Kiwi Omnicup versus Malmstrom metal cup in vacuum assisted delivery: a randomized comparative trial

The Impact of Total Deceleration Area and Fetal Growth on Neonatal Acidemia in Vacuum Extraction Deliveries

We aimed to investigate the correlation between total deceleration area (TDA), neonatal birthweight and neonatal acidemia in vacuum extractions (VEs). This is a retrospective study in a tertiary hospital, including VE performed due to non-reassuring fetal heart rate (NRFHR). Electronic fetal monitoring during the 120 min preceding delivery was interpreted by two obstetricians who were blinded to neonatal outcomes. TDA was calculated as the sum of the area under the curve for each deceleration. Neonatal birthweights were classified as low (<2500 g), normal (2500-3999 g) or macrosomic (>4000 g). A total of 85 VEs were analyzed. Multivariable linear regression, adjusted for gestational age, nulliparity and diabetes mellitus, revealed a negative correlation between TDA in the 60 min preceding delivery and umbilical cord pH. For every 10 K increase in TDA, the cord pH decreased by 0.02 (p = 0.038; 95%CI, -0.05-0.00). The use of the Ventouse-Mityvac cup was associated with a 0.08 decrease in cord pH as compared to the Kiwi OmniCup (95%CI, -0.16-0.00; p = 0.049). Low birthweights, compared to normal birthweights, were not associated with a change in cord pH. To conclude, a significant correlation was found between TDA during the 60 min preceding delivery and cord pH in VE performed due to NRFHR.

Head position and vacuum-assisted delivery using the Kiwi Omnicup

OBJECTIVE

To evaluate the association between fetal head position during prevacuum assessment and adverse outcomes.

METHOD

This retrospective cohort study included all vacuum-assisted deliveries using the Kiwi Omnicup over 5 years. Primary outcomes were third- or fourth-degree perineal tear, pH < 7.1, and subgaleal hematoma (SGH). AGAR, neonatal intensive care unit admission, cephalohematoma, Erb's palsy, third-stage duration, and postpartum hemorrhage were secondary. Outcomes were compared between the occiput posterior (OP) and occiput anterior (OA) positions.

RESULTS

The study included 1960 patients. OP position was more likely to involve epidural analgesia (311 [82.5%] vs. 1216 [77%], P = 0.020), higher fetal head station (P = 0.001), higher percentage of cup detachments (121 cases [32.1%] vs. 307 [19.4%], P = 0.001), and longer procedure (5.5 ± 3.7 min vs. 4.7 ± 2.8 min, P = 0.001). OP was associated with umbilical cord pH < 7.1 (21 [5.5%] vs. 52 [3.9%], P = 0.032), NICU admissions (16 [4.2%] vs. 38 [2.4%], P = 0.049), SGH (18 [4.8%] vs. 38 [2.4%], P = 0.013), and high-degree perineal tears (12 [3.2%] vs. 26 [1.7%], with borderline significance, P = 0.051). SGH and high-grade tears remained significantly associated with OP position (P = 0.008 and P = 0.016, respectively) after adjusting for maternal age, nulliparity, diabetes, epidural anesthesia, preprocedure head station, and birth weight.

CONCLUSION

OP position is an independent risk-factor for anal sphincter injury and SGH during vacuum-assisted delivery.

Head Injuries Related to Birth Trauma in Low Birthweight Neonates During Vacuum Extraction

Introduction Preterm delivery (gestational age < 34 w) is a relative contraindication to vacuum extraction. Current data do not differentiate clearly between preterm delivery and low birthweight. We aimed to evaluate the impact of non-metal vacuum cup extraction on neonatal head injuries related to birth trauma in newborns with low birthweights (< 2500 g). Materials and Methods A retrospective cohort of 3377 singleton pregnancies delivered by vacuum extraction from 2014 to 2019. All were gestational age ≥ 34 w. We compared 206 (6.1%) neonates with low birthweights < 2500 g to 3171 (93.9%) neonates with higher birthweights, divided into 3 subgroups (2500-2999 g, 3000-3499 g, and ≥ 3500 g). A primary composite outcome of neonatal head injuries related to birth trauma was defined. Results The lowest rates of subgaleal hematoma occurred in neonates < 2500 g (0.5%); the rate increased with every additional 500 g of neonatal birthweight (3.5%, 4.4% and 8.0% in the 2500-2999 g, 3000-3499 g, and ≥ 3500 g groups, respectively; p = 0.001). Fewer cephalohematomas occurred in low birthweight neonates (0.5% in < 2500 g), although the percentage increased with every additional 500 g of birthweight (2.6%, 3.3% and 3.7% in the 2500-2999 g, 3000-3499 g, and ≥ 3500 g groups, respectively, p = 0.020). Logistic regression found increasing birthweight to be a significant risk factor for head injuries during vacuum extraction, with adjusted odds ratios of 8.12, 10.88, and 13.5 for 2500-2999 g, 3000-3499 g, and ≥ 3500 g, respectively (p = 0.016). NICU hospitalization rates were highest for neonates weighing < 2500 g (10.2%) compared to the other groups (3.1%, 1.7% and 3.3% in 2500-2999 g, 3000-3499 g, ≥ 3500 respectively, p < 0.001). Conclusions Vacuum extraction of neonates weighing < 2500 g at 34 w and beyond seems to be a safe mode of delivery when indicated, with lower rates of head injury related to birth trauma, compared to neonates with higher birthweights.

Instruments for assisted vaginal birth

BACKGROUND

Assisted vaginal births are carried out to expedite birth for the benefit of mothers and babies but are sometimes associated with significant morbidity for both. Various instruments are available, broadly divided into forceps and vacuum cups, and choice may be influenced by clinical circumstances, operator preference, experience and availability.  OBJECTIVES: To evaluate the different instruments in terms of success in achieving a vaginal birth, and the risk of morbidity for mother and baby.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) (14 May 2021), and reference lists of retrieved studies.

SELECTION CRITERIA

We selected randomised controlled trials of assisted vaginal birth using different instruments. The review did not include quasi-randomised trials, cluster-randomised trials or cross-over designs. The review included trials for which abstracts alone were available as long as there was sufficient information to assess eligibility.  DATA COLLECTION AND ANALYSIS: We used standard Cochrane methods. We used the GRADE approach to assess the certainty of evidence.  The main outcomes assessed included failed delivery with allocated instrument, any maternal trauma, third- and fourth-degree tears, postpartum haemorrhage, any neonatal trauma, low Apgar and low umbilical artery pH.  MAIN RESULTS: We included 31 studies involving a total of 5754 women.  Risk of bias criteria were largely assessed as 'unclear', due to a lack of detail in trial reports. Blinding would have been challenging for all trials due to their inability to conceal the type of instrument used from either the woman or the operator, which is reflected in the risk of bias assessment. Any type of forceps versus any type of vacuum cup (12 studies, 3129 women) Forceps may be less likely to fail in achieving vaginal birth: risk ratio (RR) 0.58, 95% confidence interval (CI) 0.39 to 0.88; 11 studies, 3080 women; low certainty. 'Any maternal trauma' may be slightly more likely with forceps: odds ratio (OR) 1.53, 95% CI 0.98 to 2.40; 5 studies, 1356 women; low certainty; and third- or fourth-degree tears may also be more likely with forceps: RR 1.83, 95% CI 1.32 to 2.55; 9 studies, 2493 women; low certainty. There is no evidence of a difference in the incidence of postpartum haemorrhage (PPH) between the two groups: RR 1.71, 95% CI 0.59 to 4.95; 2 studies, 523 women; low certainty, because the evidence is very imprecise due to a very wide CI.  More women in the forceps group reported requiring pain relief. There is probably no evidence of difference in rates of low Apgar: RR 0.83, 95% CI 0.46 to 1.51; 7 studies, 1644 women; moderate certainty; or low umbilical artery pH in the forceps group compared to any vacuum: RR 1.33, 95% CI 0.91 to 1.93; 2 studies, 789 women; low certainty; both of these outcomes are imprecise and have wide CIs that include both benefit and harm. There were also lower rates of fetal trauma with 'any forceps' (cephalhematoma, retinal haemorrhage and jaundice). The composite outcome of 'any neonatal trauma' was not reported. Low-cavity forceps versus any vacuum cup (2 studies, 218 women) We included two small studies with 218 participants in this comparison, but we judged most of the evidence as very low certainty, hence it was not feasible to make judgements on the difference in the rates of failed delivery, any maternal trauma or third- and fourth- degree tears. PPH and low umbilical artery pH were not reported. Soft vacuum cup versus any rigid cup (9 studies, 1148 women) Failed delivery may be more likely in the soft vacuum cup group: RR 1.62, 95% CI 1.21 to 2.17; 9 studies, 1148 women; low certainty. There may be no difference in the rates of 'any maternal trauma': OR 0.63, 95% CI 0.24 to 1.67; 2 studies, 348 women; low certainty, but the confidence interval is wide, indicating possible benefit or harm. There may be no difference in the rates of third- or fourth-degree tears: RR 0.93, 95% CI 0.35 to 2.44; 4 studies, 619 women; low certainty. There is probably no difference in the rates of PPH: RR 0.89, 95% CI 0.49 to 1.61; 5 studies, 737 women; moderate certainty between the soft and rigid cup groups.   There may be little or no difference in the incidence of low Apgar scores: RR 0.82, 95% CI 0.49 to 1.37; 9 studies, 1148; low certainty; or low umbilical artery pH: RR 0.80, 95% CI 0.47 to 1.36; 1 study, 100 women; low certainty. Handheld vacuum versus any vacuum cup (4 studies, 968 women) There may be no difference in the rates of failures with allocated instrument: RR 1.35, 95% CI 0.81 to 2.25; 4 studies, 962 women; low certainty, any maternal trauma: OR 1.16, 95% CI 0.71 to 1.88; 2 studies; 394 women; low certainty, PPH: RR 0.31, 95% CI 0.03 to 2.92; 1 study, 164 women; low certainty, low umbilical artery pH: RR 1.06, 95% CI 0.71 to 1.59; 1 study, 164 women; low certainty, or low Apgar scores: RR 1.25, 95% CI 0.34 to 4.61; 3 studies, 784 women; low certainty) between the two groups. There is probably no difference in the rates of third- or fourth-degree tears between the 'handheld vacuum' and 'any vacuum cup' groups: RR 1.15, 95% CI 0.62 to 2.12; 4 studies, 962 women; moderate certainty.

AUTHORS' CONCLUSIONS

This review provides low-certainty evidence that forceps may be more likely to achieve vaginal birth and have lower rates of fetal trauma, but at a greater risk of perineal trauma and higher pain relief requirements compared with vacuum cups. There was low-certainty evidence that rigid vacuum cups may be more likely to achieve a vaginal birth than soft cups but with more fetal trauma, whilst handheld vacuum cups had similar success rates compared to other cups. There was no evidence of a difference in the rates of third- or fourth-degree tears or postpartum haemorrhages between types of cups, but wide confidence intervals around the estimates indicate further research is needed in this area.

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.

Adverse outcomes in vacuum-assisted delivery after detachment of non-metal cup: a retrospective cohort study

PURPOSE

To evaluate neonatal and maternal outcomes associated with detachment of non-metal vacuum cup during delivery and to identify risk factors for these detachments.

METHODS

This retrospective cohort study included women with singleton pregnancy, who underwent vacuum-assisted vaginal delivery with a non-metal vacuum cup in a single academic institution, January 2014-August 2019. Failed vacuum deliveries were excluded. Primary outcomes were defined as subgaleal hematoma (SGH) and cord blood pH < 7.15. Secondary outcome included other neonatal complications and adverse maternal outcomes. Outcomes were compared between vacuum-assisted deliveries with and without cup detachment during the procedure.

RESULTS

A total of 3246 women had successful VAD and met the inclusion criteria. During the procedure, the cup detached at least once in 665 (20.5%) deliveries and did not detach in 2581 (79.5%). The cup detachment group experienced higher rates of SGH (8.9% vs. 3.5%, p = 0.001) and cord blood pH < 7.15 (9.8% vs. 7.1%, p = 0.03). There were also more neonatal intensive care unit admissions (NICU) (4.4% vs. 2.7%, p = 0.03) and more fetuses with occiput posterior position (70.8% vs. 79.4%, p = 0.001), the vacuum duration was slightly longer (6 ± 3.7 vs. 5 ± 2.9 min) and more neonates had birth weights > 3700 g (14.1% vs, 10.3%, p = 0.006). Interestingly, there were more males in that group (60.6 vs. 54.6, p = 0.005). All these factors remained significant after controlling for potential confounders.

CONCLUSIONS

Vacuum cup detachment has several predictive characteristics and is associated with adverse neonatal outcomes that should be incorporated into decisions made during the procedure.

Exploring the reporting standards of RCTs involving invasive procedures for assisted vaginal birth: A systematic review

OBJECTIVE

Assisted vaginal birth (AVB) is a complex intervention involving medical devices, comprising multiple components. This complexity creates difficulties when designing and conducting randomised controlled trials (RCTs), in terms of describing, standardising and monitoring the intervention, and accounting for differing clinician expertise. This review examines the reporting standards of complex interventions involving a medical device, in the context of AVB RCTs.

STUDY DESIGN

Searches were undertaken from the start of indexing to March 2021, and limited to RCTs, feasibility and pilot studies including at least one device for AVB. RCTs were selected if they included participants having an AVB with any device, with or without a comparator group. Reporting details were assessed according to the Consolidating Standards of Reporting Trials extension for non-pharmacological treatments (CONSORT-NPT), focusing on intervention descriptions, standardization, adherence and clinician expertise. Screening of abstracts, full-text articles and data extraction was performed by two independent reviewers.

RESULTS

Of 4098 abstracts and 83 full-text articles, 39 papers were included, investigating 80 interventions. Twenty-seven different named devices were identified. Intervention descriptions were provided in 20 (55%) papers with varying levels of detail and with only one covering the entire procedure. Standardization of interventions was mentioned in 25 papers (64%). Only eight (21%) papers reported any form of adherence to the intended procedure. Some data regarding expertise were reported in 25 (64%) papers.

CONCLUSIONS

Despite some compliance with reporting standards, there is a lack of detail regarding intervention description, standardization, adherence and expertise in RCTs of AVB. This creates difficulties in understanding how intervention delivery was intended and what actually occurred. Clearer guidelines for the reporting of invasive procedures and devices are required.

Which technique is better to place a manoeuvrable vacuum extractor cup on the flexion point? Vacca vs. Bird technique

Objectives The purpose of this study is to compare the vacuum extractor cup application technique described by Bird vs. the technique described by Vacca on a simulation model. Methods Six obstetricians participated in the study. Each obstetrician performed eight vacuum assisted deliveries using the Bird technique and eight vacuum assisted deliveries using the Vacca 5-Steps technique. Results A total of 96 vacuum assisted deliveries were performed. The mean distance from the centre of the cup to the flexion point was 1.78±0.96 cm for the Bird technique and 1.05±0.60 cm for the Vacca technique (p<0.001). The lateral distance (over the parietal bone) was 1.16±0.69 cm for the Bird technique and 0.66±0.52 cm for the Vacca technique (p<0.001). The vertical distance (towards the frontal or occipital bone) was 1.12±1.02 cm for the Bird technique and 0.67±0.55 cm for the Vacca technique (p=0.009). In occipito anterior positions, there were no significant differences between both techniques. Conclusions The Vacca technique was better in transverse and posterior positions.

Birth tears after spontaneous and vacuum-assisted births with different vacuum cup systems - a retrospective cohort study

Objectives Birth tears are a common complication of vaginal childbirth. We aimed to evaluate the outcomes of birth tears first by comparing the mode of vaginal birth (VB) and then comparing different vacuum cups in instrumental VBs in order to better advise childbearing women and obstetrical professionals. Methods In a retrospective cohort study, we analyzed nulliparous and multiparous women with a singleton pregnancy in vertex presentation at ≥37 + 0 gestational weeks who gave birth vaginally at our tertiary care center between 06/2012 and 12/2016. We compared the distribution of tear types in spontaneous births (SBs) vs. vacuum-assisted VBs. We then compared the tear distribution in the vacuum group when using the Kiwi Omnicup or Bird's anterior metal cup. Outcome parameters were the incidence and distribution of the different tear types dependent on the mode of delivery and type of vacuum cup. Results A total of 4549 SBs and 907 VBs were analyzed. Birth tear distribution differed significantly between the birth modes. In 15.2% of women with an SB an episiotomy was performed vs. 58.5% in women with a VB. Any kind of perineal tear was seen in 45.7% after SB and in 32.7% after VB. High-grade obstetric anal sphincter injuries (OASIS) appeared in 1.1% after SB and in 3.1% after VB. No significant changes in tear distribution were found between the two different VB modes. Conclusions There were more episiotomies, vaginal tears and OASIS after VB than after SB. In contrast, there were more low-grade perineal and labial tears after SB. No significant differences were found between different vacuum cup systems, just a slight trend toward different tear patterns.

Kiwi omnicup handheld versus Mityvac M-style conventional vacuum system: a retrospective observational study

INTRODUCTION

To improve the choice of vacuum-assisted delivery (VAD) system, we compared the outcomes of Kiwi handheld system and Mityvac M-style conventional system (both use disposable plastic cups).

MATERIALS AND METHODS

Retrospective observational study with data collection from electronic medical records. The study was conducted at a tertiary medical center, with approximately 7000 deliveries annually. Categorical and continuous variables were analyzed using chi-square test and t-test, respectively. p value < .05 was considered significant. The main outcomes assessed were the overall failure rate of each system, failure rates for occipito-anterior (OA) versus occipito-transverse/occipito-anterior (OT/OP) positions, +1 versus +2 fetal stations, and early maternal/neonatal outcomes.

RESULTS

During a 10-month period, there were 507 (8.4%) attempted VADs, 36 failed (7.1%), and eight (1.5%) converted to cesarean section. Of these, 364 were Kiwi-assisted and 143 Mityvac-assisted. Background characteristics were similar. The handheld system had more failures overall (9.6 versus 0.7%), at OA (7.6 versus 0.9%), and non-OA positions (17.3% versus none), at +1 (13.25 versus 0.96%) and at +2/3 stations (6.1% versus none), than the conventional system did, respectively. There was a higher rate of early post-partum hemorrhage (15.3 versus 7.4%) in the conventional group. Both systems had similar rates of third/fourth degree perineal tears, shoulder dystocia and adverse neonatal outcomes.

CONCLUSIONS

Our results suggest more failures with Kiwi compared to Mityvac, overall and at any fetal position/station, without a significant difference in adverse outcome profile.

Strategies to reduce and maintain low perinatal mortality in resource-poor settings - Findings from a four-decade observational study of birth records from a large public maternity hospital in Papua New Guinea

BACKGROUND

In many low- to middle-income countries (LMIC) assisted vaginal birth rates have fallen, while caesarean section (CS) rates have increased, with potentially deleterious consequences for maternal and perinatal mortality.

AIMS

To review birth mode and perinatal mortality in a large LMIC hospital with strict labour management protocols and expertise in vacuum extraction.

MATERIALS AND METHODS

We conducted a retrospective observational study at Port Moresby General Hospital in Papua New Guinea. Birth registers from 1977 to 2015 (39 years) were reviewed. Overall and modified (fresh stillbirths and early neonatal deaths ≥500 g) perinatal mortality rates (PMRs) were calculated by birthweight/birth mode.

RESULTS

There were 365 056 births (5215 in 1977; 14 927 in 2015), of which 14 179 (3.9%) were vacuum extractions, 609 (0.2%) forceps births and 14 747 (4.4%) CS (increase from 2% to 5%). The failure rate of vacuum extraction was 2.5% (range 0.5-5.4%). Symphysiotomy was employed for 184 births. From 1989 to 2015, the modified mean PMR for babies ≥2500 g was 8.1/1000 births (range 5.6-12.1; 6.9 in 2015), 9.1/1000 for babies ≥1500 g (7.3-14.8; 9.1 in 2015) and 7.5/1000 (0-21.7; 9.0 in 2015) for vacuum extractions (98% were ≥2500 g). The overall PMR for these years was 29.7/1000 births.

CONCLUSIONS

In an LMIC with rapidly increasing birth numbers a comparatively low PMR can be achieved while maintaining low CS rates. This may be in part accomplished through strict use of second-stage protocols, perinatal audit, and supportive training that promotes judicious and proficient use of vacuum extraction and CS.

A randomized comparison of video demonstration versus hands-on training of medical students for vacuum delivery using Objective Structured Assessment of Technical Skills (OSATS)

BACKGROUND

To compare medical students' skills for vaginal operative delivery by vacuum extraction (VE) after hands-on training versus video demonstration.

METHODS

We randomized medical students to an expert demonstration (group 1) or a hands-on (group 2) training using a standardized VE algorithm on a pelvic training model. Students were tested with a 40-item Objective Structured Assessment of Technical Skills (OSATS) scoring system after training and 4 days later. OSATS scores were the primary outcome. Performance time, self-assessment, confidence, and global rating scale were secondary outcomes. We assessed the constructive validity of OSATS in this VE model comparing metric scores of experts and students.

RESULTS

In all, 137 students were randomized. OSATS scores were higher in group 2 (n = 63) compared with group 1 (n = 74) (32.89 ± 6.39 vs 27.51 ± 10.27, respectively; P < 0.0001). Global rating scale (1.49 ± 0.76 vs 2.33 ± 0.94, respectively; P < 0.0001), confidence (2.22 ± 0.75 vs 3.26 ± 0.94, respectively; P = 0.04), self-assessment (2.03 ± 0.62 vs 2.51 ± 0.77, respectively; P < 0.0001), and performance time (38.81 ± 11.58 seconds vs 47.23 ± 17.35 seconds, respectively; P = 0.001) also favored group 2. After 4 days, this effect persisted with OSATS scores still being significantly higher in group 2 (30.00 ± 6.50 vs 25.59 ± 6.09, respectively; P = 0.001). The assessed OSATS scores showed constructive validity. In a multiple linear regression analysis, group assignment independently influenced OSATS scores, whereas sex, handedness, sports activities, and type of curriculum were not independently associated with OSATS scores.

CONCLUSIONS

Hands-on training is superior to video demonstration for teaching VE on a pelvic model.

Clinical impact of the disposable ventouse iCup® versus a metallic vacuum cup: a multicenter randomized controlled trial

Background

Assisted vaginal delivery by vacuum extraction is frequent. Metallic resterilizible metallic vacuum cups have been routinely used in France. In the last few years a new disposable semi-soft vacuum extraction cup, the iCup, has been introduced. Our objective was to compare maternal and new-born outcomes between this disposable cup and the commonly used Drapier-Faure metallic cup.

Methods

This was a multicenter prospective randomized controlled open clinical trial performed in the maternity units of five university hospitals and one community hospital in France from October 2009 to February 2013. We included consecutive eligible women with a singleton gestation of at least 37 weeks who required vacuum assisted delivery. Women were randomized to vacuum extraction using the iCup or usual Drapier-Faure metallic cup. The primary outcome was a composite criterion including both the risk of cup dysfunction and the most frequent maternal and neonatal harms: the use of other instruments after attempted vacuum extraction, caesarean section after attempted vacuum extraction, three detachments of the cup, caput succedaneum, cephalohaematoma, episiotomy and perineal tears.

Results

335 women were randomized to the disposable cup and 333 to extraction using the metallic cup. There was no significant difference between the two groups for the primary outcome. However, failed instrumental delivery was more frequent in the disposable cup group, mainly due to detachment: 35.6 % vs 7.1 %, p < 0.0001. Conversely, perineal tears were more frequent in the metallic cup group, especially third or fourth grade perineal tears: 1.7 % versus 5.0 %, p = 0.003. There were no significant differences between the two groups concerning post-partum haemorrhage, transfer to a neonatal intensive care unit (NICU) or serious adverse events.

Conclusions

While the disposable cup had more detachments and extraction failures than the standard metallic cup, this innovative disposable device had the advantage of fewer perineal injuries.

Trial registration

www.clinicaltrials.gov: NCT01058200 on Jan. 27 2010.

Electronic supplementary material

The online version of this article (doi:10.1186/s12884-015-0771-1) contains supplementary material, which is available to authorized users.

Choice of instruments for assisted vaginal delivery

BACKGROUND

Instrumental or assisted vaginal birth is commonly used to expedite birth for the benefit of either mother or baby or both. It is sometimes associated with significant complications for both mother and baby. The choice of instrument may be influenced by clinical circumstances, operator choice and availability of specific instruments.

OBJECTIVES

To evaluate different instruments in terms of achieving a vaginal birth and avoiding significant morbidity for mother and baby.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 May 2010).

SELECTION CRITERIA

Randomised controlled trials of assisted vaginal delivery using different instruments.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality, extracted the data, and checked them for accuracy.

MAIN RESULTS

We included 32 studies (6597 women) in this review. Forceps were less likely than the ventouse to fail to achieve a vaginal birth with the allocated instrument (risk ratio (RR) 0.65, 95% confidence interval (CI) 0.45 to 0.94). However, with forceps there was a trend to more caesarean sections, and significantly more third- or fourth-degree tears (with or without episiotomy), vaginal trauma, use of general anaesthesia, and flatus incontinence or altered continence. Facial injury was more likely with forceps (RR 5.10, 95% CI 1.12 to 23.25). Using a random-effects model because of heterogeneity between studies, there was a trend towards fewer cases of cephalhaematoma with forceps (average RR 0.64, 95% CI 0.37 to 1.11).Among different types of ventouse, the metal cup was more likely to result in a successful vaginal birth than the soft cup, with more cases of scalp injury and cephalhaematoma. The hand-held ventouse was associated with more failures than the metal ventouse, and a trend to fewer than the soft ventouse.Overall forceps or the metal cup appear to be most effective at achieving a vaginal birth, but with increased risk of maternal trauma with forceps and neonatal trauma with the metal cup.

AUTHORS' CONCLUSIONS

There is a recognised place for forceps and all types of ventouse in clinical practice. The role of operator training with any choice of instrument must be emphasised. The increasing risks of failed delivery with the chosen instrument from forceps to metal cup to hand-held to soft cup vacuum, and trade-offs between risks of maternal and neonatal trauma identified in this review need to be considered when choosing an instrument.

[Kiwi vacuum extractor versus forceps and spatula: maternal and fetal morbidity evaluation in 169 fetal extractions]

AIM

To evaluate maternal and fetal complications resulting from the use of the Kiwi vacuum extractor and to compare them with those resulting from the use of forceps or spatula.

PATIENTS AND METHODS

Patients who had instrumental extraction between November 2006 and April 2007 were included in a unicentric retrospective study. Complications resulting from the use of Kiwi vacuum extractor and those of other instruments were compared.

RESULTS

One hundred and sixty-nine patients where included, 79 had extraction with Kiwi vacuum extractor. The two populations (women having extraction with Kiwi and woman having extraction with spatula or forceps) were similar in terms of maternal characteristics, progress of labour and delivery. The rate of episiotomies was significantly lower with KIWI (73.1% versus 94.4%; P=0.0001), as well as was postpartum haemorrhage rate (8.9 % versus 18.9%; P=0.04). No perineal tear of second or third degree occurred with Kiwi. Kiwi vacuum extractor was associated with a higher rate of shoulder dystocia (12.8% versus 6.7%, NS), but related fetal complication rates were similar in the two groups. The extraction failure rate was significantly higher with Kiwi (11.4% versus 4.4%; P=0.04), but cesarean section rate was similar for the two groups (1.3 % versus 4.4%).

DISCUSSION AND CONCLUSION

This study is the first comparing complications occurring after extraction with KIWI vacuum extractor to those occurring with other instruments. Although the results are limited by the retrospective nature of the study and the small size of the workforce, our study suggests that Kiwi vacuum extractor is associated with a lower rate of maternal complications and a rate of fetal complication similar to other kind of instruments. This instrument should be promoted and taught to younger patricians. Our study also revealed higher failure and shoulder dystocia rates. Larger studies are needed to better evaluate risks factor concerning these two complications in order to optimise the use of Kiwi vacuum extractor.