The NHS is investigating claims by a new mother who says she found bandages in her body seven weeks after giving birth at Wexham Park Hospital, Slough.
"I took out a large piece of decomposing material from inside me that was soaked in blood," Alexandra Loredana told BBC News.
Ms Loredana added that she had suffered from thrush and 'light vaginal wounds'.
A hospital trust spokesman told the BBC: "We are aware. We have started an investigation."
The new mother, from Slough, Berkshire, gave birth to baby Dominic in January.
Ms Loredana said she initially explained to her midwife how she felt uncomfortable going to the toilet and that something smelled terrible - her midwife checked her stitches and said 'everything was fine'.
The new mother said she was unable to get an appointment with her local walk-in centre until 7 March, 2018.
She said: "For seven weeks I changed my pads more than 10 times a day.Whether I had bleeding or not I just wanted my pads to absorb the horrible smell.
"Last night I had a bath for the first time and I felt courageous enough to wash with my fingers inside my vagina to clean it.
"I was breathless when I took out a large piece of decomposing material from inside me that smelled horrible and was soaked in blood.
"How did this happen?"
Ms Loredana then went to the accident and emergency department at the same Slough hospital and saw a doctor.
James Taylor, head of communications at Frimley Health NHS Foundation Trust, said: "I don't know how frequently these things happen".
He said the Trust would make a further statement once it had spoken to Ms Loredana and completed an investigation into the case.