Errors in Prenatal Diagnosis: Mitigating Risk and Preventing harm

Professor Dilly OC Anumba Chair in Obstetrics and Gynaecology, The University of Sheffield Medical School

Consultant in Obstetrics and Fetomaternal MedicineClinical Lead, Wesfield Fetomaternal UnitJessop Wing, Sheffield Teaching Hospitals

Sheffield UK

Outline• Definitions• Scope and classification of prenatal diagnostic

errors• Epidemiology of errors – Relative prevalence– Contribution of system failures– Contribution of individual and patient-related errors

• Strategies for preventing, investigating and mitigating errors in prenatal diagnosis

What is a clinical error?• Failure of a planned action to be completed

as intended, or the use of a wrong plan to achieve an aim.

• Clinical intervention– Appropriate but incomplete– Erroneous– Misdirected– Mis-delivered

Classification of prenatal diagnostic (PND) errors

• Individual errors• Latent errors – “errors waiting to happen”– system failures: faulty systems, processes,

and conditions

Domains of PND errors

• Diagnostic • Treatment • Preventive • Others- latent errors

Diagnostic • Error/delay in diagnosis: fetal malformation

or disease • Failure to employ indicated tests (e.g.

amniocentesis, chorionic villus sampling)

Diagnostic (2) • Use of outmoded tests or therapy – (e.g. inferior prenatal screening tests for aneuploidy

with poor sensitivities and high false positive values)• Failure to act on results: of monitoring/testing– Suggestion of fetal compromise and risk of in utero

demise– Poor interpretation of antenatal surveillance CTG)– Failure to act on +ve test, failure to stop acting on a –

ve test

Treatment• Error in performance of

operation/procedure/test– procedure-related fetal trauma– miscarriage from invasive testing/therapy– system failures in batch prenatal screening for

aneuploidy– Computer errors– technical errors in sample retrieval for genetic

investigations

Treatment (2)• Error in administering treatment – treating the “wrong” unaffected fetus in multiple

pregnancy– Fetal trauma

• Error in dose or method of drug• Delay in treatment/response to an abnormal

test • Inappropriate (not indicated) care

Preventive• Failure to provide prophylaxis– maternal Rhesus sensitisation from failure to

administer prophylactic anti-D following potential fetomaternal haemorrhage

• Inadequate monitoring or follow-up of treatment– Managing the small fetus on scan

Other system failures

• Failure of communication • Equipment failure– resuscitation equipment– cytogenetic and molecular genetics

• Other system failure

SPECIFIC ERRORS

Specific errors

Prenatal screening

Prenatal diagnosis

Prenatal treatment

interventions

Errors during prenatal screening• Incidence data sparse eg universal Downs’

syndrome screening, offered all pregnant women as standard antenatal care.

• Mistakes occur in relation to:– Counselling: failure to offer recommended

testing– Sampling– Laboratory testing and quantification

Errors during prenatal screening– Pregnancy dating • Wrong dates, wrong risks for aneuploidy

– Wrongly filled Lab forms– Wrong assessment of nuchal translucency by US

Errors may lead to false positive or negative results

Would in turn affect parental uptake of diagnostic testing

Typically, legal cases on antenatal screening can arise from failure to offer screening or failure, at the fetal abnormality scan, to identify certain defects.Fetal abnormality screening claimsFor free, expert advice on making a medical negligence claim, click here or call us free on 0800 0382 382. We are available to take your call twenty four hours a day, seven days a week.If you want to provide some details to us in advance, why not let us assess your claim now.

Errors during prenatal diagnosis• Ultrasound errors– 1st trimester errors – dating, anomalies– 2nd trimester errors- the routine anomaly scan– 3rd trimester errors - missed diagnosis not followed

up appropriately– Special circumstances –multiple pregnancies

• Invasive testing errors - cytogenetic and molecular genetics error

Detection rates for fetal abnormalities

UK anomaly detection rates

Bryant L, Fisher A, Vicente F. Social Research and Regeneration Unit A. Fetal AnomalyUltrasound Screening Programme Study: Literature Survey. Plymouth: University of Plymouth Centre; 2007.

Operator-dependent errors, subject/patient dependent errors

• Insufficient skills/training/practice – minimum prescriptions

• Maternal obesity• Fetal position• Oligohydramnios vs. renal agenesis

Maternal obesity and congenital malformationsPaldini Ultrasound Obstet Gynecol 2009; 33: 720–729

Technical factors contributing PND errorsAcoustic limiting factors • Depth of insonation required• Absorption of US energy (dropout)

by abdominal adipose

Tips for scanning obese women

Other remedies• Fetal MR scans• Amnioinfusion for oligohydramnios

Costs of errors in prenatal diagnosis

Pregnancy losses

Survival with morbidity

Additional care necessitated by

errors

Lost income and household

productivityDisability

Loss of trust in health care

system

Diminished satisfaction, patients and

professionals

Consequences of prenatal diagnostic errors

• Erroneous counselling, • Wrong/inappropriate treatment options • Wrong parental decisions

Serious Incident• Definition: an incident that occurred in

relation to services and care resulting in one of the following:– Unexpected/avoidable death of one or more

patients, staff, visitors or members of public.– Serious harm to patient(s), staff, visitors or

members of public or where outcome requires life-saving intervention, major surgical/medical intervention, permanent harm or will shorten life expectancy or result in prolonged pain or psychological harm.

Serious Incident (2)

• A scenario that prevents or threatens to prevent a provider organisation’s ability to continue to deliver healthcare services, for example, actual or potential loss of personal/organisational information, damage to property, reputation or the environment, or IT failure.

Serious Incident- screening• Actual/possible failure at any stage in pathway of

screening service, which:– exposes the programme to unknown levels of risk that

screening, assessment or treatment have been inadequate

– and hence there are possible serious consequences for the clinical management of patients.

• Level of risk to individual may be low, but because of large numbers involved corporate risk may be very high.

ERROR MITIGATION

Failsafe strategies during prenatal screening

• Failsafe: back-up mechanism to ensure that if something goes wrong in screening pathway, processes are in place to (i) identify what is going wrong and (ii) what action follows to ensure a safe outcome.

• Most screening risks/errors predictable and often arise from systems failure than individual error.

• Failsafe aimed to “design out” or reduce errors

Implementation of Failsafe - roles• Assess screening pathway and identified areas of high

risk that require failsafe measures.National:

• Team provide expert advice on reducing risks in local programmes. Assess robustness of local arrangements through audit, peer review and the investigation of incidents.

Regional:

• Incorporate national guidance to reduce risk within service specifications and oversee implementation and functioning.

Commissioners:

• Review and risk assess local pathways against national guidance and develop, implement and maintain risk reduction measures.

Providers:

Downs syndrome screening

Managing serious incidents in screening service

EXAMPLES OF ERRORS LEADING TO LITIGATION

• Mrs. M, gave birth to a son GM. G suffers from Down's Syndrome. It is a matter of admission that this was noted immediately when he was born.

• In this action, the pursuers aver that members of the staff of GRMH (for whom the defenders are vicariously liable) negligently failed to diagnose Gary's condition, and advise the pursuers of it, at the appropriate stage of pregnancy. It is also averred that if the first pursuer had been advised that the baby would be affected by Down's Syndrome, she would have had the pregnancy terminated.

• Damages are claimed, under various heads, in respect of the loss, injury and damage suffered by the pursuers as a result of this negligence. Negligence was admitted.

The standard of care: the tension between medical opinion and parental autonomy

• A patient may say she understands although she has not in fact done so ... It is common experience that misunderstandings arise despite reasonable steps to avoid them. Clinicians should take reasonable and appropriate steps to satisfy themselves that the patient has understood the information which has been provided; but the obligation does not extend to ensuring that the patient has understood.

• Camb. Law J., 70 [2011], pp 523-547 at 538

Maurice and another v France (App no 11810/03) [2005] ECHR 11810/03

• The applicants were man and wife. In 1990, the applicants had their first child who was afflicted by infantile spinal amyotrophy, a genetic disorder. In 1997, the second applicant began her third pregnancy. She requested a prenatal diagnosis, and was assured by the hospital that the foetus was healthy and was not suffering from infantile spinal amytrophy.

• The child was born, and within some two years it became apparent that she did suffer from the condition.

• The applicants subsequently made a claim for compensation for damage suffered as a result of the child's disability. An interim award was made in the applicants' favour.

System failures (1) Millennium incident• In calculation of prior risk the year of birth was recorded

as two digits• After the millennium this resulted in women being

assigned negative ages i.e. approximately -80 to -60 years.

• Patient aged -80 similar to the probability of 14 year old therefore risks calculated did not appear outrageous, several months before decrease in screen positive rate was identified

•

System failures • Subsequent EU directive put Down’s Syndrome

screening software in a high risk category (2) Missing data on request forms • Lab has procedure of Faxing requests forms with

missing data to midwives for completion and return • Some Faxes were not responded to and this was

not realised until it was too late for screening• Labs need to have a robust system in place to chase

request forms with missing data •

System failures(3) Inadvertently altering parameters in Screening software• Down’s risks were affected and were inaccurate for a period

and this led to retrospective recalculation • There needs to be a robust procedure in place whenever

changes are made to any variable which is part of a screening risk calculation algorithm including a change control procedure to check risks on anonymised data sets are the same or show the expected changes pre and post change

Other incidents include: • Misinterpretation of request form information e.g.

a gestation was written on a 2T form as “15.3”. There was no scan information provided so this was interpreted as a HC of 15.3 cm.

• Increase of Fb hCG if samples stored or transported in warm conditions

• Incorrect risks due to donor date of birth not included in IVF Down’s screen

Patients may not recover from a serious error

Conclusion• Errors do happen but effort should be geared

at peventing systemic errors– Introduce failsafe strategies– Service audit and evaluation of performance– Infrastructural support– Training and staff support– Situational awareness– Root cause analysis and interventions