Diagnostic Ultrasound - Abdomen and Pelvis

Functional Ovarian Cyst
Diagnoses: Female Pelvis
TERMINOLOGY
• Follicular cyst (FC) forms from persistent follicle, ovulation
does not occur
• Corpus luteum cyst (CLC) forms from graafian follicle
following ovulation
IMAGING
• Follicular cyst
○ Intraovarian cystic lesion with thin walls
• Corpus luteum cyst
○ Occur after ovulation in latter part of menstrual cycle
○ Thick, hyperechoic wall
○ Central anechoic/hypoechoic cavity
○ Marked vascular flow within CLC wall: "Ring of fire"
appearance
○ Commonly complicated by hemorrhage
TOP DIFFERENTIAL DIAGNOSES
• Ectopic pregnancy
KEY FACTS
○ "Ring of fire" but separate from ovary, usually tubal
• Ovarian neoplasm
CLINICAL ISSUES
• Follicular and CL cysts occur during reproductive years
○ FL and CLC≤ 5 cm:No follow-up necessary
○ FL and CLC > 5 and ≤ 7 cm: Annual follow-up ultrasound
• Further imaging or surgical evaluation recommended with
simple cyst > 7 cm
• CLC may enlarge initially with fertilization and pregnancy
○ Most no longer seen by sonography by early 2nd
trimester (16 weeks)
• Malignancy rate in unilocular simple cysts < 1%
DIAGNOSTIC CHECKLIST
• Majority of functional ovarian cysts will resolve
spontaneously
• Even if CLC is persistent, may monitor through pregnancy if
no malignant features
(Left) Typical appearance of a
simple functional ovarian cyst
ſt is shown. The peripheral
follicles within the
surrounding parenchyma st
confirm this is an intraovarian
cyst. (Right) The "ring of fire"
appearance is associated with
marked vascular flow within
the corpus luteum cyst (CLC)
wall on color Doppler. In this
case, the CLC is centrally
hypoechoic due to internal
hemorrhage .
(Left) A thick-walled CLC can
appear crenulated or
decompressed after ovulation
(calipers) is seen here on
grayscale transvaginal US.
(Right) CLC can be exophytic
from the ovary ſt; look for
the bridging ovarian
parenchyma . Commonly
associated hemorrhage,
retracted clot can also be
present within a CLC .
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