Essential Resources for Gastroenterology

Emily T. Cooper


August 11, 2008

The goal of this column is to provide you with the resources you need to excel in medical school. Each edition focuses on a different preclinical course or clinical rotation, providing tips and resources to master that subject. For more clinical resources, visit Emily Cooper's blog, Med-Source, which she maintains as a "one-stop guide" for med students.

Gastroenterology (aka the gastrointestinal system or GI) is a fairly straightforward course. The most difficult component is the endocrine portion, which may or may not be taught separately in an endocrine block. Read on to learn where to focus your academic energy.

Online Resources

  1. Gastroenterology, the online journal of the American Gastroenterological Association, offers excellent review articles, and most full-text articles are free.

  2. As with most med school courses, pathology is a key component. For excellent images head to the University of Utah's Webpath site, where you will find GI images and hepatic pathology images.

  3. Medical Matrix is a good launching point, offering an extensive list of GI resources.

  4. Medline Plus from the National Institutes of Health provides tutorials on multiple GI topics. Use the search box to find what you need.

  5. Still confused about hepatitis serology? A good tutorial is provided by the Centers for Disease Control and Prevention.

Print Materials

Depending upon the quality and organization of your class notes, you may find the GI sections helpful in these 3 books:

  • Robbins & Cotran Pathologic Basis of Disease

  • Histology and Cell Biology by Kierszenbaum

  • Netter's Atlas of Anatomy

Top 5 Tips for Success

1. Refamiliarize yourself with the basic anatomy and vasculature of the GI tract. The layers of the gut wall (in to out) are:

  • mucosa -- epithelium (absorption), lamina propria (support), muscularis mucosa (motility)

  • submucosa -- includes submucosal plexus (Meissner's plexus)

  • muscularis externa -- includes myenteric nerve plexus (Auerbach's plexus)

The blood supply to the gut comes off the aorta as follows:

  • celiac artery (foregut) -- stomach to proximal duodenum, liver, gallbladder, and pancreas

  • superior mesenteric artery (midgut) -- distal duodenum to proximal two thirds of transverse colon

  • inferior mesenteric artery (hindgut) -- distal third of transverse colon to upper portion of rectum

2. Get to know and love hernia anatomy.

  • Direct inguinal hernia

    • protrudes through Hesselbach's triangle (inferior epigastric artery, lateral border of the rectus muscle, and the inguinal ligament)

    • bulges directly through the abdominal wall medial to the inferior epigastric artery, traversing through the external ring only

    • covered by transversalis fascia

    • usually seen in older men

  • Indirect inguinal hernia

    • traverses through the internal inguinal ring, the external ring, and into scrotum with all 3 layers of spermatic fascia

    • enters inguinal ring lateral to the inferior epigastric artery

    • occurs in infants due to failure of processus vaginalis to close

  • Femoral hernia -- traverses through femoral canal below and lateral to the pubic tubercle

  • Diaphragmatic hernias

    • sliding -- gastroesophageal junction displaced (most common)

    • paraesophageal -- gastroesophageal junction remains in place

3. Learn to differentiate Crohn's disease from ulcerative colitis ( Table ). It's not difficult, and this question frequently shows up on exams.

4. Know how to determine a patient's hepatitis B status (vaccinated vs infected) on the basis of a serum antigen/antibody profile.

5. Understand that all colon polyps are not equal. Learn the key features of hyperplasic polyps vs adenomas vs cancer. Also know the criteria for colon cancer screening.


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