Risk factors for and consequences of difficult fetal extraction in emergency caesarean section. A retrospective registry-based cohort study

INTRODUCTION

This study aimed to assess risk factors for difficult fetal extraction in emergency caesarean sections, focusing on top-up epidural anesthesia compared to spinal anesthesia. Additionally, this study addressed consequences of difficult fetal extraction on neonatal and maternal morbidity.

MATERIAL AND METHODS

This retrospective registry-based cohort study included 2,332 of 2,892 emergency caesarean sections performed with local anesthesia during 2010-2017. Main outcomes were analyzed by crude and multiple adjusted logistic regression providing odds ratios.

RESULTS

Difficult fetal extraction was found in 14.9% of emergency caesarean sections. Risk-factors for difficult fetal extraction included top-up epidural anesthesia (aOR:1.37[95 %CI 1.04-1.81]), high pre-pregnancy BMI (aOR:1.41[95 %CI 1.05-1.89]), deep fetal descent (ischial spine: aOR:2.53[95 %CI 1.89-3.39], pelvic floor: aOR:3.11[95 %CI 1.32-7.33]), and anterior placental position (aOR:1.37[95 %CI 1.06-1.77]). Difficult fetal extraction was associated with increased risk of low umbilical artery pH 7.00-7.09 (aOR:3.50[95 %CI 1.98-6.15]) pH ≤ 6.99 (aOR:4.20[95 %CI 1.61-10.91]), five-minute Apgar score ≤ 6 (aOR:3.41[95 %CI 1.49-7.83]) and maternal blood loss (501-1,000 ml: aOR:1.65[95 %CI 1.27-2.16], 1,001-1,500 ml: aOR:3.24[95 %CI 2.24-4.67], 1,501-2,000 ml: aOR:3.94[95 %CI 2.24-6.94] and ≥ 2001 ml: aOR:2.76[95 %CI 1.12-6.82]).

CONCLUSION

This study identified four risk factors for difficult fetal extraction in emergency caesarean section: top-up epidural anesthesia, high maternal BMI, deep fetal descent and anterior placental position. Additionally, difficult fetal extraction was associated with poor neonatal and maternal outcomes.

The acceptability and feasibility of a randomised trial exploring approaches to managing impacted fetal head during emergency caesarean section: a qualitative study

BACKGROUND

Caesarean sections (CS) account for 26% of all births in the UK, of which at least 5% are done at full dilatation, in the second stage of labour. Second stage CS may be complicated by the fetal head being deeply impacted in the maternal pelvis, requiring specialist skills to achieve a safe birth. Numerous techniques are used to manage impacted fetal head, however, there are no national clinical guidelines in the UK.

AIM

To explore health professionals' and women's views on the acceptability and feasibility of a randomised controlled trial (RCT) designed to explore approaches to managing an impacted fetal head during emergency CS.

METHODS

Semi-structured interviews with 10 obstetricians and 16 women (6 pregnant and 10 who experienced an emergency second stage CS). Interviews were transcribed and analysed using systematic thematic analysis.

RESULTS

The findings considered the time at which you obtain consent, how and when information about the RCT is presented, and barriers and facilitators to recruiting health professionals and women into the RCT. Obstetricians emphasised the importance of training in the techniques, as well as the potential conflict between the RCT protocol and current site or individual practices. Women said they would trust health professionals' to use the most appropriate technique and abandon the RCT protocol if necessary. Similarly, obstetricians raised the tension between the RCT protocol versus safety in reverting to what they knew under emergency situations. Both groups reflected on how this might affect the authenticity of the results. A range of important maternal, infant and clinical outcomes were raised by women and obstetricians. However, there were varying views on which of the two RCT designs presented to participants would be preferred. Most participants thought the RCT would be feasible and acceptable.

CONCLUSIONS

This study suggests an RCT designed to evaluate different techniques for managing an impacted fetal head would be feasible and acceptable. However, it also identified a number of challenges that need to be considered when designing such an RCT. Results can be used to inform the design of RCTs in this area.

Techniques for managing an impacted fetal head at caesarean section: A systematic review

A complication arising at caesarean birth when the baby's head is deeply engaged in the pelvis and may be difficult to deliver, is known as an 'impacted fetal head'. This obstetric emergency occurs in 16% of second stage caesarean sections. Multiple techniques are described in the literature to manage the complication but there is no consensus regarding which technique results in the best maternal and neonatal outcomes. The objective of this review is to determine which technique for managing impacted fetal head at caesarean section has the best maternal and neonatal outcomes. A literature search of three electronic databases was conducted in November 2021. Studies directly comparing two methods for the management of impacted fetal head at caesarean section in the second stage were included. Systematic reviews, meta-analyses, case-control studies, and studies not fitting the search criteria were excluded. Data was extracted in Covidence and meta-analysis of the six most commonly reported outcomes was conducted using RevMan 5.4. In total, 16 studies (3344women) were included. 13 studies (2506women) compared the push method with reverse breech extraction. meta-analysis showed that risk of extension of the uterine incision, blood transfusion, bladder injury, postpartum haemorrhage, NICU admission and Apgar score <7 at 5 min were significantly higher with the push method compared with reverse breech extraction. Three studies (838women) compared the push method with Patwardhan's technique. meta-analysis of studies comparing the push method with Patwardhan's technique found no significant differences between the two groups in any of the six maternal or neonatal outcomes. Evidence derived from small, inadequately powered studies suggests reverse breech extraction is associated with better outcomes than the push method. The method which produces the best outcomes is still unknown as not all methods have been tested. Further high quality, adequately powered RCTs are warranted for definitive conclusions to be drawn and to ameliorate the paucity of evidence on how best to manage this complication.

Impacted fetal head during second stage Caesarean birth: A prospective observational study

OBJECTIVE

To determine the incidence of, and complication rates from, impacted fetal head at full dilatation Caesarean birth in the UK, and record what techniques were used.

DESIGN

Prospective observational study using the UK Obstetric Surveillance System (UKOSS).

SETTING

159 (82%) of the 194 UK hospitals with obstetric units.

POPULATION

All women who underwent second stage Caesarean birth in the UK between 1st March and 31st August 2019. Further information was collected on cases where a dis-impaction technique was used, or the operating surgeon experienced 'difficulty' in delivering the head.

METHODS

Prospective observational study.

MAIN OUTCOME MEASURES

Technique(s) used, maternal and neonatal outcomes.

RESULTS

3,518 s stage Caesarean births reported. The surgeon used a dis-impaction technique or reported 'difficulty' in 564 (16%) of these. The most common dis-impaction techniques used were manual elevation of the head by an assistant through the vagina (n = 235) and a fetal "pillow" (n = 176). Thirteen babies (2%) died or sustained severe injury. Four babies died (two directly attributable to the impacted fetal head).

CONCLUSIONS

Difficulty with delivery of the fetal head and the use of dis-impaction techniques during second stage Caesarean sections are common but there is no consensus as to the best method to achieve delivery and in what order.

Impacted fetal head: A retrospective cohort study of emergency caesarean section

OBJECTIVE

To investigate risk factors, management and outcomes of impacted fetal head (IFH) at caesarean section (CS).

STUDY DESIGN

This is a retrospective cohort study of all women with singleton, cephalic pregnancies who had an emergency CS during one-year (2016) at North Bristol NHS Trust, UK (n = 838). The incidence of caesarean section at full dilatation (CSFD) and IFH were calculated using the annual birth rate. To identify risk factors for IFH, maternal, perinatal and intrapartum characteristics were compared according to the presence or absence of IFH, and separately for first- and second-stage CS. Techniques employed to disimpact the fetal head were described. Univariable and multivariable comparisons of maternal and perinatal outcomes were made between cases with and without an IFH. Characteristics and outcomes were compared using modified Poisson regression.

RESULTS

CSFD accounted for 2.1 % of all births. IFH complicated 1.5 % of all births (11.3 % of emergency CS), with 55.8 % occurring prior to full cervical dilatation. Increased rates of IFH at CS were associated with: oxytocin augmentation (RR = 2.47 [1.61-3.80]), full cervical dilatation (RR = 4.24 [2.96-6.07], mid/low station (RR = 4.14 [2.72-6.32]), moulding (RR = 4.39 [2.55-7.54]) and caput (RR = 6.60 [3.09-14.10]). Junior operators documented IFH more than consultants (RR = 9.61 [1.35-68.2]). The strategies recorded for managing IFH included: tocolysis, reverse breech extraction and vaginal push up (33.7 %, 14.7 % and 11.6 % cases respectively) with two or more techniques used in 21.1 % cases. IFH at CS was independently associated with an increased risk of uterine extensions (RR = 3.09 [1.96-4.87]) and a composite adverse perinatal outcome (RR = 1.66 [1.21-2.28]).

CONCLUSIONS

IFH is a common and heterogeneous complication associated with increased complications for both mother and baby, independent of those of CSFD. Obstetricians must remain vigilant to the possibility of IFH at all emergency CS, particularly those at full cervical dilatation or with evidence of obstructed labour. There is an urgent need for a standardised management algorithm and training in evidence-based disimpaction techniques.

Maternal and neonatal outcome of reverse breech extraction of an impacted fetal head during caesarean section in advanced stage of labour: a retrospective cohort study

Background

Caesarean section with extraction of a deeply impacted fetal head is technically challenging and is associated with serious maternal and neonatal complications. The purpose of the study was to identify risks and evaluate selected outcome parameters associated with difficult fetal head extraction during caesarean section in advanced labour comparing two different extraction techniques (head pushing vs. reverse breech).

Methods

This retrospective cohort study was conducted at the Division of Obstetrics in a tertiary care hospital in Zurich, Switzerland. 629 women at term with a singleton pregnancy in cephalic presentation during advanced intrapartum caesarean section from December 2012 until December 2016 were evaluated. Primary outcome was the incidence of uterine incision extensions. Secondary outcomes were other selected maternal and neonatal outcome parameters. Data analysis was performed using SPSS with Mann-Whitney U independent sampling test and two-tailed Fisher’s exact test (p < 0.01).

Results

Difficult fetal head extractions are associated with significantly elevated maternal and neonatal risks. When performed by reverse breech technique, significant lower rates of extensions of the uterine incision, shorter operation times and less operative blood loss were identified compared to the head pushing method. No statistically significant differences for the neonatal outcomes were described so far. However, among the group of difficult fetal delivery with the head pushing method two neonates had perinatal skull fractures, with one of those resulting in neonatal death.

Conclusions

The head pushing method is associated with higher maternal morbidity than the reverse breech method for extraction of a deeply engaged fetus during intrapartum caesarean section in advanced stage of labour.