This common misconception came about when ultrasound first began being used for PD work, and is still very prevalent in the cattle industry.

Before ultrasound, early pregnancy was undetectable. Being the most common time for resorption of the foetus, many pregnancies began and self-terminated completely without the knowledge of either farmer or vet.

When ultrasound was introduced, however, pregnancy was easily detected even in its earliest stages. When pregnancy was confirmed but the cow later failed to show any signs, the positive correlation between ultrasound scanning and subsequent realisation of a later abortion was given the wrong conclusion, and the practice of performing an ultrasound scan was automatically blamed for the loss of the calf.

So is there a correlation between scanning and the subsequent knowledge that an abortion had occured? Yes, of course. But these abortions always have and always will occur naturally - it's just that before ultrasound, nobody knew the animal was pregnant in the first place to realise she'd resorbed.

Now, thanks to advances in ultrasound technology, handheld ultrasound scanners can be used to closely monitor pregnancies so as to minimise downtime and quickly detect failing or failed pregnancies.