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Clinic Type

Gastroenterology

Address

121 Eileen Way, Syosset, NY 11791

Phone

219-476-7246

Email

marketplace@tebra.com

Opening Hours

Not published — contact the clinic to confirm hours.

Services Offered

Team

  • Kostas Sideridis — DO, gastroenterologist
  • Jaydeep Kadam — MD, gastroenterologist
  • Jeffrey Crespin — MD, gastroenterologist
  • Jeffrey M. Loria — MD, gastroenterologist
  • Albert M. Harary — MD, gastroenterologist
  • Gil I. Ascunce — MD, gastroenterologist

Insurance & Payment

Languages Spoken

Photos

What Patients Say

Overall sentiment across review platforms: mixed

  • Zocdoc: 4.85 out of 5 (103 reviews)
  • Healthgrades: 3.3 out of 5 (13 ratings)
  • Tebra: 5.0 out of 5 (3 reviews)

Patients praise

  • High level of medical expertise and experience
  • Patient-focused care and willingness to go the extra mile
  • Effective treatment results with minimal discomfort

Common complaints

  • Long wait times
  • Office disorganization and perceived unprofessionalism (for some patients)

"Dr. Immanuel is highly experienced and knows his stuff! He has done colonoscopies on my husband and myself without any issues or fears of tearing. He also did a lazer procedure to remove multiple obstructions in my colon. I didn't even hurt the day after! Yes, wait times are long and his office is..."

Healthgrades

"He was once a good doctor but now he is money-hungry, disorganized and unprofessional."

Healthgrades

"I have no complaints about this office, Dr. Pearlman or the staff!"

Zocdoc (regarding Dr. Theodore Perlman)

Synthesized from public review platforms as of Jul 11, 2026 — sources: [1][2][3][4].

Information sourced from the clinic's website as of July 11, 2026.

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Gastrointestinal Specialists of Long Island is a small medical practice based in Wantagh, NY (3019 Merrick Rd), serving Wantagh and Malverne (Long Island). The team (3 employees) offers gastroenterology services with a partner-led structure (Zachary Marwil). Key details: - Industry: Medical Practices - Type: Partnership - Contact: 516-785-8075 / 516-785-8139 - Website: gislimd.com - Web presence: low traffic (~124 monthly visits) with typical engagement (3.4 pages per visit) - LinkedIn: company page available If you’re specifically looking for Gastrointestinal Specialists of Long Island in or around Hempstead, note their listed locations are Wantagh and Malverne, NY. No Hempstead office is mentioned in the provided profile.

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Hempstead, NY·Gastroenterology

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