Risk factors associated with subaponeurotic haemorrhage in full-term infants exposed to vacuum extraction.

Objectives: To determine obstetric and neonatal risk factors associated with subaponeurotic haemorrhage (SAH) in infants exposed to vacuum extraction.

Design: A prospective observational study.

Setting: In the labour room, operation theatre, postnatal wards and neonatal intensive care unit (NICU) of a tertiary teaching hospital.

Population: All infants born in the hospital with a history of exposure to vacuum extraction.

Methods: A prospective observational study carried out over a 26-month period. All eligible infants were examined at birth and during the first 24 hours of life.

Main Outcome Measures: A diagnosis of SAH was based on detection of a tender fluctuant scalp swelling that crossed the skull suture lines of infants.

Results: Of 10,066 infants born in the hospital during the study period, 338 (3.4%) had exposure to vacuum extraction. SAH was detected in 71 (21.0%) of them. Forward multivariate logistic regression analysis showed that five factors were significantly associated with development of SAH: maternal nulliparity (adjusted odds ratio [OR]: 4.0; 95% confidence intervals [CI]: 1.6, 10.0), failed vacuum extraction (adjusted OR: 16.4; 95% CI: 2.0, 135.6), Apgar score of less than 8 at 5 minutes of life (adjusted OR: 5.0; 95% CI: 1.7, 15.2), marks of vacuum cup over the sagittal suture (adjusted OR: 4.4; 95% CI: 1.9, 10.2) and marks of leading edge of vacuum cup at <3 cm away from the anterior fontanel of infants' heads (adjusted OR: 6.0; 95% CI: 1.7, 21.0).

Conclusion: Maternal nulliparity, placement of vacuum extraction cup over the sagittal suture at a distance too close to infant's anterior fontanel and failed vacuum extraction predisposed infants to develop SAH.