Ch 15 - Small & Large Intestine Flashcards
What is the average length of the adult small intestine?
22 ft
The diameter gradually diminishes from 1 ½ inches to 1 inch.
Where does the small intestine extend from?
The pyloric sphincter of the stomach to the ileocecal valve of the large intestine
What are the functions of the small intestine?
Digestion and absorption
What are the finger-like projections in the mucosa of the small intestine called?
Villi
Villi assist in the process of absorption and digestion.
How is the small intestine divided?
- Duodenum
- Jejunum
- Ileum
What quadrant is the Duodenum located in?
RUQ and LUQ
What quadrant is the Jejunum located in?
LUQ and LLQ
What quadrant is the ileum located in?
RUQ, RLQ and LLQ
What quadrant is the ileocecal valve located in?
RLQ
What is the widest portion of the small intestine?
Duodenum
What is the length of the duodenum?
8-10 inches long (shortest segment)
Where does the Duodenum extend?
From the pylorus to the jejunum
What is the shape of the duodenum and where does it lie in the body?
Horseshoe shaped and lies behind the liver
What is the duodenal bulb?
The rounded segment of the duodenum just distal to the pyloric sphincter
What are the four segments of the duodenum?
Superior, descending, horizontal and ascending
What are two features of the second segment of the duodenum?
- Greater duodenal papilla, where the bile and pancreatic ducts open
- Duodenal loop
What is the most common problem of the duodenum?
Peptic ulcers
What is the final and longest segment of the small intestine?
Ileum
What are common pathological indications in the small bowel?
- Gastroenteritis
- Meckel’s diverticulum
- Neoplasm
- Malabsorption syndrome
- Paralytic ileus
- Crohn’s disease
- Giardiasis
What are the small bowel procedures that can be completed?
- Upper gi/small bowel combo
- Small bowel alone
- Enterocylsis
- Intubation method
What is the main function of the large intestine?
Reabsorption of fluid and elimination of waste
How long is the large intestine and where does it extend?
About 5ft long and extends from the lieum to the anus
What are haustra?
A series of pouches along the long intestine
What are taeniae coli?
Muscular bands that form the haustra
What are the four main parts of the large intestine?
- Cecum
- Colon
- Rectum
- Anal Canal
What is the pouch-like portion of the large intestine that is below the junction of the ileum and the colon?
Cecum
What is attached to the posteromedial side of the cecum?
Appendix- narrow worm-like tube that is 3”
What is the function of the ileocecal valve?
Guards the opening between the ileum and the cecum
What are the subdivisions of the colon?
- Ascending colon
- Transverse colon
- Descending colon
- Sigmoid colon
What is the name of the angle between the ascending colon and the transverse colon?
Right colic flexure
What is the angle between the transverse colon and descending colon?
Left colic flexure
How long is the rectum?
Approximately 6 inches long and extends from the sigmoid colon to the anal canal
What is the anal canal?
External aperture of the large intestine at the end of the anus
In hyperstenic patients where is the large intestine positioned?
Around the periphery of the abdomen and may require more images to show its entire length
What is the position of the large intestine in Asthenic patients?
Bunched together and positioned in the lower abdomen
What are the 3 ways barium sulfate is administered for exams of the small intestine?
1) Orally
2) Complete reflux examinations
3) Direct injection into the bowel (Enteroclysis)
When should a complete reflux exam or Enterocylsis be used?
Only when oral methods fail to provide conclusive information
What are contraindications of Barium Sulfate?
- pre-surgical patients
- perforated hollow viscus
- large intestine obstruction
What are contraindications of water soluble iodinated contrast?
- young or deydrated patients
- sensitivity to iodine
What is the process for an Upper GI/Small bowel combo?
- Routine upper GI done first
- Second cup of contrast injested
- 30 minute interval radiographs
- 1 hour interval radiographs as needed
- Spot ileocecal valve film
What dietary preparation is recommended for patients before a small intestine examination?
Soft or low residue diet for 2 days and food and fluid withheld after the evening meal the day before the exam
What is another name for an oral exam of the small bowel?
Small bowel series since identical images are done at timed intervals
What is the process of a small bowel series?
Ingestion of barium by mouth, preceded by a images of the abdomen
What is a requirement in each image of a small bowel series?
A time marker indicating the interval between its exposure and ingestion of barium
What are the two positions used for radiographic examinations of the small intestine?
- Supine
- Prone
What is the benefit of a supine position in a small bowel series?
1) take advantage of the superior and lateral shift of the barium filled stomach for visualization of the retrogastric portion
2) To prevent possible compression overlapping loops in the intestine
What is the benefit of a prone position in a small bowel series?
Compression of the abdomen contents to enhance radiographic image quality
What position should be used for thin patients for final images of the small bowel?
Trendelenberg to unfold loops of the ileum
When is the first image taken in a small bowel series?
15 minutes after the patient drinks the barium
What are the other time intervals used in a small bowel series?
15-30 minutes depending on the transit time of the barium
What is the purpose of a glass of ice water during a small bowel series?
It accelerates peristalsis in patients with hypomotility
When should a small bowel series end?
When barium is visualized in the cecum
What is a small bowel follow through used to assess?
The jejunum and ileum and distal portions of the small bowel
- Pain and diarrhea
- To make Crohns diagnosis
How is a complete reflux exam conducted?
- The patient’s colon/small intestine are filled by a BE administered to show the colon and small bowel
- Flow is terminated when the barium reaches the duodenal bulb
- Enema bag is then lowered to the floor to drain the colon before images are taken
What is also administered as a part of a complete reflux exam?
Glucagon to relax the intestine
Which weight/volume barium is used for complete reflux exams?
15% ± 5% weight/volume
What type of enema tip is used for complete reflux examinations?
Retention enema tip
What is the term for the radiographic procedure in which contrast medium is injected into the duodenum?
Enteroclysis Procedure
How is the barium administed in an Enterocylsis procedure?
Injected through a enteroclysis catheter (Bilbao/Sellink)
How is an enteroclysis procedure conducted?
Under fluoro control, the catheter is advanced to the end of the duodenum where a retention balloon is filled and then barium is instill at a rate of 100mL/min
- spot images are taken as needed
What is an intubation small bowel exam procedure?
A procedure in which a long tube is inserted into the nose and passed to the stomach for the purpose of injecting barium/fluid and gas aspiration
What are the two types of intubation procedures?
- Therapeutic intubation where gas/fluid are suctioned out
- Diagnostic intubation with contrast
What position is best used for an intubation exam of the small bowel?
RAO, where gastric peristalsis is more active and allows the tube to pass to the duodenum quickly
Where the part position for a PA/AP projection of the small bowel? (initial image)
- MSP centered to the grid
- IR/CR centered to the level of L2
Where the part position for a PA/AP projection of the small bowel? (delayed image)
- MSP centered to the grid
- IR/CR centered to the level of the iliac crests
What are the structures shown in a AP/PA Small bowel projection?
Small intestine filling progressively until barium reaches the ileocecal valve
What is the evaluation criteria for a PA/AP Small bowel?
- Entire small intestine on each image
- Stomach on initial images only
- Time marker
- Vertebral column centered on the image
- No rotation
- Barium filled cecum on the delayed image
What are the two basic methods of examining the large intestine by contrast?
- Single contrast
- Double contrast
What is single contrast exam of the large intestine?
When the colon is examined with barium sulfate or water-soluble iodine only
What is a double contrast exam of the large intestine?
When a positive contrast medium (barium) is introduced to the colon followed by a negative contrast medium (air/gas)
What does positive contrast medium (barium) show in the colon?
Anatomy and tonus of the colon
What does negative contrast medium (air) show in the colon?
Distention of the lumen of the bowel for optimum visualization
What is an alternate gas that can be used in double contrast studies?
Carbon dioxide since it is more rapidly absorbed
What are double contrast studies of the large intestine used for?
To demonstrate small intraluminal lesions like polyps
What are the two types of postive contrast mediums used in large bowel examination?
Barium sulfate and water soluble iodinated contrast
Which type of positive contrast medium are used for routine exams of the large intestine?
Barium sulfate, specifically high-density barium
Which type of contrast medium is used when there is a suspected perforation or leak in the large intestine?
Water soluble iodinated contrast
What is the primary disadvantage of water-soluble iodinated contrast?
Evaluation often is insufficient for satisfactory double contrast visualization
What is the normal patient prep for a large bowel examination?
- Large intestestine completely emptied of all its contents
- Clear liquid diet and a bowel cleansing regiment
What does retained fecal matter in the large intestine simulate?
Small masses or polyps
For single contrast exams, what density barium should be used?
Low density barium at 15-20% weight/volume
For double contrast exams, what density barium should be used?
High density barium at 80-100% weight/volume
What density contrast is required for water soluble contrast exams?
60-70% density
What is the purpose of the Miller-Abbott tube in gastrointestinal intubation?
To relieve postoperative distention in the small intestine
What position should the patient be instructed to turn into for enema insertion?
Left side, rolling forwards 35-40 degrees, resting on flexed right knee above and in front of left knee
This position is known as Sims’ position.
What is the purpose of the Sims’ position during enema insertion?
Relaxes abdominal muscles, decreases abdominal pressure, and aids in relaxation of anal sphincter.
How high should the IV pole be adjusted during the procedure?
No higher than 24 inches above the level of the anus.
What is the first step in preparing the rectal tube for insertion?
Lubricate the rectal tube.
During the insertion of the enema tip, at what angle should the tip be directed?
Direct anteriorly 1 to 1.5 inches, then slightly superiorly.
What is the maximum distance for the insertion of the enema tip?
No more than 4 inches.
What should be done if resistance is met during insertion?
Ask patient to assist if capable.
What is the first step after the enema tip is inserted?
Hold in place while patient turns to supine or prone position.
What is the purpose of the retention cuff during the enema procedure?
It may be inflated to hold the enema in place.
What should be done after the enema tip is removed?
Deflate retention balloon first, if present.
Which type of enema tips should be used for patients with strictures, fissures or inflamed hemorrhoids?
Smaller enema tip
When should the balloon be inflated in fluoro exams?
Just before the examination to increase patient safety
What is the capacity of a standard enema bag?
3 quarts (3000 mL)
What temperature should the barium suspension be kept at?
Below body temperature between 85-90 degrees to avoid burning
What instructions should be provided to patients to minimize discomfort in a BE exam?
◦ Relax abdomen
◦ Deep oral breathing
◦ Communicate cramping so that filling may be
slowed or stopped
What are the two methods for a Double-Contrast Barium Enema?
- Closed system
- Welin method
How does the closed system method differ from the Welin method?
Closed system does not require removal and reinsertion of enema tip.
What is the process used for the Welin method?
Barium is introduced to the left colic flexure, tip is removed and patient evacuates
- tip is then reinserted and barium is introduced to sigmoid and air instilled then patient is repositioned
How is the patient positioned for a PA/AP projection of the large intestine?
Prone or supine
What are the Essential Projections for the large intestine?
- PA
- PA axial
- PA oblique
◦ RAO position
◦ LAO position - Lateral
- AP
- AP axial
- AP oblique
◦ RPO position
◦ LPO position - AP or PA
◦ Right lateral decubitus position
◦ Left lateral decubitus position
What scout film is done before all large intestine projections?
KUB scout
If a patient is positioned upright for large intestine projections how is the IR placed?
Slightly lower to compensate for a drop in anatomy
What is the central ray direction for the PA/AP Projection of the large intestine?
Perpendicular to the IR to enter the midline of the body at the level of the iliac crests.
What is the evaluation criteria for a PA/AP Projection of the large intestine?
- Entire colon including the flexures and rectum
- Penetration of the contrast medium
What is the patient position for the PA Axial projection of the large intestine?
Patient in the prone position with MSP centered to the midline of the grid
What is the angle of the central ray for the PA Axial Projection of the large intestine?
Directed 30 to 40 degrees caudad.
What is the Central ray position in the PA Axial projection of the large intestine?
CR angled at the midline of the body and at the level of the ASIS
What structures are demonstrated in the PA Axial Projection large intestine?
The rectosigmoid area of the colon.
- BEST DEMONSTRATED IN THIS POSITION
What is the evaluation criteria for the PA Axial projection of the large intestine?
- Rectosigmoid area centered to image
- Rectosigmoid area with less superimposition than in PA projection
- Transverse colon and both flexures not always included
In the PA Oblique Projection - RAO position, how is the patient positioned?
Patient in the prone position rolls onto their right hip to obtain a 35- to 45-degree to the table
In the PA Oblique Projection - LAO position, how is the patient positioned?
Patient in the prone position rolls onto their left hip to obtain a 35- to 45-degree to the table
Where is the central ray positioned for the PA Oblique projection-RAO/LAO position of the large intestine?
Perpendicular to the IR and 1-2 inches lateral to the midline of the body on the elevated side at the level of the iliac crest
What structures are shown in the PA Oblique Projection - RAO/LAO Position?
RAO-The right colic flexure and the ascending portion of the colon.
LAO- The left colic flexure and the descending portion of the colon.
What is the evaluation criteria for the PA Oblique projection RAO poistion of the large intestine?
- Entire colon
- RAO: Right colic flexure less superimposed or open compared with the PA projection
- Ascending colon, cecum, and sigmoid colon
What is the evaluation criteria for the PA Oblique projection LAO poistion of the large intestine?
- Entire colon
- Left colic flexure less superimposed or open compared with the PA projection
- Descending colon
What is the purpose of the lateral projection of large intestine?
To demonstrate the rectum and distal sigmoid portion of the colon.
How is the patient positioned for the lateral projection of the large intestine?
In the lateral recumbent position on the left or right side, with the MCP to the center of the grid
Where is the central ray positioned in the Lateral projection of the large intestine?
Perpendicular to the IR and entering the MCP at the level of the ASIS
What are the structures demonstrated in the Lateral projection of the large intestine?
The rectum and the distal sigmoid portion of the colon.
What is the evaluation criteria for the Lateral Projection of the large intestine?
- Rectosigmoid area in the center of the image
- No rotation of the patient
- Superimposed hips and femora
What is the patient position for the APAxial projection of the large intestine?
Patient in the supine position with MSP centered to the midline of the grid
What is the angle of the central ray for the APAxial Projection of the large intestine?
Directed 30 to 40 degrees cephalic.
What is the Central ray position in the AP Axial projection of the large intestine?
CR centered to the midline of the body and 2” below the level of the ASIS
What structures are demonstrated in the AP Axial Projection large intestine?
The rectosigmoid area of the colon.
What is the evaluation criteria for the AP Axial projection of the large intestine?
- Rectosigmoid area centered
- Rectosigmoid area with less superimposition than in the AP projection
- Transverse colon and flexures not included
In the AP Oblique Projection - LPO position, how is the patient positioned?
Patient placed in the supine position and then rolled onto their left side to form a 35-45 degree angle with the table
In the AP Oblique Projection - RPO position, how is the patient positioned?
Patient placed in the supine position and then rolled onto their right side to form a 35-45 degree angle with the table
Where is the central ray positioned for the AP Oblique projection-LPO/RPO position of the large intestine?
Perpendicular to the IR to enter approximately 1 to 2 inches lateral to the midline of the body on the elevated side at the level of the iliac crest.
What structures are shown in the AP Oblique Projection - LPO/RPO Position?
LPO - The right colic flexure and the ascending and sigmoid portions of the colon
RPO- The left colic flexure and the descending colon
What is the evaluation criteria for the AP Oblique Projection - LPO position?
- Entire colon
- Right colic flexure less superimposed compared with the AP projection
What is the evaluation criteria for the AP Oblique Projection - RPO position?
Entire colon
Left colic flexure and descending colon
How is the patient position for a AP/PA projection - right lateral decubitus position of the large intestine?
- Patient placed on the right side with the back or abdomen in contact with the IR
- MSP centered to the grid
In the right lateral decubitus position, where should the central ray enter?
Horizontal and perpendicular to the IR at the level of the iliac crests.
What are the structures demonstrated in a right lateral decubitus postion?
- AP or PA projection of the contrast filled colon
- Best shows, the ‘up’ medial side of the ascending colon and the lateral side of the descending colon.
What is the evaluation criteria for the right lateral decubitus of the large intestine?
- Area from the left colic flexure to the rectum
- No rotation of the patient, as demonstrated by symmetry of the ribs and pelvis
How is the patient position for a AP/PA projection - left lateral decubitus position of the large intestine?
- Patient placed on the left side with the back or abdomen in contact with the IR
- MSP centered to the grid
In the left lateral decubitus position, where should the central ray enter?
Horizontal and perpendicular to the IR to enter the midline of the body at the level of the iliac crests.
What are the structures demonstrated in the left lateral decubitus of the large intestine?
- PA or AP projection of the contrast-filled colon.
- The ‘up’ lateral side of the ascending colon and the medial side of the descending colon when inflated with air.
What is the evaluation criteria of the left lateral decubitus of the large intestine?
- Area from the left colic flexure to the rectum
- No rotation of the patient, as demonstrated by symmetry of the ribs and pelvis
What type of mechanical digestion occurs in the mouth?
Mastication and deglutition
What type of mechanical digestion occurs in the pharynx?
Deglutition
What type of mechanical digestion occurs in the esophagus?
Deglutition and peristalsis
What type of mechanical digestion occurs in the stomach?
Mixing and peristalsis to produce chyme
What type of mechanical digestion occurs in the small intestine?
Rhytmic segmentation (churning) and perstalsis
Where is the large intestine located in Hypersthenic patients?
Widely distributed
Where is the large intestine located in Sthenic patients?
Left colic flexure is high
Where is the large intestine located in Hyposthenic/Asthenic patients?
Low near pelvis
