In my 16 years as a photojournalist, I have seen my share of drama and poignant moments from behind the lens.

I have covered the aftermath of 2004 tsunami in Aceh, and stood amid a crossfire between police and bank robbers in the Philippines.

But none of them has been so intense, yet so personal (I have two young sons), as witnessing a father giving part of his liver to save his infant son's life.

I had been a little hesitant about this assignment, because injections make me weak in the knees and the sight of needles and blood make my heart beat faster.

What if I fainted, or worse, collapsed over the patient as the doctor was opening his abdomen?

But being given full access to document the procedure was a once-in-a-lifetime opportunity.

I took control of my anxieties, went into professional mode and on July 30, two days before his major operation, I met 22-month-old Jeremy Guo.

He had biliary atresia, a life-threatening condition where his liver cannot get rid of toxins.

Initially shy, the bubbly and playful toddler was soon wrapping his hands round my camera to try to take pictures.

But a few signs betrayed his grave illness: his yellowish complexion, a yellow tint on the whites of his eyes from the poisons in his body, and a swollen belly.

His father, project engineer Guo Yang, 34, and and his mother, trading assistant Maggie Yu, 33, trailed their only child protectively in the hospital playground.

Jeremy's two grandmothers were also within arm's reach, in case their "guo guo", (Jeremy's nickname, meaning "apple" in Mandarin), took a tumble.

The big day came.

At 5.30am, a pale-looking Mr Guo, wheeling a stand with a bag of saline solution, emerged from his ward to see his son one last time before the operation.

Jeremy was still fast asleep when his father leaned over and gently kissed his face, before leaving to get prepped for his procedure.