The Use of the Vacuum Extractor

Prospective assessment of vacuum deliveries from midpelvic station in a tertiary care university hospital: Frequency, failure rates, labor characteristics and maternal and neonatal complications

BACKGROUND

Midpelvic vacuum extractions are controversial due to reports of increased risk of maternal and perinatal morbidity and high failure rates. Prospective studies of attempted midpelvic vacuum outcomes are scarce. Our main aims were to assess frequency, failure rates, labor characteristics, maternal and neonatal complications of attempted midpelvic vacuum deliveries, and to compare labor characteristics and complications between successful and failed midpelvic vacuum deliveries.

STUDY DESIGN

Clinical data were obtained prospectively from all attempted vacuum deliveries (n = 891) over a one-year period with a total of 6903 births (overall cesarean section rate 18.2% (n = 1258). Student's t-test, Mann-Whitney U-test or Chi-square test for group differences were used as appropriate. Odds ratios and 95% confidence intervals are given as indicated. The uni- and multivariable analysis were conducted both as a complete case analysis and with a multiple imputation approach. A p-value of <0.05 was considered statistically significant.

RESULTS

Attempted vacuum extractions from midpelvic station constituted 36.7% (n = 319) of all attempted vacuum extractions (12.9% (n = 891) of all births). Of these 319 midpelvic vacuum extractions, 11.3% (n = 36) failed and final delivery mode was cesarean section in 86.1% (n = 31) and forceps in the remaining 13.9% (n = 5). Successful completion of midpelvic vacuum by 3 pulls or fewer was achieved in 67.1%. There were 3.9% third-degree and no fourth-degree perineal tears. Cup detachments were associated with a significantly increased failure rate (adjusted OR 6.13, 95% CI 2.41-15.56, p< 0.001).

CONCLUSION

In our study, attempted midpelvic vacuum deliveries had relatively low failure rate, the majority was successfully completed within three pulls and they proved safe to perform as reflected by a low rate of third-degree perineal tears. We provide data for nuanced counseling of women on vacuum extraction as a second stage delivery option in comparable obstetric management settings with relatively high vacuum delivery rates and low cesarean section rates.

Comparison of a practice-based versus theory-based training program for conducting vacuum-assisted deliveries: a randomized-controlled trial

PURPOSE

Vacuum-assisted deliveries (VAD) are complex procedures that require training and experience to be performed proficiently. We aimed to evaluate if a more resource intensive practice-based training program for conducting VAD is more efficient compared to a purely theory-based training program, with respect to immediate training effects and persistence of skills 4-8 weeks after the initial training.

METHODS

In this randomized-controlled study conducted in maternity staff, participants performed a simulated low-cavity non-rotational vacuum delivery before (baseline test) and immediately after the training (first post-training test) as well as 4-8 weeks thereafter (second post-training test). The study's primary endpoint was to compare training effectiveness between the two study groups using a validated objective structured assessment of technical skills (OSATS) rating scale.

RESULTS

Sixty-two participants were randomized to either the theory-based group (n = 31) or the practice-based group (n = 31). Total global and specific OSATS scores, as well as distance of cup application to the flexion point improved significantly from baseline test to the first post-training test in both groups (p_all < 0.007). Skill deterioration after 4-8 weeks was only found in the theory-based group, whereas skills remained stable in the practice-based group.

CONCLUSION

A practice-based training program for conducting VAD results in comparable immediate improvement of skills compared to a theory-based training program, but the retention of skills 4-8 weeks after training is superior in a practice-based program. Future studies need to evaluate, whether VAD simulation training improves maternal and neonatal outcome after VAD.

A technological advance for 21st century obstetricians: the electronically-controlled vacuum extractor

OBJECTIVE

To describe an innovative electronically-controlled vacuum extractor (VE) in detail and to illustrate its performance characteristics, as observed in a laboratory study.

DESIGN

Thirty simulated, vacuum-assisted deliveries.

MAIN OUTCOME MEASURE(S)

(1) The ability to measure in real-time of the pull applied and to sound an alert, when the traction approaches the negative pressure under the cup, to prevent its detachment. (2) The recording and printing of a graphic representation of the pull applied (vacuum delivery graph). (3) The emission of a warning signal when the 15-min time limit of continuous cup application on the fetal scalp, is reached.

RESULTS

No cup detachment occurred in any of the 15 vacuum-assisted deliveries, in which traction was kept below the adhesive force of the cup [44 lb (20 kg)], except in three cases, due to loss of negative pressure. In the remaining 15 tests, in which traction was greater than the adhesive force of the cup, "pull-offs" inevitably occurred. Furthermore, upon reaching the 15-min time limit of continuous cup application on the fetal cephalic model, a warning signal was emitted, as programmed. Conclusions We demonstrated that the electronically-controlled VE, with its distinctive pull-sensing handle, performs suitably for its intended purposes. The ability of the modernized device to decrease the incidence of cup detachment, secondary to the inadvertent application of excessive traction, may result in considerable safety, medico-legal and didactic advantages.

Obstetric management in vacuum-extraction deliveries

OBJECTIVE

The aim of this observational study was to describe the obstetric management in vacuum extraction (VE) deliveries and to compare these findings to instructions in clinical guidelines on VE.

METHODS

In 2013, detailed data on management of 600 VE cases were consecutively collected from six different delivery units in Sweden. Each unit also contributed their own clinical VE guideline.

RESULTS

In total, 93% of the VEs ended with a vaginal delivery while 7% failed and were converted to an emergency cesarean section. In 2.3% extraction time exceeded 20 minutes, and in 6% more than six pulls were used to deliver the fetus. Cup detachment occurred in 14.6%, and fundal pressure was used in 11% of the deliveries. In 2.3%, fetal station was assessed as above the level of the maternal ischial spines. The clinical guidelines on VE varied in scope and content between units, and were often incomplete according to best practice.

CONCLUSION

The vast majority of the VEs were conducted in accordance with safety recommendations. However, in a few extractions, safety rules were disregarded and more than six pulls or an extraction time of more than 20 minutes were used to complete the delivery.

Neonatal subgaleal hemorrhage

Subgaleal hemorrhages, although infrequent in the past, are becoming more common with the increased use of vacuum extraction. Bleeding into the large subgaleal space can quickly lead to hypovolemic shock, which can be fatal. Understanding of anatomy, pathophysiology, risk factors, differential diagnosis, and management will assist in early recognition and care of the infant with a subgaleal hemorrhage.

Alopecia Associated With Birth Injury

BACKGROUND

Alopecia after birth-related caput succedaneum is an extremely rare complication.

CASE

The case of a child with permanent alopecia due to birth-related caput succedaneum is presented. After delivery with vacuum extraction, caput succedaneum at the left occipitoparietal region of the neonate's head was noted, which subsided within a week, leaving a circular necrotic crust and finally a circular bald area. At age 4, the child was referred at a tertiary center for the management of alopecia. Treatment initially consisted of the expansion of the hair-bearing skin adjacent to the bald area, which was excised at a second stage and covered with the expanded skin. A pleasing esthetic result was achieved.

CONCLUSION

Neonatal alopecia is a rare birth-associated complication. Premature rupture of the membranes, prolonged second stage of the labor, and prolonged vacuum extraction time may be important features in the pathogenesis of this complication. In case of permanent alopecia, excellent esthetic results can be achieved with the use of reconstructive plastic surgery techniques.

Head injuries after instrumental vaginal deliveries

PURPOSE OF REVIEW

The types, mechanisms and clinical manifestations of head injuries (extracranial, cranial and intracranial) after instrumental delivery are described along with current evidence of their prevention and management.

RECENT FINDINGS

Asymptomatic subdural hematomas can occur in up to 6.1% of uncomplicated vaginal deliveries. Maternal nulliparity, incorrect placement of vacuum extraction cup and failed vacuum extraction are predisposing factors to subgaleal hemorrhage. Injuries associated with the vacuum devices may be minimized if the recommended limits for a safe traction force are not exceeded. There is no difference in the incidence of scalp trauma between vacuum deliveries by a rigid plastic cup (Omnicup) and the standard, silastic cup. The use of a metal cup may increase the occurrence of head injuries. Protective covers over forceps reduce the rates of neonatal facial abrasions and skin bruises. There is no difference in the incidence of cephalhematoma comparing a sequential operative vaginal delivery and a caesarean section following a failed vacuum delivery.

SUMMARY

Instrumental vaginal deliveries carry substantial risks. Only practitioners who are adequately trained or are under supervision should undertake instrumental delivery. The mode of intervention needs to be individualized after consideration of the operator's skills and experience and the clinical circumstances.

[Complications of vacuum extractor deliveries]

OBJECTIVES

To describe maternal and neonatal complications following deliveries assisted by vacuum extraction and to compare outcomes with those obtained after spontaneous vaginal delivery. We wanted to know if vacuum extractor was a risk factor by itself.

MATERIALS AND METHODS

We conducted a retrospective study of two years activity involving 4524 deliveries of which 845 (18.7%) were vacuum extractor assisted. We precisely defined maternal and neonatal complications to compare their rates in spontaneous vaginal delivery and vacuum extractor groups.

RESULTS

There were 1333 maternal complications and 114 neonatal complications. The adjusted risks of maternal complications were significantly higher in the vacuum extractor group for simple vaginal tears (OR=3.0; p<0.001), the simple perineal tears (OR=1.8; p<0.001) and third degree perineal tears (OR=2.7; p<0.01). For neonatal complications, the difference was significant for cephalhematomas (OR=10; p<0.001) and scalp abrasions (OR=53; p<0.001). No cases of skull fracture or subgaleal subaponeurotic hemorrhage were recorded.

CONCLUSION

Our rates of maternal and neonatal complications after vacuum extractor were similar to those described in the literature. We have been able to show that vacuum extraction is itself a risk factor for third degree perineal tears and cephalhematoma. However, these complications are so infrequent that the advantages of this method of extraction argue in favor of wide use in obstetrics.

Neonatal Subgaleal Hemorrhage and Its Relationship to Delivery by Vacuum Extraction

Subgaleal hemorrhage is a rare condition of the neonate often associated with instrumental delivery. It is a potentially fatal condition that is often underreported and underdiagnosed. The vacuum extractor is being advocated as the instrument of first choice for assisted vaginal delivery, but appears to be associated with an increased incidence of subgaleal hemorrhage. It is widely believed that the vacuum cup will dislodge before causing serious fetal trauma. Because of the ease of application, vacuum extractors could be used potentially in circumstances in which forceps would not be attempted, allowing an operator of average experience to perform rotational deliveries. The worrisome increase in the incidence of subgaleal hemorrhage associated with vacuum extraction leads to the issuance of warnings from governmental authorities in Canada and the United States. This review discusses the anatomy of this lesion, etiology, clinical presentation, management, and possible prevention.

Operative vaginal delivery: clinical appraisal of a new vacuum extraction device

The efficacy of a new vacuum extraction device, the Kiwi OmniCup, and its effects on mothers and infants were tested in a study of 18 non-rotational and 32 rotational vacuum assisted deliveries. Forty-nine (98%) of the extractions resulted in successful vaginal births. Autorotation of the fetal head when the occiput was transverse or posterior was achieved in 31 (97%) of the 32 vacuum procedures. The high success rates recorded for both vaginal delivery and autorotation of the fetal head were largely attributable to the fact that flexing cup applications were achieved in 90 % of the vacuum attempts. There were no cases of serious maternal trauma or clinically significant neonatal injuries. Two infants had cephalohaematomas and one infant developed a small subgaleal haemorrhage following a difficult delivery, which resolved rapidly without complications. It was concluded that the Kiwi OmniCup is an efficient and safe vacuum device for assisted vaginal delivery, provided it is used correctly and appropriately.

Vacuum extraction: a randomized controlled comparison of the New Generation cup with the original Bird cup

A new design of vacuum extractor cup--'the New Generation cup'--has recently been introduced into clinical practice. Its major modification is a traction cord which passes around the rim of the cup for 180 degrees and is free to slide within the rim. Claims that this design 'enables the operator to pull obliquely without causing the cup to tilt' and thereby 'reduces failure rates, reduces the incidence of scalp trauma and increases operator confidence' have been evaluated in a randomized controlled trial. 123 women with singleton pregnancies of 37 completed weeks or more, with a cephalic presentation and for whom a decision to deliver by vacuum extraction had been taken, were randomly allocated to the 'New Generation' cup or BIRD's original vacuum extractor cup; 50 mm anterior and posterior cups were used in both groups as appropriate. The two groups were comparable at entry and delivered by obstetricians of similar status. The two types of cup were similar in respect of number of failures to deliver with the vacuum extractor, correct positioning of the cup, number of pulls required for delivery and time taken to expedite delivery. Cup detachments occurred in nine cases allocated to the 'New Generation' cup compared with four allocated to the original BIRD cup. The babies in the two groups were in similar condition at birth and sustained similar amounts of scalp trauma. Neonatal jaundice, both clinical and biochemical, was more common in babies delivered with the 'New Generation cup' and this was reflected in greater use of phototherapy in this group. Operators were equally divided in their preference of cup.(ABSTRACT TRUNCATED AT 250 WORDS)