What happens if the gut does not rotate 270 degrees? What condition is a result?
Intestinal malrotation. Intestinal obstruction.
What is the most common malformation of the GI tract? How does it form?
Meckel’s diverticulum. Results if the Vitelline duct does not obliterate.
Why does Meckel’s sometimes bleed?
Has gastric tissue in it that responds to circulating blood gastrin and subsequently produces HCL, which erodes the intestinal wall.
What are the characteristics of Meckel’s?
True congenital diverticulum. Small bulge (remnant of the Vitelline duct) in the small intestine at birth. On antimesenteric border of small bowel. Bleeding may not start until adulthood.
What is the incidence of Meckel’s and what is the most common population group affected?
2% of overall population. More frequent in males.
What is the #1 cause of painless bleeding in children?
What are the 4 conditions that can occur if the vitelline duct fails to completely close?
- Meckel’s diverticulum
- Vitelline cyst
- Vitelline fistula
- Abdominal closure prior to retraction of intestines
What is intussusception?
Telescoping (invagination) of one segment of intestine into another
What does it mean when it says that there is a “lead point” for intussusception?
Usually a swelling that leads the telescoping segment into the other (enlarged Peyer’s patches, lymphoma, Meckel’s)
What is the most common lead point for intussusecption for a child? For an adult?
For children, the lead point is often a swollen lymph node, for an adult it is often a tumor
What is the most common cause of small bowel obstruction? Large bowel obstruction?
Small bowel: Intra-abdominal adhesions
Large bowel: Cancer
What are the branches of the inferior mesenteric artery?
Left colic a.
Superior rectal a.
What area(s) does the left colic artery supply?
What area(s) does the superior rectal artery supply?
What area(s) do the sigmoid branches of the inferior mesenteric artery supply?
Lower part of the descending colon, the iliac colon, and the sigmoid or pelvic colon
What is the function or consequence of Tenia Coli?
Being shorter than the underlying viscus, they create Haustra and attachment points for structures
What are the divisions of the large intestine?
Ascending colon, transverse colon, descending colon, Sigmoid colon, Rectum, Anal canal
Why is the sigmoid colon’s “floppiness” clinically important?
The sigmoid colon is floppy, so diseases there can appear to be on the right side since it can flip over to that side even though the sigmoid is on the left
What is the underlying problem that causes Hirschsprung’s disease?
Failure of neural crest cells (ganglion cells) to progress in craniocaudal direction
What layers are missing in “diverticular disease”?
How do a true and false diverticula differ?
C - Congenital, not acquired
R - Right side of colon
A - Asians, more common in
M - Muscular layers
What is the difference between Diverticulosis and Diverticulitis?
Diverticulitis is inflammation, usually from infection, occurring in a diverticula
Diverticulosis is the presence of several diverticuli
What structure is missing in the appendix?
What are the characteristics of Crohn’s disease?
F - Fissures
L - Lesions (called skip lesions)
A - Anus, can involve
B - Bleeding absent 30% of the time
What are the characteristics of Ulcerative colitis?
F - Fever L - Loss of weight A - Abdomenal pain R - Rarely fistulas and strictures D - Diarrhea, bloody (always)
UC always has bloody diarrhea, Crohn’s about 70% of the time
What tissues/structures are involved in Ulcerative Colitis?
Involves mucosa and submucosa
Mucosal involvement contiguous
What plexus do hemorrhoids form in?
Both the internal rectal venous plexus, and the inferior rectal venous plexus
What plexus do suppositories take advantage of for absorption?
Internal rectal venous plexus