View source for Ultrasound: Pelvic

''See [[pelvic ultrasound (transabdominal)]] and [[pelvic ultrasound (transvaginal)]] for more detailed info on technique and findings''
==Background==
*Ultrasound is the preferred imaging modality for the female pelvic organs

==Indications==
*To evaluate female reproductive organs in pediatric patients or those that are not sexually active or refuse transvaginal exam
*Start with transabdominal ultrasound when evaluating to rule out ectopic (less invasive than transvaginal), particularly if bHCG >6,000

===General===
*[[Pelvic pain]]
*Abnormal pelvic or abdominal exam

===Uterus===
*[[Vaginal bleeding]]
*Fibroids
*IUD placement 

===Ovaries and adnexa===
*[[Ovarian cyst]]
*[[Ovarian torsion]]
*Ovarian masses
*[[Tubo-ovarian abscess]]
*Hydrosalpinx

===[[Pregnancy]]===
*Confirm intrauterine pregnancy
*Gestational dating 
*Fetal monitoring and surveillance
*Evaluation of placenta
*[[Spontaneous abortion]]
*[[Intrauterine fetal demise]]
*[[Ectopic pregnancy]]
*Heterotopic pregnancy
*[[Molar pregnancy]]


==Technique==
===[[pelvic ultrasound (transabdominal)|Transabdominal]]===
*3.5 MHz curvilinear probe
*Start above pubic symphysis in longitudinal axis
*Locate endometrial stripe (echogenic line) which represents the center of the uterus
*Scan through longitudinal axis of uterus and sweep laterally to try to visualize ovaries (though often difficult to visualize on transabdominal ultrasound)
*Rotate probe to transverse plane above pubic symphysis and scan through uterus from cervix to fundus
*Scan hepatorenal recess to assess for free fluid

===[[pelvic ultrasound (transvaginal)|Transvaginal]]===
====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

<gallery mode="packed">
File:longitudinal uterus.jpg|Uterus in longitudinal plane
File:cornual flare.jpg|Cornual flare (uterus and fallopian tube junction) in transverse plane
File:ovary with follicles.jpg|Normal ovary with follicles
</gallery>

==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

<gallery mode="packed">
File:secretory_endometrium.jpg|Normal thickened endometrial stripe during secretory phase
File:Menstrual_endometrium.JPG|Normal thin endometrial stripe during menses
</gallery>

===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
[[File:yolk sac.jpg|thumbnail|In a normal pregnancy, the gestational sac appears as a hypoechoic structure encircled by an echogenic border within the endometrial cavity at 4-5 weeks]]
[[File:IUP.jpg|thumb|IUP at 6 wks]]
<gallery mode="packed">
File:double_decidual_sac_sign.jpg|Double decidual sac sign
File:intradecidual sign.jpg|Intradecidual sign
File:double_bleb_sign.jpg|Double bleb sign (yolk sac and amniotic cavity)
File:fetal_pole.jpg|Fetal pole (Thickening of yolk sac on one side)
</gallery>

==Abnormal Findings==

===Abnormal Pregnancy===

*Gestational sac >10mm without visible yolk sac
*Gestational sac >18mm without fetal pole
*Collapsed gestational sac
*Pseudogestational 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"

<gallery mode="packed">
File:large gestational sac.jpg|Gestational sac greater than 10mm without yolk sac
File:Gestational_sac_without_fetal_pole.jpg|Gestational sac greater than 18mm without fetal pole
File:collapsed gestational sac.jpg|Collapsed gestational sac
File:pseudogestational sac.jpg|Pseudogestational sac
File:molar pregnancy.jpg|Molar pregnancy with multiple cystic lesions in endometrium ("snowstorm appearance")
</gallery>

====[[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:
{| {{table}}
| align="center" style="background:#f0f0f0;"|'''Cervical ectopic'''
| align="center" style="background:#f0f0f0;"|'''Spontaneous abortion at cervix'''
|-
| Hour-glass shaped uterus||Elongated gestational sac
|-
| Gestational sac with yolk sac, fetal pole, or heartbeat||Absent embryonic cardiac activity
|-
| Closed internal os||Dilated internal os
|-
| Color doppler showing hypervascular trophoblastic ring||Sac moves in cervix with gentle probing (“Sliding sac sign”)
|-
| Empty uterine cavity||Loss of sac on serial imaging
|-
| 
|}

<gallery mode="packed">
File:ectopic pregnancy.jpg|Ectopic pregnancy
File:free_fluid_ectopic.png|Free fluid in cul-de-sac with no gestational sac visualized in uterus
File:tubal ring.jpg|Ectopic pregnancy between ovary and uterus, suggestive of tubal ectopic
File:interstitial pregnancy.png|Interstitial pregnancy
File:cervical ectopic.jpg|Cervical pregnancy
</gallery>

===[[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 syndrome
*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)

<gallery mode="packed">
File:simple_cyst.jpg|Large ovarian cystadenoma
File:hemorrhagic_cyst.jpg|Hemorrhagic ovarian cyst with blood clot
File: ovarian_torsion 1.png|Large midline ovary with multiple peripherally located follicular cysts (torsion)
File:absent_waveforms.png|Absent color doppler and venous and arterial waveforms (torsion)
</gallery>

==Pearls and Pitfalls==
*Free pelvic fluid with positive hCG is ectopic pregnancy until proven otherwise
*Presence of doppler flow cannot rule out ovarian torsion

==See Also==

*[[Ultrasound (Main)]] 
*[[Pelvic ultrasound (transabdominal)]]
*[[Pelvic ultrasound (transvaginal)]]
*[[Ectopic Pregnancy]]

==References==
<references/>

[[Category:Radiology]] [[Category:OBGYN]]
[[Category:Ultrasound]]