't
June 09, 2019
Dr. Merrigan is amazing! When I asked her a question about mastectomy options, she answered my question like she was going through the same thing. She is very knowledgeable and gave me more resources to look into so I can make the best decision for myself
June 01, 2019
very caring
May 31, 2019
I have been very pleased with Dr. Merrigan- and the folks at the breast care center in general. Dr. Merrigan is thorough, friendly, and professional-
May 20, 2019
Everyone was very kind and helpful.
May 18, 2019
I have never had any complaints about my care at Avera. And Dr. Merrigan is the absolute best!!
May 10, 2019
Just the best of everything
May 05, 2019
Dr Merrigan is amazing
May 04, 2019
Dr Merrigan is the best,
April 29, 2019
It is a great clinic. Everyone is friendly. First time use for the valet parking, and they were kind, efficient, and friendly.
April 25, 2019
I went in so sure that the worst was about to become my new normal. I felt so respected and well cares for. And best of all, the news wasn't the worst case scenerio at all. Thank you to a wonderful and caring team of professionals!!
April 25, 2019
The staff makes an unbearable time tolerable. I depend on their kindness and it really helps so much. Everyone has been very compassionate and positive and cheerful, which is really needed.
April 21, 2019
I'm very happy to have Dr.Merrigan as part of my medical team to walk through my preventive surgery I had almost 3 years ago. I will continue to see Dr. Merrigan for yearly check ups. She is an expert in her field.
April 12, 2019
Very happy to be a patient at Avera
April 05, 2019
Dr. Merrigan has always been wonderful and her whole staff!
March 30, 2019
Dr Merrigan is the best Dr I have ever had, and I have had many
March 23, 2019
Dr. Merrigan is very personable and easy to talk to about anything. She and her staff are outstanding!
January 05, 2019
Dr. Merrigan is awesome! The staff at the office are great and work well together.
December 30, 2018
I love the staff at this clinic and the dr I have is amazing
December 21, 2018
I always go in a little it scared and I leave feeling confident that I will be ok.
December 20, 2018
Thank you!
December 18, 2018
Dr. Merrigan is the best, caring Dr. I could ever want.
December 14, 2018
Seriously amazing care. Love my care team!
December 14, 2018
I'm satisfied with the level of care I received. Thank you.
December 14, 2018
I live in Spearfish, SD, a 6 hour drive, but chose Avera specifically for Dr. Merrigan and her wonderful staff. Very pleased with my care and decision to come to Avera.
December 13, 2018
Such great staff and a great clinic. Appreciate all they do!
December 07, 2018
I only have 100% positive things to say, and am always delighted by the empathy, courtesy and respect shown by the doctor and all of the staff. I feel so fortunate to have this kind of care in Sioux Falls.
December 05, 2018
Dr. Merrigan is awesome. She always listens and responds immediately to my questions, even when i ask the same question again. I am very grateful i have her taking such great care of me.

This directory contains information about the provider members of Independent Health Care Associates, Avera Health and all Avera entities, members of the Avera Medical Group, and employed select providers with Avera McKennan, Sioux Falls, SD and Avera Marshall, Marshall, MN and physicians with hospital privileges at Avera St. Luke's, Aberdeen, SD; Avera Sacred Heart, Yankton, SD; Avera Queen of Peace, Mitchell, SD; Avera St. Mary's, Pierre, SD.

Non-Avera web sites (e.g., Facebook, Twitter, etc.) linked to from this Web page, including any blogs or other personal, networking or social media Web sites, are not affiliated with, nor endorsed by any Avera facility. Opinions, views, and comments posted on these Web sites are not Avera's.  Avera assumes no legal liability or responsibility for the accuracy, completeness, or usefulness of any information, product, or process disclosed on these sites. The opinions of those posting comments, views or opinions on these sites do not necessarily state or reflect those of Avera and shall not be used for advertising or product endorsement purposes.

Live Better. Live Balanced. Avera.

Avera is a health ministry rooted in the Gospel. Our mission is to make a positive impact in the lives and health of persons and communities by providing quality services guided by Christian values.

© 2019 Avera, Sioux Falls, SD. All Rights Reserved.