Toni Steedman, 25, was at the Aqualand water park in Costa Adeje, Tenerife, when she suffered horror injuries.
She was left with a 7cm tear to her uterus and lost nearly six pints of blood.
The Kamikaze slide was only the second ride she had been on at the park before she suffered the injury.
Mum-of-two Toni, from Clackmannan, Scotland, had planned the trip with her husband Adam, 32, to celebrate his birthday.
She nearly died after being rushed to hospital and says she needed three blood transfusions before doctors brought over a defibrillator.
"The slide had a free-fall drop and the lifeguards at the top never told me to fold my arms or cross my legs," Toni told the Sun Online.
She went on: "The slide was really fast and when I hit the water at the bottom I felt something just burst inside me.
"When I stood up I felt as though I needed the toilet but as I moved blood started pouring from between my legs. It was making a trail as I walked from the pool."
Toni said a doctor was fetched who examined her and realised what had happened.
“When I hit the water at the bottom I felt something just burst inside me”Toni Steedman
She was put into an ambulance and rushed to a nearby hospital, before being taken to a major hospital in North Tenerife where she was given an epidural to perform the surgery.
Toni said at one stage she believed she was going to die, and told Adam to look after their kids.
The couple had flown to Las Americas - popular with Brit tourists - on May 15, 2017, and bought the water park trip through a tour guide for the following day.
It is the latest accident to happen at a Spanish waterpark to make the news.
On Tuesday, British holidaymaker David Briffaut, 23, snapped his neck while sliding head-first down a ride at Aqualandia in Benidorm.
Doctors have warned the talented golfer could lose the use of his legs or all feeling below his chest and will need an operation when he is stable.
A visitor to the same park, Joe Pollard, claimed he lost most of his face after going down the same ride face-first.
Daily Star Online has contacted Aqualand water park in Tenerife for comment.