Abdomen 1 Flashcards
1
Q
Imaging studies of the abdomen
A
- Single KUB and plain abdominal series (plain xrays)
- Ultrasound
- Barium studies
- Nuclear studies
- GU tract - ultrasound, IVP
- All things CT next week
2
Q
abdominal plain films
A
- Utilized much less - limited
- Conventional radiographs of the abdomen (plain films) are NOT the first choice to evaluate organs, structures – CT, ultrasound much better
3
Q
Single, supine film (KUB) indications
A
- KUB = kidney, ureter, bladder
- Bowel gas pattern, foreign bodies, calcifications, tubes
4
Q
Abdominal series (KUB, upright abdomen, and CXR) indications
A
- Suspected bowel obstruction or perforation (pneumoperitoneum): Upright abd: air-fluid levels in bowel, free air, CXR: free air under diaphragms, lung pathology near diaphragm
- substitute LL decubitus if can’t stand (free air, air fluid levles)
- special views: prone abdomen, lateral rectum
5
Q
Adequacy of abdominal plain films
A
- KUB - diaphragms to symphysis, lateral walls
- Upright - Pt stands for 5-10min, mid abdomen, beam must be horizontal to floor
- CXR – must include both diaphragms and costophrenic angles
6
Q
Normal bowel characteristics: small bowel
A
- Central distribution
- Little air in lumen
- No feces
- Valvulae conniventes (Traverse entire lumen, Narrow spacing)
- <2.5cm diameter
- Wall thickness <3mm
7
Q
Normal bowel characteristics: large bowel
A
- Peripheral distribution (Except RUQ, transverse)
- Contains feces/air
- Haustra (Do not usually traverse lumen – wide spacing)
- <5cm diameter
- Wall thickness <3mm
8
Q
Patterns: plain films
A
- Bowel Gas & Air/fluid levels: Normal - Gas in stomach, air-fluid level on upright films, Gas in colon/rectum (No air-fluid levels, variable pattern), small bowel – small amount gas/fluid ok (2 or 3 loops))
- Calcifications: Not normal - indicate subacute or chronic process, +/- sx’s
- Organomegaly/Mass: Plain film not study of choice, Displaced bowel may be seen
9
Q
abnormal gas/fluid patterns
A
- Abnormal location of gas filled bowel (Shifted/displaced by a mass)
- Abnormal air-fluid patterns (upright) (Multiple loops of dilated small bowel w/ air-fluid levels, Gastric dilation (stomach) )
- Abnormal bowel gas patterns (Mechanical Ileus -> SBO - small bowel obstruction, LBO - large bowel obstruction)
- Functional Ileus (Localized, Generalized (adynamic))
10
Q
Small bowel obstruction
A
- Abnormally dilated loops of small bowel
- Mechanical obstruction – lumen is obstructed from inside or outside (squished)
- Complete: no air distal to obstruction site (No air in sigmoid or rectum)
- Partial: some air distal but the bowel is less dilated than obstructed segments of bowel
- Early obstructions or ileus - difficult to tell
- Gas in rectum does not “rule out” SBO
- Location: if proximal, less dilated loops than if distal
- You know it is small bowel by the valvulae conniventes
- In SBO – there should always be more dilated small bowel compared to large bowel
11
Q
What can you see on supine view (KUB) of SBO
A
- Supine view (KUB) ->
- Dilated loops small bowel, >3cm
- See the valvulae conniventes
- Centrally located, lines up in rows
- “Stack of coins”, “bent finger sign”
- Little or no air in rectum
12
Q
What can you see on upright view of SBO
A
Upright view ->
- Air-fluid levels: Upside down “U” or broad base
- “U” ends at different heights, step-ladder appearance
- “String of pearls” sign - air in valvulae conniventes
13
Q
Large bowel obstruction
A
- Large bowel dilated, >5cm (Large, diffuse throughout)
- Causes: mechanical (mass or twist), fecal impaction, inflammation
- If ileocecal valve competent - no air in small bowel, cecum most dilated
- If ileocecal valve incompetent - air in both large and small bowel (Difficult Dx – resembles SBO/generalized ileus)
- Few/no air-fluid levels, little/no air in rectum
14
Q
Special types of LBO
A
- Sigmoid volvulus - “coffee bean” - Huge single loop, usual direction from LLQ to RUQ, 60% of volvulous in adults )
- Cecal volvulus - Huge, single, kidney-shaped segment, Usual direction from RLQ to LUQ)
- Toxic megacolon/Ischemic colitis - Huge with bowel wall edema - “thumbprinting”
- Ogilvie’s Syndrome - Elderly, bedbound, anticholinergics, Lose peristalsis, entire colon dilated
15
Q
DDx mechanical obstruction
A
- SBO: Hx SBO strong risk, Post-surgical - adhesions, Malignancy - tumor, Hernia, Intussusception, Inflammatory Bowel Dz
- LBO: Malignancy - tumor, Hernia, Volvulous, Diverticulitis, Intussusception, Fecal Impaction
16
Q
Colitis
A
-Large bowel dilated and inflamed but not obstructed
-Loss of haustra
“thumb-printing” of bowel wall from bowel edema, pseudopolyps (TM)
- Usually very sick patient
- Toxic Megacolon, Ischemic colitis, Ulcerative colitis, C. Diff colitis, etc.
- High risk for perforation
-CT best imaging study
17
Q
types of functional ileus
A
- Localized
- Generalized (adynamic)
18
Q
Localized ileus
A
- Single or few dilated loops - usually SB
- theres nothing actually blocking the bowel, its just inflamed and pissed off
- Located near inflammatory process -appy, pancreatitis, tic’s, stones, fx’s
- “Sentinel loop”
- Usually air in LB, rectum
- Less dramatic than SBO
- Persistent – seen on all views
- dilated loops near area of inflammation. Persistently dilated on all views, can have air-fluid levels on upright
19
Q
Generalized Ileus
A
-Entire bowel dilated - both large and small loops
-Air-fluid levels common
-Causes: post-surgical, electrolytes, DKA, medications
-Usually air in LB and rectum
-see dilation of BOTH large and small bowel. Hx is key: post surgery common. Bowel sounds often absent if generalized
Ogilvie’s – pseudo-obstruction – bowel sounds often present
20
Q
Calcifications on KUB
A
- Lamellar (laminar)
- Amorphous
- Rimlike
- Tracklike
21
Q
extraluminal air
A
Pneumoperitoneum – CXR (Lateral most sensitive for small amounts)
- Retroperitoneal air – plain ok but CT best (Streaky outlining of aorta, psoas, kidneys, bladder - may have pneumomediastinum, Little movement of air w/ position change (xray), Trauma, perforation, infection)
- Air in bowel wall - Pneumatosis intestinales (Kids: necrotizing enterocolitis; adults: ischemic bowel)
- Air in the biliary system – pneumobilia (Gas in/around GB or “tubelike” lucencies in RUQ, Erosion or gas forming bacteria)
22
Q
pneumoperitoneum
A
- Air or gas in the peritoneal cavity 3 xray signs: Free air under the diaphragm(s) on upright PA CXR, Rigler’s sign – see both sides of bowel wall – large amt, KUB, upright, Visualize falciform ligament on KUB)
- CT – (best test) “double wall sign”, falciform ligament
- Causes: Perforation of hollow viscous, Iatrogenic: surgery, procedures, trauma (After surgery, last 5-7 days, less daily), Peritonitis with gas forming organisms
23
Q
rigler’s sign
A
can see both sides of bowel wall clearly – air must surround it to see it so clearly (we can normally only see the air inside the bowel and the wall is not so distinct). Need a large amount of free air to see this sign.
24
Q
Barium studies
A
- Being replaced by Endoscopy (upper) and Colonoscopy (lower)
- Fluoroscopy utilized for the study
- Contrast fills spaces, avoids masses
- Double contrast = air + liquid contrast
- Bowel prep important (fasting, cathartics)
- Used to study lesions in: Esophagus, stomach, small bowel, colon
25
Esophagus - contrast studies
- Indications: Dysphagia, perforation, foreign body, strictures, motility problems, malignancy
- Specific conditions: Zenker’s diverticulum, Barrett’s esophagitis, Hiatal hernia, etc
- Technique: biphasic esophagogram: Fluoroscopic swallowing studies
- Endoscopy now more common
- Zenker’s diverticulum: upper esophageal pouch (diverticulum). Rare, elderly, dysphagia, aspiration.
- barium is more common for looking at function, edoscopy is more common for looking for THINGS or masses
26
Normal Barium Swallow Indentations
1. aortic arch
2. left mainstem bronchus
3. esophagogastric junction
27
"apple core" lesion vs achalasia
- apple core: you have masses on the sides of the esophagus - “Apple core” type lesions also seen in the colon and rectum - high incidence malignancy
- achalasia: you have a stricture, narrowing, or closure of esophagus
28
Upper GI - SB follow through
-Timed oral contrast
Flouroscopy
-Ruggae of Stomach
Entire small bowel, esp terminal illeum
-Crohn’s Dz – see patchy
“skip lesions”, ulcers, “cobblestoning”
Can also dx Inflamatory Bowel Dz, masses, etc
29
Large Bowel - barium enema
- Colonoscopy is now the initial study for rectal bleeding, suspected malignancy
- CT w/ con not initial test for lesions inside the bowel
- Double Contrast study common: Barium + Air
- Barium enema still used for: Crohn’s dz, Ulcerative Colitis, Diverticular disease, Malignancy, Fistula formation, Intussusception
30
Endoscopy of the esophagus
- Same indications as for barium studies
- Biopsy possible during procedure
- Esophagitis
- Malignancy
- UGI Bleeds, Mallory Weiss Tear, Esophageal Varices, Boerhaave’s
- Swallowed FB’s
31
Endoscopy of the stomach
- May include proximal small bowel
- Biopsy possible during procedure
- Indications: Gastritis, gastric ulcers, Gastric Tumors, Gastric Outlet Obstruction, Post surgical
-Alternative: Video Capsule Endoscopy
32
Colonoscopy
- Bowel prep is key
- Same diagnostic indications as barium enema
- Screening for malignancy >50yo, family hx
- Rectal bleeding (painless)
- Stool abnormalities, Hx LBO
- Colitis: Crohn’s, Ulcerative Colitis
- Biopsy of suspicious lesions possible
33
Abdominal ultrasound
- Indications:
- Biliary system - best initial test: Gall Bladder, Gallstones, Common Bile Duct
- Bladder – urinary retention, post-void residual
- Kidneys – hydronephrosis, cystic masses, parenchyma
- Liver & Ascites - free fluid in abdomen, liver parenchyma
- Aorta – aneurysm
- Appendix – kids, adults too
- Trauma - free fluid in abdomen (FAST exam)
- BEST FIRST TEST FOR GALLBLADDER
34
Biliary system
- Where is the problem?
- Ultrasound - the first test
- ERCP: Endoscopic Retrograde Cholangiopancreatography
- MRCP: MR Cholangiopancreatogram, MRI images of biliary tree; no contrast needed
35
Cholecystitis on ULS: dx criteria
```
-Gallbladder wall
thickening
-Peri-cholescystic
fluid (black stripe)
-Sonographic
Murphy’s Sign
-Common Bile Duct dilation
>6mm diameter
-Gallstones commonly seen; “acalculous cholecystitis” possible
```
36
ERCP
- Endoscopy with Flouroscopy: Dye into Ampulla of Vater, past Spinchter of Oddi
- Biliary tree stones/obstruction, pancreas
- Malignancy
- Cholangitis
37
MRCP
- Same indications
- No contrast (T2)
- Non-invasive
- Can use gad in special situations
-Preferred if MRI available
38
HIDA Scan (biliary scan)
- HIDA scan = hepatobiliary iminodiacetic acid scan
- Nuclear medicine study
- Integrity of hepato-biliary tree
- Indications: Acute cholecystitis, Chronic tract disease, Congenital disease, Post operative bile leak/fistula, Assess liver transplant functioning
39
GU tract - kidneys/bladder
-Ultrasound – bladder (retention), kidney (hydronephrosis), formal study for renal parenchymal disease/kidney failure
-CT scan - renal/ureteral stones - no contrast
-IVP - intravenous pyelogram – structural abnormalities
Plain film (KUB) no longer used for renal stones
-Cystoscopy: Bladder cancer, recurrent infections
-Retrograde Urethrogram -> Flouroscopy, Urethral strictures, Trauma – urethra/bladder injury
40
Bladder ultrasound
- Indications:
- Bladder mass/cancer
- Urinary retention: Common w/ prostate enlargement, Measure volume of bladder before and after voiding = “post-void residual”, Helps guide foley placement, Urologist tx
- FAST exam: Looking for free fluid around the bladder
41
Hydronephrosis on ULS
- A ureteral stone (kidney stone passing downstream) obstructs the ureter. Kidney continues to produce urine, urine backs up into the ureter and renal pelvis = hydroureter (best on CT) and hydronephrosis (seen on US).
- Hydronephrosis is diagnostic for obstructing renal calculi.
42
Intravenous pyelogram (IVP)
-Plain KUB series after contrast. Evaluates the patency/efficiency
of the renal collecting system. Usually ordered by Urologists
43
Appendicitis on Ultrasound
-Thin pt? High frequency linear probe
Not thin? Low frequency curvilinear probe
- Classic location: RLQ (or where it hurts): Identify illiac crest, illiac artery, psoas muscle, cecum
- Can be hard to see it if not inflamed
- Positive findings:
* Dilated >6mm
* Non-compressible
* Thickened wall
* Peri-appendiceal fluid
44
free fluid: abdomen
- Ascites (cirrhosis, cancer, etc.): Ultrasound – best choice to identify/confirm ascites, CT w/ oral & IV contrast for cause (liver, etc…)
- Trauma: Ultrasound - FAST exam immediately, If FAST positive for fluid in trauma – assume blood
- Clinical scenario dictates both ultrasound and CT interpretation
