Background Instrumental delivery is increasingly scrutinised for complication rates, in particular in association with multiple instruments and rotational delivery. There is a paucity of recent UK data describing complication rates for these deliveries, thus we aimed to report complication rates for a large UK cohort.

Methods Data was collected from all instrumental deliveries conducted at a large tertiary referral centre in Manchester from October 2008–June 2011. Data was collected using an electronic audit proforma that also served as the medical record.

Results Data was available for 1985 deliveries; 688 (35%) ventouse, 905 (46%) forceps, 178 (9%) Kiellands, 51 (2%) rotational ventouse, 163 (8%) 2 instruments. There was no increased risk of third degree perineal trauma with the use of Kielland's forceps (2%) or multiple instruments (7.9%) compared to forceps use (6.6%). Rotational delivery and multiple instrument use were associated with a reduction in fetal cord pH (table 1, p<0.05 except for arterial pH for double instrumentation p=0.12 Mann-Whitney).

Conclusions Surprisingly, the use of Kielland's forceps in this study did not increase the risk of third degree perineal tears, possibly reflecting the presence of senior operators. However, rotational deliveries and multiple instrument use were associated with reduced fetal cord Ph, although the differences were small so may be of dubious clinical significance.