Normal Labor & Delivery Flashcards
Define labor vs. false labor
Labor = progressive cervical dilation resulting from regular uterine contractions that occur every 5 mins and last 30-60 seconds
False labor = irregular contractions without cervical change (braxton-hicks contractions)
Classic type of female pelvis with good prognosis for delivery vs. worst type of pelvis for delivery (poor prognosis)
Classic type with good prognosis = gynecoid
Poor prognosis for delivery = platypelloid (fetal head has to engage in the transverse diameter)
Narrowest fixed distance through which fetal head must pass through during a vaginal delivery; estimated by subtracting 2 cm from the diagonal conjugate
Obstetric conjugate
[diagonal conjugate is approximated by measuring from the inferior portion of the pubic symphysis to the sacral promontory — if >11.5cm, the AP diameter of the pelvic inlet is adequate]
Initial evaluation of pt presenting with signs of labor
Review prenatal records, identify complications of pregnancy, confirm gestational age, review lab findings
Focused hx including nature/frequency of contractions, loss of fluid, vaginal bleeding
PE: vital signs, fetal heart tones and contractions, cervical exam if appropriate
Assess fetal lie and presentation
5 Elements of cervical exam
Dilation — check at level of internal os; range from closed to completely dilated at 10 cm
Effacement — thinning of the cervix reported as % change in length; range is thick to 100% effaced
Station — degree of descent of the presenting part of the fetus; measured in cm from presenting part to ischial spines beginning when bony portion of head reaches level of ischial spines; range is -5 to +5 (or -3 to +3)
Position and Consistency — used to calculated Bishop score
4 Leopold maneuvers to evaluate fetal lie
- Palpate the fundus
- Palpate for spine and fetal small parts
- Palpate what is presenting in the pelvis with suprapubic palpation
- Palpate for cephalic prominence
Types of fetal presentation
Face Brow Vertex Breech Shoulder
4 stages of labor
Stage 1: onset of true labor to complete cervical dilation (latent phase and active phase)
Stage 2: complete cervical dilation to delivery of infant
Stage 3: delivery of infant to delivery of placenta
Stage 4: delivery of placenta to stabilization of patient
Describe the first phase of labor in terms of latent vs. active, duration, and rate of cervical dilation
Latent (early labor) — period between onset of labor characterized by slow cervical dilation
Active — associated with faster rate of dilation and usually begins when cervix is dilated to 4 cm; admit for labor at this stage in term gestations
Duration of first stage is 6-8 hours in primiparas and 2-10 hours in multiparas
Rate of cervical dilation is 1.2 cm/hr in primiparas and 1.5cm/hr in multiparas
Management of first stage of labor in terms of maternal position, fluids, labs, maternal monitoring, and fetal monitoring
Maternal position: pt may ambulate if head is engaged and reassuring monitoring is noted; if lying in bed encourage left lateral recumbent position
Fluids: IV used to hydrate pt, provide access to administer meds
Labs: CBC and Type and screen
Maternal monitoring: obtain vitals q1-2 hours while in labor
Fetal monitoring: can do external or internal, and either continuous or intermittent
Management of first stage of labor in terms of uterine activity and vaginal exam
Uterine activity tracked via external tocodynamometer and/or internal pressure catheter (IUPC)
Vaginal exam: during active phase, should perform cervical check q2 hrs, record dilation, effacement, and station
What does it mean if vaginal exam during stage 1 of labor is documented 4/50/-2?
4cm dilated
50% effaced
-2 cm station
Benefits vs. risks of amniotomy (AROM) during first stage of labor
Benefits: augment labor, allows assessment of meconium status
Risks: cord prolapse, prolonged rupture associated with chorioamnionitis
7 Cardinal movements of labor
Engagement — defined as presenting part at “zero” station
Descent
Flexion — changes presenting part from occipitofrontal to smaller suboccipitobregmatic
Internal rotation — usually at ischial spines, fetal head enters pelvis in transverse diameter and then rotates so occiput is either anterior or posterior
Extension — crowning occurs when largest diameter of the fetal head is encircled by the vaginal introitus (station +5); head is born by rapid extension
External rotation — delivered head now returns back to original position to align with back and shoulders
Expulsion — anterior shoulder then delivers, followed by posterior shoulder and remainder of body
Describe management of the second stage of labor in terms of maternal position, fetal monitoring, and vaginal exam
Maternal position: avoid supine; dorsal lithotomy is most common for spontaneous and operative deliveries
Continuous fetal monitoring
Vaginal exam to assess descent and confirm position
Describe delivery of the fetus during stage 2 of labor
Antiseptic soap used to cleanse vulvar area and drape placed under pt
As perineum becomes flattened by crowning head, an episiotomy may be warranted
To facilitate delivery of fetal head, a modified Ritgen maneuver is often performed. Once head is delivered, can bulb suction oral cavity first then nares to clear airway of blood and amniotic fluid
Use index finger to assess for nuchal cord
Deliver anterior shoulder with gentle downward traction on the fetal head. The posterior shoulder is then delivered by elevating the head
Support the baby as the body is delivered; bulb suction again if indicated; dry and stimulate, cord clamped x2 and cut; obtain cord blood specimens
Indications for and types of episiotomy
Indications: likelihood of spontaneous laceration seems high; to expedite delivery by enlarging the vaginal outlet
Midline episiotomy: most commonly performed; greater risk of extension into 3rd or 4th degree tear, less postpartum pain
Mediolateral episiotomy: greater blood loss, more difficult to repair, more postpartum pain, increase risk of dyspareunia
What is the modified Ritgen maneuver?
Fingers of the right hand used to extend head while counterpressure 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]
4 types of perineal lacerations
First degree — superficial lac involving vaginal mucosa and/or perineal skin
Second degree — lac extending into muscles of perineal body bu does not involve anal sphincter
Third degree — lac extends into or completely through anal sphincter but not into rectal mucosa
Fourth degree — involves rectal mucosa
The third stage of labor/delivery is the interval between delivery of the infant and delivery of the placenta, which usually occurs w/i 2-10 minutes. A retained placenta is diagnosed if placenta has not delivered within 30 minutes. Signs of placental separation include gush of blood from vagina, lengthening of umbilical cord, fundus of uterus rises up, and change in shape of uterine fundus from discoid to globular. Describe ways that the physician can assist with placental delivery
Apply counterpressure between symphysis and fundus
[do NOT pull on cord until classic signs are noted as this could result in uterine inversion]
Management of third stage of labor after placenta has been delivered
Look for lacerations of cervix, vagina, and perineum
Monitor uterine bleeding
Repair episiotomies or spontaneous lacerations
Inspect the placenta for completeness
Management of the fourth stage of labor involves close monitoring, vitals (BP and pulse), uterine fundal checks, and assessing for vaginal bleeding. Postpartum hemorrhage commonly occurs during the fourth stage. What is the most common cause of postpartum hemorrhage?
Uterine atony
[other causes include retained placenta and unrepaired vaginal or cervical laceration]
Indications for induction of labor
Abruptio placentae Chorioamnionitis Fetal demise Preeclampsia/eclampsia Gestational HTN Premature rupture of membranes Postterm pregnancy Maternal medical conditions Fetal compromise
Contraindications to induction
Unstable fetal presentation
Acute fetal distress
Placenta previa or vasa previa
Previous C section or transfundal surgery
Any contraindications to vaginal delivery (HIV with high viral load, active HSV outbreak)
What is the Bishop score and what is it used for?
Score based on cervical dilation, effacement, station, consistency, and position — used to determine if mom is favorable to induce
A Bishop score of < 6 is considered unfavorable. A score of >8 indicates probability of vaginal delivery after labor induction is similar to that of spontaneous labor.
Cervical ripening agents and techniques
Cervidil (dinoprostone) — prostaglandin E2 vaginal insert; contraindicated in pts with previous C section
Cytotec (misoprostol) — prostaglandin E1 placed orally or vaginally and cannot be readily removed; contraindicated in pts with previous C section
Mechanical dilators — foley bulb catheter, laminara japonicum (dilation occurs by swelling of laminara rods)
Only FDA approved drug for induction and augmentation of labor
Pitocin
[synthetic oxytocin which stimulates myometrial contractions; dosed 1-30 mu/min, uterine response w/i 3-5 mins]
Most common side effect of pitocin (as well as some other side effects)
Uterine tachysystole — defined as >5 contractions in a 10min period
Other AEs: Antidiuretic effect, uterine muscle fatigue, increased risk of postpartum hemorrhage (secondary to uterine atony)
What is important to consider prior to administering obstetric anesthesia?
Give IV fluids — adequate hydration is necessary to avoid hypotension and its effects on uterine blood flow
Uterine contractions and cervical dilation result in visceral pain (T10-L1). Descent of fetal head and pressure from pelvic floor, vagina, and perineum generate somatic pain via the pudendal n. (S2-4). Regional anesthesia refers to partial or complete loss of pain sensation below T10 level. What are all the anesthesia options in labor?
Nonpharmacologic — lamaze, emotional support, back massage, hydrotherapy, acupuncture
Parenteral — morphine, fentanyl, meperidine, nalbuphine
Regional — local+narcotic, epidural, spinal
Local — lidocaine, pudendal block
General — usually propofol
