Diagnostic Ultrasound - Abdomen and Pelvis

Abdominal Wall Hernia
Diagnoses: Abdominal Wall/Peritoneal Cavity
○ CT most useful for large or complex hernias or in larger
patients: Better for bowel complications
○ MR similar anatomic information to CT but dynamic
• Protocol advice
○ Identify anatomical layers, localize focal abdominal wall
defect, compare with opposite side (if possible), and
identify hernial contents
– Use light transducer pressure to minimize reduction
of hernia
– Routine use of Valsalva maneuver to accentuate
hernia and examine contents
– Examine in standing position if this clinically
accentuates hernia or if no hernia detected while
supine
– Measure size of hernial sac and fascial defect
– If bowel content, check for complications
(irreducibility/obstruction/strangulation)
DIFFERENTIAL DIAGNOSIS
Abdominal Wall Tumor
• Primary (lipoma, desmoid tumor, endometriosis) or
secondary tumor (scar metastasis, melanoma metastases,
Sister Mary Joseph nodule)
• Differentiate by location, lack of fascial defect or change
with Valsalva
• Thin capsule encircling lipoma distinguishes it from fat
herniating through an abdominal wall defect (also has a
neck)
Abdominal Wall Abscess or Seroma
• No fascial defect present
Abdominal Wall or Rectus Sheath Hematoma
• Post-traumatic or spontaneous: Bleeding of epigastric
vessels or muscle tear
• No fascial defect present, no change with Valsalva
Divarication (Diastasis) of Rectus Abdominis Muscles
• Bulging of abdominal cavity due to stretching and thinning
of linea alba
○ Particularly in elderly multiparous women
Dilated Abdominal Wall Vessels
• Compressible, tubular, vascular flow
Suture Granuloma
• Incisional, lack of fascial defect or change with Valsalva
• Echogenic internal suture may be detected
PATHOLOGY
General Features
• Etiology
○ Primary: Congenital defect; epigastric and umbilical
○ Secondary
– Weak abdominal wall musculature
□ Chronic increased intraabdominal pressure,
abdominal distension (cirrhosis, ascites), muscle
laxity (obesity, old age, pregnancy)
□ Physical exertion, chronic cough, prostatism, or
constipation
– Trauma: Blunt force or hyperextension strain
□ Sudden ↑ in intraabdominal pressure
□ Insufficient to penetrate skin but strong enough to
disrupt muscle and fascia
– Postoperative abdominal wall weakness, surgical scar,
suture dehiscence, wound infection
CLINICAL ISSUES
Presentation
• Most common signs/symptoms
○ Abdominal bulge increasing in size with ↑ in
intraabdominal pressure
○ Reducible swelling, positive cough impulse
○ Discomfort, pain, intermittent intestinal obstruction
Demographics
• Age
○ Umbilical hernia: Young children
○ Paraumbilical hernia: Adults
○ Epigastric hernia: 20-50 years
○ Incisional hernia: More frequent in elderly
• Gender
○ Epigastric hernia is 2x more common in males
• Epidemiology
○ Most common abdominal wall lesion seen in ultrasound
practice
Natural History & Prognosis
• ~ 1/3 of umbilical hernias close within 1 month of birth and
rarely persist beyond 3-4 years
• All other hernias persist and frequently enlarge with time
• 20% need emergency repair for incarceration and
strangulation
○ Less common with very small (< 1 cm) or very large
hernia necks
Treatment
• Repair of muscle/fascial defect: Open or laparoscopic
technique, meshplasty
• Intestinal obstruction/strangulated hernia; urgent
exploratory laparotomy
DIAGNOSTIC CHECKLIST
Consider
• Abdominal wall hernia if posterior margin of any abdominal
wall mass cannot be seen on ultrasound
Image Interpretation Pearls
• Check for abdominal wall defect, hernial sac contents,
peristaltic movement, and vascularity (if bowel)
SELECTED REFERENCES
1. Murphy KP et al: Adult abdominal hernias. AJR Am J Roentgenol.
202(6):W506-11, 2014
2. Yeh DD et al: Hernia emergencies. Surg Clin North Am. 94(1):97-130, 2014
3. Arend CF: Static and dynamic sonography for diagnosis of abdominal wall
hernias. J Ultrasound Med. 32(7):1251-9, 2013
4. Lee RK et al: Ultrasound of the abdominal wall and groin. Can Assoc Radiol J.
64(4):295-305, 2013
5. Stavros AT et al: Dynamic ultrasound of hernias of the groin and anterior
abdominal wall. Ultrasound Q. 26(3):135-69, 2010
6. Muysoms FE et al: Classification of primary and incisional abdominal wall
hernias. Hernia. 13(4):407-14, 2009
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