Chapter 40 – Failed Operative Vaginal Delivery




Abstract




Operative vaginal birth rate has been stable in the United Kingdom at about 10%–13% [3, 4]. The caesarean section at full dilation as an alternative approach to instrument delivery has a high maternal and neonatal morbidity, but failed instrument vaginal deliveries (FID), which lead to caesarean sections, are associated with potentially serious maternal and fetal complications such as angular tears, postpartum haemorrhage, difficulty in delivery of the fetal head, fetal ischaemic-hypoxic injuries, birth trauma and perinatal deaths. Therefore, it is important to identify factors which can help to predict successful operative vaginal delivery.


There are various established risk factors which increase the chances of instrument delivery, including advanced maternal age, high body mass index (BMI; >30), high birth weight (>4.0 kg) and epidural analgesia.





Chapter 40 Failed Operative Vaginal Delivery Minimising Maternal and Fetal Morbidity


Naheed Tahir and Edwin Chandraharan




Key Facts


Definition Failed instrumental (operative) vaginal delivery occurs when the clinician has to resort to an emergency caesarean section following an unsuccessful attempt at forceps or ventouse to accomplish a vaginal birth during the second stage of labour.


Type of Instruments Ventouse or forceps are two instruments used for trial.


Incidence Overall approximately 5%–10% of attempted instrumental deliveries fail and end up in emergency caesarean section at full dilation [1]. The rates of instrument delivery range from 5% to 20% in developed countries [2]. Failed instrument vaginal deliveries are associated with adverse maternal and neonatal outcomes.




Table 40.1 Complications after failed operative vaginal delivery













Maternal


  • Increased rate of general anaesthetic



  • Lateral extension of the uterine incision during disimpaction of the fetal head



  • Uterine artery laceration, resulting in excessive haemorrhage. In cases of extreme haemorrhage, hysterectomy may be indicated.



  • Broad ligament haematoma



  • Bladder injury



  • Urethral and ureteric injury due to inadvertent suturing to stop haemorrhage



  • Postpartum haemorrhage secondary to atonic uterus, a result of prolonged second stage and augmentation



  • Accidental suturing of the lower uterine incision with the posterior wall of the cervix, resulting in occlusion



  • Wound infection



  • Psychological trauma



  • Impact on future delivery, women with previous failed attempt are likely to opt for elective caesarean section [5]

Fetal


  • Lacerations



  • Umbilical pH<7.0



  • Apgar ≤ 3 at 5 min



  • Hypoxic ischaemic encephalopathy



  • Cephalohaematoma



  • Subgaleal haemorrhage



  • Craniofacial injuries



  • Intracranial haemorrhage



  • Skull fracture



  • Seizures



  • Jaundice



  • Neonatal death (hypoxia, trauma or sepsis)



Key Implications


Operative vaginal birth rate has been stable in the United Kingdom at about 10%–13% [3, 4]. The caesarean section at full dilation as an alternative approach to instrument delivery has a high maternal and neonatal morbidity, but failed instrument vaginal deliveries (FID), which lead to caesarean sections, are associated with potentially serious maternal and fetal complications such as angular tears, postpartum haemorrhage, difficulty in delivery of the fetal head, fetal ischaemic-hypoxic injuries, birth trauma and perinatal deaths. Therefore, it is important to identify factors which can help to predict successful operative vaginal delivery.


There are various established risk factors which increase the chances of instrument delivery, including advanced maternal age, high body mass index (BMI; >30), high birth weight (>4.0 kg) and epidural analgesia.


A Cochrane systematic review on the choice of instrument delivery emphasises the importance of training of the operator for successful instrument delivery [6]. However, there is no evidence, based on randomised controlled trails, which can guide obstetricians to decide between embarking on a trial of instrumental delivery or directly proceeding for an emergency caesarean section.



Key Pointers


Before starting an operative vaginal (instrumental) delivery and making it successful, it is very important to ensure that prerequisites for operative vaginal delivery are fulfilled.


A number of studies have suggested the following factors as determinants of a failed instrument delivery [9, 10]:




  1. One persistent OP position



  2. Birth weight >4 kg



  3. Maternal BMI>30



  4. Mid cavity delivery or when one-fifth fetal head palpable abdominally


A clinical study at a tertiary referral centre in London (St George’s University Hospital) analysing the determinants and outcomes of emergency caesarean sections after failed operative vaginal delivery during a 5-year period [11]. According to this study, the incidence of caesarean sections after failed instrument delivery was 0.44% and the incidence of failed instrument delivery was 5.1%. The authors suggested a failed instrument delivery scoring (FIDS) system to predict the success of instrument delivery, based on the determinants of failed operative vaginal births in their study.




Table 40.2 Prerequisites for operative vaginal delivery
















Full abdominal and vaginal examination


  • Head is ≤1/5th palpable per abdomen



  • Cephalic presentation.



  • Cervix is fully dilated and the membranes ruptured.



  • Exact position of the head can be determined so proper placement of the instrument can be achieved.



  • Assessment of caput and moulding.



  • Pelvis is deemed adequate. Irreducible moulding may indicate cephalo–pelvic disproportion.

Preparation of mother


  • Clear explanation should be given and informed consent obtained.



  • Appropriate analgesia is in place for mid-cavity rotational deliveries. This will usually be a regional block. A pudendal block may be appropriate, particularly in the context of urgent delivery.



  • Maternal bladder has been emptied recently. In-dwelling catheter should be removed or balloon deflated. Aseptic technique.

Preparation of staff>


  • Operator must have the necessary knowledge, experience and skill on the type of instrument chosen.



  • Adequate facilities are available (appropriate equipment, bed, lighting).



  • Back-up plan in place in case of failure to deliver. When conducting mid-cavity, rotational deliveries, theatre staff should be immediately available to allow an immediate caesarean section to be performed without delay (less than 30 minutes).



  • A senior obstetrician competent in performing mid-cavity deliveries should be present if a junior trainee is performing the delivery.



  • Anticipation of complications that may arise (e.g. shoulder dystocia, postpartum haemorrhage). Personnel present who are trained in neonatal resuscitation.


May 9, 2021 | Posted by in OBSTETRICS | Comments Off on Chapter 40 – Failed Operative Vaginal Delivery
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