Thai doctors have successfully corrected a bladder blockage in an unborn baby in an operation claimed to be the first of its kind in Asia.

The procedure remedied a condition that could have led to a miscarriage or stillbirth.

Dr Tuangsit Wathakanara of Bangkok-based Siriraj hospital, who treated the unborn baby and mother, said he detected the condition in the woman’s fourth month of pregnancy.

The operation technique required doctors to perform the operation through small incisions with the help of a video camera, local media reports said.

After applying a spinal block on the mother, the medical team inserted a tiny fetoscope, about 1.3 millimetres in diameter, through an incision in the abdominal wall to examine the baby’s bladder.

After finding the block, the doctors applied a low-power laser to unclog it and allow urine to flow through the urinary tract as normal, Wathakanara said.

The unborn baby’s swollen urinary bladder returned to its normal shape, he said, adding the operation took about an hour to finish.

The medical team checked the baby’s bladder using ultrasound scans until they were certain the organ could function normally.

The mother went into labour slightly ahead of her due date. The baby was born by caesarean section, and weighed 1.8 kilogram at birth.

The baby required an oxygen mask for a short period, said Dr Pimol Wongsiridech, head of the hospital’s neonatology division. He said the infant now weighs 2.4kg.

Urinary blockage causing swelling and failure to the kidneys are estimated to afflict one in every 50,000 babies.

The ailment was previously considered incurable, according to Dr Witthaya Thithaphan, head of Siriraj’s maternal-fetal medicine unit, Bangkok Post reported.