In fact, in patients with large abnormalities, very distorted anatomic features and abnormalities more than 8 cm from the TV probe, the TV study may miss the findings or the TV findings may be misinterpreted in the absence of a TA study. It has not been shown that the TV examination should be performed instead of the TA study for an initial pelvic study. For example, a woman with normal ovaries but with a strong family history of ovarian cancer should have a TV study. However, the TV study should always be considered when the TA findings are uncertain or when a patient has normal findings but is at high risk for abnormalities. If the TA study findings are deemed completely normal or a well-defined anomaly and its site of origin are detected, it is often possible to stop the examination. This allows visualization of the entire pelvic area. It is therefore recommended that TA scanning be performed first in a patient who has not undergone a previous pelvic ultrasound study. A mass that is high in the pelvis, beyond the field of view of the TV probe, will be missed. These exceptions generally are attributable to the limited field of view afforded by TV ultrasound. There are, however, exceptions in which TA ultrasound detects an abnormality not seen at TV ultrasound ( Fig.

In general, TV ultrasound has been found to be superior for identifying and characterizing most lesions ( Figs. The TA and TV techniques have been compared in their abilities to image the adnexa to determine which is better for the following: to identify an abnormality, to analyze its ultrasound characteristics, and to determine its site of origin. The transducer is typically placed only part of the way into the vagina, and there is no undue pressure on the adnexal regions. Second, although there are no universally established contraindications to TV scanning, it is recommended that TV sonography not be done in patients who have never been sexually active. In both cases it may be necessary to turn the probe a full 180 degrees. The left adnexa can be similarly difficult to image when the probe is turned toward the right in the axial-coronal plane. Although this is excellent for evaluating anteverted structures in their long axis, it can cause difficulties in imaging ovaries when they are positioned posteriorly. First, the TV transducer beam usually exits from the probe at an angle. Two issues with regard to TV scanning discussed in Chapter 22 need reemphasis. Axial-coronal views of the adnexa are then obtained. After the long axis of the uterus is identified, parallel sagittal scans are obtained laterally to image the long axis of the adnexa and identify the ovaries. Sonographically, the technique for evaluating the adnexa is the same for both the TA study performed through the distended urinary bladder and the TV examination performed with the bladder empty. Hertzberg MD, FACR, in Ultrasound (Second Edition), 2004 TRANSABDOMINAL VERSUS TRANSVAGINAL SCANNING

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