The Marist Sisters convent in the Italian capital where the two nuns were trapped.

A New Zealand nun and her Irish colleague who spent three nights stuck in a lift in Rome survived by drinking their own urine.

The 68-year-old New Zealander and her 58-year-old companion got stuck on Friday (Saturday NZT) when the lift they were in broke down while taking them to the ground floor in a convent in the Italian capital.

They weren't freed until Monday, after which they were taken to hospital and found to be seriously dehydrated.

MAX ROSSI The Marist Sisters host visitors to Rome from religious missions around the world.

"To avoid losing consciousness they drank their own urine," a doctor told the Italian daily La Repubblica. "It's a miracle they were still conscious when they were rescued."

The women were considered well enough to leave hospital once they had been drip-fed saline solution.

While the Marist nuns said they had "prayed so much" when they were trapped in the lift, a spokesperson in the Marist Mother House in Rome told the Irish Times: "We don't need to be stuck in a lift to pray. We pray all the time."

The average temperature during the weekend was 34 degrees Celsius.

After the lift became stuck, the nuns yelled for help but everyone else had left the Marist Sisters' convent on Via Aurelia for the weekend, Il Messaggero reported. Neither nun had a mobile phone with her.

The alarm was raised on Monday when a cleaner was unable to get into the convent.

She rang the bell insistently but no one opened the door. Alarmed, she called the police who were able to get in using a set of keys kept by another religious institute nearby.

"Is there anyone there?" one of the officers called out, while his colleague climbed the stairs.

"Yes, we are here in the lift," the nuns replied with a faint whisper.

Without waiting for the fire brigade, one of the officers activated emergency procedures to bring the lift down to the ground floor.