Diagnostic Ultrasound - Abdomen and Pelvis

Tubo-Ovarian Abscess
TERMINOLOGY
Definitions
• Pelvic inflammatory disease (PID)
○ Spectrum of disease including endometritis, salpingitis,
tubo-ovarian abscess, and oophoritis
○ Usually sexually transmitted disease involving organism
such as Chlamydia trachomatis or Neisseria gonorrhoeae
but can also be polymicrobial
○ Can occur from extension of inflammation from adjacent
organs such as appendicitis, diverticulitis, and colitis
• Pyosalpinx
○ Tube distended with pus
• Tubo-ovarian complex (TOC)
○ Abscess adherent to tube
○ Distinguishable separate ovary
• Tubo-ovarian abscess (TOA)
○ Abscess involving tube and ovary
○ Separate ovary no longer distinguishable
IMAGING
General Features
• Best diagnostic clue
○ Pyosalpinx: Tubular fluid-filled structure with incomplete
septa
○ TOA: Painful complex cystic adnexal mass
• Location
○ TOA often bilateral, infection spreads from 1 side to
other, often in posterior cul-de-sac
○ Early PID is unilateral
Ultrasonographic Findings
• Thickened dilated fallopian tubes
○ Distal obstruction causes distention
– Distended serpiginous, ovoid or pear-shaped tube
○ Complex fluid
– Layering debris common ± gas
○ Thickened tube walls, often > 5 mm
○ Thickened endosalpingeal folds: Cogwheel sign in cross
section
○ Incomplete septa: Distended tube folding on itself
• Inflammation of ovaries
○ Enlarged edematous ovary
– Separate from tube but may be adherent to tube in
later stage
– ↑ number and size of follicles
○ Tubo-ovarian abscess
– Complex adnexal mass, ovary not recognizable
– May still see components of pyosalpinx
• Complex pelvic fluid collection
○ Can be seen early
○ Can form pelvic abscess
• Doppler ultrasound findings
○ Increased color Doppler flow of walls and folds of tube
or ovary
○ Pulsed Doppler: Low-resistive flow
• Sonographic findings resolve quickly with treatment
○ Pyosalpinx → hydrosalpinx → ± resolution
○ Complex pelvic fluid resolution
CT Findings
• CT often ordered 1st with generalized or vague lower
abdominal pain
○ Early findings subtle
– Mild pelvic edema resulting in thickening of
uterosacral ligament
– Haziness of pelvic fat, obscured pelvic fascial planes
○ Inflammation/thickening of tube due to mild salpingitis
○ Enlarged abnormally enhancing ovaries due to oophoritis
○ Endometritis: Fluid in uterine cavity with abnormal
uterine enhancement
• More advanced disease: Inflammatory changes seen better
○ Difficult to differentiate between pyosalpinx, TOC, and
TOA
○ TOA and pelvic abscess
– Thick-walled complex fluid collection
• Involvement of adjacent structures
○ Ureteral obstruction
○ Secondary inflammation of other organs
• Fitz-Hugh-Curtis syndrome
○ Peritoneal spread of infection to perihepatic surfaces
and right lobe of liver
– Pouch of Douglas → paracolic gutter → peritoneum
– Right upper quadrant pain presentation
– Hepatic capsular enhancement
– Transient hepatic attenuation difference on anterior
hepatic surface
– Hepatic capsular retraction and adhesions
• Complicated ascites
Imaging Recommendations
• Best imaging tool
○ Transvaginal ultrasound
○ Transabdominal ultrasound of pelvis for large/extensive
abscesses
• Protocol advice
○ Acute PID has subtle, nonspecific findings
○ Use probe pressure to diagnose tubo-ovarian complex
– Do ovary and tube move together or apart?
– Increase gain settings to see echoes of complex fluid
collection in pelvis
○ Evaluate abdomen with US when pelvic findings are
extensive
– Consider CT to evaluate full extent of abnormalities or
for complex disease
– Complex fluid may ascend: Evaluate perihepatic
region
– Look for hydronephrosis
MR Findings
• T1WI
○ ± fat suppression useful for differentiation of blood/pus
from simple fluid
– Addition of contrast helps distinguish collections,
inflammation, pyosalpinx
• T2WI
○ High signal fluid in dilated tubes and abscesses
○ Improved conspicuity of inflammation and free fluid
○ Pyosalpinx: Fluid-filled, dilated tortuous tubular structure
○ Abscess: Thick-walled complex cystic mass in the adnexa
Diagnoses: Female Pelvis
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