Health Insurance

New Patients

Appointment Request

Please examine​ website and see multiple verified actual patient positive reviews posted under Dr. McMahon's profile.  

Dr. McMahon is a Board Certified Gastroenterology specialist and is a Fellow of the American College of Gastroenterology (FACG).

He is a Graduate of Washington University Medical School in St Louis

He performs screening and diagnostic colonoscopies, polyp removal, upper endoscopy and digestive health consultations.

Meet the Doctor

Colonoscopy Doctor

All new patients are welcome to call for appointment or procedure scheduling

Robert McMahon MD 

Board Certified Gastroenterologist (Colonoscopy Doctor)

Colonoscopy Screening

in St Louis, Missouri.


Contact Us

  • Gastroenterology
  • Digestive Health
  • Colonoscopy
  • Endoscopy
  • Polyps
  • Ulcers
  • Colon cancer screening​

Call Us:  1 (314) 492-4100

Office Hours

By appointment:

Monday - Thurs: 8:30 - 4:30 pm.

Friday, Saturday, Sunday: Closed

Robert McMahon MD

5139 Mattis Rd Suite 101

St Louis MO 63128 

(314) 492-4100

Robert McMahon MD in St Louis; colonoscopy doctor.  We typically have convenient appointment availability.

Call (314) 492-4100 for scheduling.

Additional Information:

The American College of Gastroenterology has resources ( including "What is a gastroenterologist"

Some Gastroenterologists receive special recognition from national societies when they demonstrate extraordinary achievement in research, teaching, or other unique service to the field of Gastroenterology. The American College of Gastroenterology designates such physicians as "Fellows" with the suffix FACG added to denote these honors. This means that these physicians have fulfilled the respective organizations’ rigorous requirements to gain this added distinction.

We accept most public and private insurance plans. We may also offer special pricing for cash-paying patients for most procedures.