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Normal Labor and Delivery. Midwifery Division Department of OB/GYN University of North Carolina School of Medicine. OBJECTIVES. Describe the maternal factors in birth List the various fetal positions and presentations Review the 7 Cardinal Movements Define the 4 stages of labor
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Normal Labor and Delivery Midwifery Division Department of OB/GYN University of North Carolina School of Medicine
OBJECTIVES • Describe the maternal factors in birth • List the various fetal positions and presentations • Review the 7 Cardinal Movements • Define the 4 stages of labor • Describe a normal fetal heart rate pattern • Discuss the factors affecting the US C/S rate and VBAC rate.
NORMAL LABOR & DELIVERYDefinitions • Labor: progressive dilatation of the cervix in association with uterine contractions • Term : > 37 weeks gestation • Preterm: < 37 weeks gestation • 11% of all US births in 1997 • 80% of preterm births between 34 - 36 weeks • Preterm delivery < 35 weeks: 3.5%
Obstetrical Pelvic Exam • Dilation (dilatation): patency of the internal cervical os • 0 = “closed” • 10 cm = “complete” • Effacement: shortening of the cervical length • 0% = “thick” • 100% = “fully effaced”
Obstetrical Pelvic Exam • Station: level of presenting part (bony portion) in relation to the maternal ischial spines • Ischial spines = O station • Above spines: -5 to -1 • Below spines: +1 to +5
Obstetrical Pelvic Exam • Presentation: fetal part closet to pelvic inlet • vertex • brow • face • breech • shoulder • Position: relationship of particular point on the presenting part of the fetus and the vertical and horizontal planes of the maternal pelvis • Vertex: occiput for orientation • Breech: sacrum • Face: mentum
Vertex Parietal Brow Face
Obstetrical Pelvic Exam • Lie: relationship between the long axis of the fetus and the mother • Longitudinal • Transverse • Asynclitism: anterior or posterior parietal bone precedes the sagittal suture • Anterior • Posterior
Cardinal Movements of Labor • Engagement: descent of biparietal diameter to the level of the ischial spines (0 station) • Often occurs before onset of labor in nulliparous patients • Descent • Flexion: presenting diameters of fetal head presenting to maternal pelvis are optimized
Cardinal Movements of Labor • Internal rotation: fetal occiput rotates from transverse to AP • Extension: head rotates under symphysis pubis • External rotation (restitution): occiput and spine assume same position • Expulsion: fetal body delivers
NORMAL LABOR & DELIVERYStages of Labor • First stage: Onset of labor to full dilation (10m cm) • Second stage: Full cervical dilation to delivery of infant • Third stage: Delivery of infant to delivery of placenta • Fourth stage: First hour after birth
Ritgen Maneuver Erb’s palsey
NORMAL LABOR & DELIVERYPhases of Labor • Latent phase: onset of contractions until active phase • Active phase: 3 cm dilation in nulliparas; 4 cm dilation in multiparas to deceleration phase • Deceleration phase: 8 – 9 cm dilation to complete dilation
POST PARTUM HEMORRHAGE • Not a diagnosis but a consequence of an event • Atony of the uterus • Placenta problem • Laceration Defined as greater than 500 ml. Estimated as 5 % of vaginal births. Average EBL with C/S = 1000ml.
TREATMENT FOR PPH • Find the cause and treat promptly • Active management of the third stage • Med: Pitocin Cytotec Methergine Hemabate Repair lacerations promptly
Abnormal Latent Phase of Labor • > 20 hours in nulliparas • > 14 hours in multiparas • Treatment • Therapeutic rest • Morphine (10- 20 mg) • Hypnotic (Ambien) • 85% proceed into active phase of labor • 10% - no contractions • 5% - may need oxytocin
Primary Dysfunctional Labor Slow rate of dilation in the active phase of labor • < 1.2 cm/hr in nulliparas • < 1.5 cm/hr in multiparas
Disorders of the Active Phase • Secondary Arrest: cessation of previously normal rate of dilation for two hours • Combined Disorder: cessation of dilation when patient has previously exhibited a primary dysfunctional labor
Disorders of the Second Stage • Protracted Descent: • < 1 cm/hr in nulliparas • < 2 cm/hr in multiparas • Prolonged: • Nulliparas • With epidural – 3 hours • No epidural – 2 hours • Multiparas • With epidural – 2 hours • No epidural – 1 hour
Abnormalities of Labor THE 5 “P” • Passageway: maternal pelvis • Powers: uterine contractions • Passenger: fetus • Placenta: profusion • Psyche: mother’s readiness
Uterine Contractions • External tocodynamometry • Less accurate • 3-5 contractions/10 minutes • Internal tocodynamometry • Measures mm Hg • 180 – 220 Montevido units/10 minutes
INDUCTION OF LABOROxytocin • Peptide from posterior pituitary • Usually given IV; can be given IM • IV bolus = hypotension • 10 units/ml; dilute in 1000 cc LR • Routine dose: Start at 2mu/min, • 2 mu/min every 15-30 minutes to 36 IU/min • Active management of labor: start at 6 mu/min, by 6 mu/min every 15 minutes to 36 mu/min • High doses – ADH effect = water intoxication
INDUCTION OF LABORMisoprostol (Cytotec®) • PO tablet FDA approved to prevent gastric ulceration in patients taking NSAID’s • PGE1 • 25 mcg (1/4 of 100mcg tablet) in vagina Q 4 hours X 4 doses • Wait 6 hours after last dose to start oxytocin • Contraindicated with uterine eschar
NORMAL LABOR & DELIVERYFoley Bulb • Place special foley through cervix and inflate balloon to 30 cc • Tape to thigh – remove by 12 hours • Used when Cytotec contraindicated – uterine eschar • Mechanism: mechanical/local release of prostaglandins • Frequently used with pitocin
NORMAL LABOR & DELIVERYAnesthesia • Cesarean section • Spinal • Epidural • General (more risky in obstetrics) • Vaginal delivery • Local • Pudendal • Epidural • Combined spinal/epidural
NORMAL LABOR & DELIVERYLacerations • Cervical (use clock to describe location) • Vaginal (left or right) • Periurethrael • Clitoral • Perineal • 1st degree: skin only involved • 2nd degree: skin and subcutaneous tissue • 3rd degree: external rectal sphincter • 4th degree: rectal mucosa not intact
NORMAL LABOR & DELIVERYEpisiotomy • Types • Midline • Mediolateral • Proctoepisiotomy • Originally thought to protect perineum • Now thought to result in more 3rd and 4th degree extensions • More perineal pain • At UNC less that 3% of patients
First degree External sphincter External sphincter Second degree Third degree
NORMAL LABOR & DELIVERYCesarean Delivery • Skin incisions • Vertical • Pfannensteil • Uterine incisions • Low cervical transverse (Kerr) • Low vertical or “T” shaped • Classical
VBAC/Trial of Labor • One previous LUT incision (1% rate of rupture) • Two previous LUT incisions (2% rupture) • Unknown incision (up to 7% rupture) • Success of TOLAC = VBAC (vaginal birth after cesarean section): 60 – 80%
BREECH Complete breech Frank breech Incomplete breech