Scientists disagree over ultrasound images showing male foetus 'masturbating in womb'

The images were captured in an ultrasound scan (file photo) (Getty Images)

Ultrasound images that appear to show a male foetus masturbating in the womb have sparked a heated debate between scientists who can’t agree if one shape is an index finger or the tip of a penis.

According to two Spanish researchers, the scan of the foetus at 32 weeks shows “very clear sexual behaviour”, with its fingers wrapped tightly around its genitals.

“The foetus is grasping his tumescent penis using an evident force,” wrote Vanesa Rodriguez Fernandez and Carlos Lopez Ramon y Cajal in the medical journal Prenatal Diagnosis.

The series of images picture the foetus pulling back its foreskin to reveal the urethral opening – also known as the meatus – then using its hand to return it into place, they said.

But an Israeli ultrasound expert said the researchers had made a “huge error” by misidentifying the foetus’s index finger as its foreskin, reported Discover Magazine.

“What the authors mark as foreskin is the normal index finger,” wrote Israel Meizner in a comment on the study, asserting that the first image “represents a grasped normal hand with five fingers”.

The second image shows “the flexed hand with five fingers,” he wrote. “What the authors mark as meatus is the flexed index finger, a bit drawn backwards.”

Professor Meizner said the penis and scrotum were visible in the first image to the left of the hand – a claim refuted by the Spanish obstetricians, who said the bulge he was referring to was the umbilical cord.

Responding to the criticism, the scientists said they disagreed with Professor Meizner’s analysis of the imagery, as they had observed the professed act take place – over a period of half an hour.

“The behavior reported in our study was observed and confirmed by several doctors over a period of time,” they said. “The image is a snapshot of an exploration that was performed over a period of 30 minutes."

“Typically, I work using two ultrasound machines and seven transducers (three-dimensional mechanical and electronic transducers),” added the doctors. “I would be happy for you to visit my hospital and ultrasound lab to witness this.”

A report on the spat was published by a writer using the alias Neuroskeptic, who wrote on Twitter: “I used to dream of my posts being picked up by New Scientist. Didn't think it would be a post about a wanking foetus.”

In 1996, two Italian doctors described their observation of a female foetus at 32 weeks “touching the vulva with fingers of [her] right hand,” focused “primarily on the region of the clitoris,” according to The Week.

Their letter, published in The American Journal of Obstetrics and Gynecology, said the foetus had carried out this action for 20 minutes before experiencing rapid muscle contractions and then appearing “relaxed and rested”.