The patient may not have been in any condition to appreciate it, but the surgical team treated her as carefully as a newborn baby.
Unlike a newborn baby, however, it took three vets to lift her on to the operating table.
And to ensure there was no chance of Liesel the lowland gorilla waking up inconveniently they made sure the 32-year-old was given a hefty anaesthetic.
Heavy! Veterinarians lift Liesel onto the operating table
Once she was under and flat on her back, the operation proceeded smoothly, with Liesel fast asleep.
The three-hour procedure was to remove a tumour in her uterus and was carried out in Budapest, Hungary.
Budapest Zoo spokesman said that when Liesel came to them in 1989 from Germany's Frankfurt Zoo, she may have a malignant tumour on her right ovary, and it was now a danger to her.
Surgeons remove the tumour - Liesel will be kept away from the other gorillas in the zoo for at least a week
Liesel, whose name is a short version of Elizabeth popular in the 17th century, is the oldest gorilla in the Eastern European country and the operation was a first for its veterinarians.
She will be kept under observation and apart from the rest of gorillas at the zoo for about a week.
More exams will be needed to determine why the mother of three - Dango, Gorka and Ebobo - has not given birth since 2000.
Most kinds of lowland gorillas are critically endangered, although a census of western lowland gorillas, which are found in the northern part of the Republic of Congo, found populations are doing much better than anyone expected.
The census found 125,000 of the apes alive and well in two adjacent areas of the Congo in an area covering 47,000 sq km.
A census in the 1980s estimated that about 100,000 remained, but numbers were since thought to have halved.
King Kong-ed out: Liesel, Budapest's oldest gorilla, goes under the knife | Mail Online