A mother accused of murdering her son should not have been told to carry out two-handed resuscitation on the two-year-old boy’s little body, a medical expert has said.

Dr Evan Matshes, a forensic pathologist, said it was his opinion that Phylesia Shirley should have been told to administer one-handed CPR on her son, Kyrell Matthews, after phoning the NHS’s 111 number when he became “floppy” at her flat in Thornton Heath, south London, in October 2019.

The toddler, who was non-verbal, was found to have 41 rib fractures by the time he died, as well as internal bleeding and a 1.6in (4cm) cut to his liver.

The prosecution claim he suffered the injuries in at least five separate incidents in the four weeks leading up to his death, allegedly caused by Shirley and her then-boyfriend Kemar Brown.

Your Local Guardian: Court artist sketch by Elizabeth Cook of Phylesia Shirley, and her partner, Kemar Brown, appearing at the Old Bailey in London charged with murder and causing or allowing the death of a child, Shirley's two-year-old son Kyrell Matthews who died after he was found in cardiac arrest at a home in Thornton Heath, south London, on October 20 2019Court artist sketch by Elizabeth Cook of Phylesia Shirley, and her partner, Kemar Brown, appearing at the Old Bailey in London charged with murder and causing or allowing the death of a child, Shirley's two-year-old son Kyrell Matthews who died after he was found in cardiac arrest at a home in Thornton Heath, south London, on October 20 2019

Brown’s defence say the injuries were the result of incorrect advice from NHS 111 on how to resuscitate the little boy.

Giving evidence at the Old Bailey via video link in the United States, Dr Matshes said: “From my experience and from the literature, it is clear that, however infrequent, bruising may happen to the front of the chest, fractures may occur in a variety of different parts of the ribs, the soft tissue around the heart – and the heart itself – may be bruised, the lungs may be bruised and the liver may be bruised and even lacerated in some circumstances.”

Dr Matshes said he could not rule out that Kyrell’s rib fractures were not caused by CPR.

The jurors previously heard harrowing audio recordings – secretly made by Shirley to see if Brown was cheating on her, later discovered by police – which captured the violence said to have been meted out by the pair in Shirley’s one-bedroom flat.

Shirley performed two-handed CPR for several minutes after phoning the NHS, the trial heard.

Shirley, 24, and Brown, 28, of separate addresses in Thornton Heath, deny murder.

Brown also denies two further charges – causing or allowing death, and causing or allowing serious physical harm to a child.

Shirley has admitted allowing the death and allowing serious physical harm to a child.

The trial continues.