Retinal hemorrhages and traction forces in vacuum extraction

Association of traction force and adverse neonatal outcome in vacuum-assisted vaginal delivery: A prospective cohort study

INTRODUCTION

Traction force is a possible risk factor for adverse neonatal outcome in vacuum extraction delivery, but the knowledge is scarce and further investigation is needed. Our hypothesis was that high-level traction force increases the risk of admission to the neonatal intensive care unit.

MATERIAL AND METHODS

The study was a hospital-based prospective cohort study on low- and mid-vacuum extractions at the labor and delivery ward, Karolinska University Hospital, Huddinge, Sweden. Traction forces were measured in 331 women. An electronical handle was used to measure and register traction force. The main exposure variable was high-level traction force (≥75th percentile) during the first three pulls and the primary outcome was admission to the neonatal intensive care unit. Logistic regression was used to estimate the adjusted risk.

RESULTS

Among the exposed, 14/84 (16.7%) were admitted to neonatal intensive care, and among the unexposed 10/247 (4%). The crude odds ratio (OR) of admission to the neonatal intensive care unit when exposed to high-level traction force was 4.7, and the adjusted (birthweight, gestational length, cup detachment, number of pulls, duration, duration >15 minutes, mid-cavity fetal head station, failed extraction, indication and parity) OR was 2.85 (95% confidence interval [CI] 1.09-7.48). No significant effect was seen in Apgar scores <7 at 5 minutes or pH <7.1.

CONCLUSIONS

High-level traction force may be a risk factor for neonatal complications. Although these results do not mandate any alterations in clinical guidelines, perioperative feedback on traction force may be useful to alert the obstetrician to a timely conversion to cesarean section. To study plausible traction force specific outcomes such as head traumas, a larger sample size is required.

Newborn retinal hemorrhages: a systematic review

PURPOSE

To systematically review the characteristics, prevalence, evolution, and obstetric associations of retinal hemorrhages (RH) in newborns.

METHODS

A systematic review, searching 10 databases (1970-2011), identified 45 studies, which underwent two independent reviews via the use of standardized critical appraisal. Studies meeting the following criteria were included: examination by an ophthalmologist, use indirect ophthalmoscopy, and first examination conducted within 96 hours of birth and before hospital discharge.

RESULTS

Thirteen studies were included, representing 1,777 infants. The studies revealed that 25.6% of newborns born via spontaneous vaginal deliveries had RH. In contrast, infants delivered by vacuum extraction had a 42.6% rate of RH (OR, 2.75; 95% CI, 1.32-5.70), and infants delivered by double-instrument deliveries (forceps and vacuum) had a 52% rate of RH (OR, 3.27; 95% CI, 1.68-6.36). The hemorrhages are commonly bilateral (59%), of varying severity, from "mild" (22%-56%) to "severe" (18%-37%), and predominantly intraretinal and in the posterior pole. The majority of RH (83%) resolved within 10 days; isolated cases persisted to 58 days.

CONCLUSIONS

Birth-related RH in infants occurs in one-quarter of normal deliveries and are far more common after instrumental deliveries. Commonly bilateral, they were predominantly intraretinal, posterior, resolved rapidly, and very rarely persisted beyond 6 weeks.

Validation of traction force indicator in ventouse devices

OBJECTIVE

To evaluate whether the traction force indicator in a ventouse device gave an accurate estimation of the force applied.

METHODS

The study was carried out at the Derby City Hospital. An estimate of measurement errors was made by analyzing the standard deviation of the residuals for 30 Kiwi OmniCup devices (Clinical Innovations, Abingdon, Oxfordshire, England) and a standard industrial spring balance.

RESULTS

The measurement errors for the traction forces were very small and acceptable for the OmniCup. The overall estimate of measurement errors was 0.45 kg (1.35 lb).

CONCLUSION

The overall measurement error for the traction force indicator of the OmniCup was found to be very small. Injuries associated the ventouse, such as cephalohematomas and subgaleal hemorrhages, may be minimized if the recommended limits for a safe traction force are not exceeded.

Obstetric vacuum extraction: state of the art in the new millennium

This article summarizes the current state of knowledge of obstetric vacuum extraction. The discussed topics include the history of vacuum extraction, indications and contraindications, technique of the procedure, currently marketed instruments, special uses of the vacuum extractor, comparison of vacuum extraction with forceps delivery, and maternal and fetal outcomes. Areas of controversy are identified and discussed. Vacuum extraction is replacing forceps as the preferred method of instrumental delivery.

Impact of FDA advisory on reported vacuum-assisted delivery and morbidity

OBJECTIVE

In May 1998 the US Food and Drug Administration (FDA) issued a health advisory reporting neonatal injuries/deaths following vacuum delivery and encouraged voluntary reports of future adverse events. We compared FDA reports of vacuum delivery adverse events prior to and following the advisory.

METHODS

The FDA database (MAUDE) was searched for vacuum deliveries using brand name, manufacturer name, and procedure "string searches." Cases were sorted by report date, source, and manufacturer. Neonatal morbidity was quantified as deaths and life-threatening or nonlife-threatening events.

RESULTS

A total of 80 reported adverse cases were identified after duplicate cases were consolidated. Twenty-five were reported to the FDA prior to the 1998 advisory and 55 in the immediate 6-month period following the advisory. There was a 22-fold increase in reported events from five events/year prior to the advisory to an estimated 110 events/year following the advisory. The distribution of reporting sources changed significantly following the advisory with increased "manufacturer" (8-43%) and decreased "voluntary" reports (56-20%). All major brand names were represented. During the 6 months following the FDA advisory there were 10 neonatal deaths, 30 life-threatening events, 12 nonlife-threatening events, and three equipment-related reports. Infant deaths were due to intracranial or subgaleal hematomas. Injuries included skull fracture, scalp abrasions, and cephalohematomas.

CONCLUSIONS

The FDA advisory was associated with a 22-fold increase in the rate of reported adverse events. This increase in reporting likely represents both enhanced awareness of complications as well as an increase in vacuum-related adverse neonatal sequelae. As vacuum delivery is associated with greater neonatal morbidity/ mortality than was previously recognized, the adage that the vacuum is "designed to come off before infant damage occurs" appears unsubstantiated. It is recommended that manufacturers quantify the suction and traction capabilities of present and new proposed vacuum cup designs.

Survey of retinal haemorrhages in neonatal thoroughbred foals

Twenty-seven of 167 neonatal thoroughbred foals (16 per cent) were found to have retinal haemorrhages after a careful examination of the entire fundus. Experience in differentiating haemorrhages from other lesions, and the selection of foals from normal populations, were considered to have an important effect on their apparent incidence. Bilateral haemorrhages were more common and there was a significantly higher incidence in female foals. The numbers of haemorrhages ranged between one and 20; 36 per cent of eyes with retinal haemorrhages had the small punctate type and 56 per cent had the splash-like form. There was no change from one type of haemorrhage to another, and the patterns of resolution were similar. The haemorrhages were in the tapetal fundus, except two that were recorded in the optic disc, and they resolved within 10 days. No short- or long-term ocular or neurological effects of the retinal haemorrhages were detected, and they were not related to the incidence of abnormal foal behaviour.