This week completes the series of articles on X-rays and ultrasounds, and we finish by looking at when in general practice we commonly use ultrasound examinations to help aid diagnosis.
The first and, if I’m honest, the most fun, common use is pregnancy diagnosis. In addition to seeing baby puppies or kittens present in the womb the scan can also give reassurance by seeing heart beats (if taken far enough into the pregnancy). Measurements of the size of the foetuses can be taken which can then be used to estimate a due date. When our pregnant bitch was in pup we checked everything was well later on in pregnancy and had the joy of one of her pups waving its tiny paw at us!
The womb is also routinely scanned if an infection is suspected. For either open pyometra (womb infection with a discharge present) or closed pyometra (when the end of womb remains closed so the pus builds up inside it) visualisation of the distended womb, combined with the other symptoms, helps aid a quick provisional diagnosis.
It’s not just the hearts of puppies and kittens to be that can be scanned. A particular type of scanning known as echocardiography is used to get 2D and 3D images of the heart and incorporates Doppler (to see the movement of blood flow within the vessels). Scanning of the heart allows information to be gathered about not only its sizes and shape but also how well it’s pumping and if there is any damage.
The information gathered can help determine what medication is needed and repeat scans keep an accurate track of how the condition is progressing allowing modification of drugs when needed. The fact most pets don’t need sedation for the examination is a huge advantage, especially for these cardiac cases as the sedatives themselves can pose risks to the heart. A great number of abdominal organs are also commonly scanned in practice, including the liver and the spleen. Both these organs can be prone to tumours.
It’s worth mentioning that visualising a mass on ultrasound does not itself provide a definitive diagnosis but a biopsy can be taken being guided by the ultrasound if needed (this is normally done at a specialist centre), or seeing the mass can give the justification needed to go to surgery. For example, as mentioned recently, in the case of a mass on the spleen surgery can be life-saving as the mass may cause internal bleeding.
In contrast, sometimes with all the history, clinical signs and other factors such as blood tests, the presence of a mass on ultrasound gives enough evidence to the likely diagnosis to decide just to monitor the condition with minimal intervention. This can be especially useful if the pet is very old with other problems and something like an aggressive tumour which is likely to inoperable and to already to have spread is suspected. In this case, it can prevent the stress for owner and pet of a high risk anaesthetic for exploratory surgery when the operation is unlikely to affect the prognosis anyway.
In addition, useful information about the kidneys and bladder is also gathered by ultrasound examination. A common reason for scanning would be looking for stones in either location but general kidney size and structure is also looked at, as is bladder wall thickness.
When thinking about diagnostic techniques, one of the most important things to realise is that often it is a combined approach that allows the best chance of getting an accurate diagnosis.