OBGYN - Normal and Abnormal Labor
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Labor: Normal, Abnormal, and Points Between
Definitions
- Labor: regular / rhythmic contractions, cervical dilation and effacement.
- 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.
- 17alpha-hydroxyprogesterone caproate
- Gap juctions of the uterine smooth muscle are increased near term.
- Presumably to augment myofiber-myofiber communication for a well sequenced contraction.
- Oxytocin, surprisingly, shows no change in blood levels.
- Oxytocin receptors, however are elevated.
**Furthermore, there is elevated decidual production.
- Several prostaglandins are elevated for labor: PGE1, PGE2, PGF2alpha
- 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.
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
- There are several technical methods for fetal monitoring.
- With fetal monitoring we are concerned with the baby's heart rate and the uterine pressure.
- For baby's heart rate, the baseline should be around 120-160 bpm.
- We are looking for: variability, accelerations / decelerations
- For uterine pressure (contractions) we are looking for: frequency, duration, uterine tone.
Variability and Accelerations / Decelerations
- Variability:
- Absent: 0-2 bpm
- Minimal: 3-5 bpm
- Moderate: 6-25 bpm
- Marked: saltatory, >25 bpm
- Fetal Monitoring:
- Accelerations- “15 x 15”
- Reactive fetal heart tracing (nonstress test)
- 2 accelerations in 20 minutes or less
- Contraction stress test (Oxytocin challenge test)
- 3 UC’s x 40 sec in 10 mins
- Negative = no decelerations
- Positive = >50% UC’s with late decelerations
- Equivocal = intermittent or late decelerations or significant variable decelerations
Decelerations
- Early declerations: occur with cntx
- Head compression leads to vagal stimulation
- 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.
- Variable: can occur at any time
- Variable decelerations should raise one's suspicion for cord compression
- Variable Decelerations: mild, moderate, and severe.
Sinusoidal
- Fetal Lie, Presentation, Attitude, and Position
- Clinical: abd palpation, auscultation of fht’s, vaginal exam
- Studies: u/s, x-ray, MRI
Definitions
- Lie: relation of long axis of fetus to long axis of mother
- Longitudinal
- Transverse
- Oblique
- Presentation: part foremost in the pelvis
- Cephalic
- Breech
- Shoulder
- Other Presentations:
- Compound
- Head / hand -> watch
- Head / foot-> c-section
- Compound
- Cord prolapse (funic presentation): an emergency.
- Attitude: folded on itself w/ flexed head
- extension of head
- Position: relation of presenting part to maternal pelvis
- Cephalic -> occiput
- Face -> mentum
- Breech -> sacrum
- Transverse -> acromion process
Fetal Attitude
- There are a variety of ways the fetus can present at the os; these are called attitudes:
- Full flexion
- Military attitude
- brow presentation
- face presentation
- Leopold’s Maneuver can be used to reposition the fetus into another attitude.
Vaginal Exam
- Nullip Multip
� Vaginal Exam stations fetal head.jpg 000138B4 Macintosh HD BB8E171A: Station � Vaginal Exam (Position) bones fetal head.jpg 000138B4 Macintosh HD BB8E171A: fetal position.jpg 000138B4 Macintosh HD BB8E171A: � Vaginal Exam (Pelvimetry) pelvic inlet.jpg 000138B4 Macintosh HD BB8E171A: transverse diameter.jpg 000138B4 Macintosh HD BB8E171A: Diagonal Conjugate Ischial Spines � Vaginal Exam – Pelvic Inlet . Diagonal conjugate >11.5 cm = adequate . Diagonal conjugate – 1.5 to 2.0 cm = True Obstetric conjugate
DiagonalConjugate � Vaginal Exam - Midpelvis . Ischial spines – blunt vs. prominent . Pelvic sidewalls . Parallel = OK . Divergent = good . Convergent = bad
. Sacrum – hallow vs. shallow (flat)
ProminenceoftheSpines � Vaginal Exam – Pelvic Outlet . Bituberous diameter >6- 8 cm . Pubic arch >90 degrees
TransverseOutlet � Stages of Labor . 1st- beginning of cervical dilation to complete dilation . 2nd- complete dilation to delivery of fetus . 3rd- delivery of placenta (up to 30 min.) . 4th- first hour after delivery of placenta
� Cardinal Movements of Labor . Engagement . Flexion . Descent . Internal rotation . Extension . External rotation . Expulsion
cardinal.jpg 000138B4 Macintosh HD BB8E171A: � Labor Curve scan1.jpg 000138B4 Macintosh HD BB8E171A: � Prolonged/Arrested Labor . Power- uterine contractions . Pelvis- ?adequate . Passenger- EFW, position/attitude
� Dysfunctional Labor Pattern
Nullip
Multip
Rx
Prolonged latent phase
>20 hr
>14 hr
Rest, AROM, Pit
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 . Francois Rousset (1581) . Max Sanger (1882)- Leipzig
. Most common surgical procedure . 1965 <5%, 1996 - 20.7%, 2004 - 29.1% . No change in cerebral palsy rate
-National Center for Health Studies � C-section - Techniques uterine incision.jpg 000138B4 Macintosh HD BB8E171A: � C-section - Indications . Fetal . Distress/intolerance of labor . Malpresentation (breech, transverse) . Twins, multiples . Vtx/Vtx = allow to labor
. Some congenital anomalies . NTD
� C-sections – Indications (cont.) . Maternal-Fetal . Arrest of active labor . Failed induction of labor (?) . Placenta previa, vasa previa . Active HSV outbreak . HIV+ (viral load >1000/ml) . EFW >4500 - 5000 gms (increasing risk of shoulder dystocia)
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C-section – Indications (cont.)
. Maternal
. Obstructive tumors (some leiomyomas)
. Severe condylomata acuminata
. Cervical cancer . Abdominal cerclage . Prior c-section . Prior vaginal colporrhaphy . Vaginal delivery contraindicated medically . Pregnant ???
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C-section - Risks
. At time of surgery/Immediate post-op
. Infection- endometritis, wound infection,
Septic pelvic thrombophlebitis (SPT)
. Bleeding- transfusion, hysterectomy
. Damage to fetus
. Damage to adjacent organs
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C-section – Risks (cont.)
. Subsequent pregnancy
. Uterine rupture
. Placenta previa->accreta
. 0 –> 5%
. 1 –> 24%
. 2 –> 48%
. 3 –> 67%
. Adhesions
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Operative Vaginal
Delivery
. Forceps
and
vacuum
forceps.jpg 000138B4 Macintosh HD BB8E171A: � Classification of Delivery . 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
� Indications for Operative Vaginal Delivery . Nonreassuring FHT’s . Prolonged 2nd stage of labor . Shortened 2nd stage if pushing/Valsalva not indicated . Maternal exhaustion
� Prerequisites for Operative Vaginal Delivery . Cervix completely dilated . Ruptured membranes . Fetal skull engaged in pelvis . Empty bladder . Position! Position! Position! . Adequate pelvis . Adequate anesthesia
� Forceps Assisted Vaginal Delivery hrphysioL08 � Risks of Operative Vaginal Delivery . Maternal . Vaginal/perineal trauma, damage to rectal sphincter
. Fetal . Cephalohematoma . Subgaleal hemorrhage . Bony facial trauma . Facial nerve injury . Intraventricular hemorrhage
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Birth Trauma
. Caput succedaneum
. Very common
. Crosses midline
. Subgaleal hemorrhage . Rare . Hypovolemia and DIC
2925
vacuum-fig1
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Common Post Partum
Problems
. PP Hemorrhage- >500cc (>1000cc for
c/s)
. Atony
. Lacerations (cervix, vagina, perineum)
. Retained placenta
. Uterine rupture
. Uterine inversion
. Amniotic fluid embolism
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PP Problems (cont.)
. Endometritis- Fundal tenderness w/
T>38°C x 2 or >38.5°C
. Polymicrobial infection
. More common after c/s
. Prolonged ruptured membranes
. chorioamnionitis
� PP/Post-Op Fever . Wind . Wound . Water . Walk . Wonder drug . Womb . Wean
. Atelectasis, pneu . Seroma, nec. Fasc. . UTI . Thrombophlebitis . Drug rxn . Endometritis . Mastitis, engorgement
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