An inquest has heard how a scan on a woman when she was 33 weeks pregnant and whose baby subsequently died just hours after being delivered at Cavan General Hospital failed to pick up an abnormality in the placenta.

Dr Angela Mortimer, a consultant radiologist in the hospital at the time, told the second day of the inquest that the ultrasound failed to see a bilobed placenta.

This is where the placenta is divided into two lobes, joined by the arteries via the membrane, and was identified following baby Conor Whelan's death.

Under questioning by solicitor Roger Murray for the family, Dr Mortimer said the abnormality would have been present at the time the scan was carried out.

Conor died on 14 May 2014, just over 17 hours after being born at Cavan General Hospital.

He suffered a brain injury caused by a condition known as vasa previa, where blood vessels block the entrance to the birth canal.

Dr Mortimer told the inquest that a bilobed placenta was a risk factor for vasa previa.

Professor Anne Marie Cody, a consultant radiologist employed by the UK's National Health Service, told the inquest that a bilobed placenta would be much easier to see in a 20-week scan. 

Speaking via skype Prof Cody described the 20-week scan as "very useful" for detecting abnormalities of the heart or spine or for detecting conditions including Down syndrome.

The inquest heard earlier that a 20-week scan is not carried out at Cavan General Hospital.

It is routine in the UK to perform a 20-week scan on a pregnant woman, the inquest was told.

Mary Reilly, a former midwife manager at the hospital, said staff at the hospital were pressing for a specialist obstetric sonographer.

The inquest earlier heard that there is nobody in the hospital dedicated to only carrying out ultrasounds on pregnant women.

Earlier, the consultant radiologist told the inquest that "it is not her practice" to reassure a patient following a scan.

Dr Mortimer said that she reviewed a scan performed on Siobhan Whelan on 21 March 2014.

Ms Whelan told the inquest yesterday that Dr Mortimer was called into the room following the scan.

She told the hearing that when Dr Mortimer was asked for her opinion, she said the scan was not clear enough.

Ms Whelan said she was asked by Dr Mortimer what consultant she was attending and she told her.

Ms Whelan said Dr Mortimer told her then she was in good hands and the consultant would do his own internal scan.

Under questioning today by the solicitor for the family, Dr Mortimer denied she made those comments and said it would not be practice to go into detail with patients.

She told the inquest she had no recollection of going into the room and had never met Ms Whelan.

Earlier an ultrasound specialist at the hospital told the inquest that she does not recall telling Ms Whelan that she had a "very close call of low lying placenta".

Anne Emmo, who has worked at Cavan General Hospital for 26 years, told the inquest that she performed a third trimester scan on Ms Whelan on 21 March 2014.

Ms Emmo told the inquest that she no longer performs obstetrics ultrasounds at the hospital.

She said she was "deeply upset" by baby Conor's death and now works in a specialist unit scanning stroke patients.

She also said that she was not aware if changes to ultrasound procedures had been made since Conor's death.

The midwife in charge of the labour ward at Cavan General Hospital on the day Ms Whelan presented with contractions said she put a halt to a junior doctor breaking the patient's waters.

Anne Arnott said she knew consultant Obstetrician Dr Rita Mehta was in the hospital and she wanted her to carry out the procedure.

The inquest heard that Dr Mehta was attending a weekly statistics meeting when Ms Arnott sought her assistance at 1.15pm. 

Ms Arnott said Dr Mehta told her she would be there in ten minutes.

Following the phonecall Ms Arnott that she noted the foetal heart rate had dipped and she requested that Dr Mehta be called immediately.

Ms Arnott said she became worried and concerned about the unexplained bleeding but she could not establish where the blood was coming from.

She told the inquest that she did not think the blood was coming from the baby.

"Unfortunately, I didn't think of it on the day" she said.

Under questioning from Mr Murray for the family, Ms Arnott said she began to listen to Ms Whelan who clearly knew something was wrong.

"It was a mother's instinct", she said.

Dr Mehta arrived in the room at 1.30pm and at 1.38pm a Caesarean section was ordered and Ms Whelan was taken to theatre.

Dr Mehta told the inquest that would not have broken Ms Whelan's waters, had she been aware of the her vasa previa.

She said she had no recollection of a discussion Ms Whelan had with staff, during which Ms Whelan said she pleaded with them not to allow the doctor to break her waters.

Dr Mehta was asked about the mortality rate in cases of vasa previa and she told the inquest it was very high - between 60 and 80%.

However she said if it is identified before birth, a plan is put in place for a planned C-section.

The inquest heard statistics from the Royal Australian and New Zealand College of Obstetricians that, survival rates, if identified before birth stand at 97%.