Patient Reviews

We understand that finding a provider that will truly listen to your concerns isn’t always easy. At Adult Gastroenterology Associates, our patients are our top priority. We strive to create a thoughtful and compassionate environment where you can trust that your care is customized to your needs. Take some time to browse through our reviews below, so you can read first-hand about the dedication and care that our specialists provide patients in the Tulsa, OK community.

5.0 Review from D.M. Source: Google May 26 2023

"This is Joyce McCoy I have been a patient of Dr Nightingale for over 18 years.. he is the BEST ! I have PBC and he takes care of me 100% I do all my endoscopy and colonoscopy there at his office on Kelly Dr. In Tulsa"

5.0 Review from B.M. Source: Google Feb 25 2023

"Office has a nice atmosphere, helpful staff and Dr. Knightengale is always friendly and puts me at ease."

4.0 Review from H.G. Source: Google Feb 25 2023

"Very direct to the point! No hassle, just true honest opinion. Well trained staff. Like them alot."

5.0 Review from J.H. Source: Google Jan 25 2023

"Dr Nightengale is a great doctor and truly cares about you."

5.0 Review from J.S. Source: Google Jan 25 2023

"I have used Dr Nightengale For over 25 Years & I have always been very Satisfied in every way With Him. I Highly Recommend Dr . Nightengale"

5.0 Review from K.B. Source: Google Dec 25 2022

"Very professional doctor and staff is excellent. Would definitely refer Dr. Markham Nightengale and will continue to use his services."

5.0 Review from L.D. Source: Google Dec 25 2022

"Dr. Nightingale is friendly and thorough. His staff are friendly, kind and very efficient. Couldn't ask for a better gastro facility."

5.0 Review from B.S. Source: Google Dec 25 2022

"Absolutely a wonderful experience. This was the first time I met Dr. Nightengale for my first colonoscopy potential need. I felt like he had been my physician for years. He made me feel completely comfortable and answered all my questions respectfully and thoroughly."

5.0 Review from J.C. Source: Google Nov 25 2022

"Dr. Nightengale has been my gastroenterologist for over 20 years. In my opinion he is as knowledgeable in his field as any person could be. He is very efficient in his consultations with you. No questions left unanswered. I have had multiple EGD’s as well as colonoscopies and his review of the results is always very thorough. I highly recommend Dr. Nightengale."

5.0 Review from S.A. Source: Google Nov 25 2022

"I have known Dr Mark Nightengale for years, have trusted his colonoscopy experience and will continue to reschedule whenever he recommends. A great friend as well."

5.0 Review from B.W. Source: Google Oct 25 2022

"Pleasent demeanor and professionalism, with a sense of humor to boot. His staff were super helpful with making sure I had all my questions answered."

5.0 Review from D.W. Source: Google Oct 25 2022

"Dr. Nightingdale's staff is Tulsa's best in colonoscopy's in my opinion. His staff has preformed my last 4 colonoscopys. Each time his staff was always very professional and courteous. I was in and out in under 1 hour. I will go back to him for my next one as well! I can't say enough Great surgeon Great Staff!!!"

5.0 Review from K.F. Source: Google Aug 25 2022

"Excellent care, staff, location, and procedures. Thank you"

5.0 Review from C.D. Source: Google Aug 25 2022

"He’s Been my doctor for over 20 years. He’s great!"

5.0 Review from G.P. Source: Google Aug 25 2022

"Doctor talked with me before and after the procedure. Seemed to really care about me being relaxed and ok. Would highly recommend Dr. Nightingale."

5.0 Review from P.U. Source: Google Aug 25 2022

"I was pleased with the services that I received from Dr. Nightengale and staff for my colonoscopy/endoscopy procedure."

5.0 Review from N.K. Source: Google Jul 25 2022

"The facility and all staff are attentive, thorough, caring and cordial. They make you feel comfortable in a speedy, quick process from start to finish."

5.0 Review from J.W. Source: Google Jul 25 2022

"Dr. Nightengale and his staff are wonderful! They truly care about their patients. I was impressed how Dr. Nightengale knew my background before I met him. That really meant so much because that told me he is thorough. I won't go to any other doctor."

5.0 Review from K.C. Source: Google May 25 2022

"Very pleasant , i was surprised to meet a doctor that seems like he really cared . i am kind of spooked with my condition but Dr Nightengale assured me that everything would be okay , those were the words i wanted too hear . Thank you Dt . Nightengale and see you soon"

5.0 Review from L.E. Source: Google May 25 2022

"I have seen Dr. Markham Nightengale 2 other times and have an up coming appt. He is very professional and kind. He gives lots of information about what he is going to do and what he has found. I am so glad a friend recommended him. I would recommend Dr. Nightengale to anyone."

5.0 Review from J.M. Source: Google May 25 2022

"Staff was so kind and compassionate! It had been 4 years since my last procedure and Dr. Nightingale remembered me."

5.0 Review from J.B. Source: Google May 25 2022

"I first want to say the Dr Mark Nightingale he did what 80% doctors don't do he listened to the patient he said there on the bed next to me he'd listen to every word I said as long as I didn't take too long like saying the same thing over and over and then he examined me and if he was not touching the spots that did not pertain to what I was saying he allowed me to show him and I walked out of there with a completely different feeling I have been suffering for 6 years losing weight from 240 to 167 standing six six so skinny I'm about to blow away dying the first visit he said my life I appreciate him so much to the point if I saw him I would break down in front of him and shine his shoes he probably wouldn't let me lol but from what he did to me I know I will have 100% recovery after 6 years of brutal pain thank you Mr Nightingale can't wait till my next visit thank you very much Vincent l Jones"

5.0 Review from A.T. Source: Google May 25 2022

"I recently had a colonoscopy and an upper GI which Dr Markham Nightengale performed. I was totally happy with his services and my care from his staff. I was complete informed on how to take my prep and how it would work. I arrived on time the next morning and filled out my papers I was taken back to get prepared and his staff was so nice and told me exactly what they were going and how it would go. When it was my turn and by the way it was on time I was taken back and they did the procedures and then off I went to recover. Everyone that I came in contact with was so nice and pleasant. For a procedure no one looks forward to it was no problem and Dr Nightengale came in before I left to let me know what he had done and that he had told my husband already. I was completely satisfied with my experience with him. Thank you Dr Nightengale"

5.0 Review from B.D. Source: Google May 25 2022

"Just completed 3rd colonoscopy procedure done by Dr. Nightengale. He spoke with me prior to the procedure in his usual pleasant manner. A detailed report including photos was provided afterwards. Checking in at the lobby was efficient. Initial prep by nurse and anesthesiologist went smoothly. Checkout also. All staff from checkin to checkout were pleasant."

5.0 Review from C.J. Source: Google May 25 2022

"If you have to have a colonoscopy this is the place to go, they are so nice. They make everything as comfortable as possible. They stay on schedule . Dr. Nightingale has a good bedside manner"

5.0 Review from D.D. Source: Google May 25 2022

"Dr. Nightingale was great. He didn't have all my test results and advised we would reschedule appointment as soon as he did and reviewed them. Surgery not necessary at this time other test to run before that discussion is to be had. I really appreciate his straight forward answers."

5.0 Review from E.F. Source: Google May 25 2022

"Dr. Nightengale has performed at least six procedures on me over a number of years. Each and every time his work has been very professional, he has always been on time and provided me with the results very quickly. He always makes me feel very comfortable before and after every procedure and I have never had the slightest amount of pain or discomfort. Besides being a wonderful doctor, he is a very kind and caring person. I also cannot say enough good things about his staff. They have things organized to go like clock work. I know I will need another procedure within the next two years and I have absolutley no fear or anxiety about having it done."

5.0 Review from G.E. Source: Google May 25 2022

"I’ve been going to Dr. Nightengale since 2014. I find him to be very knowledgeable and companionate. As it I have an appointment with him in the near future for an evaluation. He’s the best in his field."

5.0 Review from G.N. Source: Google May 25 2022

"This was as good as it gets for a colonoscopy. Everyone was very cordial and professional. Had absolutely no complications from procedure. See you in five years!"

5.0 Review from S.H. Source: Google May 25 2022

"Dr.. Nightingale has been.my GI doctor doe years. He has always been knowledgeable and professional. I highly recommend him!"

5.0 Review from S.R. Source: Google May 25 2022

"Dr. Nightingale is an excellent physician. He is very caring and does not rush through an appointment. He listens and is compassionate."

5.0 Review from M.L. Source: Google May 25 2022

"Been going to Dr. Nightingale since I had my first colonoscopy 30 years ago. He is very friendly, direct, professional, concerned about you when speaking with you. He’s a great person. His staff is very helpful and professional. The center where the procedures take place is clean and comfortable. Both the Dr.’s office and the center are taking Covid precautions."

5.0 Review from S.C. Source: Google May 25 2022

"Very thorough by listening and asking questions to get the best diagnosis and care. He is friendly and personable. I was at ease when I left the office knowing the best way to take care of my problem is to have a colonoscopy/endoscopy to get a thorough diagnosis. I asked questions that he took the time to answer and explain his answers. I highly recommend Dr. Nightengale. He is an excellent gastroenterologist!"

5.0 Review from D.G. Source: Google May 25 2021

"Dr. Nightengale was my Mothers Dr., and is now mine. He is very knowledgeable, pleasant, professional, and caring. I have recommended him to others and will continue to do so."