An Adelaide aged care nurse who sexually exploited his former partner's two young sons has avoided a jail term after the judge declared he was unlikely to be a danger to other children.

The District Court heard the 37-year-old flicked the boys' genitals while putting on their nappies at Edwardstown and encouraged them to urinate on each other and their mother.

The man, who worked at the Royal Adelaide Hospital, pleaded guilty to two counts of sexual exploitation of a child.

Judge Paul Cuthbertson said the crime was not sexually motivated and the man regarded the behaviour as "mischievous and funny rather than an attempt to corrupt minors".

The man also pleaded guilty to aggravated assault for forcing the head of one boy into a toilet and flushing it.

The crimes came to light after the boys' mother attempted suicide, bringing the man to the attention of child protection officers.

Judge Cuthbertson sentenced him to more than 19 months in jail but suspended the term, partly because of the man's mental health.

"The children first regarded you as a father figure," he told the man during sentencing.

He said he accepted the man did not commit the offences "for prurient or sexual reasons".

"The offending was more acts of mild cruelty which you took to be humour, rather than sexually motivated," he said.

"You committed these offences because you thought they were amusing and that probably your diminished responsibility arising from your mental issues is the reason you thought this offending was amusing and continued with it.

"I think it is unlikely you'll be a danger to children in the future and I think it is appropriate that you get some psychological help."

The man is currently an aged care nurse and deregistration is now likely.