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Assisted Vaginal Delivery – Rotational Forceps
Rotational Forceps – Historical Context
The development of nonrotational forceps, manual rotation and vacuum as part of the obstetric armamentarium has been described in the previous three chapters. Obstetric forceps required adaptation in order to achieve rotation within the confines of the mid pelvis. The Norwegian obstetrician, Christian Kielland (1871–1941) originally designed his straight forceps to manage ‘deep transverse arrest’ associated with obstructed labour and cephalopelvic disproportion (CPD). William Smellie had used similar principles of rotation almost two centuries before. Kielland laid down very precise rules for the use of his forceps, which could be more correctly applied than forceps with a pelvic curve to the incompletely rotated fetal head in the mid or even upper pelvis. He also promoted their use for rotating not only occipitoposterior (OP) position but also face presentation (mentotransverse or mentoposterior), as well as for delivering the after-coming head in breech presentation.
In 1928, Lyman Barton (1866–1944), a rural general practitioner in New York State, developed straight forceps with a hinged anterior blade to facilitate application to the fetal head arrested in the transverse position at the pelvic brim. Moolgaoker later modified the Kielland forceps to incorporate a distance-spacing wedge between the handles to maintain the parallel positions of the forceps blades around the fetal head.
Friedrich Scanzoni (1821–91), a German obstetrician, described his original manoeuvre in 1849. The ‘modified Scanzoni manoeuvre’ is used in the USA and requires forceps with a solid blade and a standard pelvic curve (e.g. Tucker-McLane or Elliot). The technique involves applying the forceps blades twice to rotate and deliver from OP to occipitoanterior (OA). The forceps are first applied directly to the head lying in an OP position (i.e. applied as though the head was OA). The handles are lifted upwards to flex the fetal head and rotated in a wide sweep of up to 180 degrees, to rotate the head to an OA position. The forceps are now ‘upside down’ and cannot be used for delivery in that position. The posterior blade is removed, while the anterior blade splints the head preventing rotation back to its original position. The posterior blade is reinserted between the side of the fetal head and the inside of the anterior blade. Finally the anterior blade is removed and reinserted as the ‘posterior blade’ and delivery is accomplished using standard traction techniques as described in Chapter 16 (including Pajot’s manoeuvre). Solid blades are preferred as fenestrated blades may become entangled at the reinsertion stage.
Kielland forceps remained popular in Europe through the late 20th century but enthusiasm for their use waned with reports of significant maternal and neonatal morbidity and the increasing popularity of the vacuum as an alternative means of achieving rotation. However more recent publications have shown comparable outcomes overall in terms of maternal and neonatal outcomes for rotational Kielland’s delivery.
Background
Where assisted delivery is required for the fetus in an OP or occipitotransverse (OT) position, rotation should be considered to enable the smallest diameter of the head to pass through the pelvis. The alternatives include: rotational forceps, rotational vacuum or manual rotation (with vacuum or forceps delivery). In some circumstances, moving directly to a second-stage caesarean section (CS) will be appropriate. A meta-analysis of eight trials showed a significantly reduced risk of ‘failure to deliver’ using rotational forceps compared with rotational vacuum (relative risk [RR] 0.32; 95% confidence interval [CI] 0.14–0.76; P =0.009) with no significant differences in adverse maternal or neonatal outcomes. In terms of comparing rotational forceps with ‘manual rotation followed by direct forceps’ outcomes vary. Bahl et al found no differences in vaginal delivery rates or neonatal outcomes. In another single centre trial, the chance of vaginal delivery was significantly higher with rotational forceps (RR 1.17; 95% CI 1.04–1.31; P =0.017). Use of rotational forceps was associated with a higher risk of shoulder dystocia (RR 2.35; 95% CI 1.23–4.47; P =0.012), but otherwise maternal and neonatal outcomes were similar. Available data supports the continued use of the instrument in selected cases but we recommend that the procedure should be undertaken or closely supervised by a senior experienced obstetrician.
Fig. 18.1 highlights the anatomy and the three unique features of the instrument:
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The sliding lock. This makes the instrument unique in its ability to correct asynclitism associated with obstructed labour.
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The absence of any appreciable pelvic curve. This means that when the forceps are rotated about their axis, the ends of the blades describe a small circle, minimizing the risk of maternal trauma (vaginal, cervical or urinary tract).
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The direction indicator markers. These are small nodular metal markings on the shanks/handles that indicate which way the forceps should lie in relation to the occiput. They are referred to colloquially as the ‘knobs’ and point towards the occiput when the forceps are correctly applied.
The forceps themselves are light, with fenestrated blades. However, the handles can easily be compressed, which will approximate the blades. Care must be taken to avoid compression after application, during rotation and when traction is applied.
Asynclitism is the oblique presentation of the fetal head in labour, and is important in the context of Kielland forceps as it is easily corrected by the sliding lock on the instrument. Asynclitism may result from dystocia rather than being the cause of it and a comprehensive understanding of the process is required. As a result of asynclitism in a transverse arrest, either the anterior or the posterior parietal bone presents. In anterior parietal presentation (Naegele’s obliquity), the posteriorly lying parietal bone is arrested by the promontory of the sacrum ( Fig. 18.2c ). In posterior parietal bone presentation (Litzmann’s obliquity), the anterior parietal bone is arrested at the symphysis while the posterior parietal bone engages in the brim ( Fig. 18.2a,d ). This latter situation is more often associated with CPD.
‘Every instrument, tool, vessel, if it does that for which is made, is well, and yet he who made it is not there.’ Marcus AureliusEMperor of Rome, AD 161–180
Preparation and Technique for Rotational Forceps
Assisted vaginal delivery involving rotation from OT and OP positions requires some of the finest clinical judgement in obstetrics. It is in situations where the instrument is not used with skill and respect that the risk of maternal or fetal trauma is highest. The criteria to be fulfilled prior to a Kielland’s rotation are broadly similar to those described in Chapter 15, Chapter 16 and we recommend that the reader reviews the relevant sections. In particular the head must be no more than 1/5 palpable above the pelvic brim and the position and level must be carefully defined. As in all types of assisted vaginal delivery (AVD), clear and ongoing communication with the couple is vitally important. Kielland’s are now more often performed in the obstetric theatre under neuraxial blockade and it is in that environment that the woman may feel most vulnerable. The woman should be informed of the reasons for the operative birth and if a formal ‘trial of forceps’ is planned, written consent should be taken, both for the ‘trial’ itself and for the possibility of an emergency CS. The anaesthetist must be made aware and a multidisciplinary approach should always be followed, ensuring that the whole team are gathered and prepared.
In taking consent, it makes sense to list the common complications such as haemorrhage, infection, perineal and vaginal trauma, minor fetal marking/injury, etc. Specific to Kielland’s, the much less common injuries such as ‘spiral’ vaginal tears, cervical tears and paravaginal haematoma should also be discussed. In outlining much rarer complications (e.g. urinary tract trauma and significant fetal injury), the accoucheur must ensure a balanced discourse which will mean describing significant rare complications associated with the alternative option of second-stage CS. This is never an easy discussion but remember that a well-conducted forceps rotation, following the guidance given in this chapter, should rarely result in significant trauma for either the woman or her baby.
Analgesia and Place of Delivery
Kielland forceps deliveries are usually conducted in an obstetric theatre under spinal or epidural analgesia. In individualized circumstances where the likelihood of success is high, an accoucheur experienced in the use of Kielland’s may elect to undertake the procedure in the delivery room under an effective epidural blockade. Although we have seen Kielland’s performed successfully under bilateral pudendal blockade and perineal infiltration, the ready availability of neuraxial blockade makes this an infrequently needed choice. If there is any doubt, and certainly when there is the opportunity to offer supervised training, we recommend undertaking the procedure in an obstetric theatre setting. This will give the trainee an additional degree of security and confidence with immediate recourse to emergency CS if required.
With analgesia established in the appropriate environment, the woman should be placed semirecumbent with her legs supported in the lithotomy position. Ensure that her buttocks are over the edge of the bed by a few centimetres, allowing the Kielland handles to be angled towards the floor during rotation and initial traction. Set up a clean operative field and ensure the bladder is emptied. The accoucheur should re-examine carefully to confirm the position and level of the presenting part. A combined abdominal and vaginal examination is particularly useful. Ultrasound assessment may be performed if there is any doubt. Transabdominal and transperineal scanning (TAS and TPS) can help to define position and descent and are reviewed in Chapter 15 . The former is easy to learn and can be a useful adjunct where clinical examination leaves the accoucheur unsure of the position. However, careful digital examination offers much useful information beyond just defining position and we encourage the accoucheur to keep this as their primary method of assessment.
Assembling the Forceps
Take the forceps and ensure they are a pair (i.e. they should have matching numbers imprinted on them). Assemble the forceps and hold in front of the perineum in the position in which they will lie when correctly applied. This is known as ‘ghosting’ ( Fig. 18.3a ). Remember that the small buttons on the shanks of the forceps indicate the direction of the occiput – the old adage ‘knobs point towards the occiput’ always acts as a useful reminder. This practice also confirms which blade is anterior and has to be inserted first. Lubricate the forceps and prepare to apply the anterior blade.
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