30 Years of Experience
Affiliated with a Castle Connolly Top Hospital
Who is Dr. Marks, Colon & Rectal Surgeon (Proctologist) in Bryn Mawr, PA?
Castle Connolly Top Doctor
Castle Connolly Top Doctors are doctor-nominated and selected by a physician-led research team.
What are Areas of Expertise for Dr. Marks?
Dr. John Marks, MD is a highly-rated, board-certified Colon & Rectal Surgeon (Proctologist) known for expertly diagnosing, treating, and managing a wide array of related conditions and procedures. Utilizing the latest medical advancements and evidence-based practices, Dr. Marks empowers patients to confidently navigate their health journey, specializing in Colon & Rectal Cancer & Surgery, Diverticulitis, Rectal Cancer/Sphincter Preservation, Robotic Surgery, and comprehensive wellness support. Serving the Bryn Mawr, PA community, Dr. Marks is dedicated to enhancing lives through expert, patient-centered care.
Where did Dr. Marks go to medical school and complete their residency?
Residency: Thos Jefferson Univ Hosp, Colon And Rectal Surgery; Thos Jefferson Univ Hosp, General Surgery | Thomas Jefferson University Hospital Program
Medical School: Jefferson Medical College of Thomas Jefferson University | Sidney Kimmel Medical College at Thomas Jefferson University
Is Dr. Marks board certified as a Colon & Rectal Surgeon (Proctologist)?
Yes, Dr. John Marks, MD is board certified by the American Board of Colon & Rectal Surgery , American Board of Surgery
What languages does Dr. Marks speak?
Dr. Marks and their clinical team can communicate with patients in the following languages:
- English
- French
What conditions does a Colon & Rectal Surgeon (Proctologist) like Dr. Marks typically treat?
As a Colon & Rectal Surgeon (Proctologist), Dr. Marks diagnoses, treats, and manages a wide range of conditions. This condition information is derived from anonymized insurance claims and highlights the medical conditions most commonly treated by Dr. Marks. It provides insight into the doctor’s areas of experience and expertise based on real-world patient encounters from the past two years, updated quarterly. Learn more about our claims-based healthcare methodology.
Also known as:
- Colorectal Cancer
- Rectal cancer
- Colon cancer
- Bowel cancer
- Malignant neoplasm of rectum
- Malignant neoplasm of colon
- Malignant neoplasm of sigmoid colon
ICD-10 Codes:
- C20: Malignant neoplasm of rectum
- C189: Malignant neoplasm of colon, unspecified
- C187: Malignant neoplasm of sigmoid colon
Also known as:
- Colon Cancer Screening
- Health Screening
- Colorectal Cancer Screening (PDQ®)
- Screening Tests to Detect Colorectal Cancer and Polyps
- Tests to Detect Colorectal Cancer and Polyps
- Colorectal Cancer Screening
- Colonoscopy Screening
- Bowel Cancer Screening
ICD-10 Codes:
- Z1211: Encounter for screening for malignant neoplasm of colon
Also known as:
- Overweight
- Body Weight
- High Body Mass Index
- Excess Weight
- Weight Management Issues
ICD-10 Codes:
- Z6825: Body mass index [BMI] 25.0-25.9, adult
- Z6826: Body mass index [BMI] 26.0-26.9, adult
Also known as:
- Intestine Diverticulitis
- Diverticulosis and Diverticulitis
- Inflamed Bowel Diverticula
- Bowel Diverticular Inflammation
ICD-10 Codes:
- K5792: Diverticulitis of intestine, part unspecified, without perforation or abscess without bleeding
Also known as:
- Large Intestine Diverticulosis
- Diverticulosis and Diverticulitis
- Diverticular Disease
- Colon Diverticula
- Pockets in the Colon
ICD-10 Codes:
- K5730: Diverticulosis of large intestine without perforation or abscess without bleeding
What procedures does a Colon & Rectal Surgeon (Proctologist) like Dr. Marks typically perform?
As a Colon & Rectal Surgeon (Proctologist), Dr. Marks performs a variety of medical procedures. This procedure information is derived from anonymized insurance claims and highlights the medical procedures most commonly performed by Dr. Marks. It provides insight into the doctor’s areas of experience and expertise based on real-world patient encounters from the past two years, updated quarterly. Learn more about our claims-based healthcare methodology.
Also known as:
- Diagnostic Colonoscopy with Biopsy
- Colonoscopy with Biopsy
- Colonoscopy with Polyp Removal
- Colonoscopy with Tissue Removal
- Colonoscopy
- Colorectal Cancer Screening Tests
- Flexible Colonoscopy
- Colon Exam with Biopsy
- Lower Endoscopy
- Colon Cancer Screening
- Colon Biopsy
- Large Intestine Scope
- Colorectal Cancer Screening
- Flexible Colonoscopy with Polypectomy
- Colon Polyp Removal
- Colorectal Lesion Excision
- Flexible colonoscopy with EMR
- Endoscopic mucosal resection (colon)
- Colon polyp removal during colonoscopy
CPT Codes:
- 45378: Colonoscopy, flexible; diagnostic, including collection of specimen(s) by brushing or washing, when performed (separate procedure)
- 45380: Colonoscopy, flexible; with biopsy, single or multiple
- 45385: Colonoscopy, flexible; with removal of tumor(s), polyp(s), or other lesion(s) by snare technique
- 45390: Colonoscopy, flexible; with endoscopic mucosal resection
Also known as:
- Upper Endoscopy with Biopsy
- Biopsy
- Endoscopy
- EGD with Biopsy
- Gastroscopy with Biopsy
- Esophagogastroduodenoscopy with Biopsy
CPT Codes:
- 43239: Esophagogastroduodenoscopy, flexible, transoral; with biopsy, single or multiple
Also known as:
- Removal of Multiple Hemorrhoids
- Hemorrhoidectomy
- Internal and External Hemorrhoid Surgery
- Piles Removal Surgery
CPT Codes:
- 46260: Hemorrhoidectomy, internal and external, 2 or more columns/groups;
Also known as:
- Flexible Sigmoidoscopy
- Colorectal Cancer Screening Tests
- Sigmoidoscopy
- Lower colon exam
- Flexible colon scope
- Rectum and lower colon check
CPT Codes:
- 45330: Sigmoidoscopy, flexible; diagnostic, including collection of specimen(s) by brushing or washing, when performed (separate procedure)
Also known as:
- Colonoscopy with Injections
- Colonoscopy
- Colorectal Cancer Screening Tests
- Flexible Colonoscopy with Injection
- Colon Scope with Medication
- Therapeutic Colonoscopy
CPT Codes:
- 45381: Colonoscopy, flexible; with directed submucosal injection(s), any substance
Does Dr. Marks accept my insurance?
Dr. Marks accepts most major insurance plans. Important: Please contact the office before your appointment to verify that your specific plan and network are accepted.
What insurance plans does Dr. Marks accept in Bryn Mawr, PA?
Dr. Marks in Bryn Mawr, PA accepts plans from many carriers. While this list is updated regularly, it is not a guarantee of coverage.
Top Insurances
Blue Cross Blue Shield Association
Cigna Group
CVS Health (formerly Aetna)
Federal government of the United States
Highmark Health
Humana
Independence Health Group
Independent Health Association
Medicare
UnitedHealth Group
View All Insurances
Where is Dr. Marks' office located?
What hospitals are Dr. Marks affiliated with?
Castle Connolly Top Hospital
This doctor is affiliated with a Castle Connolly Top Hospital.
Dr. Marks has admitting privileges at the following hospitals:
Recognitions
Castle Connolly Doctor’s Choice Awards
Doctor’s Choice - All Time
Among the most nominated for the Castle Connolly Top Doctor recognition across all time
Doctor’s Choice - 2025
Among the most nominated for the Castle Connolly Top Doctor recognition in 2025
What is Dr. Marks's NPI number?A National Provider Identifier (NPI) is a unique ID number that identifies doctors and healthcare providers nationwide.
Dr. Marks's National Provider Identifier (NPI) number is 1346212594.
What common questions do patients ask about Dr. Marks?
Here are answers to patients Frequently Asked Questions (FAQ’s) about Dr. Marks