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 J.M. Source: Google May 25 2024

"Prep for this procedure is still awful but other than that everything was smooth, efficient, and professional."

5.0 Review from T.J. Source: Google May 25 2024

"VERY VERY BAD EXPERIENCE! DID NOT ANSWER MY QUESTION AFTER THREE ATTEMPTS BY PHONE, AT MY APPOINTMENT THEY WANTED $300 FROM ME WITHOUT NOTICE. AFTERWARDS I GOT A STAMENT SAYING I OWE DR. NIGHTINGALE $97 and another bill for $300. Today I got a bill stating that I owe $897.76 I don't know what that is about but I want be going back."

5.0 Review from K.D. Source: Google May 08 2024

"Dr. Nightengale is an excellent physician. He’s a great listener and is so knowledgeable and helpful."

5.0 Review from B.P. Source: Google May 08 2024

"My goodness, I don’t know where to start. Dr. Nightingale is one of the most, caring, courteous, thorough GI doctors and overall, best doctor in general. It’s really rare to find a Doctor like him now a days. I am so blessed to have been referred to him."

5.0 Review from R.L. Source: Google Apr 12 2024

"Very happy"

5.0 Review from A.B. Source: Google Mar 29 2024

"Good Dr tells you the truth even tho you may not want to hear it"

5.0 Review from M.W. Source: Google Mar 21 2024

"Professional and informative. Good post-procedure appointment. Thanx"

5.0 Review from L.K. Source: Google Mar 20 2024

"Everyone was very friendly & most efficient. I felt very at ease & most comfortable. That is why I keep going back. Thanks for answering my questions before I knew I had any."

5.0 Review from G.B. Source: Google Feb 24 2024

"It was the first time we saw this Doctor. Very nice and courteous. Explains every thing and doesn’t rush to get out of the room. We were very impressed."

5.0 Review from A.S. Source: Google Jan 27 2024

"Dr. Nightengale was very thorough, not rushed and he communicated well. He is very knowledgeable and he has earned my trust."

5.0 Review from M.M. Source: Google Jan 13 2024

"Dr. Nightingale is a very nice and friendly person. He listened to me about my health and explained things to me clearly,."

5.0 Review from C.M. Source: Google Jan 13 2024

"Very kind ,detailed and informative. Feel very confident to be in his care."

5.0 Review from C.K. Source: Google Dec 20 2023

"I have used Dr. Mark Nightengale for over 15 years. He is a friendly breath of fresh air and genuinely cares about you as a person and a patient. I wouldn't use anyone else and I recommend him to everyone who asks."

5.0 Review from E.H. Source: Google Dec 13 2023

"I absolutely love this doctor. His bedside manners is the best. He made me feel so welcome and listened to me. I love how he greeted me like we were old friends and he was very concern on getting me healthy. I would recommend this provider"

5.0 Review from C.H. Source: Google Nov 14 2023

"Very friendly and very promp and they listen to the patient and we are very pleased"

5.0 Review from D.O. Source: Google Nov 13 2023

"The staff was very prompt and professional. Dr. Nightengale reviewed my chart prior to entering the exam room. He spent plenty of time with me and answered my questions. He used hand sanitizer on his hands--I never see doctors do that or wash their hands."

5.0 Review from C.P. Source: Google Nov 10 2023

"Excellent as always! Dr. Nightengale is very personable and has a way of putting you at ease talking about things we would love to pretend don’t exist! Amazing man, excellent work, wonderful office staff. Sincere “Thank You”!"

5.0 Review from M.M. Source: Google Nov 08 2023

"Dr. Nightingale is a very nice & personable individual."

5.0 Review from C.N. Source: Google Nov 07 2023

"My husband and I have gone to Dr Nightengale for years. He is very thorough and compassionate. You can’t go wrong with him as your doctor."

5.0 Review from J.G. Source: Google Nov 03 2023

"I really like Dr.Nightengale He answers any questions that you may have. Explains everything and he has patience to be sure you are confident in what is going to be done."

4.0 Review from L.B. Source: Google Oct 31 2023

"It was great"

5.0 Review from D.P. Source: Google Oct 24 2023

"Very personable. Was seen promptly!"

5.0 Review from M.G. Source: Google Oct 06 2023

"It was my first visit but made me feel like I'm going to be in good hands with an upcoming surgery well worth a 2 1/2 hour drive"

5.0 Review from D.C. Source: Google Sep 29 2023

"Long time patient. Expert in his field. Always feel like I was listened to after appt."

5.0 Review from C.A. Source: Google Sep 20 2023

"I was very pleased with my visit. Got in quickly visited with doctor. Set up appointment for procedure. So far great. Everyone was nice and very professional. I would recommend them. Actually already did."

5.0 Review from S.N. Source: Google Aug 19 2023

"Dr. Nightengale is a wonderful Dr. He spends time with you and explains things thoroughly. I highly recommend him!"

5.0 Review from J.W. Source: Google Aug 18 2023

"I have been going to Dr Nightingale for so many years and he is consistently professional, knowledgeable and responsive. Would (and have) recommend him to anyone!"

5.0 Review from B.R. Source: Google Aug 18 2023

"Very personable and thorough. Is genuine and takes time needed with patients. Listens to patients."

5.0 Review from S.D. Source: Google Aug 04 2023

"As usual, this is the greatest group of Gastrologists and staff in the State of Oklahoma. Dr Markham Nightengale is the one I see. He treats you with kindness, and answers all of your questions. I give this office a solid 10 out of 10."

5.0 Review from D.M. Source: Google Aug 04 2023

"Everything was fantastic! Very friendly and professional."

5.0 Review from D.B. Source: Google Jul 21 2023

"It’s first class and they always make you feel like your the only patient there. Love the service girls and the doctor interaction is beyond excellent."

4.0 Review from T. Source: Google Jul 21 2023

"Dr Nightingale is great at what he does. It just looks forever to get to see him . You have to go through the nurse practitioners before you see him . I don't like that if your not there 30 minutes early change are your not going to get seen I've seen it happen. Dr. Nightingal has been my doctor for 10 years .thing have changed since I first meet him some good something I still don't know . And not thing about the portal and email. I can tell for me a call is better then being told we send you a email about that . There is a thing called a phone . Nowadays we carry them with us so there really is no reason not to call your patient about things . Like test results that can change there life forever."

5.0 Review from C.W. Source: Google Jul 11 2023

"Everyone in the office, from the ladies that check you in to Doctor Nightengale were exceptional."

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 W.Q. Source: Google Mar 25 2023

"Great man! Super friendly down to earth, but professional and understanding!"

5.0 Review from E.E. Source: Google Mar 25 2023

"Yes I would recommend Dr Markham Nightengale. We have you him for years"

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 K.H. Source: Google Jan 25 2023

"Customer service very friendly does a wonderful job answering questions"

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 J.H. Source: Google Jan 25 2023

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

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 G.F. Source: Google Dec 25 2022

"Dr. Nightengale is always cheerful, friendly and thorough. He explains everything in detail and always asks if you need more info. Highly recommend!!!"

5.0 Review from C.P. Source: Google Dec 25 2022

"Doc is always super fast, and place is clean."

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

"Dr Nightengale and staff are courteous, professional. The office is safe as well as lovely."

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

"Great Doctor who is very professional and listens to your concerns."

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 K.R. Source: Google Nov 25 2022

"Dr. Nightengale always gives me as much time as I need when it comes to Questions and answer to all my questions. I ask for a better doctor and I would highly recommend him to anyone."

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.S. Source: Google Nov 25 2022

"I've been seeing Dr. Nightengale for years and he is wonderful! He makes me feel comfortable with every procedure and is patient with all of my questions. He doesn't try to rush out of the room, which is nice. I've never seen him without a smile on his face."

5.0 Review from M.A. Source: Google Oct 25 2022

"He was confident in his approach which was encouraging."

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 E.C. Source: Google Sep 25 2022

"Dr Nightingale is a great Doctor and has the best personality of any Doctor I’ve ever known. He’s through and explains everything. I’ve gone to him for over 15 years and would highly recommend him!"

4.0 Review from M.D. Source: Google Sep 25 2022

"Dr. takes the time to talk with you and explain your condition. He put me at ease which allowed me to ask questions concerning treatment of my disease. The staff seem a little less patient."

5.0 Review from L.H. Source: Google Sep 15 2022

"He listens, does his best to help with your care. My procedure was a success and he is a gorgeous doctor inside and out."

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

"He listens, does his best to help with your care. My procedure was a success and he is a gorgeous doctor inside and out."

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

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

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 C.J. Source: Google Aug 25 2022

"I’ve been with Dr Nightengale for several years now. He is an incredible physician."

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 D.G. Source: Google Aug 25 2022

"Dr. Nightengale and his team are amazing. They make having to have a scope easy. Everyone is kind and caring. Tulsa Endoscopy Center is great. Teresa Griffith"

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 M.J. Source: Google Jul 25 2022

"Awesome Job. I've completed my frequency card. I get the 5th one free... .Yahoooo"

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

"Dr nightgale is a awesome doctor he makes u feel comfortable and safe with him! He ginuine and cares about his patients"

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

"Dr Nightengake provided excellent service. He and his nurse were thorough in explaining my procedure, doing my procedure was with ease and my wait time was less than 5 minutes in the lobby! One and done!"

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

"Dr. Nightingale is the best for problems with your colon."

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 C.W. Source: Google May 25 2022

"I visited Dr. Nightengale for the first time in September. He was extremely nice and made you feel comfortable. His nurse was wonderful as well. We’ve got tests scheduled and I feel confident that he’s going to get me lined out."

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 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 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 D.W. Source: Google May 25 2022

"He is very sincere and totally focused on your care and what is best for you. I would recommend him everyday all day!"

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 G.P. Source: Google May 25 2022

"Dr Nightengale has been taking care of me for around 15 years. Every interaction is completely reassuring, and every procedure very comfortable. For me, it couldn't be better."

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

"I have been a patient of Dr. Nightengale for over 10 years. He is so kind, thorough, and has the best bed side manner. He has treated my c.diff problems, post gallbladder issues, and reflux. Whatever your GI symptoms are, I highly recommend him!!!"

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 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 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 L.B. Source: Google May 25 2022

"Very nice staff and Dr. Markham Nightengale M. D. Is very good and explainable on his findings and great with his patients"

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 T.C. Source: Google May 25 2022

"Everyone in the office was so super nice from the front desk all the way to the recovering nurse. It's just a very great experience nothing to fear just really wonderful place wonderful doctor and wonderful nurses. I've gone to. Dr. Nightingale for two colonoscopies now, he has taken wonderful care of me. I totally put my trust in him. I would recommend him to anyone and everyone."

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

"I highly recommend Dr Nightengale. He is great at what he does and has an excellent bedside manner."

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.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 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."

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

"He is always friendly and listens well. He is board certified and did his residency at Mayo Clinic. I highly recommend him."

5.0 Review from T.S. Source: Google May 25 2021

"He is a very positive and uplifting dr. The first appointment that I had with him. He gave me a lot of Hope and gave me a lot of confidence and knowing that he would be a good doctor and would do everything for me that he could that could possibly be done anyway about my situation. I left the office with the with the confidence and feeling that I had a chance to beat this ugly disease I have and great news it happened exactly that way. He definitely seems like the doctor that would go that extra mile for you or any patient, and I feel very fortunate that I have lucked onto him as the first liver doctor, that that I searched for in a very careful way."