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Normal Labor and Delivery Midwifery Division Department of OB/GYN University of North Carolina School of Medicine OBJECTIVES • Define labor and its stages • Exam of the laboring woman and her fetus • Review the cardinal movements of labor and birth • Review Disorders of Labor • Induction of Labor • Other labor issues Define Labor and its Stages • Labor: progressive change of the cervix in the setting of uterine contractions • Term Labor: > 37 weeks gestation • Preterm Labor: < 37 weeks gestation – 11% of all US births in 1997 – 80% of preterm births between 34 - 36 weeks – Preterm delivery < 35 weeks: 3.5% Define Labor and its Stages • Stages of Labor • 1st stage – onset of labor until full cervical dilitation • 2nd stage – from full dilitation to birth of infant • 3rd stage – from birth of infant until delivery of placenta • 4th stage – 2 hours after the delivery of placenta Define labor and its Stages 1st stage and its phases • 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 Exam of the Laboring woman and her Fetus • Review of prenatal records and labs • Physical exam – 1. Vitals and routine physical exam – 2. Abdominal Exam • Palpation of contractions • Leopold’s maneuvers – 3. Pelvic Exam – 4. Fetal heart rate monitoring Review of Prenatal Records • Allergies • Medications • Past medical, surgical, obstetrical, gynecologic, social and family histories • Routine prenatal lab work • Complications of current or past pregnancies Abdominal Exam – 1. Palpation of contractions for duration and intensity – 2. Leopold’s maneuvers • To assess estimated fetal weight, fetal lie, presentation and position, attitude, and (a)synclitism NORMAL LABOR & DELIVERY Estimated Fetal Weight • Leopold’s maneuvers (palpation of the maternal abdomen) • Ultrasound estimate of fetal weight (error of 10 – 15%) • Maternal estimate of fetal weight (best) Fetal Lie • Lie: relationship between the long axis of the fetus and the mother Longitudinal – Transverse – Oblique – Fetal presentation • Presentation: fetal part closet to pelvic inlet – cephalic – breech – shoulder Fetal position • Position: relationship of fetal presenting part to the maternal pelvis – – – – – Occiput Brow Mentum Breech Shoulder Fetal Attitude • The relationship of the fetal parts to one another (i.e. flexion extension of head relative to body). Vertex Parietal Brow Face (A)synclitism • Synclitism is when the biparietal diameter of the fetal head is parallel to the planes of the maternal pelvis. Pelvic Exam • Pelvic Exam – sterile vaginal exam +/sterile speculum exam • Dilation • Effacement • Station • Also position of cervix and consistency important. 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 • Also includes same assessment included in Leopold’s maneuvers (fetal lie, presentation, position, etc.) Fetal Monitoring • Intermittent • Continuous Continuous Fetal Monitoring • Baseline rate • Variability • Presence of accelerations • Presence of decelerations • Changes or trends of FHR patterns over time • Contractions Fetal Heart Rate Baseline • 10 minute window • Duration: at least 2 minutes • Bradycardia: < 110 bpm • Tachycardia: > 170 bpm Fetal Monitoring (Variability) • Concept of short and long-term variability dropped • Absent: undetectable • Minimal: undetectable - < 5 bpm • Moderate: 6 - 25 bpm • Marked: > 25 bpm Fetal Monitoring (Accelerations) • Onset to peak: < 30 seconds • > 32 weeks: >15 bpm X >15 secs • < 32 weeks: > 10 bpm X > 10 secs • > 2 minutes in duration: prolonged • > 10 minutes in duration: change in baseline DECELERATIONS Fetal Monitoring (Variables) • Onset to nadir < 30 secs • > 15 bpm below baseline • Duration: > 15 seconds • < 2 minutes from onset to return to baseline DECELERATIONS Fetal Monitoring (Variables) Treatment • Pelvic exam (rule out prolapsed cord) • Maternal oxygen • Change maternal position • Stop pushing • Amnioinfusion Fetal Monitoring (Early Decelerations) • Onset to nadir > 30 secs • Coincident in timing with UC • Nadir occurring simultaneously with the peak of the contraction Fetal Monitoring (Late Decelerations) • Onset to nadir > 30 secs • Delayed in timing • Nadir occurring after the peak of the contraction • Reccuring can be ominous Fetal Monitoring (Late Decelerations) Treatment • Correct hypotension or other maternal conditions • Maternal oxygen • Scalp stimulation • Cesarean delivery if repetitive Uterine Contractions • External tocodynamometry • Internal tocodynamometry What’s going on in there? • The cardinal movements of labor are the mechanism by which the fetus moves progressively through the birth canal. Cardinal Movements of Labor – Occurring during first and second stages of labor 1. Engagement: descent of biparietal diameter to the level of the ischial spines (0 station) – Often occurs before onset of labor in nulliparous patients 2. Descent 3. Flexion: presenting diameters of fetal head presenting to maternal pelvis are optimized Cardinal Movements of Labor 4. Internal rotation: fetal occiput rotates from transverse to AP 5. Extension: head rotates under symphysis pubis 6. External rotation (restitution): occiput and spine assume same position 7. Expulsion: fetal body delivers 3rd and 4th stages • Delivery of placenta • Bonding, etc So what if it doesn’t happen like that? • Disorders of the 4 stages of labor Abnormalities of Labor THE 5 “P” • Passageway: maternal pelvis • Powers: uterine contractions • Passenger: fetus • Placenta: perfusion • Psyche: mother’s readiness 1st stage disorders Slow rate of dilation in the active phase of labor – < 1.2 cm/hr in nulliparas – < 1.5 cm/hr in multiparas • Abnormal latent phase • Abnormal Active phase 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 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 2nd stage disorders 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 Episiotomy Need for this now signifies an abnormality of second stage • 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 Forceps Assisted Vaginal Delivery • Outlet forceps: – Scalp visible at the introitus w/o parting the labia – Sagittal suture < 45 degrees • Low forceps: – Leading point of skull at +2 or below • < 45 degrees • > 45 degrees • Mid-forceps: – Head is engaged but presenting part is above +2 station – Rarely done NORMAL LABOR & DELIVERY Vacuum vs Forceps • Forceps – More maternal trauma – Minimal fetal trauma (bruising) • Vacuum – Less maternal trauma – Potential for increased fetal trauma (subgaleal bleeding) Mitivac vacuum Ritgen Maneuver Erb’s palsey 3rd stage disorders Retained placenta • Adherent • Accreta, etc POST PARTUM HEMORRHAGE Causes: – Atony of the uterus – Placenta problem – Laceration Defined as greater than 500 ml for vaginal birth 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 And now you want to do what? • Laceration repair NORMAL LABOR & DELIVERY Lacerations • • • • • Cervical (use clock to describe location) Vaginal (left or right) Periurethral Clitoral Perineal – – – – 1st degree: skin only involved 2nd degree: skin and subcutaneous tissue 3rd degree: external rectal sphincter 4th degree: rectal mucosa not intact First degree External sphincter Second degree External sphincter Third degree Disorders of 4th stage • Bonding • Delayed postpartum hemorrhage Induction of Labor – Why mess with a good thing? • Maternal or fetal medical indications • EGA • PROM/PPROM INDUCTION OF LABOR Bishop Score 0 1 2 3 Dilation Closed 1-2 3–4 >5 Effacement 0 – 30 40 – 50 60 – 70 > 80 Station -3 -2 -1 +1, +2 Consistency Firm Medium Soft Position Posterior Mid Anterior INDUCTION OF LABOR Oxytocin • • • • • 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 LABOR Misoprostol (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 & DELIVERY Foley Bulb • Place special foley through cervix and inflate balloon to 30 cc • Tape to thigh – remove by 12 hours • Used when Cytotec contraindicated – previous uterine incision • Mechanism: mechanical/local release of prostaglandins • Frequently used with pitocin Other things to consider • • • • • • Maternal pain relief GBS status Twins/Multiple Breech Caesarean delivery VBAC NORMAL LABOR & DELIVERY Anesthesia/Analgesia • Cesarean section – Spinal – Epidural – General (more risky in obstetrics) • Vaginal delivery – IV pain meds – – – – Local Pudendal Epidural Combined spinal/epidural Pudendal Block GBS Protocol • Routine culture at 35-37 weeks • Culture lower 1/4 vaginal and perianal area • Culture stable up to 96 hours in Amies transport media • If patient allergic to penicillin, get susceptibility testing GBS Epidemiology • 10-30% of pregnant women colonized • Vertical transmission may occur • Neonatal invasive GBS infection decreased 21% from 1993 to 1998. • In 2000 rate was .23 per 1000 live births • Early onset infection – Antibiotics in labor will reduce – Prevents 225 newborn deaths per year • Late onset infection Multiple Gestation • Twins – Vertex/vertex – vaginal delivery – Vertex/breech or transverse lie – breech extraction of 2nd twin – Breech/other – C-section (locked twins) • Triplets or higher order gestation – Cesarean delivery indicated NORMAL LABOR & DELIVERY Breech Presentation • 37 weeks gestation – external cephalic version (50% success) – Ultrasound – – – – Non-stress test IV/subcutaneous terbutaline for tocolysis Ultrasound monitoring Repeat non-stress test • Cesarean section vs. vaginal birth BREECH Frank breech Complete breech Incomplete breech NORMAL LABOR & DELIVERY Cesarean Delivery Other 14% Breech 12% Fetal Distress 9% Repeat C/S 35% Dystocia 30% VBAC/Trial of Labor • One previous LTCS (1% rate of rupture) • Two previous LTCS (2% rupture) • Unknown incision (up to 7% rupture) • Success of TOLAC = VBAC (vaginal birth after cesarean section): 60 – 80% USA TRENDS