Endovaginal ultrasound-guided interventional procedures are an important tool for the interventionist. These procedures are typically well tolerated by women and can be performed with local anesthesia or no anesthesia at all. Lesions located within the central pelvis, which can be difficult to access by the usual percutaneous transabdominal or transsciatic methods, can often be easily and safely accessed with the endovaginal technique. Real-time needle visualization and no ionizing radiation are additional benefits of endovaginal ultrasound guidance.

• Biopsies of adnexal masses, iliac nodes, and vaginal cuff
  
• Aspirations and drainages of endometrial fluid collections
  
• Pelvic fluid collections and abscesses

• Prepubescent girls and women with vaginal stenosis

• Women who are not sexually active

• For most fine-needle aspirations and biopsies, antibiotic prophylaxis is usually not necessary. Antibiotic prophylaxis may be prudent in certain patients, such as patients with prosthetic heart valves and artificial joint replacements because it can be difficult to sterilize the vaginal vault.
  
• In patients undergoing a pelvic abscess drainage procedure, appropriate antibiotic coverage is usually recommended prior to starting the procedure.

• Place the patient on a cart in lithotomy position, lying supine with feet placed in stirrups or other foot supports.
  
• If a cart with foot supports is not available, the patient should flex hips and bend knees so that feet are close to hips.
  
• The patient should spread her legs and relax her hips.
  
• Place several folded towels or sheets under the patient’s hips to raise the hips ∼10 cm above the bed, allowing more freedom of motion of the ultrasound probe within the vagina.

Positioning is particularly important if the target is located in the anterior aspect of the pelvis. To direct the probe tip toward the anterior pelvis, the probe handle must be moved posteriorly. Raising the patient’s hips with the folded sheets makes it easier to move the probe handle posteriorly. Otherwise, the cart or table that the patient is lying on will prohibit the interventionist from moving the probe handle posteriorly.

• Use one of the commercially available guides. Most will accept up to 18-gauge needles.
  
• The redundant vaginal wall can be difficult to penetrate. Exert enough pressure on the endovaginal probe to “tent” the vaginal wall (easier for the needle to penetrate the vaginal wall).
  
• With the commercially available guide, use 20-cm or longer needles. Be sure needle length extending beyond the needle guide is sufficient to reach the target by measuring the distance to the lesion before placing the needle.
  
• For lesions that are beyond the reach of the 20-cm needle, get a 30-cm (or longer) single-step trocar-based catheter, discard the outer catheter, and use only the metal stiffener with the trocar needle in the needle guide of the endovaginal probe.

• Use a 20-gauge Chiba needle
  
• Instill 1–2 cc 1% lidocaine as a local anesthetic in the appropriate site in the vaginal wall

It can be difficult to have subsequent needle passes enter the vaginal wall at the same site; therefore, it is important to use other landmarks in the pelvis (i.e., vessels, the bladder wall) to help ensure needle penetration at or near the lidocaine wheal. A fine-needle aspiration (FNA) also allows one to assess the vascularity of a lesion directly. With most FNAs, only a few drops of blood or no blood at all may come out while the needle is within the lesion. If several milliliters or more of blood are aspirated during the performance of the FNA, then this suggests that the lesion is quite vascular. For such vascular lesions, it may be prudent to defer performing a cutting needle biopsy to avoid a potential bleeding complication. Alternatively, if a cutting needle is needed, one could perform a core needle biopsy, but with a small needle, such as a 20-gauge cutting needle or smaller.