The number of sexual crimes has been rising over the last four years.

And given that minors may find it harder than adults to pick up the pieces, experts are urging parents to build open relationships with their children so they will feel safe in opening up about possible wrongdoing.

Last year, there were 272 cases filed in the State Courts involving either sexual assault by penetration, sexual grooming of a minor under 16, outrage of modesty or rape. Another 169 cases involving these crimes led to convictions.

This is an overall increase of about 60 per cent from 164 cases filed and 105 convictions in 2011.

In the High Court, 13 rape cases were filed last year, up from four the year before and six in 2012. Eight people were convicted of rape last year compared to four in 2013 and six in 2012.

The Association of Women for Action and Research (Aware) also said that 234 people sought help at its Sexual Assault Care Centre last year, up from 192 in 2013.

While the rise could be due to an increased willingness to come forward, it could be only the "tip of the iceberg", said Aware's programmes and communications senior manager Jolene Tan, pointing out that a majority of cases also go unreported.

"If children feel they can confide without facing judgment or shaming... parents and caregivers are more likely to be in a position to know about situations that involve sexual violence and provide assistance," she said.

It is especially critical to catch abuse of minors early because "children might carry the trauma for the rest of their lives", said Dr Carol Balhetchet, senior director for youth services at the Singapore Children's Society. "At least with adults, they have some experience to help them process what happened. Children are a blank slate."

Girls might suffer from depression and inflict self-injury by cutting themselves in an attempt to deal with the stress, said the clinical psychologist. Boys, on the other hand, tend get angry and aggressive, becoming defiant and getting into fights, she said.

Consultant psychologist and traumatologist Elizabeth Ho from mental health practice the Resilienz Clinic, said boys may also struggle with their sexual orientation, after finding themselves sexually aroused during the abuse.

"Arousal in males is a biological thing, it's not something they can effectively control," said Ms Ho. The problem is exacerbated if the abuse occurs during adolescence when sexual identity is formed.

Experts also told The Sunday Times that the impact on victims is even worse if the offender is "known to the child's family".

The Ministry of Social and Family Development (MSF) handled 38 cases of sexual abuse involving minors last year. In 2013, there were 40 cases. In most cases, the perpetrator was a family member.

Such victims tend to suffer deeper emotional trauma, said Dr Joy Low, senior clinical psychologist with MSF's Clinical and Forensic Psychology Service. "Many victims may be unwilling to disclose or even engage in treatment due to feelings of guilt which comes from implicating their loved ones."

For years, "Nick's" stepfather would "massage" him at night before he went to sleep. It involved the man fondling the boy's privates.

The abuse began when he was in primary school. It stopped only earlier this year after counsellors in school found out and reported the case to the police.

The Secondary 3 student continues to struggle with feelings of guilt and shame, said Ms Lena Teo, assistant director of counselling at the Children-at-Risk Empowerment Association (Care). "He also has so much anger because an adult he trusted and was supposed to respect abused him sexually."

Therapy to help survivors lead normal lives again can take from six months to a year on average, but can stretch up to 18 months, said Dr Low. It typically involves getting survivors to talk about the experience in order to help them process the hurt, and adapt psychologically.

It is also crucial that victims be in an environment in which they feel safe to share their experience.

Mrs Kim Lang Khalil, director of DaySpring Residential Treatment Centre, which helps abused teenage girls, said: "Those who are abused tend to be hyper-vigilant. They are always concerned about possible attacks on them, they get startled easily, and do not trust adults as most of the time they were abused by one."

DaySpring can take up to 22 girls, who are mostly referred by MSF and typically stay for a year at its Turf Club compound. Each girl has a care team - a counsellor and a coach to help her get over her trauma. When the girls are well enough to leave, there is a "graduation" ceremony where they share with other girls their experience.

Said Mrs Khalil: "By being willing to share, they show that they have made peace with their past, and are no longer ashamed."