Monthly Archives: September 2019

Double Bladder Sign

In a female patient presenting with lower abdominal pain, abnormal ovarian (cyst) location, that is, in midline above the uterus and adjacent to urinary bladder on transabdominal scan suggests ovarian torsion. As both bladder and the cyst are anechoic structures, it appears as if there are two bladders next to each other. In addition, watch for free fluid in the pouch of Douglas.

Why talking about cyst? Note that torsion is usually associated with an ovarian cyst that twists along the infundibulopelvic ligament and pedicle, subsequently compressing the ovarian vein and artery leading to stromal edema and ovarian enlargement. Presence of the cyst is a clue to ovarian location as the ovarian tissue itself is not clearly visualized on abdominal scans.

Lung contusion

While nephrologists are not the first line of contact for trauma patients, we are often asked to evaluate the need for renal replacement therapy in these patients. It is important that we are aware of the sonographic findings seen in lung contusion so that we don’t confuse them with interstitial syndrome. As mentioned before, B-pattern in two or more sonographic lung zones bilaterally is suggestive of interstitial syndrome and this term encompasses pulmonary edema of various causes. Usually the pleural line is regular in these cases unless there is underlying lung disease such as pulmonary fibrosis.

Lung contusion is typically associated with B-lines in conjunction with pleural line irregularities, subpleural hypoechoic areas and may be localized pleural effusion. Unless the trauma is diffuse, these findings are localized to certain lung zones. The B-lines are frequently confluent, which means, too numerous and difficult to identify each line separately. In addition, Z-lines can be seen: lines that arise from the pleural line and fade away vertically and do not reach the edge of the screen.

It is also important to note that the contusion can be associated with pneumothorax, particularly in cases of rib fracture. Presence of B-lines almost always rules out pneumothorax even when you are not sure about absent pleural sliding. It is because there is air in between pleural layers, which does not allow B-lines to form. If you notice absent pleural sliding and suspect pneumothorax, look for ‘lung point’, which is the junction between normally sliding pleura and the pneumothorax with absent sliding. It is virtually diagnostic of pneumothorax.

Renal angiomyolipoma

A classic angiomyolipoma (AML) has abundant fat and therefore appears hyperechoic on a sonogram, similar to the sinus fat. Acoustic shadowing may be seen in up to a 3rd of the lesions. Unlike stones, these lesions do not typically exhibit twinkle artefact on color Doppler. Definitive diagnosis of AML is possible only by CT or MRI because they ‘diagnose’ fat and ultrasound can only ‘suggest’ fat. On non-contrast CT scan, the presence of regions of interest containing attenuations less than -10 HU allows confident identification of fat. Following are some examples of classic AMLs.

In patients with tuberous sclerosis, multiple renal AMLs are seen and often difficult to characterize on ultrasound. Corticomedullary differentiation is typically lost. Management should be guided by CT or MRI in such cases. Following is an example.

Small, well circumscribed bright lesions can be followed by ultrasound alone while any suspicion for malignancy warrants CT or MRI. The following lesion looks hyperechoic and most likely is AML but I would get a CT if possible because it’s more hypoechoic compared to sinus fat.

Renal cell carcinomas are hypoechoic to heterogeneous. They can be isoechoic also, which can be easily missed on quick scans. Therefore, it is important to image kidneys from multiple scan planes. Hardly takes an additional minute of your time! In addition, if you see anechoic rim surrounding the lesion or intralesional cysts or calcifications, think renal cell carcinoma. Following are some examples of RCC.

“Fat-poor AMLs” can be of heterogeneous echotexture or just isoechoic to renal parenchyma. It is challenging to differentiate them from malignancy and therefore, almost always require further imaging.