Operative vaginal delivery

Definition: Delivery of a baby vaginally using an instrument for assistance.

Introduction Incidence of Operative Vaginal Delivery (OVD) – 10-15% The incidence of instrumental intervention varies widely both within and between countries and may be performed as infrequently as 1.5% or as often as 26%. These difference are often related to labour ward management. Percentage of forceps declining compared with vacuum extraction

Indications for OVD No indication is absolute Prolonged 2nd stage Nulliparous: lack of continuous progress >3hrs with regional anesthesia >2hrs without regional anesthesia Multiparous: lack of continuous progress >2hrs with regional anesthesia >1hr without regional anesthesia Fetal compromise Maternal benefit to shortened 2nd stage specially those with medically significant conditions, such as aortic valve disease with significant outflow obstruction or myesthenia graves.

Prerequisites for OVD Vertex presentation with identification of the position. Engaged head. Fully dilated cervix Membranes ruptured Adequate maternal pelvis Adequate analgesia/ anesthesia Maternal empty bladder A knowledgable and experienced operator with adequate preparation to proceed with an alternative approach if necessary. Informed consent

Safe practice: prerequisites for instrumental delivery Fully dilated cervix One-fifth or nil palpable abdominally Ruptured membranes Contractions present Empty bladder Presentation and position known Satisfactory analgesia

Contraindication - OVD Unengaged vertex Incompletely dilated cervix (possible exceptions occurs with the vaccum delivery of a second twin where the cervix has contracted or with a prolapsed cord at 9 cm if rapid delivery is anticipated). Clinical evidence of CPD Fetal conditions (e.g. thrombocytopenia) < 35 weeks gestation (vacuum) face or breech presentation (vacuum)

Evaluation: The size of the baby should be estimated per abdomen and the head should be fully engaged (none of the head should be palpable above the pubic symphysis). A careful pelvic examination is essential to determine whether there are any ‘architectural’ contraindication to performing an instrumental vaginal delivery (the shape of the subpubic arch, the curve of the sacral hollow, the presence of flat or prominent ischial spine, all contribute to the decision as to whether vaginal delivery may be safely performed). In ventouse delivery, the position of the vertex and the amount of caput should be determined by vaginal examination and no attempt should be made to deliver the baby vaginally if the presenting part is above the ischial spine.

Station At the 0 station, the fetal head is at the bony ischial spines and fills the maternal sacrum. Positions above the ischial spines are referred to as -1 through -5 As the head descends past the ischial spines, the stations are referred to as +1 through +5 (head visible at the introitus).

Analgesia: Analgesic requirements are greater for forceps than ventouse delivery. Rotational forceps----- regional anasthesia is preferred. Rigid cup ventouse------pudendal block with perineal infiltration. Soft cup-----analgesic requirement may be minimal. A requirement for haste should not preclude the use of analgesia.

Forceps delivery: For forceps, all the prerequisties above apply, but in addition it is essential that the operator check the pair for forceps to ensure that a matching pair has been provided and that the blade lock with ease. It is generally advised that catheterization and an episiotomy is required for forceps delivery.

:Types of forceps There are three main types of forceps: • Low-cavity outlet forceps (e.g. Wrigley's), which are short and light • Mid-cavity forceps (e.g. Simpson's) for when the sagittal suture is in the anteroposterior plane (usually occipitoanterior). • Kielland's forceps for rotational delivery (the reduced pelvic curve allows rotation about the axis of the handle).

Forceps: from left to right, Kielland's, mid-cavity, Wrigley's.

(b) Wrigley's forceps, (c) Simpson's midcavity obstetric forceps. (d) Kielland's forceps.

Williams Obstetrics - 22nd Ed. (2005) care being taken to ensure that the pelvic curve will be sitting over the malar aspect of the baby's head, convex towards the baby's face.

Williams Obstetrics - 22nd Ed. (2005)

Williams Obstetrics - 22nd Ed. (2005)

Williams Obstetrics - 22nd Ed. (2005)

Williams Obstetrics - 22nd Ed. (2005)

Vacuum (Ventouse) Delivery The advantage of the vacuum extractor over forceps include the avoidance of insertion of space-occupying steel blades within the vagina. A metal cap designed so that the suction creates an artificial caput, or chignon, within the cup that holds firmly and allows adequate traction. In the United States, the metal cup generally has been replaced by newer soft cup vacuum extractors

Vacuum Cups Soft vs. Rigid Soft cups were more likely to fail to achieve vaginal delivery Soft cups were associated with less scalp injury. There appear to be no difference in terms of maternal injury. The soft cups are appropriate for straightforward deliveries with an occipitoanterior position; metal cups appear to be more suitable for occipitoposterior, occipit transverse and difficult occipitoanterior position deliveries where the infant is larger or there is a marked caput.

Vacuum Placement Proper cup placement is the most important determinant of success in vacuum extraction. The center of the cup should be over the sagittal suture and about 3 cm in front of the posterior fontanelle and thus 6 cm posterior to the anterior fontanelle – flexion point.

Vacuum Procedure The entire 360º circumference of the cup must then be digitally inspected to insure that no vaginal or vulvar tissues are trapped between the cup and the fetal surface. The operating vaccum pressure for nearly all ventouse is between 0.6 and 0.8 kg/cm2. It is prudent to increase the suction to 0.2 kg/cm2 first and then to recheck that no maternal tissue is caught under the cup edge. When this is confirmed the suction can then be increased.

The fingertips of the dominant hand pull the device's crossbar, while the nondominant hand monitors the progress of descent and prevents cup detachment by placing counter pressure with the thumb Apply traction along the axis of the pelvic curve. Initially, the angle of traction is downward (toward the floor). The axis of traction is then extended upwards to a 45 degree angle to the floor as the head emerges from the pelvis and crowns. The handle of the device is allowed to passively turn as the head auto-rotates through its descent. This will usually be at 90° to the cup.

Ventouse - method of traction. Note the finger-thumb position.

Mid Pelvis Pelvic Floor Outlet

Axis Animation

Traction is applied in concert with uterine contractions and voluntary expulsive effort. Descent should occur with each application of traction. When the head is delivered, the suction is released, the cup is removed, and the remainder of the delivery proceeds as usual. During the procedure: A maximum of two cup detachments should be allowed. 3 sets of pulls Total vacuum application time should be ideally less than 15 minutes

Complications: Assisted deliveries with both vacuum and forceps can be associated with significant maternal and fetal complications, however, with good technique and adherence to guidelines, the risk of complications to mother or baby is small. Trauma to the genital tract is the commonest maternal comlicpation. Postpartum haemorrhage. Fetal complication: most babies will have a chignon (oedematous skin bump) at the site of the cup application. Some will also have a cephalhaematoma (subperiosteal bleed). Rare serious intracranial injuries will be more likely to occur if multiple attempts at delivery are made (especially if a variety of instruments is used).

CT of Subgaleal

Swellings and Bleeds Associated With Normal and Operative Vaginal Delivery

With any difficult instrumental delivery, the risk of shoulder dystocia occurring after successful delivery of the fetal head should always be remembered.

Vacuum versus Forceps The obstetricians should be competent and confident in the use of both forceps and ventouse. “Selection of the appropriate instrument and decisions about the maternal and fetal consequences should be based on clinical findings at the time of delivery.

The ventouse,when compared to the forceps: is significantly more likely to: Fail to achieve a vaginal delivery. Be associated with cephalhaematoma (subperiosteal bleed). Be associated with retinal haemorrhage (but this dosen’t seem to be of any clinical significance). Be associated with maternal worries about the baby.

And is significantly less likely to be associated with: Use of maternal regional/ general anasthesia. Significant maternal perineal and vaginal trauma Severe perineal pain at 24 hours And is equally likely to be associated with: Delivery by cesarean section Low 5 minutes Apgar score

Episiotomy Intentional incision at perineum made to enlarge vulval outlet to ease birth process or to protect mother from uncontrolled perineal lacerations. During the procedure, the STSR should note amt of local medication used. For primary & secondary incisions, a handheld vaginal retractor may be used. For 3rd & 4th degree, may use a Gelpi perineal retractor. Improperly closed wounds can lead to postpartum hemorrhage, sepsis, fistulas, and coital pain

Technique: An episiotomy is performed in the second stage, usually when the perinium is being stretched (when the head is crowning) and it is deemed necessary. If there is not a good epidural, the perinium should be infiltrated with local anaesthetic. The incision can be midline or at an angle from the posterior end of the vulva (a mediolateral episiotomy). A mediolateral episiotomy is usually recommended; a midline episiotomy results in less bleeding, quicker healing and less pain, however,there is an increased risk of extension to involve the anal sphincter (third/ fourth-degree tear).

Episiotomies: Midline & Rt Mediolateral Olds page 754: The 2 most common types of episiotomies are midline and mediolateral. A midline episiotomy is performed along the median raphe of the perineum. It extends down from the vaginal oriface to the fibers of the rectal sphincter. It is the preferred method if the perineum is of adequate length and no difficulty is anticipated during the birth because it entails less blood loss, is easy to repair, and heals with less discomfort for the mother. The main disadvantage is that it may extend thru the anal sphincter and rectum. In the presences of a short perineum, macrosomia, and instrument-assisted birth (use of forceps or vacumn extractor), a mediolateral episiotomy provides more room and decreases the possibility of a traumatic extension into the rectum. Usually performed w/regional or local anesthesia. Repair of episiotomy (episiorrhaphy) and any lacerations is performed either during the period between birth of the baby and before expulsion of the placenta or after expulsion of the placenta.

In 2009, a Cochrane meta-analysis based on studies with over 5,000 women concluded that: "Restrictive episiotomy policies appear to have a number of benefits compared to policies based on routine episiotomy. There is less posterior perineal trauma, less suturing and fewer complications, no difference for most pain measures and severe vaginal or perineal trauma, but there was an increased risk of anterior perineal trauma with restrictive episiotomy".

Indications: Previous pelvic reconstructive surgery When perineal muscles are excessively rigid There is a serious risk to the mother of spontaneous irregular tear When instrumental delivery is indicated Prolonged late decelerations or fetal bradycardia during active pushing shoulder dystocia (Note that the episiotomy does not directly resolve this problem, but it is indicated to allow the operator more room to perform maneuvers to free shoulders from the pelvis) Fetal macrosomia

Complication: Haemorrhage Infection Extension to the anal sphincter (third/ fourth-degree tears) Dyspareunia.