Unio Specialty Care Gastroenterology Welcomes Dr. Robert Mecum!

Dr. Robert Mecum has joined Unio Specialty Care, California’s largest independent medical group providing gastroenterology, urology, and radiation oncology services. Your care team and office locations remain the same.  If you have questions about this transition, please call our office directly at (562) 789-5577.

Staying the Same

  • Your Care team
  • Our office locations
  • Our office phone number

Changing

  • Practice name on paperwork
  • Billing entity (Genesis Healthcare Partners, LLP)

Unio Specialty Care Gastroenterology Welcomes GI Specialists!

GI Specialists has joined Unio Specialty Care, California’s largest independent medical group providing gastroenterology, urology, and radiation oncology services.

Your physicians, office locations, and care team will remain the same.  If you have questions about this transition, please call your office directly.

What's staying the same?

  • Your doctors and care team
  • Your office locations
  • Office phone number

What's changing?

  • Practice Name on paperwork becomes Unio Specialty Care
  • Billing entity becomes Genesis Healthcare Partners, LLP
  • Athena patient portal access
  • New ways to pay bills online and with your phone
GI Specialists is now part of Unio Specialty Care

Unio Specialty Care – Gastroenterology – Castro Valley

Unio Specialty Care – Gastroenterology – Castro Valley

Office Hours

Monday

8:00 am - 5:00 pm

Tuesday

8:00 am - 5:00 pm

Wednesday

8:00 am - 5:00 pm

Thursday

8:00 am - 5:00 pm

Friday

8:00 am - 5:00 pm

Saturday

Closed

Sunday

Closed

Office Hours

Monday

8:00 am - 5:00 pm

Tuesday

8:00 am - 5:00 pm

Wednesday

8:00 am - 5:00 pm

Thursday

8:00 am - 5:00 pm

Friday

8:00 am - 5:00 pm

Saturday

Closed

Sunday

Closed

Choose a Provider Below to Schedule an Appointment

If you are an existing patient, please select your provider

Reviews

Expert Gastroenterology Services in Castro Valley – Accepting New Patients

Castro Valley residents now have a local option for specialized digestive care. Located on Lake Chabot Road beside the Sutter Eden Medical Center campus, our gastroenterology office serves patients who need expert evaluation and treatment for the full range of GI concerns. Our board-certified gastroenterologists — Wei Fang Ko, MD, Staya Allaparti, MD, Jeffrey Singerman, MD, and Vishal Ghevariya, MD — are accepting new patients and work with most major insurance plans. The location puts high-quality digestive care within easy reach of Hayward, San Leandro, San Lorenzo, and the wider East Bay.

It's tempting to wait out digestive trouble and hope it fades, but symptoms that stick around usually deserve a closer look. Our team works to pinpoint what's really going on, explain it in plain terms, and map out a treatment plan you're comfortable with — whether that means managing a chronic condition or arranging a colonoscopy you may be overdue for. Care stays as conservative and minimally invasive as your situation allows.

The Castro Valley office provides services that include:

  • Colonoscopy and colon cancer screening
  • Upper endoscopy (EGD)
  • Evaluation and management of GERD, IBS, IBD (Crohn's & ulcerative colitis)
  • Liver and pancreatic disease care
  • Hemorrhoid treatment
  • Abdominal pain and bloating diagnostics

Digestive discomfort has a way of touching nearly every part of daily life. With an emphasis on prevention, timely screening, and today's diagnostic technology, our Castro Valley practice helps East Bay patients get clear answers and effective care without a long trip.

Our Castro Valley office cares for patients from across the East Bay, including:

  • Castro Valley

  • Hayward

  • San Leandro

  • San Lorenzo

  • Oakland

  • Dublin

  • Pleasanton

  • Fremont

  • Union City

  • Fairview

  • Cherryland

  • Ashland


Digestive and liver conditions treated in Castro Valley
Our Castro Valley gastroenterology practice addresses the entire range of digestive and liver conditions — from frequently seen issues like acid reflux and irritable bowel syndrome to inflammatory diseases such as Crohn's and ulcerative colitis. Routine screening, colonoscopy included, is a standard part of the care available here.
Now accepting colon cancer screening patients
Catching colon cancer early makes it far more treatable — and screening often stops it before it starts — so our office keeps openings for new screening patients. If you've reached age 45, missed a past colonoscopy, or need closer surveillance because of your history, getting scheduled is quick and simple.
Getting ready for your first visit
The first appointment is largely about understanding your health story. Your gastroenterologist will go over your history, hear out your symptoms, and answer your questions before suggesting a plan — which could mean anything from dietary changes to lab work or a procedure like a colonoscopy or upper endoscopy.
Colonoscopy explained, and how to prepare
A colonoscopy lets the physician inspect the colon lining directly, spotting polyps, inflammation, or early cancer — usually before any warning signs appear. Once yours is booked, the office provides easy-to-follow prep instructions and reviews sedation options so you stay comfortable from start to finish. Learn more about colonoscopy screening.
Conditions We Treat at the Castro Valley GI Clinic
Our Castro Valley team diagnoses and manages a wide array of conditions, including:
  • Acid reflux (GERD)
  • Irritable Bowel Syndrome (IBS)
  • Crohn's disease and ulcerative colitis
  • Constipation and diarrhea
  • Colon polyps and colorectal cancer
  • Celiac disease
  • Liver disease and hepatitis
  • Barrett's esophagus
  • Gallbladder and pancreatic disorders
  • Hemorrhoids
GI Services Offered at Our Castro Valley Office
From preventive screenings to advanced diagnostics, the Castro Valley office offers a complete range of gastrointestinal services: Every procedure is carried out with a focus on accuracy, patient comfort, and the least invasive method suited to your needs.

Frequently Asked Questions

Do I need a referral to see a gastroenterologist in Castro Valley?

That depends on your insurance. Certain plans require a referral from your primary care doctor before a GI visit, while others allow you to book directly. When you call to schedule, our staff checks your coverage and lets you know exactly what's needed.

What GI conditions are treated at the Castro Valley office?

Our Castro Valley practice handles a broad range of digestive and liver concerns — reflux, IBS, and hemorrhoids as well as inflammatory bowel disease, colon polyps, celiac disease, and liver or pancreatic conditions. If you're not certain your issue is a match, a quick call to the office will help.

Is my insurance accepted here?

We participate with most major insurance plans, though coverage specifics vary by policy. We'll confirm your benefits and explain any expected out-of-pocket costs before your visit.

What should I bring to my first appointment?

Please bring a photo ID, your insurance card, a current list of medications, and any recent test results or imaging. Fasting isn't necessary unless a procedure has already been scheduled.

Will any testing be done at the first visit?

The initial appointment is usually a consultation. If testing such as blood work or an endoscopy is recommended, it's scheduled for a later date and fully explained to you beforehand.

Is colon cancer screening offered in Castro Valley?

Yes. The Castro Valley office provides full colon cancer screening, including colonoscopy and any follow-up care. Screening is generally advised beginning at age 45, and earlier for those with elevated risk or a family history.

Ready to Make an Appointment?

We are the largest gastroenterology physician group in California. Our organization is committed to providing high-quality, patient-centered care in a private practice setting. Our physicians are experts in the diagnosis and treatment of diseases of the gastrointestinal system, including those of the esophagus, stomach, colon, liver, small intestine, gallbladder, pancreas, and biliary tract.

Make an appointment today to start your journey to better health!