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About Gastrointestinal Care of Long Island


Gastrointestinal Care of Long Island is a premier gastroenterology group comprised of Dr. Herbert Pasternak, DO, FACOI, Avigail Itzkowitz, APRN, FNP-C and highly trained staff that work together to offer our patients the highest care possible.

We combine state-of-the-art medicine with cutting-edge diagnostic technology to provide the highest-level care for gastrointestinal disease, liver disease and colorectal cancer prevention, detection and screening in the Nassau County area. We are committed to providing professional, personal and compassionate care while obtaining complete patient satisfaction and comfort during the patient’s visit with Gastrointestinal Care of Long Island.

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Meet Our Providers

Dr. Herbert Pasternak provides compassionate and reliable care to all of his patients. He prioritizes delivering quality care and cutting-edge treatments. He is on staff at both St. Joseph Hospital in Bethpage, NY, and Northwell Hospital at Plainview in Plainview NY. Avigail Itzkowitz is a board certified Family Nurse Practitioner. She completed her BS in Nursing at Adelphi University, and completed her Master of science in Nursing at Georgetown University. Avigail is passionate about gastroenterology, and is excited to join the Gastrointestinal Care of Long Island team.

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Colonoscopy

A colonoscopy is now the gold standard used to detect or prevent individuals from getting colon cancer. Adults starting at age 45 years are strongly recommended to have a colonoscopy or some other test to screen for colon cancer.

Capsule Endoscopy

During the procedure, a patient swallows a vitamin-sized pill with a camera inside (pill camera). Transported smoothly and painlessly through the GI tract by the body’s own natural peristalsis, the video pill capsule transmits images of different parts of your intestine, such as the small intestine and the esophagus.

ERCP

An endoscopic retrograde cholangiopancreatography, more commonly known as ERCP, is an endoscopic procedure that is also combined with X-rays. ERCP is very much like a typical upper GI endoscopy; however, your gastroenterologist will inject a dye during the procedure, which highlights problems in certain digestive organs through X-ray technology.

Flexible Sigmoidoscopy

A sigmoidoscopy is an internal exam of the lower part of the large intestine (colon) using a short, thin, flexible, lighted tube with a camera at the tip. This procedure helps determine the cause of abdominal pain, rectal bleeding, changes in bowel habits, chronic diarrhea, and other intestinal problems.

Hemorrhoid Treatments

Two of the most common treatments for hemorrhoid removal are hemorrhoid banding, which cuts off blood flow to the hemorrhoid, and infrared coagulation (IRC) therapy, which uses infrared light to shrink and shrivel hemorrhoids. The treatment method depends highly upon whether the hemorrhoids are external (around the anus) or internal (in the rectum).

Upper Endoscopy

An endoscopy is a very common and safe procedure that is used to examine the esophagus, stomach, and upper part of the small intestine, known as the duodenum, to get a closer look at what may be causing symptoms.

Celiac Disease

Celiac disease is an autoimmune disease where a patient’s immune system abnormally responds to the ingestion of gluten. It is estimated that 1 in 100 people worldwide is affected by celiac disease. However, up to 2.5 million people in the United States may have celiac disease and not know it, as the symptoms range from mild to severe.

Constipation

Constipation is defined as having a bowel movement fewer than three times per week. With constipation, stools are usually hard, dry, small in size, and difficult to eliminate. Some people who are constipated find it painful to have a bowel movement and often experience straining, bloating, and the sensation of a full bowel.

GERD

Gastroesophageal reflux disease (GERD) is a more serious form of gastroesophageal reflux (GER) which is common. GER occurs when the lower esophageal sphincter (LES) opens spontaneously, for varying periods of time, or does not close properly, and stomach contents rise up into the esophagus.

Hemorrhoids

Hemorrhoids are swollen veins in the anal canal. This common problem can be painful and can be caused by too much pressure on the veins in the pelvic rectal area. Normally, tissue inside the anus fills with blood to help control bowel movements, but if you strain or sit on the toilet a long time to move stool, the increased pressure causes the veins in this tissue to swell and stretch.

Inflammatory Bowel Disease + Crohn's Disease & Ulcerative Colitis

Inflammatory bowel disease (IBD) encompasses a set of gastrointestinal diseases where parts of the digestive tract are chronically inflamed by a dysfunctional interaction immune system. Hereditary factors and an abnormal interaction between microorganisms and the immune system are felt to play a role.

Irritable Bowel Syndrome

It is estimated that 10 to 15 percent of Americans have Irritable Bowel Syndrome (IBS). IBS is a functional GI disorder that refers to a group of symptoms that affect the digestive tract, often resulting in abdominal pain, bloating, or cramping. However, some people with IBS have no symptoms at all.

What Our Patients Say About Us

Dr Pasternak was the first gastro who encouraged testing to properly diagnose my issues before trying to just treat my symptoms alone. He was very thorough, kind, and professional. His office is clean and efficient. Everything I had done in this office went smoothly. Because of him I now know exactly where to go from here. I thank him and his office for their efforts!
Kelly R.
Kelly R.
Not only is Dr. Pasternak awesome, but so is everyone who works there. The nurses are so nice and make you feel very comfortable, and everyone has a great sense of humor. After a procedure, Dr. Pasternak always asks if everyone was nice and if you were comfortable and gives you results right there. Very caring people.
Trish T.
Trish T.
Dr. Pasternak is super amazing. He's very professional, easy to talk to, and caring. I owe a lot to him for ending a personal health mystery and preventing terrible future illness.
Erica
Erica
Very friendly staff very friendly doctor who knows his stuff. The most comfortable atmosphere I've ever had in a doctor's environment. I highly recommend going to dr. Pasternak he is fantastic
Peter
Peter
This doctor is a total professional, does everything right, Dr Pasternak is also a compassionate man.
R. Fogelman
R. Fogelman
Courteous staff. Dr Pasternak is highly favored. I would recommend him as the one to go to for any gastrointestinal issue . A++
Jay P.
Patient Testimonials
Dr. Pasternak is the best doctor I've ever came across. Very thorough, professional, kind, considerate. Had to see him about 5 times in the last few months and every single time he took his time and explained everything. I never felt rushed. His whole staff is like that too. The nurses, the ladies at the reception area, the anesthesiologist... The whole office runs like a well oiled machine. I can only wish, all my doctors were like him and his practice.. Highly recommended.
Csilla P.
Csilla P.
The office was kind and professional. Dr. Pasternak has excellent bedside manner and is thoughtful, and thorough. A very pleasant experience comparably speaking.
Robert S.
Robert S.
Dr. Pasternak is the best! His staff is wonderful and kind. I love them all! This doctor will spend time with you and make you feel comfortable. He cares! Highly recommended!
Christine G.
Christine G.

Blogs
IBS

Signs to Visit Your Doctor for IBS

Cramping, bloating, and unpredictable trips to the bathroom are common signs of irritable bowel syndrome (IBS). IBS is a long-term condition that affects how the large intestine works.

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November 9, 2026
Colonoscopy

How to Make Colonoscopy Prep Easier

For many people, the hardest part of a colonoscopy isn’t the procedure itself. It’s the bowel prep the day before. The good news is that colonoscopy prep has become easier

Read More »
October 12, 2026

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