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Digestive & Liver Care · Katy & Cypress
Digestive Disease Specialist for Greater Houston
Persistent stomach pain, reflux, bloating, bowel changes, rectal bleeding, swallowing problems or abnormal liver tests may need evaluation by a digestive disease specialist. United Gastroenterology Associates, PLLC provides board-certified gastroenterology and hepatology care through Muhammad Ali Khan, MD, FACP, FASGE, with offices in Katy and Cypress serving patients throughout Greater Houston.
Appointments: (346) 340-4414
What Is a Digestive Disease Specialist?
A digestive disease specialist is generally a gastroenterologist: a physician trained to evaluate and manage disorders of the gastrointestinal tract and the organs that support digestion. That includes the esophagus, stomach, small intestine, colon and rectum, along with the liver, gallbladder, bile ducts and pancreas. "Digestive disease specialist," "GI specialist" and "gastroenterologist" are different search terms for the same kind of physician, not separate specialties. Gastroenterologists diagnose the cause of digestive symptoms, perform procedures such as colonoscopy and upper endoscopy, and manage chronic conditions over time.
What Doctor Treats Digestive Diseases?
For persistent or recurring problems involving the esophagus, stomach, intestines, colon or rectum, the specialist patients usually see is a gastroenterologist. Gastroenterologists also evaluate many liver, pancreatic, gallbladder and bile duct disorders, depending on the condition. At United Gastroenterology Associates, Dr. Muhammad Ali Khan provides gastroenterology and hepatology care at offices in Katy and Cypress. Some conditions, such as those needing surgery or hospital care, are managed together with surgeons or other specialists.
Board-Certified
Gastroenterology, hepatology and internal medicine
Former MD Anderson Faculty
Former Associate Professor
100+ Publications
Peer-reviewed gastroenterology research
Two Offices
Katy and Cypress, serving Greater Houston
Digestive Symptoms That May Need Specialist Evaluation
Digestive symptoms can have many possible causes, from diet and medicines to infection, inflammation or structural problems. A symptom alone does not tell you what is wrong. What matters is how long it lasts, whether it keeps coming back, and whether warning signs come with it.
Learn more about abdominal pain, heartburn and acid reflux, nausea and vomiting, bloating and gas, chronic diarrhea, constipation, changes in bowel habits, rectal bleeding, blood in the stool, difficulty swallowing and abnormal liver enzymes.
Symptoms often evaluated by a GI specialist
- Persistent or upper abdominal pain
- Recurring heartburn or acid reflux
- Nausea, vomiting or bloating
- Chronic diarrhea or constipation
- Rectal bleeding, blood in stool or black stool
- Difficulty swallowing or food sticking
- Unexplained weight loss
- Abnormal liver tests or yellowing of the skin
These symptoms have many causes. Only an evaluation can tell what is behind yours.
What Conditions Does a Digestive Disease Specialist Treat?
Digestive diseases are easiest to understand by the part of the body they affect. This overview links to more detailed pages.
| Organ system | Common conditions | Learn more |
|---|---|---|
| Esophagus | GERD and acid reflux, esophagitis, Barrett's esophagus, swallowing problems, esophageal strictures | GERD · Barrett's esophagus · Esophageal dilation |
| Stomach and upper GI tract | Gastritis, peptic ulcer disease, H. pylori infection, indigestion (dyspepsia) | Gastritis · H. pylori |
| Small intestine | Celiac disease, Crohn's disease, malabsorption | Celiac disease · Crohn's disease |
| Colon and bowel | IBS, chronic constipation, chronic diarrhea, diverticular disease, colon polyps | IBS · Constipation · Screening |
| Inflammatory bowel disease | Crohn's disease and ulcerative colitis | IBD · Ulcerative colitis |
| Liver | Fatty liver disease (MASLD), abnormal liver enzymes, hepatitis, chronic liver disease, fibrosis and cirrhosis evaluation | Hepatology · Fatty liver · FibroScan |
| Pancreas, gallbladder and bile ducts | Pancreatitis and pancreatic disorders, gallbladder and bile duct conditions, bile duct stones | Pancreatic disorders · Biliary disorders · ERCP |
Some conditions need care beyond the office, such as surgery or hospital treatment. In those cases, Dr. Khan coordinates with surgeons, hospitals and other specialists. See all GI symptoms and conditions.
Digestive Disease Specialist vs. Gastroenterologist: Is There a Difference?
Patients search for digestive care using many different names. In most cases, they are looking for the same physician: a gastroenterologist.
| Term | What it usually means |
|---|---|
| Gastroenterologist | A physician who completed internal medicine training followed by fellowship training in diseases of the digestive tract and related organs. |
| GI specialist or GI doctor | A common short name for a gastroenterologist. |
| Digestive disease specialist | A patient-friendly term that almost always refers to a gastroenterologist. |
| Stomach, bowel or colon specialist | Everyday names for a gastroenterologist; a colorectal surgeon is a different specialist who operates on the colon and rectum. |
| Hepatologist | A physician focused on liver disease. Many gastroenterologists also treat liver conditions, and some are board-certified in hepatology. |
Dr. Muhammad Ali Khan is board-certified in gastroenterology, hepatology and internal medicine. That combination lets him evaluate digestive and liver problems in the same practice, which helps when symptoms involve more than one organ.
When Should You See a Digestive Disease Specialist?
Not every digestive symptom needs a specialist. Occasional heartburn after a large meal or a short bout of diarrhea often settles on its own or with your primary care doctor's help. A gastroenterologist becomes the right next step when symptoms persist, return, worsen, or come with warning signs.
You should also see a gastroenterologist for colorectal cancer screening, for a family history of colorectal cancer or polyps, and for long-term care of a diagnosed condition such as IBD, celiac disease or chronic liver disease. Read more about when to see a gastroenterologist for digestive problems.
Consider a specialist visit for
- Symptoms lasting several weeks
- Symptoms that keep coming back or get worse
- Unexplained changes in bowel habits
- Chronic reflux or trouble swallowing
- Any GI bleeding
- Abnormal liver tests
- Unexplained anemia or weight loss
- Screening or family history concerns
Your primary care doctor can also help decide whether a referral makes sense.
When Digestive Symptoms May Be an Emergency
Call 911 or go to the nearest emergency department if you believe you are experiencing a medical emergency.
Warning signs include- Vomiting blood or material that looks like coffee grounds
- Heavy rectal bleeding
- Black, tarry stool with weakness, dizziness or fainting
- Sudden, severe abdominal pain
- Severe vomiting that will not stop
- Fainting or loss of consciousness
- Signs of severe dehydration, such as confusion or very little urine
How a Digestive Disease Specialist Evaluates Symptoms
Testing depends on your symptoms, risk factors and examination. Most patients do not need every test.
Medical and symptom history
When symptoms started, how often they happen, what makes them better or worse, and any warning signs.
Medicine and family history review
Medicines such as NSAIDs can affect the digestive tract, and family history can change screening and testing decisions.
Physical examination
A focused examination based on your symptoms.
Lab, stool and imaging tests
Blood tests, stool studies or imaging may be ordered when they can help narrow the cause.
Procedures when needed
Endoscopy, colonoscopy or specialized tests are recommended when they are likely to answer a specific question.
Digestive Procedures and Diagnostic Testing
When testing is needed, the choice depends on the question being asked. These are the procedures and tests most often used to evaluate digestive and liver conditions.
| Procedure or test | What it evaluates |
|---|---|
| Colonoscopy | The entire colon and rectum; used for screening, bleeding and bowel changes, and to remove polyps. |
| Upper endoscopy (EGD) | The esophagus, stomach and duodenum; used for reflux, swallowing problems, pain, bleeding and biopsies. |
| Flexible sigmoidoscopy | The rectum and lower colon. |
| Capsule endoscopy | The small intestine, using a swallowed camera capsule. |
| ERCP | The bile ducts and pancreatic duct; can remove stones or place stents. |
| FibroScan | Liver stiffness and fat, to help assess fibrosis and fatty liver. |
| Esophageal dilation | Gently widens a narrowed esophagus to improve swallowing. |
| Esophageal pH monitoring | Measures acid reflux into the esophagus over 24 to 96 hours. |
| Anorectal manometry | Rectal and anal muscle function in constipation and bowel control problems. |
Preparing for a procedure? See colonoscopy prep instructions and all GI procedures.
Not Sure Whether Your Symptoms Need a Specialist?
Dr. Khan can review your symptoms and history and recommend the right next step, whether that is testing, treatment or simply reassurance.
Care for Chronic Digestive Diseases
Many digestive conditions are long-term. IBS, Crohn's disease, ulcerative colitis, celiac disease, chronic GERD, recurring constipation, chronic diarrhea and chronic liver disease often need care over months or years rather than a single visit.
Ongoing care may include:
- Regular follow-up to track symptoms and response to treatment
- Medication management when appropriate
- Nutrition and lifestyle guidance
- Periodic lab tests or imaging
- Surveillance endoscopy or colonoscopy when clinically indicated
Learn more about chronic GI conditions care and gut inflammation.
Preventive Digestive Care
Prevention is part of digestive disease care. Adults at average risk should begin colorectal cancer screening at age 45, and people with a family history of colorectal cancer or polyps may need to start earlier. Colonoscopy can find and remove polyps before they become cancer, and a gastroenterologist can also review liver and hepatitis risk.
See colorectal cancer screening guidelines, colonoscopy and preventive health counseling for digestive diseases.
“My gastroenterology & hepatology practice is dedicated to working closely with you to develop a personalized treatment plan that meets your unique needs and preferences.”
Dr. Muhammad Ali Khan, MD, FACP, FASGE
Board-certified gastroenterologist and hepatologist, United Gastroenterology Associates
Meet Muhammad Ali Khan, MD, FACP, FASGE
The digestive disease specialist at United Gastroenterology Associates is Dr. Muhammad Ali Khan, a GI specialist board-certified in gastroenterology, hepatology and internal medicine. He evaluates and treats digestive and liver diseases and performs endoscopic procedures at the practice's Katy and Cypress offices.
Dr. Khan is a former Associate Professor at The University of Texas MD Anderson Cancer Center, a Fellow of the American College of Physicians (FACP) and the American Society for Gastrointestinal Endoscopy (FASGE), and has authored more than 100 peer-reviewed publications.
Areas of care
- Digestive symptoms and GI conditions
- Liver disease and hepatology
- Inflammatory bowel disease
- Colonoscopy and upper endoscopy
- Colorectal cancer screening
Digestive Disease Care Throughout Greater Houston
United Gastroenterology Associates provides specialist digestive and liver care through two offices, in Katy and Cypress, serving patients from communities throughout Greater Houston, including Fulshear, Richmond, Rosenberg and surrounding West and Northwest Houston areas. The practice does not have offices in those other communities; patients choose whichever office is more convenient.
Digestive Disease Specialist for Fulshear
Fulshear-area patients can be evaluated at the Katy office on Katy Freeway. See the Katy gastroenterologist page for office details.
Digestive Disease Care for Richmond and Rosenberg
Patients from Richmond and Rosenberg can schedule at either the Katy or the Cypress gastroenterologist office, depending on which is more convenient.
Choose the GI Office Most Convenient for You
Both offices are open Monday through Friday. Call (346) 340-4414 to schedule at either location.
United Gastroenterology Associates – Katy
Katy Freeway (I-10) near the Grand Parkway
- Address: 23920 Katy Freeway, Suite 555, Katy, TX 77494
- Phone: (346) 340-4414
- Hours: Monday–Friday, 8:30 AM–5:00 PM (closed 12:00–1:30 PM for lunch; last appointment 4:30 PM)
United Gastroenterology Associates – Cypress
Northwest Freeway (US-290) in Cypress
- Address: 21216 Northwest Freeway, Suite 640, Cypress, TX 77429
- Phone: (346) 340-4414
- Hours: Monday–Friday, 8:30 AM–5:00 PM (closed 12:00–1:30 PM for lunch; last appointment 4:30 PM)
Frequently Asked Questions
Answers to common questions about digestive disease specialists and seeing one in Greater Houston.
What is a digestive disease specialist?
A digestive disease specialist is usually a gastroenterologist: a physician trained to diagnose and treat conditions of the esophagus, stomach, small intestine, colon, rectum, liver, gallbladder, bile ducts and pancreas. At United Gastroenterology Associates, that specialist is Muhammad Ali Khan, MD, FACP, FASGE, who is board-certified in gastroenterology, hepatology and internal medicine.
Is a digestive disease specialist the same as a gastroenterologist?
In everyday searches, yes. "Digestive disease specialist," "GI specialist" and "stomach doctor" usually describe a gastroenterologist. A hepatologist focuses on the liver; some gastroenterologists, including Dr. Khan, are also board-certified in hepatology.
What doctor should I see for chronic stomach problems?
Start with your primary care doctor or see a gastroenterologist if stomach pain, indigestion, nausea or bloating lasts for weeks, keeps coming back or does not improve with treatment. A gastroenterologist can look for causes such as gastritis, ulcers, H. pylori infection, reflux or gallbladder problems.
What doctor treats bowel problems such as constipation, diarrhea or rectal bleeding?
A gastroenterologist evaluates ongoing constipation, chronic diarrhea, changes in bowel habits and rectal bleeding. Testing, if needed, depends on your age, symptoms and risk factors and may include lab work, stool tests or a colonoscopy.
What specialist treats IBS, Crohn's disease and ulcerative colitis?
Gastroenterologists diagnose and manage irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD), which includes Crohn's disease and ulcerative colitis. IBD usually needs long-term follow-up, medication management and periodic colonoscopy.
What doctor should I see for persistent acid reflux?
See a gastroenterologist if heartburn or reflux happens often, continues despite medicine, or comes with trouble swallowing, weight loss, vomiting or signs of bleeding. Evaluation may include an upper endoscopy or esophageal pH monitoring.
Can a gastroenterologist evaluate fatty liver and abnormal liver tests?
Yes. Gastroenterologists evaluate many liver conditions, and hepatologists focus on them. Dr. Khan is board-certified in both gastroenterology and hepatology and evaluates fatty liver disease, abnormal liver enzymes and hepatitis, using tests such as FibroScan when appropriate.
When should I see a digestive disease specialist?
Consider seeing one if digestive symptoms last several weeks, keep returning or get worse, or if you have rectal bleeding, trouble swallowing, unexplained weight loss, abnormal liver tests or anemia. You should also see one for colorectal cancer screening or for ongoing care of a diagnosed digestive condition. Mild symptoms that pass quickly often do not need a specialist.
Do I need a referral to see a gastroenterologist?
It depends on your insurance. HMO and POS plans often require a referral from your primary care doctor, while PPO plans generally do not. Check with your insurance carrier before your visit.
Where can I see a digestive disease specialist near Houston?
United Gastroenterology Associates has two offices: 23920 Katy Freeway, Suite 555, Katy, TX 77494, and 21216 Northwest Freeway, Suite 640, Cypress, TX 77429. Patients come from across Greater Houston, including Fulshear, Richmond and Rosenberg. Call (346) 340-4414.
Does United Gastroenterology Associates accept insurance?
United Gastroenterology Associates participates with many major insurance plans. Coverage and benefits depend on the patient's specific plan and must be verified. Please contact the office or your insurance carrier to verify benefits for your specific plan and service. Self-pay options are also available.
Will I automatically need a colonoscopy?
No. Testing depends on your symptoms, age, risk factors and examination. Many patients are evaluated with a history, examination and lab or stool tests first. Colonoscopy or upper endoscopy is recommended when it is likely to answer a specific question or is due for screening.
Get Answers About Persistent Digestive Symptoms
Persistent or recurring digestive symptoms deserve an appropriate medical evaluation. United Gastroenterology Associates provides gastroenterology and hepatology care from Katy and Cypress offices for patients throughout Greater Houston.
Sources
- National Institute of Diabetes and Digestive and Kidney Diseases. Your Digestive System & How It Works. niddk.nih.gov
- National Institute of Diabetes and Digestive and Kidney Diseases. Digestive Diseases. niddk.nih.gov
- American College of Gastroenterology. Patient Center. gi.org
- U.S. Preventive Services Task Force. Colorectal Cancer: Screening (2021). uspreventiveservicestaskforce.org
This page provides general information and does not replace personal medical advice. For a medical emergency, call 911. Last updated October 5, 2026.