Pelvic ultrasound was first introduced into the acute care setting to answer simple yes or no questions such as "Is there an intrauterine pregnancy?" Pelvic ultrasound applications in the emergency setting have now expanded to include the nonpregnant patient. The improvement in skills now allows the clinician to evaluate for other pelvic pathology such as adnexal cysts or masses, ovarian torsion, fibroids, or tuboovarian abscesses.
The complaint of abdominal or pelvic pain in the young female patient comprises a significant number of the total emergency department visits throughout most institutions. Both transabdominal ultrasound (TAUS) and transvaginal ultrasound (TVUS) can help the physician diagnose the cause of these complaints and can guide clinical decisions and expedite patient care. While point-of-care pelvic ultrasound is a very useful tool in the acute care setting, it still remains focused and is not intended to examine all potential pathology.
Bedside ultrasound evaluation of the female pelvis should be performed in:
- The pregnant patient who presents with pelvic or abdominal pain
- The pregnant patient who presents with vaginal bleeding
- The pregnant trauma patient
- The nonpregnant patient who presents with pelvic or lower abdominal pain with suspicion for a gynecological cause
Curvilinear Probe with a Frequency of 3.5–5.0 MHz
A wide footprint curvilinear probe is appropriate for transabdominal pelvic imaging. This probe has a lower frequency with better penetration, which is suitable for imaging the pelvic organs through the abdominal wall. Smaller footprint or phased array probes may be used for transabdominal pelvic imaging but are not optimal.
Endocavitary Probe with a Frequency of 8.0–13.0 MHz
The endocavitary probe has a higher frequency, which produces an image with better resolution. It also has a wider field of view and provides more detail. It is used for all transvaginal pelvic scanning, especially when the structure of interest is not visualized well using transabdominal imaging alone, such as in an early intrauterine pregnancy (IUP) or in evaluation of the adnexa.
In TAUS the sonographer should start with a deeper field and survey the areas surrounding both the uterus and bladder. This is important in the evaluation for free fluid, which will appear in the most dependent areas first, posterior to the uterus. Also, a deeper field allows the sonographer to better evaluate the adnexa for pathology. Once the far field is completely evaluated, the depth can be decreased so that the uterus appears more superficial and intrauterine structures better visualized.
The zoom control allows for magnification of a particular portion of the image being scanned. This becomes important when attempting to visualize small structures, such as obtaining the fetal heart rate (FHR) of an early pregnancy. The zoom function can sometimes distort the image, therefore the depth should be optimized first before the image is magnified.