Introduction Voluntary incident reporting of errors to determine adverse events is handicapped because only 20% are reported. The Institute for Healthcare Improvement (IHI) developed the perinatal trigger tool (PTT) for accurately identifying and measuring adverse events in perinatal care. IHI definition of harm is “Would you want this event to happen to you or your loved one?”

Objective To measure adverse events in a typical UK maternity unit.

Setting Tertiary hospital delivering 6200 babies annually

Methods From April 2012 to March 2013 monthly retrospective chart review of twenty mother-baby pairs was conducted using PTT methodology. Records were randomly selected from all term deliveries for the month under review. Two senior midwives independently reviewed each record pair assessing for 22 triggers defined in PTT and graded harm. For categorising errors the NCC MERP Index was used:

E: Temporary harm to patient, required intervention

F: Temporary harm, required initial or prolonged hospitalisation

G: Permanent harm

H: Intervention to sustain life

I: Death

With disagreement a consultant obstetrician was adjudicator.

Results 240 mother-baby pairs were reviewed. 70 (29%) mother-baby pairs were graded as harm. Highest and lowest harm months were August (55%) and February (10%) respectively. In total there were 48 category E, 20 category F, 1 category H (Readmission after caesarean with intra-abdominal pus collection, laparotomy and ITU), 1 category I (neonatal death).

Conclusions At least 1 in 4 women or babies with a term delivery will experience harm in a typical UK maternity unit, although most harm will be temporary.