Fig. 10.1
Old diagram of different types of obstetrical forceps
The vacuum extractor was first described by James Young Simpson in 1848 and was popularized in Europe by Malmstrom in 1954 [5]. This instrument has also undergone many modifications over the years, most notably the evolution of the metal cup to the silastic and rubber cup, to what is now the modern vacuum extractor. In the 1970s, the vacuum extractor had almost completely replaced forceps for assisted vaginal deliveries in most northern European countries, but even its popularity in many English-speaking countries, including the United States and the United Kingdom, was limited. In later years, the number of vacuum-assisted deliveries surpassed the number of forceps deliveries in the United States, and in the year 2000, approximately 66 % of operative vaginal deliveries were by vacuum [6]. The latest modification to the vacuum is that by the late Australian obstetrician named Aldo Vacca. It is a handheld device that has a small cup connected to the body of the vacuum by a tube. This allows for an easier application over the occiput and can be used with any fetal head position. This Australian instrument is oddly named after a New Zealand bird the “Kiwi” [7] (Fig. 10.3).
Fig. 10.3
(a) Different types of vacuum extractors; (b) Kiwi vacuum extractor
10.2 Incidence
In the Western world, approximately 5–10 % of deliveries are instrumental vaginal deliveries. In the United Kingdom, the rates of instrumental vaginal delivery range between 10 and 13 % [8]. A survey of 37 maternity hospitals in France revealed the rate constituted 11.2 % of all live births in 2002 [9]. In Australia and New Zealand, forceps and vacuum extraction accounted for 7.4–16.4 % of all deliveries in 1999–2000 [10]. Recent figures from the United States are lower. The US rate of operative vaginal delivery decreased from 9.01 % of all deliveries in 1992 to 3.3 % of all deliveries in 2013 [11]. While in some area of the world forceps remains the instrument of choice, in the United States, forceps deliveries accounted for only 0.6 % of vaginal births, and vacuum deliveries accounted for 2.7 % of vaginal births [12] despite good evidence for their efficacy and safety [13]. This reflects a worldwide trend of declining rates of instrumental vaginal deliveries along with interrelated rising rates of cesarean deliveries. Between 1996 and 2006, cesarean delivery increased by 50 %, while both spontaneous and operative vaginal births declined [14]. Despite this rising cesarean section rate, there has been no reduction in childhood cerebral palsy attributable to this practice [13, 15]. Rather, the explanation for this decline includes among other reasons lack of adequate training in residency programs and litigation concerns. A survey of graduating obstetricians in the United States reported alarmingly that half did not feel confident performing a forceps delivery [16].
A recent ACOG practice bulletin underscored that operative vaginal delivery, whether that be forceps or vacuum delivery, remains an important part of modern obstetric care and in the appropriate circumstances should be used to safely avoid cesarean delivery, in an effort to decrease first cesarean rates [13].
However, the FDA did publish a Public Health Advisory in 1998 warning about the possible complications of vacuum delivery and a warning about their use. This warning still appeared in the FDA site in 2015.
10.3 Indications
Operative vaginal deliveries are accomplished by applying direct traction on the fetal head either with forceps or a vacuum extractor. Regardless of the instrument chosen to expedite delivery, indications for instrumental deliveries remain the same. An operative vaginal delivery should only be performed if an appropriate indication exists. The clinical decision to proceed with an assisted operative delivery balances the maternal, fetal, and neonatal risks and benefits of the procedure with those of the alternative options, namely, cesarean birth or expectant management. It is also obviously dependent on operator skills, training, and expertise.
Forceps and obstetric vacuums are employed to assist a vaginal delivery for their potential to increase the expelling force (carefully adding to, or replacing, the maternal expelling forces); decrease the resistance force of the maternal birthing canal by modifying the perimeter of the fetal head and correcting fetal head malpositions, asynclitism, and deflection (Figs. 10.4, 10.5, 10.6, 10.7, 10.8, 10.9, 10.10, 10.11, 10.12, 10.13, 10.14, 10.15, 10.16, and 10.17); and decrease the resistance of the birthing canal by increasing the perimeter of the soft pelvis (in the case of forceps) [17, 18].
Fig. 10.4
Lateral asynclitism and persistent occiput posterior position ultrasonographic signs: (1) asymmetric fetal profile (sagittal section), on the top of the image; (2) squint sign (transversal section), in the medium; (3) four chambers (transverse chest section), the bottom image; (4) posterior spine (transverse fetal chest section)
Fig. 10.5
Translabial transverse ultrasonographic section of a malpositioned fetal head, as a consequence of internal rotation failure. In fact in this image, the fetal midline shows an angle with the symphysis pubis – sacral line (or anterior posterior pelvis line) >45°. In this case, the fetal head is in occiput posterior position
Fig. 10.6
Translabial 2D ultrasonographic section in a dystocic second stage labor. The fetal head has a malrotation and a malposition in the pelvis. The midline angle is of 90° (the fetal midline crosses at 90° the anterior-posterior diameter, perpendicularly).
Fig. 10.7
Translabial 2D ultrasonographic scan of a fetal head in persistent occiput posterior position and anterior asynclitism (the midline is anterior and the squint sign not detectable). The caput succedaneum measures 35.7 mm, and it reduces the efficacy of the digital palpation for the diagnosis of sutures and fontanel positions. However, the caput succedaneum dimensions do not have a clinical correlation with the modality of delivery
Fig. 10.8
Translabial sagittal ultrasonographic section in the second stage of labor: the fetal head is in occiput posterior position, in upward direction. The image shows the physiologic molding and the caput succedaneum. A molding associated to the caput succedaneum represents a reason of vacuum application failure, during vaginal operative delivery
Fig. 10.9
Transverse transabdominal 2D ultrasonographic section of fetal head in second stage dystocic labor. The fetal head is positioned into the pelvis in anterior asynclitism associated to right posterior occiput position
Fig. 10.10
Transabdominal longitudinal ultrasonographic scan of the fetal head in second stage dystocic labor. The fetal head has malrotation and malposition in persistent occiput posterior position and lateral asynclitism. The trace marked the ultrasonographic sign of bundle ring, on the left; on the right, the bundle ring showed during cesarean section
Fig. 10.11
Transabdominal transverse ultrasonographic scan during a dystocic second stage of labor showing the fetal head in left persistent occiput posterior position. This malposition usually provokes the vacuum application failure, especially in case of “soft vacuum” application (i.e., the Kiwi vacuum extractor). To avoid the vacuum application failure, literature suggests to preliminary diagnose the fetal head position and rotation before vacuum application by intrapartum ultrasonography
Fig. 10.12
Translabial longitudinal 2D ultrasonographic section of the fetal head with molding in consequence of occiput posterior position and asynclitism (in second stage of labor)
Fig. 10.13
Transabdominal transverse ultrasonographic section of the fetal head in transverse position (with right occiput position) and posterior asynclitism. Transverse midline sign, transverse thalami, and transverse orbits represent the ultrasonographic signs
Fig. 10.14
Translabial sagittal ultrasonographic scan of the fetal head in the birth canal with caput succedaneum in dystocic second stage labor. In this case, the fetal head is positioned in left occiput posterior position and posterior asynclitism. The asynclitism and the molding lead to an operative vaginal delivery, with presumable failure of vacuum extraction and urgent cesarean delivery
Fig. 10.15
Translabial longitudinal ultrasonographic section during a second stage dystocic labor. Measurement of the angle progression shows the downward direction. The vacuum application, in such case, leads to a failure of fetal extraction (operative delivery failure)
Fig. 10.16
Transabdominal transverse ultrasonographic scan of the fetal head in right occiput posterior position with posterior asynclitism (left squint sign) during a second stage dystocic labor
Fig. 10.17
Transabdominal transverse ultrasonographic section of the fetal head in linear occiput posterior position (anterior orbits lens and nasal bridge), on the left. Asymmetric fetal profile in transabdominal sagittal ultrasonographic section, on the right. These signs indicate the lateral asynclitism signs
As such, operative delivery may be elective in case of maternal medical comorbidities that a priori dictate refrainment from maternal pushing efforts such as congestive heart failure, cerebral vascular malformations [18], as well as inadequate maternal expulsive efforts as in women with spinal cord injuries or neuromuscular diseases [19].
However, more often operative intervention is performed in an urgent manner when labor does not progress as expected or fetal distress is suspected (Table 10.1).
Table 10.1
Indications of operative vaginal deliveries
Indication | ACOG | RCOG | SOGC | RANZCOG |
|---|---|---|---|---|
Fetal | Suspicion of imminent or potential fetal compromise | Presumed fetal compromise | Nonreassuring fetal status | Fetal compromise suspected or anticipated |
Maternal/medical | Shortening of the second stage for maternal benefit | Indications to avoid Valsalva Examples: Cardiac disease Class III or IV Hypertensive crises Cerebral vascular disease Myasthenia gravis Spinal cord injury | Medical indications to avoid Valsalva Examples: Cerebral vascular disease Cardiac conditions | Maternal effort contraindicated Examples: Aneurysm Risk of aortic dissection Proliferative retinopathy Severe hypertension, or Cardiac failure |
Obstetric | Prolonged second stage: Nulliparous women: lack of continuing progress for 3 h with regional anesthesia, or 2 h without regional anesthesia Multiparous women: lack of continuing progress for 2 h with regional anesthesia, or 1 h without regional anesthesia | Inadequate progress: Nulliparous women: lack of continuing progress for 3 h (total of active and passive second stage of labor) with regional anesthesia, or 2 h without regional anesthesia Multiparous women: lack of continuing progress for 2 h (total of active and passive second-stage labor) with regional anesthesia, or 1 h without regional anesthesia Maternal fatigue/exhaustion | Inadequate progress: Adequate uterine activity documented No evidence of cephalopelvic disproportion Lack of effective maternal effort | Delay in the second stage of labor: There is no clear demarcation as to an appropriate length of time to wait before embarking on instrumental delivery for failure to progress It is a matter for the clinician and patient given the particular circumstance |
Another common indication used is maternal exhaustion, yet this clearly is highly subjective and risks should be carefully weighed against benefits prior to proceeding with the above as a single indication. Other less common indications are for instrumental intervention may be the delivery of the after-coming head in an assisted breech delivery as well as during cesarean section to deliver a “floating” fetal head.
10.4 Contraindications
In certain clinical situations, an operative vaginal delivery should not be attempted due to the potential harm to the mother or fetus. Prior to proceeding with an operative vaginal delivery, the operator should ensure no maternal or fetal contraindication to the procedure exists.
Contraindications related to the delivery process include unengaged fetal head or station above the mid-cavity, unknown position of the fetal head, and unruptured membranes and also if cephalopelvic disproportion is suspected or fetal malpresentation exists (such as breech, brow).
Fetal conditions that preclude operative vaginal delivery are known or strongly suspected bone demineralization conditions (e.g., osteogenesis imperfecta) or a bleeding disorder (e.g., alloimmune thrombocytopenia, hemophilia, or von Willebrand disease) [13, 19].
Performance of an operative vaginal delivery in a fetus with suspected macrosomia is supported by ACOG but should be performed with caution given the possible increased risk of fetal injury of shoulder dystocia. Because of the risk of intraventricular hemorrhage, vacuum extraction is not recommended in fetuses with an estimated weight less than 2,500 g (which corresponds to 34 weeks of gestation) [19].
10.5 Nonoperative Practices that Decrease the Need for Operative Birth
Several nonoperative interventions have been shown to decrease the need for operative birth:
- 1.
Involvement of one-to-one birth attendants who provide experienced continuous physical and emotional support care during labor [20].
- 2.
- 3.
- 4.
Flexibility with regard to time limits for the second stage of labor. Before diagnosing arrest of labor in the second stage, if the maternal and fetal conditions permit, allow for the following: at least 2 h of pushing in multiparous women and at least 3 h of pushing in nulliparous women. Longer durations may be appropriate on an individualized basis (e.g., with the use of epidural analgesia or with fetal malposition) as long as progress is being documented and provided fetal testing is reassuring [25, 26].
10.6 Prerequisites to Operative Delivery
The operator should verify that all criteria are met prior to proceeding with an operative vaginal delivery. The fetal head is engaged, the cervix is fully dilated, the membranes are ruptured, and the bladder is empty. The fetal lie, presentation, head position, and degree of asynclitism must be known (Figs. 10.18, 10.19, and 10.20).
Fig. 10.18
High asynclitism
Fig. 10.19
Medium asynclitism
Fig. 10.20
Low asynclitism
Adequacy of the maternal pelvis by clinical pelvimetry should be evaluated, and adequate anesthesia provided. A recent study of obstetricians in Canada compiled an expert task list to describe the detailed assessment of the second stage of labor that is necessary to perform an operative delivery (Table 10.2).
Table 10.2
The detailed assessment of the second stage of labor, necessary to perform an operative delivery
Summarized expert task list of the assessment of the second stage of labor for operative delivery |
|---|
1. Focused history |
Demographics, medical history, past obstetric and relevant gynecological history, antenatal history, medications, allergies, intrapartum history, use of oxytocin, need for analgesia, fetal wellbeing (EFM, scalp sample, color of liquor) |
2. Vital signs (maternal and fetal heart rate monitoring/fetal scalp sample) |
3. Abdominal examination (performed first) |
Size of the fetus |
Position |
Room between the breech and the maternal ribs |
Amount of head palpable abdominally (coordinate with maternal breathing): 0/5 fingerbreadths above pelvic brim reassuring, 1/5 consider trial of delivery in the OR, more than 1/5 operative delivery contraindicated |
4. Vaginal examination |
“Sweep” at full cervical dilatation |
Strategies to detect fetal position: counting sutures technique, 3-finger technique, peace sign, 10 o’clock to 2 o’clock, fetal ear (tragus and pinna), ultrasound rarely necessary |
Confirm station: consistent definition of bony prominence at ischial spines; beware caput; asymmetry of maternal spines; push head up vaginally to abdominal hand; palpable ear usually means low enough for operative delivery; relationship of fetal head and neck (e.g., deflexed); deep transverse arrest may give asynclitism and more room posteriorly with true station higher anteriorly |
Caput and molding: degree of relative (or absolute) cephalopelvic disproportion |
Adequacy of pelvis: format measurements not required; general feel appropriate; if the fetal head is touching three of five pelvic points (ischial spines, anterior pubic rami, sacrum) there may not be enough room to deliver the fetus vaginally |
5. Assessing descent with maternal pushing: does the fetus fill the pelvis? |
6. Communication to the mother and her support personnel in detail why the baby is not yet born, strategies to achieve delivery, and obtaining informed consent |
7. Documentation |
10.7 Classification of Operative Vaginal Deliveries
Operative vaginal deliveries are classified by the station of the fetal head at application and the degree of rotation necessary for delivery (Table 10.3). The lower the fetal head in the maternal pelvis and the less degree of rotation needed to deliver, the less associated risks for the mother and fetus. Operative vaginal delivery is contraindicated if the fetal head is not engaged in the maternal pelvis or if the position of the vertex cannot be determined.
Table 10.3
Operative vaginal delivery
Criteria for the different types of forceps delivery |
|---|
Outlet forceps ← |
Scalp is visible at the introitus without separating the labia |
Fetal skull has reached the pelvic floor |
Fetal head is at or on perineum |
Sagittal suture is in anteroposterior diameter or right or left occiput anterior or posterior position |
Rotation does not exceed 45 degrees |
Low forceps |
Leading point of the fetal skull is at station +2 cm or more and not on the pelvic floor |
Without rotation: Rotation is 45 degrees or less (right or left occiput anterior to occiput anterior, or right or left occiput posterior to occiput posterior) |
With rotation: Rotation is greater than 45 degrees |
Midforceps |
Station is above +2 cm but head is engaged |
10.8 Consent
There exists no absolute indication for an operative vaginal delivery, and alternative delivery options such as cesarean delivery or continued expectant management with oxytocin augmentation should be communicated to the patient according to the specific case. Operative vaginal delivery is not without risk to the parturient as well as to the fetus as detailed below. Therefore, patient informed consent regarding potential risks, benefits, and alternatives to operative vaginal delivery should be discussed as part of the preparations to an operative delivery. This may not be comprehensive when the intervention is deemed urgent for acute fetal distress, but can still be achieved quickly, and maternal compliance is essential for safe and effective operative delivery. In the absence of emergency, patient consent is paramount. The 2011 ROGC guidelines refer to the issue of informed consent. It states that women should be informed about operative vaginal delivery ahead of time as part of routine antenatal education.
This information should include the strategies known to be effective in reducing the need for operative vaginal birth as detailed above. The principles of obtaining valid consent during labor should be followed. Where possible, information should be given to women in labor between contractions. Obstetricians must document the decision, the reasons for proceeding to an operative birth, and consent. An accurate record of the operative vaginal delivery must be completed [27].
10.9 Forceps
There are many different designs for forceps, all consist of two separate halves that have four basic components: blade, shank, lock, and handle. More than 700 different types of forceps have been described (Fig. 10.1).
Those could be divided into three categories:
Classical forceps: have cephalic and pelvic curvatures. Usually indicated when no rotation of the fetal head is necessary before delivery. Common types include Simpson, Tucker-McLane, and Elliot forceps. Some further divide these into forceps more appropriate for primipara (e.g., Simpson) and those for multipara (Tucker-McLane).
Rotational forceps: have cephalic curvature but lack a pelvic curvature. Also have a sliding lock to allow forceps to slide to correct asynclitism of the fetal head if present. When rotation of the fetal head is accomplished, classical forceps can be considered to complete the delivery but this is an individual’s preference. Types include Kielland, Luikart, Barton (for deep transverse arrest), and Salinas forceps.
Forceps for breech delivery: indicated to help with the after-coming head in a breech delivery. These forceps lack a pelvic curvature and have blades that are beneath the plane of the shank. Types include Piper and Laufe forceps.
10.10 Forceps Application
10.10.1 Phantom Application
The operator holds the forceps in front of the perineum in the same angle and position expected for application.
10.10.2 Application
The forceps blades are applied and checked. The posterior fontanelle should be located midway between the sides of the blades, with the lambdoid sutures in an equal distance from the blades and one finger-breadth above the plane of the shanks. The sagittal suture must be perpendicular to the plane of the shanks throughout its length; the fenestration of the blades should be barely felt, and the amount of fenestration felt on each side should be equal. If the blades have not been applied deeply enough, the palpable fenestration will be more than a fingertip, and the operator is alerted to the risk of facial nerve injury.
10.10.3 Traction
Gentle traction in the direction of the vaginal canal is applied concurrent with contractions and maternal bearing down effort. Between contractions the grip is relieved to reduce compression of the baby’s head. Episiotomy should be considered, as discussed below.
If no descent is apparent with three contractions or pulls or if 15 min have elapsed abandoning the procedure and proceeding with a cesarean delivery should be strongly considered. The results of an expert task list developed for forceps and rotational forceps delivery are shown in Tables 10.4 and 10.5.
Table 10.4
Expert task lists developed for forceps
Key points |
|---|
1. Careful maternal and fetal assessment; ensure analgesia is adequate; and empty bladder |
2. Assemble team; one team member to palpate contractions; and check equipment |
3. Phantom application of forceps |
4. Application: lubrication, apply between contractions, “pencil grip,” and check the application
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