Abstract
When performing ultrasound examination, there are times when the views are not optimal. This chapter will highlight such situations and help one to recognize them. This chapter aims to describe the findings and possible suggestions, which may help to optimize the ultrasound imaging. Following the basic principles as described in Chapters 1 and 2 will go a long way to helping with difficult cases, and these will be reinforced in each scenario described below. While reporting the findings, acknowledging the limitations of the scan findings is very important, especially as many clinicians will be managing the patients on the basis of the report only.
When performing ultrasound examination, there are times when the views are not optimal. This chapter will highlight such situations and help one to recognize them. This chapter aims to describe the findings and possible suggestions, which may help to optimize the ultrasound imaging. Following the basic principles as described in Chapters 1 and 2 will go a long way to helping with difficult cases, and these will be reinforced in each scenario described below. While reporting the findings, acknowledging the limitations of the scan findings is very important, especially as many clinicians will be managing the patients on the basis of the report only.
The Awkward Uterus
Ultrasound images of the uterus in an axial position are not optimal. In the axial position the end-on view of the body of the uterus in relation to the probe leads to image artefacts and poor image resolution, which does not allow for good-quality images. The axial uterus is more likely to be associated with the presence of a Caesarean scar, pelvic adhesions or large leiomyomas. The cervix and cervical canal will generally be easily accessible with scan and the image quality will be good, but the body of the uterus may align axially or even retroflexed, making it difficult to get good images of the body of the uterus or any endometrial details (Figure 3.1).
It is often observed that the end-on view of the endometrium in an axial uterus may give an echogenic appearance even in the follicular phase of the cycle. Bimanual manipulation with the ultrasound probe may help at times. Applying gentle pressure on the cervix with the transvaginal scanning (TVS) probe where the uterus is mobile will help to correct to an anteverted or a retroverted uterus, hence improving the image quality. At times, bimanual examination with the probe may correct an axial uterus to an anteverted or retroverted one, thus improving the visibility. It is important to emphasize that this should be done gently, after a rapport is built up with the patient and letting her know that you are applying gentle pressure. This will minimize pain or discomfort for the patient and will allow for completion of the study. On occasion, it may be possible to alter the flexion and version of an axial uterus for the duration of the scan by asking the patient to have a full bladder. This may be uncomfortable, hence all other structures should be scanned and the patient asked to come back with a full bladder. The bladder may push the axial uterus and make it appear retroverted and retroflexed, thus allowing for an easier assessment of endometrial details. In women with uterine prolapse the correction is easy with application of gentle pressure with the ultrasound transducer. Where there is restricted mobility due to adhesions or large fibroids, any correction of uterine flexion or version may not be possible, and in such situations only slight correction may be the best one can achieve (Figure 3.2). This slight correction, along with abdominal pressure with the left hand while doing the scan with the right hand, may enable you to improve the quality of the image. An abdominal scan with an under-filled bladder may allow for a better visualization of the uterus and the endometrium, but good results can only be obtained in women with a normal BMI.
Figure 3.2 Partial correction of axial uterus with previous LSCS scan with IUCD in the uterine cavity using bimanual pressure with the TVS probe.
Assessment of endometrial pathology in women with very large fibroid uteri may never be possible using ultrasound. In some cases, even demonstrating the endometrial stripe is very difficult with conventional ultrasound; however, tracing the cervical canal into the cavity can be helpful (Figures 3.3–3.6). Contrast-enhanced sonography with gel or saline may allow for visualization of the endometrial cavity, relationship of the cavity to the fibroids and even assessment of fine details of the endometrium (Figure 3.7). Adjustment of depth where there are large fibroids or cysts will help in visualization of the whole lesion (Figure 3.8). Contrast-enhanced ultrasound is described in detail in Chapter 6. Where ultrasound fails to demonstrate endometrial details or for fibroid mapping for larger lesions before surgery, magnetic resonance imaging (MRI) is indicated as the imaging of choice.
Figure 3.6 Anterior submucous fibroid (calipers) with degenerative changes (hypoechoic area; thick arrow) impinging on the endometrium.
The Awkward Ovaries
Following basic principles as described in Chapter 1, it is easy to find ovaries, especially in the reproductive age group. For women who are postmenopausal, have had adhesions following previous surgery or pelvic infection, it may be difficult to localize the ovary. Large fibroids with calcification also can make it difficult to clearly see the ovaries due to shadowing. Following the landmarks described in Chapter 2, especially a thorough assessment of the area medial to common iliac vessels, may result in identification of the ovary. The most useful feature is bimanual examination with the left hand while scanning with the transvaginal probe. Generally, the bowel tends to be displaced and the ovary comes into view. Once the ovary is seen, by sustaining pressure the left hand can be released to increase the depth and freeze the image. At times releasing the left hand may lose the image of the ovary and in such situations an assistant is needed to freeze the image captured, or the patient is asked to press on the abdomen while the person scanning captures the image. The former is the preferred option.
Occasionally the ovary will be located behind the uterus (Figure 3.9). Increasing the depth to get a ‘panoramic overview’ of the pelvis will help to localize the ovary in such instances. When seen behind the uterus and if the ovary is mobile, it can be displaced laterally with gentle sustained pressure to get better images (Figures 3.10, 3.11). When mobility is restricted due to adhesions, this pressure may be associated with tenderness or discomfort (Figure 3.12). This could be worse if a myomectomy scar is present or a large lateral fibroid is obstructing the view. Using the penetrative frequency is preferred as the ovary is at a depth behind the uterus.
