From Iusmicm

Contents 1 Labor: Normal, Abnormal, and Points Between 1.1 Definitions 1.2 Physiology of Labor 1.3 Labor and Delivery Admission 1.3.1 Fetal Monitoring 1.3.1.1 Fetal Monitoring - Normals 1.3.1.2 Variability and Accelerations / Decelerations 1.3.1.2.1 Decelerations 1.3.1.3 Categories of Heart Tracings 1.3.2 Fetal Lie, Presentation, Attitude, and Position 1.3.2.1 Definitions 1.3.2.2 Fetal Attitude 1.3.2.3 Vaginal Exam 1.3.2.3.1 Pelvic Inlet 1.3.2.3.2 Midpelvis 1.3.2.3.3 Pelvic Outlet 1.3.3 Stages of Labor 1.3.4 Cardinal Movements of Labor= 1.3.5 Labor Curve 1.3.6 Prolonged / Arrested Labor 1.3.7 Dysfunctional Labor 1.3.8 Cesarean Section 1.3.8.1 C-section - Techniques 1.3.8.2 C-section - Indications 1.3.8.2.1 Fetal C-section Indications 1.3.8.2.2 Maternal-Fetal C-section Indications 1.3.8.2.3 Maternal C-section Indications 1.3.8.3 C-section - Risks 1.3.9 Operative Vaginal Delivery 1.3.9.1 Operative Vaginal Delivery - Classification 1.3.9.2 Operative Vaginal Delivery - Indications 1.3.9.3 Operative Vaginal Delivery - Prerequisites 1.3.9.4 Operative Vaginal Delivery - Forceps Assisted 1.3.9.5 Operative Vaginal Delivery - Risks 1.3.9.6 Birth Trauma 1.3.10 Common Post Partum Problems 1.3.10.1 PP / Post-Op Fever

Labor: Normal, Abnormal, and Points Between

Definitions

• Labor: regular / rhythmic contractions, cervical dilation and effacement.
  • Must have cervical change to call it labor.
  • Dilation: cervix develops a wider opening.
  • Effacement: becomes shorter.
• Labor is considered "preterm" if it commences before 37 weeks EGA (estimated gestational age)
  • 10-12% of pregnancies include preterm labor.
• Labor is considered "postdates" if it commences after 42 weeks EGA.
• Braxton Hicks contractions are contractions of a weak or irregular nature.

Physiology of Labor

• There are many factors that play a role in the coordinated contraction of all the uterine smooth muscle for labor.

• Progesterone and Relaxin are key regulating factors in animals.
  • Relaxin does not play a role in humans.
  • When 17 alpha-hydroxyprogesterone caproate is given, we see fewer preterm contractions so we know progesterone plays a role but we don't see it physiologically.
  • Progesterone levels don't drop until after the placenta is delivered.

• Gap juctions of the uterine smooth muscle are increased near term.
  • Presumably to augment myofiber-myofiber communication for a well sequenced contraction.
  • Allow easy ability for electrical potential to cross.

• Oxytocin, surprisingly, shows no change in blood levels but there are increased number of oxytocin receptors.
  • Oxytocin receptors, however are elevated.
  • Oxytocin does promote the influx of calcium ions (and therefore increased contractions).
  • There is a paracrine oxytocin production from the dicidual and placenta with subsequent increase in receptors in the myometrium.
  • Made in the posterior pituitary.

• Several prostaglandins are elevated for labor: PGE1, PGE2, PGF2alpha
  • Makes collagenase to help break down collagen of the cervix to allow dilation and effacement.

• Mother becomes more sensitive to changes in Ca at term.
  • This is presumably because the uterine muscle is storing up more and more Ca to augment contraction.

• Like prostaglandins, many cytokines are elevated: IL-1, IL-6, IL-8, TNF-alpha.
  • Intermediate reactions in the labor pathway.
  • Infections can sometimes induce these types of cytokines and thus induce labor.
  • NO is another intermediate reactor.

Labor and Delivery Admission

• The workup for a L&D admission includes:
  • H&P:
    • Fetal monitoring
    • Leopold’s maneuver
    • Vaginal exam
      • R/o (rule out) placenta previa and ROM first
      • Cervical dilation / effacement / station and fetal position

Fetal Monitoring

• With fetal monitoring we are concerned with the baby's heart rate and the uterine pressure.
• There are several technical methods for fetal monitoring.
  • We can monitor externally via ultrasound and pressure transducers.
  • We can monitor internally (if the membranes are ruptured) by putting a pressure transducer into the uterine cavity.
    • A clip on the baby's scalp can mark each R wave.

Fetal Monitoring - Normals

• For baby's heart rate, the baseline should be around 110-160 bpm.
• We are looking for: variability, accelerations / decelerations
• For uterine pressure (contractions) we are looking for: frequency, duration, uterine tone.
  • Tone is important because the baby gets better blood flow when the uterus is resting.

Variability and Accelerations / Decelerations

• Variability:
  • Absent: 0-2 bpm
    • Start worrying about fetal acidosis.
    • Fix the environment or get the baby out.
  • Minimal: 3-5 bpm
  • Moderate: 6-25 bpm (ideal).
  • Marked: saltatory, >25 bpm

• Fetal Monitoring:
  • Good, classic accelerations go up by 15 beats per minute and last for 15 seconds.
  • If the pregnancy is less than 34 weeks, "10x10" is acceptable.

Decelerations

• Early declerations: occur with cntx
  • Start and end with the contraction
  • Non worrisome
  • Head compression leads to vagal stimulation at the posterior fontanelle
  • Recall that vagus carries parasympathetics to the heart
• Late decelerations: begin at peak of cntx or after
  • Fetal hypoxia is usually the culprit of late decelerations.
  • Occurs due to chemoreceptors in the carotid arch that sense the decreased pO2 leading to vasoconstriction and then bradycardia
• Variable: can occur at any time
  • Variable decelerations should raise one's suspicion for cord compression

• Variable Decelerations: mild, moderate, and severe.
  • Lower the blood pressure the more severe.
  • Longer the duration the more severe.
  • Severity of variable decelerations are a function of blood pressure and duration

Categories of Heart Tracings

• Category 1:
  • Baseline rate: 110-160 bpm
  • Baseline FHR variability is moderate
  • Accelerations: present or absent
  • Late or variable decelerations absent
• Early decelerations present or absent

• Category 2:
  • Everything not in 1 or 3

• Category 3:
  • Absent baseline variability (recall, a sign of acidosis)
  • Recurrent late decelerations
  • Recurrent variable decelerations
  • Bradycardia
  • Sinusoidal pattern (a sign of fetal hypoxia with severe anemia; think Rh disease)

Fetal Lie, Presentation, Attitude, and Position

• Clinical: abdomenal palpation, auscultation of fht’s, vaginal exam
• Studies: u/s, x-ray, MRI
  • These are done very rarely as we can determine the lie and presentation rather easily via physical examination.

Definitions

• Lie: relation of long axis of fetus to long axis of mother.
  • Longitudinal
  • Transverse
  • Oblique

• Presentation: part of baby foremost in the pelvis
  • Cephalic
  • Breech (bottom)
  • Shoulder
  • Face
  • Compound:
    • Head / hand -> watch (usually resolves itself; may apply a noxious stimuli to the hand)
    • Head / foot-> c-section (will not resolve itself; requires c/s)
• Cord prolapse (funic presentation): an emergency.
  • When the cord drops into the vagina.
  • Must move quickly to c/s.

• Attitude: how the baby presents its head
  • Normal attitude is folded on itself w/ flexed head

• Position: relation of presenting part to maternal pelvis anterior aspect
  • When the baby presents cephalically, the reference point on the baby to be referenced to the anterior pubis of the mother is the occiput
  • When the baby presents facially, the reference point is the mentum
  • When the baby presents as a breech, the reference point is the sacrum
  • When the baby presents transverse (shoulder), the reference point is the acromion process

Fetal Attitude

• There are a variety of ways the fetus can present at the os; these are called attitudes:
  • Full flexion (A)
    • Normal, smallest diameter.
  • Military attitude (B)
  • Brow presentation (C)
  • Face presentation (D)

• Leopold’s Maneuver can be used to determine the attitude of the fetus.
  • First maneuver: what is occupying the fundus?
    • Soft like a butt or hard like a head?
  • Second maneuver: on which side is the fetal spine?
    • Third maneuver: what is presenting at the pelvis?
    • Soft like a butt or hard like a head?
  • Fourth maneuver: what is the attitude, based on the flexion / extension of the head?
• Can correlate with CT if there is any questions.

Vaginal Exam

• We are trying to determine if the cervix is starting to dilate or efface.
• We describe effacement as a percent of normal length:
  • Normal length of a cervix is 4cm.
  • So if the cervix is observed as being 2 cm effaced, we call it 50%.

• Station: the lowest point of the fetus in reference to the ischial spines.
  • The stating is described as -1 (and so on, for every centimeter) it is above the ischial spines.
  • The station is described as +1 (and so on, for every centimeter) it is below the ischial spines.

• Position:
  • Most common is cephalic.
  • Use the occiput as the baby reference point when describing position against the maternal anterior pubis.
  • "right" and "left" shifts describe maternal right and left
  • To determine which aspect is the occiput, recall there are ant and post fontanelles (along which to orient) and the frontal suture (to identify the anterior aspect of the baby).

• Pelvimetry:
  • Performed at the first pre-natal visit and upon admission for L&D.
  • Describes adequacy of the pelvis for baby delivery.
  • Measures pelvic inlet, the midpelvis, and the pelvic outlet.

Pelvic Inlet

• True pelvic inlet measurement is from superior pubic ramus to the sacral prominence.
  • However, this can't be measured directly so we measure it indirectly.
  • True conjugate is also called the obstetric conjugate.

• The diagonal conjugate is measured with one's third finger, along toward the thumb.
• True obstetric conjugate = diagonal conjugate – 1.5 to 2.0 cm

• Diagonal conjugate: >11.5 cm is adequate

Midpelvis

• Sacrum – hallow versus shallow (flat):
  • Hallow is concave like a bowl of soup and gives more room for baby moving.

• Ischial spines – blunt vs. prominent
  • blunt is better; more room

• Pelvic sidewalls
  • Parallel = OK
  • Divergent = good
  • Convergent = bad

Pelvic Outlet

• Bituberous diameter:
  • > 6-8 cm is good
  • Measured by placing fist up against the butt.

• Pubic arch:
  • > 90 degrees is good

Stages of Labor

• 1st Stage: beginning of cervical dilation to complete dilation (10 cm)
• 2nd Stage: complete dilation to delivery of fetus
• 3rd Stage: delivery of placenta
  • up to 30 minutes
• 4th Stage: first hour after delivery of placenta
  • Big fluid shift, high risk of post-partum hemorrhage.
  • Monitoring mom for vitals
  • Monitoring firmness of uterus (should remain firm to inhibit hemorrhage by pressing layers of endometrium together)

Cardinal Movements of Labor=

• Engagement
• Flexion (of the head)
• Descent
• Internal rotation
• Extension
• External rotation
• Expulsion

• If the face is anterior, it can still extend.
• If mentum-posterior, there can be no extension, so it cannot deliver.

Labor Curve

• The first phase of minimal cervical change is latent phase.
  • Minutes, hours, days!
• Active phase
  • > 1 cm change / hour
• Baby will move from -5cm station to 0 to +5 as it delivers.

Prolonged / Arrested Labor

• When labor isn't moving along, consider your 3 Ps
• Power: uterine contractions
  • Are they strong enough?
  • Give oxytocin?
• Pelvis: adequate?
  • Do your pelvimetry to make sure pathway is sufficient
• Passenger: EFW, position / attitude
  • Is the baby too big?
  • Is the position wrong? (occiput posterior)
  • Is the attitude wrong? (military)

Dysfunctional Labor

Pattern	Nullip	Multip	Rx
Prolonged latent phase	>20 hr	>14 hr	Rest, AROM (augmented rupture of membranes; helps augment maternal environment for labor), Pitocin (oxytocin)
Protracted dilation	<1.2 cm/hr	<1.5 cm/hr	AROM, Pit
Protracted descent	<1 cm/hr	<2 cm/hr	Pit	Arrest of dilation	>2 hr	>2 hr	AROM, Pit, C/S
Arrest of descent	>2 hr	>1 hr	Vacuum, forceps, C/S

Cesarean Section

• History
  • Caedere -> caesura: to cut; seco: to cut.
  • "Cut Cut"
• Francois Rousset (1581)
  • First reported case with survival.
  • Questionable
• Max Sanger (1882)- Leipzig
  • Work on the American frontier
  • Sewed the womb shut! (Whoa!)
  • Crazy b/c the womb was considered an awful, evil thing, that shouldn't be sewn shut b/c all those bad humors would stay inside!

• Most common surgical procedure
  • 1965: <5%, 1996: 20.7%, 2004: 29.1%
• No change in cerebral palsy rate

C-section - Techniques

• Uterine Incisions
• Low transverse
  • The most common way because it runs with the grain of the muscular fibers.
  • Also, this area does less labor contracting so next pregnancy is less likely to result in rupture.
• Low verticle
• Classical
• Kerr

C-section - Indications

Fetal C-section Indications

• Distress / intolerance of labor
  • FHT of category 2 or 3
• Malpresentation (breech, transverse)
• Twins, multiples
  • Vertex / Vertex = allow to labor
• Some congenital anomalies
  • NTD

Maternal-Fetal C-section Indications

• Arrest of active labor
  • Pretty common
• Failed induction of labor (?)
• Placenta previa, vasa previa
  • When the placenta covers the cervical os.
  • When the placental vessels course between baby and os.
    • 50% mortality post-rupture!
• Active HSV outbreak
• HIV+ (viral load >1000/ml)
  • If mom is on ARV therapy, there is no decrease in transmission with c/s.
• EFW > 4500 - 5000 grams (increasing risk of shoulder dystocia)
  • Use u/s to estimate weight.

Maternal C-section Indications

• Obstructive tumors (some leiomyomas)
• Severe condylomata acuminata
• Cervical cancer
• Abdominal cerclage
• Prior c-section
  • Risk of uterine rupture is 0.5-1%
  • Can be catastrophic
• Prior vaginal colporrhaphy
• Vaginal delivery contraindicated medically
• Pregnant???
  • No!

C-section - Risks

• At time of surgery / Immediate post-op
• Infection: endometritis, wound infection, septic pelvic thrombophlebitis (SPT)
• Bleeding: transfusion, hysterectomy
• Damage to fetus
  • Very small; no larger than with vaginal delivery.
• Damage to adjacent organs

• Subsequent pregnancy:
  • Adhesions
  • Uterine rupture
  • Placenta previa (when the placenta covers the os) may convert to accreta (when the placenta invades the myometrium).
  • Accreta carries huge risks because there is often massive bleeding.
  • Accreta puts the mother a risk of death.
  • That is, placenta previa with a previous c/s has a very high risk of being bad!
    • 0 –> 5% (number of previous c/s, risk of accreta given a placenta previa)
    • 1 –> 24%
    • 2 –> 48%
    • 3 –> 67%

There will be a test question on prior c/s and placenta previa.

Operative Vaginal Delivery

• Forceps and vacuum can be used to guide the baby's head out of the pelvis.
• There are many different types and procedures.

Operative Vaginal Delivery - Classification

• We want, first, to be sure the baby has reached the pelvic inlet.

• Didn't talk about any of this:
• Outlet: scalp visible at introitus w/out separating labia; no rotation
• Low: leading point of skull at or below +2 cm station
  • Rotate < 45°
  • Rotate > 45°
• Mid: above +2 cm station but engaged

Operative Vaginal Delivery - Indications

• Nonreassuring FHT’s
• Prolonged 2nd stage of labor
• Shortened 2nd stage if pushing / Valsalva not indicated
• Maternal exhaustion

Operative Vaginal Delivery - Prerequisites

• Cervix completely dilated
• Ruptured membranes
• Fetal skull engaged in pelvis
• Empty bladder
• Position! Position! Position!
  • Before we put anything on the baby's head, we have to know the position so we don't break the nasal bone or deform the child.
• Adequate pelvis
• Adequate anesthesia

Operative Vaginal Delivery - Forceps Assisted

• Use the same angles when applying traction.
• Apply the extension just like in a non-operative vaginal delivery.

Operative Vaginal Delivery - Risks

• Maternal:
  • Vaginal / perineal trauma, damage to rectal sphincter
  • Mostly forceps issues with mom
• Fetal:
  • Mostly vacuum issues with baby
  • Cephalohematoma
  • Subgaleal hemorrhage
  • Bony facial trauma
  • Facial nerve injury
  • Intraventricular hemorrhage

Birth Trauma

• Caput succedaneum:
  • Very common
  • Crosses midline
• Subgaleal hemorrhage:
  • Does not cross midline
  • Rare
  • Hypovolemia and DIC

Common Post Partum Problems

• PP Hemorrhage: >500cc (>1000cc for c/s):
  • Atony
    • When the uterus won't contract.
    • Linings aren't collapsed together to stop bleeding.
  • Lacerations (cervix, vagina, perineum)
  • Retained placenta
    • Keeps the endometrium layers from coapting (collapsing together).
  • Uterine rupture
  • Uterine inversion
  • Amniotic fluid embolism

• Endometritis:
  • Fundal tenderness w/ temperature >38°C x 2 or >38.5°C
  • Polymicrobial infection
  • More common after c/s
    • Prolonged ruptured membranes
    • Chorioamnionitis
  • Treat with broad spectrum antibiotics

PP / Post-Op Fever

• Causes and symptoms
  • Wind (atelectasis, pneumonia)
  • Wound (seroma, necrotizing fasciitis)
  • Water (UTI)
  • Walk (thrmobophlebitis)
  • Wonder drug (drug reaction)
  • Womb (endometriosis)
  • Wean (mastitis, engorgement)