Normal Labor and Delivery Flashcards
What is labor defined as?
- Progressive cervical dilation resulting from regular uterine contractions that occur at least every 5 minutes and last 30-60 seconds
What is false labor?
- Braxton Hick contractions
- Irregular contractions without cervical change
How long is the suboccipitobregmatic diameter?
- 9.5 cm
How long is the occipitofrontal diameter?
- 11 cm
How long is the supraoccipitaomental diameter?
- 13.5 cm
- Longest anterior-posterior diameter of the head
How long is the submentobregmatic diameter?
- 9.5 cm
What is the average circumference of a term fetal head?
- 34.5 cm
- Measured in the occipitofrontal plane
What are the different pelvic shapes?
- Gynecoid
- Android
- Anthropoid
- Platypelloid
What is a gynecoid pelvis?
- Classic female type of pelvis
- Round at inlet
- Wide transverse diameter only slightly greater than the anteroposterior diameter
- Wide suprapubic arch
- Good prognosis for delivery
How does the head rotate in a gynecoid pelvis?
- Rotates into the occiput anterior (OA) position
What is an android pelvis?
Classic male type of pelvis
- Widest transverse diameter closer to the sacrum
- Prominent ischial spines
- Narrow pubic arch
- Amount of space is restricted and arrest of descent is common
- Poor prognosis for delivery
How does the head rotate in an android pelvis?
- Forced to be in the occiput posterior (OP) position
What is an anthropoid pelvis?
- Resembles ape pelvis
- Much larger anteroposterior than transverse diameter
- Creates a long narrow oval shape
- Narrow pubic arch
- Prognosis for delivery good
How does the head rotate in an anthropoid pelvis?
- Engages only in the anteroposterior diameter
- Usually in the OP position
What is a platypelloid pelvis?
- Described as a flattened gynecoid pelvis
- Short AP and wide transverse diameter
- Wide bispinous diameter
- Wide suprapubic arch
- Poor prognosis for delivery
How does the head rotate in a platypelloid pelvis?
- Has to engage in the transverse diameter
What is a diagonal conjugate?
- Approximated by measuring from the inferior portion of the pubic symphysis to the sacral promontory
- If > 11.5 cm the AP diameter of pelvic inlet is inadequate
What is a obstetric conjugate?
- Estimated by subtracting 2 cm from the diagonal conjugate
- Is the narrowest fixed distance through which the fetal head must pass through during a vaginal delivery
What is the palpate?
- Anterior surface of the sacrum which is usually concave
- Ischial spines to assess prominence
How is pelvic outlet measured?
- By measuring the ischial tuberosities and the pubic arch
- Measure between the ischial tuberosities (8.5 is adequate)
- Measure infrapubic angle (place thumb next to each inferior pubic ramus and estimate angle –> 90 degrees is good)
What does a MRI or CT do for pelvimetry?
- Used to look if clinical or obstetric history is suggestive of pelvic abnormalities
What is done on initial evaluation?
- Review prenatal records
- Identify complications of pregnancy
- Confirm gestational age
- Review pertinent laboratory findings
- Focused history
- PE
What is included in the focused history during the initial evaluation?
- Nature and frequency of contractions
- Loss of fluid
- Vaginal bleeding
What is included in the PE during the initial evaluation?
- Vital signs
- Fetal heart tones and contractions
- Cervical exam if appropiate
What is the fetal lie?
- Reference is maternal spine to fetus spine
- Determines if infant is longitudinal, transverse, or oblique
What is a part of the obstetric exam?
- Fetal lie
- Fetal presentation (presenting part to the pelvis)
- Cervical exam
What is a part of the cervical exam?
- Dilation
- Effacement
- Station
- Position
- Consistency
What are the leopold maneurvers?
- Series of 4 maneuvers
1. Palpate the fundus (fetal head vs buttocks vs transverse position)
2. Palpate for spine and fetal small parts
3. Palpate what is presenting in the pelvic with suprapubic palpation
4. Palpate for cephalic prominence (can feel chin or occipital protuberance if head isn’t deep in pelvis)
What is the dilation stage of the cervical exam?
- Check at level of internal os
- Range from closed to completely dilated at 10 cm
What is the effacement stage of the cervical exam?
- Thinning of the cervix occurs and is reported as a % change in length
- Normal cervical length is 3-5 cm
- Rang is thick to 100% effaced
What is the station stage of the cervical exam?
- Degree of descent of the presenting part of the fetus
- Measured in cm from presenting part to ischial spine
- When the bony portion of the head reaches the level of the ischial spines the station is zero
- Range is -5 to +5 cm
What are the consistency and position stages of the cervical exam?
- Commonly used to calculate Bishop score
What is the first stage of labor?
- Onset of true labor to complete cervical dilation
- Latent phase
- Active phase
What is the second stage of labor?
- Complete cervical dilation to delivery of infant
What is the third stage of labor?
- Delivery of infant to delivery of placenta
What is the fourth stage of labor?
- Delivery of placenta to stabilization of patient
What is the latent phase of stage 1 in labor?
- Period between onset of labor and is characterized by slow cervical dilation
What is the active phase of stage 1 in labor?
- Associated with a faster rate of dilation and usually begins when cervix is dilated to 6 cm
- Admit for labor at this stage in term gestations
What are the different durations during the first stage of labor?
- Primiparas - Typically 6-18 hours
- Multiparas - Typically 2-10 hours
What is the rate of dilation during the first stage of labor?
- Primiparas - 1.2 cm per hour
- Multiparas - 1.5 cm per hour
What management is done during the first stage of labor?
- Maternal position
- Fluids
- Labs
- Maternal and fetal monitoring
- Analgesia
How is maternal position changed during the first stage of labor?
- Patient may ambulate if head is engaged and reassuring monitoring is noted
- If lying in bed, encourage left lateral recumbent position
How fluids managed during first stage?
- IV used to hydrate patient and provide access to administer meds
- Oxytocin to augment labor or after delivery of placenta
What labs are done during the first stage?
- CBC and T&S
What maternal monitoring is done during the first stage?
- Obtain vitals every 1-2 hours while in labor
How is fetal monitoring done during the first stage?
- External monitoring
- Continuous
- Intermittent monitoring if pregnancy is uncomplicated pr complicated
What intermittent monitoring is done for an uncomplicated pregnacy?
- Monitor every 30 min in active first stage
- Monitor every 15 in second stage of labor
What intermittent monitoring is done for a complicated pregnancy?
- Monitor every 15 min in active phase and during second stage
How is uterine activity monitored during the first stage?
- External tocodynamometer
- Internal pressure catheter (shows strength of contractions)
What is done during vaginal examination in the first stage?
- Need to do cervical checks every 2 hours during active phase
- Record dilation, effacement, and station
- 4/50/-2 = 4cm dilated/50% effaced/-2 station
What is amniotomy during the first stage?
- Benefits: augment labor and allow assessment of meconium status
- Risks: cord prolapse, prolonged rupture is associated with chorioamnionitis
What is the second stage of delivery characterized by?
- Descent of the presenting part through the maternal pelvis and culminates in delivery
- Mother usually has an increase in bloody show and desire to bear down with each contraction
What is the different durations in the second stage?
- Primipara without epidural - 2 hours
- Primipara with epidural - 3 hours
- Multipara without epidural - 1 hours
- Multipara with epidural - 2 hours
What are the cardinal movements of labor?
- Engagement
- Descent
- Flexion
- Internal rotation
- Extension
- External rotation
- Expulsion
What is engagement in labor?
- Presenting part at “zero” station
What is descent in labor?
- Brought about by the force of uterine contractions and maternal valsalva efforts
What is flexion in labor?
- OA- baby’s chin to chest thus changing the presenting part from occipitofrontal to the smaller suboccipitobregmatic
What is internal rotation in labor?
- Occurs usually at ischial spines
- Fetal head enters pelvis in transverse diameter, rotates so the occiput turns anteriorly or posteriorly toward the pubic symphysis
What is extension in labor?
- Crowning occurs when the largest diameter of the fetal head is encircled by the vaginal introitus
- Station is +5
- Head is born by rapid extension
What is external rotation in labor?
- The delivered head now returns to its original position at the time of engagement to align itself with the fetal back and shoulders
What is expulsion in labor?
- Anterior shoulder then delivers under the pubic symphysis, followed by the posterior should and the remainder of the body
What is the maternal position during the second stage?
- Avoid the supine position
- Dorsal lithotomy position is most common position for spontaneous and operative deliveries
What is bearing down during the second stage?
- With each contraction, the mother should hold her breath and bear down with expulsive efforts
What fetal monitoring should be done during the second stage?
- Continuous
- Monitor every 15 min in patients with NO risk factors or every 5 min in patients with risk factors
What does the vaginal exam consist of during the second stage?
- Access descent and confirm position
Who is in the room during delivery?
- Two RN, physician, and med tech
How is the patient set up for delivery?-
- Drape is placed under buttock
- Antiseptic soap is used to clean vulvar area
- As perineum becomes flattened by the crowning head, an episiotomy may be warranted
- To facilitate delivery of the fetal head, a Ritgen maneuver is often performed
What is done right after the head is delivered?
- An oral bulb suction is done of the oral cavity and nares to clear the airway of blood and amniotic fluid
How is the infant delivered?
- Use index finger to assess for nuchal cord
- Deliver anterior shoulder with gentle downward traction on fetal head
- Posterior should is then delivered the head
- Support the baby as the body is delivered
- Bulb suction again if needed
- Dry and stimulate
What is done after delivery?
- Cord clamped twice and cut
- Obtain cord blood specimens
- Deliver placenta
- Inspect cervix, vagina, and perineum
What are some indications of an episotomy?
- Likelihood of spontaneous laceration seems high
- To expedite delivery by enlarging the vaginal outlet
What is a midline episiotomy?
- Most commonly performed
- Greater risk of extension into third or fourth degree
- Less postpartum pain
What is a mediolateral episiotomy?
- Greater blood loss
- More difficult to repair
- More postpartum pain
- Increase risk of dyspreunia
What is the ritgen maneuver?
- Fingers of the right hand are used to extend the head while counter pressure is applied to the occiput by the left hand to allow for a more controlled delivery
- Simple manual support to the perineum may be equally effective
What is a first degree perineal laceration?
- A superficial laceration involving the vaginal mucosa and/or the perineal skin
What is a second degree perineal laceration?
- Laceration extending into the muscles of the perineal body but does not involve the anal sphincter
What is a third degree perineal laceration?
- Laceration extends into or completely through the anal sphincter but not into the rectal mucosa
What is a fourth degree perineal laceration?
- Involves the rectal mucosa
What is a retained placenta?
- Is diagnosed if placenta has not been delivered within 30 min
What are the classic signs of placental separation?
- Gush of blood from vagina
- Lengthening of umbilical cord
- Fundus of the uterus rises up
- Change in shape of the uterine fundus from discoid to globular
Why is the cord not pulled until the classic signs are noted?
- Inappropriate pulling may result in uterine inversion
What does the management look like for the third stage?
- Look for lacerations of cervix, vagina, and perineum
- Monitor uterine bleeding
- Repair episiotomy or spontaneous lacerations
- Inspect the placenta for completeness
What is done for the fourth stage?
- Monitor patient closely
- Vitals
- Uterine fundal checks and assess for vaginal bleeding
- Postpartum hemorrhage commonly occurs during this time
What is cervical ripening?
- If induction is indicated and cervix is unfavorable, agents for cervical ripening may be used
- Goal of cervical ripening is to facilitate the process of cervical softening, thinning, and dilating in hopes to reduce the rate of failed inductions
What is induction of labor?
- Is the process by which labor is induced by artificial means
What is augmentation of labor?
- Is the artificial stimulation of labor which has already begun
What are some indications for induction?
- Abruptio placentae
- Chorioamnionitis
- Fetal demise
- Preeclampsia, eclampsia
- Gestational hypertension
- Premature rupture of membranes
- Postterm pregnancy
- Maternal medical conditions
- Fetal compromise
What are some contraindications for induction?
- Unstable fetal presentation
- Acute fetal distress
- Placenta previa or vasa previa
- Previous classical cesarean section or transfundal uterine surgery
- Or any contraindications to vaginal delivery
What BISHOP score is unfavorable?
- <6
What BISHOP score is favorable?
- > 8
- Probability of vaginal delivery after labor induction is similar to that of spontaneous labor
What are some cervical ripening agents?
- Cervidil (dinoprostone)
- Cytotec (misoprostol)
- Mechanical dilators
What is Cervidil (dinoprostone)?
- Prostaglandin E2
- Vaginal insert
- Contraindicated in patients with previous cesarean sections
What is cytotec (misoprostol)?
- Prostaglandin E1
- Placed orally or vaginaly
- Downside, is this medicine cannot be readily removed if concerns arise
- Contraindicated in patients with previous cesarean sections
How do mechanical dilators ripen the cervix?
- Foley bulb catheter –> inflate to 30-80cc
- Laminaria Japonica –> dilation occurs by swelling of the laminaria rods
What is a pitocin infusion?
- Pitocin is synthetic oxytocin which stimulates myometrial contractions
- Administered through the IV
- Is only FDA approved drug for induction and augmentation
- Diluted by normal saline and delivered IV pump
- Dosed 1-30 mu/min
What are some complications of pitocin?
- Uterine Tachysystole
- Antidiuretic effect
- Uterine muscle fatigue
What is uterine tachysytole?
- Defined as more than 5 contractions in a 10 minute period
- Most common side effect
What is the antidiuretic effect from pitocin?
- Similar structure to ADH and has an intrinsic antidiuretic effect which can lead to increase water reabsorption
- Severe water intoxication can lead to convulsions and coma
What is uterine muscle fatigue (nonresponsiveness)?
- Prolonged use of pitocin can lead to increase risk of postpartum hemorrhage secondary to uterine artery
What is the goal of obstetric anesthesia?
- To provide effective pain relief for mother during the course of labor and delivery that is safe for her and her baby
What is the uterine blood flow?
- At term gestation is 700-900 ml/min
- Regional anesthesia may decrease uterine blood flow if hypotension occurs and is not promptly treated
- Adequate hydration 30-60 min prior to regional anesthesia may mitigate the risk for hypotension
What spinal levels receive uterine contraction or cervical dilation?
- T10-T12 through L1
What generates pain vai the pudendal nerve (S2-S4)?
- Descent of fetal head and pressure from the pelvic floor, vagina, and perineum
What is regional anesthesia?
- Partial or complete loss of pain sensation below T10 level
What are some anesthesia options in labor?
- Nonpharmacologic methods
- Parental
- Regional
- Local
- General
What are some nonpharmacologic anesthesia options?
- Lamaze
- Emotional support
- Back massage
- Hydrotherapy
- Acupuncture
What are some parental anesthesia options?
- Morphine, Fentanyl, Meperidine, Nalbuphine
What is an important detail about parental options?
- More effective in the early first stage of labor when pain is more visceral and less intense
- Little efficacy for relief of labor pain
- Opioids readily cross placental barrier leading to respiratory depression
What is a regional anesthesia option?
- Loss of pain sensation below T8-T10
- Local anesthesia and narcotic
What are the two types of regional anesthesia?
- Epidural
- Spinal
What is an epidural?
- Most effective form of pain relief and is used by most women in the us
- Catheter is placed in the epidural space which allows for continuous infusion of anesthetic agents
- Large bore needle is used to locate epidural space between the L2-3, L3-4, or L4-5 interspace, catheter is then placed over the needle
What is a spinal?
- Single - shot analgesia which provides excellent pain relief from limited procedures (30-250 min depending on drugs)
- Limited use in labor since it is a single shot
What are some benefits of regional anesthesia?
- Highly effective
- Mother remains alert, awake, and can communicate with medical team
- Will remember the experience
- Rarely requires local anesthesia for perineal lacerations
What are some side effects of regional anesthesia?
- Hypotension incidence is 10%
- Spinal headache incidence is 1-2% and less than 1% with epidural
- Fever, spinal hematomas and abscesses
What are some contraindications of regional anesthesia?
- Maternal coagulopathy
- Heparin use within 12 hours
- Untreated maternal bacteremia
- Increased intracranial pressure caused by mass lesion
- Skin infection over site of needle placement
What are some local anesthesia options?
- Local infiltration of perineum
- Pudendal block
What is done for local infiltration of perineum?
- Used to infiltrate perineum before episiotomy or with laceration repair
- Toxic effects are rare but are more common with intravascular injections; so aspirate for blood before injecting local anesthesia
What is done for a pudendal block?
- Can aid operative vaginal delivery in women who do not have regional anesthesia
- Complications include intravascular injection, hematomas, and infections
What are some general anesthesia options?
- Propofol is most common
- Results in loss of maternal consciousness and it must be accompanied by airway management
- All inhaled anesthetics readily cross placenta and have been associated with neonatal respiratory depression
When is general anesthesia performed?
- Emergent cases with need for rapid delivery
- Regional anesthesia has failed
