Diagnostic Ultrasound - Abdomen and Pelvis

Parovarian Cyst
Diagnoses: Female Pelvis
TERMINOLOGY
• Cyst originating from wolffian duct in mesosalpinx or broad
ligament
IMAGING
• Transvaginal ultrasound is study of choice
○ Round or oval cystic structure separate from ovary
○ Thin outer wall (< 3 mm)
○ Often unilateral
○ Lack of follicles distinguishes from ovary
○ Usually does not indent the ovary
○ Mean diameter: 40 mm (range: 15-120 mm)
○ Fluid is anechoic in 91%
○ May contain septa that are thin, smooth, complete
○ Rarely may be complicated by torsion or hemorrhage
• MR
○ Hypointense on T1WI and hyperintense on T2WI
○ If complicated by torsion or hemorrhage, hyperintense
on T1WI with thick walls
KEY FACTS
○ If soft tissue component, consider neoplasm
TOP DIFFERENTIAL DIAGNOSES
• Peritoneal inclusion cyst (PIC)
• Hydrosalpinx
• True ovarian cyst
PATHOLOGY
• Benign serous cyst in 98%
• Malignant features in 2%
CLINICAL ISSUES
• Asymptomatic in most women
DIAGNOSTIC CHECKLIST
• MR superior for identification of normal ovary when origin
of large lesion cannot be determined with ultrasound
(Left) Longitudinal
transvaginal ultrasound shows
the right ovary ſt with an
adjacent paraovarian cyst st.
On real-time scanning, they
were separable with probe
pressure. (Right) Longitudinal
color Doppler ultrasound of
the same paraovarian cyst
now shows mural nodules
and debris related to
recent hemorrhage.
(Left) Transverse
transabdominal ultrasound
shows a large simple cyst ſt
arising out of the pelvis. The
origin could not be
determined. The normal aorta
and vena cava st are seen.
(Right) Axial T2 TSE of the
large cystic mass in the pelvis
shows that the left ovary ſt is
normal and separate from the
very large paraovarian cyst
st. The right ovary was also
seen to be separate and
normal (not shown).
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