GI Tract Flashcards
What makes up the GI tract?
Mouth, pharynx, esophagus, stomach, small intestines/colon
Which areas can be identified with sonography?
Distal esophagus attached to stomach (gastroesophageal junction)
What and where is the pyloric sphincter?
A muscle controlling emptying of the stomach into the duodenum which lies within the distal stomach
What lies distal to the duodenum?
Jejunum and ileum (of the small intestines)
What and where is the ileocecal valve?
Ileum connects with cecum (proximal colon) in the right lower quadrant of the abdomen
Where is the vermiform appendix located?
Right lower quadrant of abdomen (level of cecum)
What is the ascending colon?
The colon traveling toward liver after cecum
Where does the transverse colon begin?
A bend in the colon (the splenic flexure marks the start of descending colon)
What is the final section of the colon?
The sigmoid as the colon travels inferiorly toward the rectum
Which areas are intraperitoneal?
Most GI parts with the exception of duodenum and ascending/descending colon
How many layers are in normal bowel?
5 layers
What is the name of the innermost layer and how does it appear?
Superficial mucosa / echogenic
What is the second innermost layer and how does it appear?
Deep mucosa / hypoechoic
What is the middle layer and how does it appear?
Submucosa (muscularis propria interface) / echogenic
What is the 4th layer from innermost and how does it appear?
Muscularic propria / hypoechoic
What is the outermost layer and how does it appear?
Serosa / echogenic
What conditions indicate a need for sonography?
Hypertrophic pyloric stenosis, intussusception, acute appendicitis
What may cause appendix issues?
Obstructive process like appendicolith, fecalith, lymph node, tumor, foreign body, seeds, or parasite
What is the laboratory test for appendicitis?
Leukocytosis
What may perforated appendix result in?
A loculated fluid collection which may represent abscess
Describe the anatomy of a normal appendix.
Sausage-like, mobile, compressible, blind-ending structure with a diameter of 7 mm
What can the appendix contain?
Air, some fecal matter and rarely a little fluid
What does Power Doppler reveal about the appendix?
Little to no vascular with no hyperechoic, non-compressible inflamed fat
What are clinical signs of appendicitis?
Epigastric , periumbilical , abdominal right lower quadrant pain
What is the McBurney point?
An area of rebound tenderness
What can be seen in addition to other appendicitis symptoms?
Palpable mass
What is the best method for identifying non-compressible inflamed fat?
Slowly applied intermittent compression
What indicates perforation in appendix?
Irregular, asymmetrical contour and loss of layer structure
How does vascular appear with appendix?
Either increased or absent due to high intramural pressure w/concomitant ischemic necrosis
Where is vascular always increased in appendix?
In the surrounding fatty tissue
What does the presence of a generalized, dynamic ileus indicate?
Perforated appendix (even if inflamed appendix cannot be visualized)
What is the appearance of an inflamed appendix?
Concentrically layered, non-compressible, sausage-like stucture
What are the dimensions of an inflamed appendix?
Maximum diameter of 9 mm (variation from 7-17 mm)
What is found in 30% of inflamed appendix lumen?
Intraluminal fecoliths obstruction
What happens 6-12 hours after initial appendicitis symptoms?
Inflammation progresses to the adjacent fat of the meso-appendix and becomes larger, more hyperechoic and less compressible
What happens to fatty tissue around the inflamed appendix?
It will increase in volume representing migrated mesentery/omentum attempting to block any perforation
What are physical findings of acute appendicitis?
Non-compressible, blind-ended tube measuring more than 6 mm from each outer wall
How will acute appendicitis appear on ultrasound?
Echogenic structure in lumen (appendicolith), hyperemic flow in wall and periappendiceal fluid collection
What contributes to a false positive diagnosis of appendicitis?
Normal appendices which are more than 7 mm (children/lymphoid hyperplasia or adults/fecal)
What does a generalization of peritonitis cause?
It hampers graded compression which can account for a lower score in patients with free appendiceal perforation
What can obstruct a sonographic view of the appendix?
Air-filled dilated bowel loops from adynamic ileus (passage failure) or from air in the lumen
What is hypertrophic pyloric stenosis? (HPS)
A genetic and environmentally related condition more common in male/first born over female (4-6:1) seen in 2-8 week olds and occurs in 2-5/1000
What age is HPS rarely seen in?
Children more than 6 months old
What are clinical findings of pyloric stenosis?
Palpable olive sign (enlarged pyloric muscle) non-bilious, projectile vomiting, weight loss, constipation, dehydration, insatiable appetite,
How do you scan for HPS?
Right lateral decubitus, long view of pylorus seen in epigastrium near GB
What happens during hypertrophic pyloric stenosis?
Circular muscle layer thickens and narrows/elongates pyloric areas. The mucosa becomes redundant and may appear hypertrophic
What happens to the pylorus as a result of elongation/thickening of muscle?
It deviates upward toward GB (marker anteromedial to the right of the kidney)
What results from the thickened pylorus?
It narrows the pyloric channel resulting in gastric outlet obstruction, gastric distention, and retrograde peristalsis in the stomach
What is the measurement for normal closed pylorus?
Less than 2 mm (2-3 some places)
What are sonographic findings of pyloric stenosis?
Target/doughnut sign (trans), cervix-like (long), wall greater/equal to 3mm, pyloric channel > 17 mm
How accurate is ultrasound for diagnosing pyloric stenosis?
Close to 100% from sensitivity and specificity
How does the muscular layer appear around pyloric stenosis?
Heterogenous echo texture
What creates the antral nipple sign?
A redundant mucosa
What other problems should be taken into consideration with diagnosing intestinal obstruction/HPS?
Midgut volvulus, malrotation, antral polyps, gastric duplication, pylorospasm (delays gastric opening)
What is borderline normal measurement for HPS?
10 mm
How does pylorospasm finding differ from HPS?
Pylorospasm measurements tend to be within normal limits, unlike HPS (during exam some fluid goes through pyloric channel)
What is intussusception?
Telescoping of one bowel segment into another most common ileocolic in RLQ at the ileocecal valve
What are some components of intussusception?
The proximal portion of bowel (intussusceptum) invaginates into the next distal segment (intussuscipiens)
What are clinical findings of intussusception?
Severe abdominal pain, vomiting, palpable mass, red currant jelly stool and leukocytosis
What happens as a result of intussusception?
As the intestine pulls inward into itself, it can block the passage of food or blood supply and can die
What results from pressure between intestinal walls (intussusception)?
Decreased blood flow, irritation and swelling
How will intussusception appear on ultrasound?
Target sign (trans) or pseudokidney (long)
How will bowel wall appear with intussusception?
Alternating rings of echogenicity representing edematous layers (abnormal bowel non-compressible)
What can result from intussusception?
Ischemia and gangrene of bowel (use color to detect any blood flow)
What sonographic appearance indicates intussusception in longitude?
Hay fork appearance
What are other ultrasound signs for intussusception?
Double ring sign (color doppler), large adenopathies, free fluid, bowel distention
What kind of treatment do you give intussusception?
Air/contrast enema not to be used on perforated bowel as there is a risk of bowel tearing
Describe a benign lymph node
Ovoid, hypoechoic cortex, thin/invisible with a hyperechogenic hilum from connective tissue trabeculae, lymphatic tissue cords and medullary sinusoids.
What are suspicious lymph node characteristics?
Cortical thickening (3 mm cut-off/2.3 metastasis), hilum decrease/absence, shape/vascular changes
What is lymph node protocol?
Size (measured), shape, short/long axis ration, nodal borders (sharp/smooth), internal echogenicity (hypo/hyper), echogenic hilum, vascular patterns
What are gray scale parameters for lymph node malignancy?
Larger size, round shape (L/T <2), heterogenous echotexture, thinning of hilum, thickened cortex, microcalcification, necrosis, ill defined margins
What are Color / Power Doppler features for lymph node malignancy?
Norm-mixed peripheral central blood vessels, high resistant, RI < 0.8, PI < 1.5
What other vascular features determine lymph node malignancy?
Abberent/displaced vessels, subcapsular, unperfused areas, non-tapering vessels (necrotic change may show low resistance)
