Diagnostic Ultrasound - Abdomen and Pelvis

Enlarged Ovary
Differential Diagnoses: Female Pelvis
DIFFERENTIAL DIAGNOSIS
Common
• Polycystic Ovarian Syndrome (PCOS)
• Functional Ovarian Cyst
• Hemorrhagic Cyst
• Corpus Luteum/Luteal Cyst
Less Common
• Adnexal Torsion
• Benign Masses
○ Teratoma
○ Serous Cystadenoma
○ Mucinous Cystadenoma
○ Fibroma/Fibrothecoma
○ Endometrioma
• Ovarian Hyperstimulation
• Theca Lutein Cysts
• Tubo-ovarian Abscess
Rare but Important
• Malignant Masses
• Massive Ovarian Edema (MOE) and Ovarian Fibromatosis
(OF)
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
• Size
○ Normal ovary is typically 3 x 2 x 2 cm or ~ 10 ± 6 mL, max
22 mL
○ Postmenopausal ovary ~ 2-6 mL
• Generally differential categories
○ Endocrine
○ Neoplasm
○ Vascular
○ Iatrogenic
○ Infectious
• 1 approach is to think about differential as 2 major groups
○ Enlarged ovary with maintained architecture
○ Enlarged ovary because of lesion
Helpful Clues for Common Diagnoses
• Polycystic Ovarian Syndrome (PCOS)
○ Normal architecture with multiple small follicles of
uniform size
○ Echogenic stroma
○ Diagnostic criteria for polycystic ovarian morphology
– Volume ≥ 10 mL or
– ≥ 12 follicles measuring 2-9 mm
○ Polycystic ovarian morphology is seen in 22% of women
and is not diagnostic of PCOS alone
– Hyperandrogenism or oligo- or anovulation also
needed to fulfil Rotterdam criteria
○ Several other causes of polycystic ovarian morphology
• Functional Ovarian Cyst
○ Reproductive-aged women (premenopausal)
– Every month, 1 or more follicles are stimulated and
enlarge typically to 2.0-2.5 cm prior to ovulation
○ Thin wall, anechoic, no thick septa
○ Early postmenopausal women may have functional cyst
○ Late postmenopausal women should not have functional
cyst though may have inclusion or epithelial cyst
• Hemorrhagic Cyst
○ Typically, corpus luteum that has bled centrally
○ Avascular hypoechoic ovarian mass with fine, lacy
interstices
○ May have hyperechoic retracted clot at periphery
○ Avascular strands/septa
○ Majority resolve in 6-12 weeks
○ Follow-up ultrasound
– Premenopausal women follow-up at > 5 cm
– Postmenopausal women follow-up at any size
• Corpus Luteum/Luteal Cyst
○ Very commonly encountered ovarian lesion
○ Occur after ovulation in latter part of menstrual cycle
○ Thick, crenulated wall
○ Centrally may have anechoic fluid, hemorrhagic fluid, or
little fluid and may be mostly solid-appearing
○ Hypervascular rim/wall
Helpful Clues for Less Common Diagnoses
• Adnexal Torsion
○ Enlarged ovary: > 4 cm in longest dimension or > 20 cm³
in volume
○ Peripheral follicles, heterogenous stroma
○ Presence of normal blood flow does not exclude torsion
• Benign Masses
○ Teratoma
– Most common ovarian tumor
– 10-20% bilateral
– Heterogeneous cystic mass
– Echogenic shadowing mural nodule (Rokitansky
nodule)
– "Dirty" posterior acoustic shadow
– Dot-dash sign from hair suspended in sebum
– Shadowing calcification from teeth
○ Serous Cystadenoma
– Large unilocular cystic mass
– Typically > 7-10 cm
– Minimal to no septa
○ Mucinous Cystadenoma
– Often very large, filling entire pelvis, extending into
upper abdomen
– Multilocular unilateral cystic mass
– Thin avascular to thick vascular septa
– Echogenic fluid to variable degrees in each locule
○ Fibroma/Fibrothecoma
– Most common sex cord-stromal tumor
– Hypoechoic solid mass
– Dense posterior acoustic shadowing
– Meigs syndrome: Ascites and pleural effusion
associated with benign adnexal mass
○ Endometrioma
– Cystic adnexal mass with homogenous low-level
echoes
– Thick walled, may see echogenic foci in wall of cyst
– Generally unilocular but may have septations/folds
that are often incomplete
– Range in size from small (1-2 cm) to very large (> 10
cm)
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