Operative Obstetrics: Vaginal Birth

Operative Obstetrics

• Operative obstetrics refers to methods used to deliver a fetus other than uterine contractions and pushing
• Methods can include instrumental vaginal delivery and cesarean sections

Operative Vaginal Birth

• Operative birth delivery is an important component of modern obstetrics
• Its purpose is to achieve or expedite a vaginal delivery
• The rate of operative deliveries has significantly decreased in the last two decades
• This decrease accounts for part of the increase in cesarean delivery rates

Benefits of Operative Vaginal Birth

• Can avoid cesarean birth and its associated complications: hemorrhage, infection, prolonged healing time, increased cost and likelihood of repeat cesarean birth and associated placental abnormalities in subsequent pregnancies
• Can be accomplished quicker than cesarean birth

Types of Instruments

• Vacuum extractors are believed to be easier to learn and can be used with asynclitism
• Forceps provide a more secure application and are appropriate for rotation
• There three types of forceps: Mid, Low, and Outlet

Forceps

• Obstetric forceps are metal instruments used to provide traction, rotation, or both, to the fetal head

Classification For Forceps Use

• Outlet use is the most common, the fetal head is on the pelvic floor
• With Low use, the fetal head is below +2 station but has not reached the pelvic floor
• With Mid use, which is seldom used today, the fetal head is below 0 station but has not reached +2 station
• High use is never appropriate in modern obstetrics and can cause risk to both mother and fetus; the fetal head is unengaged and above 0 station.

Indications For Forceps Use

• Prolonged second stage is the most common indication and may be caused by dysfunctional labor or suboptimal fetal head orientation
• Category III EFM strip indicates that the fetal heart rate monitor pattern suggests that the fetus is not tolerating labor
• Avoid maternal pushing in various conditions in which pushing efforts may be hazardous to the parturient, e.g., cardiac, pulmonary, or neurologic disorders
• Breech presentation can allow shortening the time to deliver the head of a vaginal breech fetus

Prerequisites For Forceps Use

• Cervix fully dilated and retracted
• Membranes ruptured
• Fetal head is engaged and the position has been determined
• Fetal weight estimation performed
• Pelvis thought to be adequate for vaginal birth
• Anesthesia adequate
• Maternal bladder has been emptied
• Patient has agreed after being informed of the risks and benefits of the procedure
• Willingness to abandon trial of operative vaginal birth, and a backup plan in place in case of failure to deliver

Contraindications For Forceps Use

• Fetal head unengaged
• Position of the head is unknown
• Known or strongly suspected fetal bone demineralization condition or bleeding disorder
• Lack of experienced provider

Complications With Forceps Use

• Fetal complications: Neonatal jaundice, scalp lacerations, cephalhaematoma, subgaleal haematoma, facial bruising, facial nerve damage, skull fractures, retinal hemorrhage
• Maternal complications: Vaginal tears, 3rd/4th degree perineal tears, VTE, incontinence, PPH, shoulder dystocia, infection

Further Considerations For Forceps Use

• Judicious use of operative vaginal delivery with suspected macrosomia
• Adequacy of pelvis and the progress of labor during the second stage should be considered
• Episiotomy should not be routinely performed with operative vaginal delivery
• Routine prophylactic antibiotics before operative vaginal delivery are not suggested
• A trial of operative vaginal delivery should be performed by experienced provider with cesarean services readily available

Vacuum Extractor

• A vacuum extractor is a cuplike instrument that is held against the fetal head with suction
• Traction is applied to the fetal scalp, which, along with maternal pushing efforts, results in descent of the head leading to vaginal delivery
• The cups may be metal or plastic, rigid or soft

Vacuum Extractor Use

• The cup is applied with its center over the flexion point on the fetal skull, in the midline, 3cm anterior to the posterior fontanelle
• During uterine contractions, traction is applied perpendicular to the cup
• Ventouse deliveries are associated with a lower success rate, less maternal perineal injuries and pain, and more cephalhaematoma, subgaleal hematoma and fetal retinal haemorrhage

Advantages Of Vacuum Extractor Over Forceps

• Precise knowledge of fetal head position and attitude is not essential
• The vacuum extractor does not occupy space adjacent to the fetal head
• Third- and fourth-degree lacerations are fewer
• Fetal head rotation occurs spontaneously at the station best suited to fetal head configuration and maternal pelvis

Disadvantages Of Vacuum Extractor Over Forceps

• Excessive traction can lead to sudden decompression as the cup suction is released
• Scalp skin injury and lacerations are common
• Subgaleal hemorrhage and intracranial bleeding are rare
• Neonatal jaundice arises from scalp bleeding

Indications For Vacuum Extractor Use

• Similar to those of Forceps
• Prolonged second stage, which may be because of dysfunctional labor or suboptimal fetal head orientation
• Non-reassuring EFM strip suggesting the fetus is not tolerating labor
• Avoid maternal pushing in conditions in which pushing efforts may be hazardous to the parturient

Prerequisites For Vacuum Extractor Use

• Clinically adequate pelvic dimension
• Experienced operator
• Full cervical dilation
• Engaged fetal head
• Gestational age ≥34 weeks

Complications Of Vacuum Extractor Use

• Vaginal lacerations from entrapment of vaginal mucosa between the suction cup and fetal head (maternal)
• Neonatal cephalohematoma and scalp lacerations (common)
• Life-threatening complications of subgaleal hematoma or intracranial hemorrhage (uncommon but associated with vacuum duration >10 min) (neonatal)

Cesarean Section

• Cesarean section is a procedure in which the fetus is delivered through incisions in the maternal anterior abdominal and uterine walls
• The overall U.S. cesarean section rate in 2011 was ~33% (includes both primary and repeat procedures)

Risks Of Cesarean Section

• Maternal mortality and morbidity are higher than with vaginal delivery, especially with emergency cesareans performed in labor. Maternal mortality is largely anesthetic-related, with an overall mortality ratio of 25 per 100,000
• Hemorrhage causes blood loss two times that of a vaginal delivery, with a mean of 1,000 mL
• Infection sites include endometrium, abdominal wall wound, pelvis, urinary tract, or lungs. Prophylactic antibiotics can decrease infectious morbidity
• Visceral injury to surrounding structures (e.g., bowel, bladder, and ureters) can occur
• Thromboisis of the deep venous is increased in the pelvic and lower extremity veins

Cesarean Section Uterine Incisions

• Low segment transverse incision is made in the noncontractile portion of the uterus and is the one most commonly used
  • The bladder must be dissected off the lower uterine segment
  • It has a low chance of uterine rupture in subsequent labor, 0.5%
• Advantages are that trial of labor in a subsequent pregnancy is safe and the risk of bleeding and adhesions is less
• Disadvantages are that the fetus(es) must be in longitudinal lie and the lower segment must be developed
• Classical incision is made in the contractile fundus of the uterus and is less commonly performed Technically it is easy to perform, and no bladder dissection is needed
• Risk of uterine rupture both before labor and in subsequent labor is significant at 5%
• Repeat cesarean should be scheduled before labor onset
• Advantages are that any fetus(es) regardless of intrauterine orientation can be delivered and lower segment varicosities or myomas can be bypassed
• Disadvantages are that trial of labor in a subsequent pregnancy is unsafe and the risk of bleeding and adhesions is higher

Indications For Primary Cesarean Section

• Cephalopelvic disproportion (CPD) is the most common indication and literally means the pelvis is too small for the fetal head
• In actual practice, it most commonly indicates failure of the adequate progress in labor, which may be related to dysfunctional labor or suboptimal fetal head orientation
• Fetal malpresentation refers most commonly to breech presentation but also means any fetal orientation other than cephalic
• Category III EFM strip indicates that the FHR monitor pattern suggests that the fetus may not be tolerating labor, but this is commonly a false-positive finding

Elective Cesarean Recommendations

Recommendations from the independent panel of experts include:

• Women should be counseled individually for risks and benefits
• Women considering having >2 children should be aware that a cesarean section causes uterine scarring and these women should avoid a primary cesarean section
• Women should not have a cesarean section prior to 39 weeks’ gestation

Operative obstetrics uses methods other than uterine contractions to deliver a fetus, including instrumental vaginal delivery and cesarean sections. Operative vaginal birth helps expedite delivery. It can avoid cesarean birth and associated complications, and be accomplished quicker than cesarean birth.