Pelvic ultrasound (transvaginal)

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Background

  • Also known as endovaginal ultrasound
  • Used to evaluate female reproductive organs including uterus, ovaries, fallopian tubes, cervix, and vagina

Indications

General

  • Pelvic pain
  • Abnormal pelvic or abdominal exam

Uterus

Ovaries and adnexa

Pregnancy

Technique

General

  • Use 5 MHz endocavitary probe (high frequency, low penetration)
  • Apply surgical lubricant inside and outside probe cover
  • Place patient in lithotomy position
  • Gently advance probe into vaginal canal and position adjacent to cervix
    • May be more comfortable for patient to insert probe into vagina herself
  • Apply gentle pressure to lower abdominal wall with one hand and manipulate probe with other hand

Longitudinal scan

  • Probe marker pointing at 12:00
  • Shows anterior structures on left side of screen
  • Begin midline at endometrial stripe
  • Scan from right to left through uterus
  • Move probe laterally to view adnexa and ovaries

Transverse scan

  • Rotate probe 90 degrees counterclockwise so probe marker is pointing at 9:00
  • Shows right-sided structures on left side of screen
  • Start at endometrial stripe and scan throughout uterus
  • Locate cornual flare (junction of uterus and fallopian tubes)
  • Move probe laterally along fallopian tube to locate ovary
  • Ovaries identified by follicular (anechoic or hypoechoic) structures

  • Uterus in longitudinal plane

  • Cornual flare (uterus and fallopian tube junction) in transverse plane

  • Normal ovary with follicles

Normal Findings

Uterus

  • Anteverted: Fundus pointing to anterior abdominal wall
  • Retroverted: Fundus pointing to posterior wall
  • Endometrial stripe: Measured from thickest echogenic area (from one basal endometrial interface to the other, including canal)
    • Pre-menopausal:
      • During menstruation: 2-4mm
      • Early proliferative phase: 5-7mm
      • Late proliferative phase: 11mm
      • Secretory phase: 7-16mm
      • After D&C or SAB: >5mm
        • Consider retained POC if thicker
    • Post-menopausal:
      • With vaginal bleeding: <5mm
      • Without vaginal bleeding: <11mm

  • Normal thickened endometrial stripe during secretory phase

  • Normal thin endometrial stripe during menses

Ovaries

  • Physiologic cysts present
    • <3 cm diameter
    • Ovarian follicle or corpus luteum
    • Typically don't cause complications

Pregnancy (1st trimester)

  • 4-5 weeks
    • Gestational sac
      • First sign of early pregnancy, usually seen between 3-5 weeks gestation
    • "Double decidual sac" sign
      • Two concentric rings (uterine lining and gestation lining) around anechoic gestational sac)
      • Highly suggestive of intrauterine pregnancy (before yolk sac or embryo embryo visualized
    • "Intradecidual sign"
      • Thickened decidua on one side of uterine cavity surrounding anechoeic sac
  • 5-6 weeks:
    • Yolk Sac
      • Circular (or sometimes as two parallel lines) echogenic structure with thick walls within gestational sac
      • Definitive evidence of intrauterine pregnancy
      • Multiple yolk sacs is earliest sign in multiple gestational pregnancy
    • "Double bleb" sign
      • Yolk sac and amniotic cavity that look like two bubbles within gestational sac
  • 6-7 weeks
    • Fetal Pole
      • First visual manifestation of fetus (or "embryo")
      • Thickening of margin on yolk sac
    • Cardiac activity present (FHR ~100-115 bpm)
    • Crown rump length: ~5mm
  • 8-9 weeks
    • Limb buds appear
    • Head identifiable
  • 9-10 weeks
    • FHR ~170-180 bpm
    • Fetal movement visible
    • End of embryonic period

  • Double decidual sac sign

  • Intradecidual sign

  • Double bleb sign (yolk sac and amniotic cavity)

  • Fetal pole (Thickening of yolk sac on one side)

Abnormal Findings

Abnormal Pregnancy

  • Gestational sac >10mm without visible yolk sac
  • Gestational sac >18mm without fetal pole
  • Collapsed gestational sac
  • Pseudgestational sac
    • Endometrial breakdown during ectopic pregnancy
    • May be erroneously interpreted as true gestational sac in ectopic pregnancy
    • Irregularly shaped
    • Located in endometrial cavity, instead of eccentrically within endometrium
    • No yolk sac present
    • May not have double decidual sac sign
  • Absence of fetal heart beat in embryo with CRL >5mm
  • FHR <90 bpm
  • Molar pregnancy
    • Many small, irregular cystic structures in endometrium
    • "Snowstorm appearance"

  • Gestational sac greater than 10mm without yolk sac

  • Gestational sac greater than 18mm without fetal pole

  • Collapsed gestational sac

  • Pseudogestational sac

  • Molar pregnancy with multiple cystic lesions in endometrium ("snowstorm appearance")

Ectopic pregnancy

  • Implantation of blastocyst outside of endometrium
  • Occur in fallopian tubes, cervix, ovaries, peritoneal cavity, or scar of prior uterine surgery
  • Most definitive sonographic sign is gestational sac with yolk sac, embryo, or fetal heart beat outside of the endometrium
  • Tubal pregnancy
    • "Tubal ring" sign: echogenic thick-walled anechoic sac visualized between uterus and ovary (separate from ovary when pressure applied to fallopian tube with probe)
  • Interstitial Pregnancy
    • Implantation of gestational sac in muscular wall of uterus at proximal regional of fallopian tubes
    • "Interstitial line" sign: hyperechoic line from endometrial stripe to cornual region adjacent to interstitial gestational sac
  • Cervical Pregnancy
    • Implantation of gestational sac below internal cervical os
    • Can cause life-threatening hemorrhage
    • Must distinguish between cervical ectopic and spontaneous abortion at level of cervix:

______

  • Ectopic pregnancy

  • Free fluid in cul-de-sac with no gestational sac visualized in uterus

  • Ectopic pregnancy between ovary and uterus, suggestive of tubal ectopic

  • Interstitial pregnancy

  • Cervical pregnancy

Ovarian Torsion

  • Bimodal age distribution: young women (15-30yo) and post-menopausal women
  • Typically occur in enlarged ovaries (>5cm)
    • Benign mature cystic teratomas
    • Hemorrhagic/large ovarian cysts
    • Cystic neoplasms
    • Cystadenomas
    • Polycystic ovarian syndome
  • Sonographic signs associated with torsion
    • Enlarged ovary from edema, engorgement, hemorrhage
    • Midline ovary
    • Free pelvic fluid
    • Underlying ovarian lesions
    • Peripherally displaced follicular cysts
    • Doppler findings:
      • Decreased/absent venous or arterial flow
      • Absent/reversed diastolic flow
      • Can have normal flow (from dual supply from uterine and ovarian arteries)

  • Large ovarian cystadenoma

  • Hemorrhagic ovarian cyst with blood clot

  • Ovarian torsion.png

    Large midline ovary with multiple peripherally located follicular cysts (torsion)

  • Absent color doppler and venous and arterial waveforms (torsion)

Pearls and Pitfalls

  • Free pelvic fluid with positive hCG is ectopic pregnancy until proven otherwise
  • Presence of doppler flow cannot rule out ovarian torsion

Documentation

Normal Exam

Abnormal Exam

Clips

External Links

See Also

References

  • www.radiopaedia.org
  • www.acep.org/sonoguide
  • www.fetalultrasound.com
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