Transvaginal Ultrasound in the Emergency Setting

Written by Ilyas Taraki, MS3

Edited by Drs. Molly Hartrich and Pavitra Kotini-Shah

Patient Positioning

In the absence of a gynecological stretcher with footrests, the patient may be placed supine on a hospital bed using an upside-down bedpan covered by sheets or chux to elevate the pelvis. Feet may rest on bed.

Dressing the Probe

Probe Insertion

Probe Orientation and Viewing

On the sagittal view, the indicator should always face anterior/upward.

In the sagittal view, the bladder may be seen anterior to the uterus (i.e. left of screen).

In the transverse view, the indicator should be rotated 90 degrees counterclockwise, to the patient’s right.

In transverse view, the bladder may be visualized inferior to the uterus (i.e. at top of screen, closest to the transducer).

Scanning Technique and Normal Anatomy

With the indicator oriented anteriorly (sagittal), sweep up/down and right/left to get whole view of uterus.

The uterus may be visualized as an echogenic endometrium of variable thickness surrounded by hypoechoic myometrium. The majority (~75%) of uteri are anteverted. A non-pregnant uterus is shown below in sagittal view:

Non-pregnant uterus, with structures labeled (source)

Reorient the probe indicator to the patient’s right (transverse view) and fan the probe toward the right adnexa. Fan anteriorly and posteriorly until the right ovary comes into view.

The ovary is said to appear as a “chocolate-chip cookie” on ultrasound due to the presence of follicles, as seen below:

"Chocolate chip cookie" appearance of the ovary (source, p. 152)

The iliac vessels may be seen along the pelvic walls lateral to the ovaries.

Return the probe to the sagittal view and fan right/left to examine the right ovary sagittally.

With the probe oriented sagittal, fan to the patient’s left to view left ovary in sagittal view. Fan right/left to view the left ovary sagittally.

Return the probe to transverse position and fan anterior/posterior to view left ovary in transverse.

Distinguishing IUP from NDIUP

To confirm IUP, on you must visualize a gestational sac, as confirmed by the presence of the following:

Additionally, there should be at least 8mm of endomyometrium; < 8mm may raise concern for ectopic implantation within the uterus itself.

You may also see a double decidual sign, which appears as 2 echogenic rings surrounding the gestational sac, as below; however, this sign alone is insufficient to confirm IUP. The decidual capsularis is the inner ring and the decidual parietalis is the outer ring. 

If beta-hCG is elevated, but an IUP cannot be confirmed on ultrasound, there is said to be no definitive IUP (NDIUP), which raises concern for ectopic pregnancy.

Ectopic Pregnancy

The discriminatory zone for IUP on TVUS is hCG ~3000; i.e. an IUP with hCG > 3000 should be visualizable on TVUS. However, the reliability of this cutoff is questionable; of greater importance is the clinical picture.

hCG positive + NDIUP on ultrasound = presumed ectopic until proven otherwise.

In this case, the presence of free fluid indicates rupture, which is a surgical emergency

Free fluid may be seen around the uterus or elsewhere in the abdomen (e.g. Morrison’s pouch):

Free fluid beneath the uterus (source, p.90)

Tubal ectopic pregnancy may show a tubal ring medial to the ovary (bagel sign):

If there is NDIUP but hCG < 1000 and vitals are stable, the patient can be discharged and reevaluated in 48 hours.

Ovarian Cysts

Ovarian cysts are cystic structures > 2.5 cm; they can be simple or complex. The most common causes of ovarian cyst are corpus luteum cysts and hemorrhagic cyst.

Most frequently they are benign, but cysts carry risk for:

Simple cyst appear as thin-walled cystic structures full of anechoic fluid. Complex cysts display multiple septations and internal echogenicity.

Simple ovarian cyst (source)

Complex ovarian cyst (source)

Ruptured cyst will cause free fluid; blood clots may be visualized as echoic structures within the free fluid (arrow):

Hemorrhagic cyst with free fluid and blood clot, indicated by arrow (Source)

Ovarian Torsion

In torsion, the ovary twists upon itself, causing obstruction of its vascular pedicles. Venous obstruction precedes arterial, causing ovarian engorgement (> 4cm) with edema. Torsion is a surgical emergency, and failure to intervene can lead to loss of the ovary and rupture with consequent peritonitis.

Doppler shows absent blood flow to the ovary or reduced flow compared to the contralateral ovary.

Normal doppler flow (source)

Absent doppler flow, indicating torsion (source)

Additionally, “whirlpool sign” may show a twisted ovarian pedicle:

Whirlpool sign, indicating ovarian torsion (source)

Tubo-ovarian Abscess (TOA)

Often a complication of pelvic inflammatory disease (PID), a TOA is a collection of pus involving the ovary and fallopian tube.

It appears as an ovarian mass with loculated purulent material (hypo-echoic):

Tubo-ovarian abscess (source)

Uterine Fibroids (Leiomyomata)

Uterine fibroids are growths of the muscular tissue of the uterus (myometrium). They are typically classified by location:

Fibroids appear as defined masses, usually hypoechoic, but of variable echogenicity based on the level of calcification. Small leiomyoma may appear only as a bulge in the uterine contour.

They are overwhelmingly benign but may cause pathology by mass effect.

A fibroid in sagittal view is shown below:

Fibroid in sagittal view (source)