Normal Labor and Delivery Bridgett Casadaban July 25, 2007

Definitions Labor – Uterine contractions that result in effacement and dilatation of the cervix. Braxton-Hicks – Uterine contractions NOT associated with cervical change. Shorter in duration Less intense Over lower abdomen and groin Resolve with ambulation Lightening – Descent of the fetal head into the pelvis Lightening – easier time breathing. Occurs earlier for G0.

Definitions Preterm labor – Prior to 37 weeks Term – 37 to 42 weeks Post term – After 42 weeks Post dates – After 40 weeks

UVA Labor and Delivery 22yo G2P1 at 39 wks comes into L&D complaining of RUC’s q5 minutes x 2 hours. Diana has hooked the patient up to the monitor and brings the patient’s chart to you to further evaluate the patient. What to do next?

UVA Labor and Delivery Talk with the patient Confirm ctx history LOF? Vaginal bleeding? Feeling baby move? Desires an epidural? Distance from home to hospital? GBS status? q5 minutes x 2 hours Yes No No

UVA Labor and Delivery Examine patient Rule out rupture Check cervix Negative pooling, nitrazine, ferning 2/50/-1

UVA Labor and Delivery Formulate a plan You decide to allow the patient to walk around the hospital for 2 hours then return for a cervical check. What steps must you take next before the patient can leave L&D? *Ultrasound to confirm fetal presentation *Confirm a reactive/reassuring strip

UVA Labor and Delivery Patient returns in 2 hours with continued, uncomfortable ctx’s q5 minutes. Now what? Recheck cervix 5/90/0 Now what?

UVA Labor and Delivery Admit patient to Labor and Delivery Complete H&P *Obtain EFW by Leopold’s Consents signed for delivery and potential blood transfusion Orders entered into MIS Clear diet IVF’s T&S/CBC GBS prophylaxis? Continuous EFM vs. intermittent Intermittent = FHTs q 30 min to include a ctx and immediately after Membranes intact or SROM and well-engaged Continuous NRFHTs, SROM and poorly engaged, augmented labor, epidural?

UVA Labor and Delivery In order to maximize the patient’s chance at a vaginal delivery it is important to understand the basics of labor and delivery: Stages of labor Mechanics of labor Cardinal movements of labor Delivery

Stages of Labor 1st Stage Interval between onset of labor and full cervical dilatation 2 phases: Latent – period between onset of labor and point at which a change in slope of rate of cervical dilatation is noted. Active – Greater rate of cervical dilatation and usually begins around 2-3cm

Stages of Labor 2nd stage 3rd stage Interval between full cervical dilatation and delivery Duration Nulliparous – 3 hrs w/ epidural; 2 hrs w/o epidural Multiparous – 2 hrs w/ epidural; 1 hr w/o epidural 3rd stage Delivery of the placenta and membranes Duration – maximum of 30 minutes

Normal Labor and Delivery In order to maximize the patient’s chance at a vaginal delivery it is important to understand the basics of labor and delivery: Stages of labor Mechanics of labor Cardinal movements of labor Delivery

Mechanics of Labor The Powers Forces generated by uterine musculature Frequency, amplitude, and duration of ctx’s Observation, manual palpation, tocodynamometry, intrauterine pressure catheter (IUPC) Measured in Montevideo units Average strength of ctx’s (mmHG) x no. of ctx’s in 10 minutes Adequate 200-250 MVUs External monitoring - measure the change in shape of the abdominal wall as a fxn of uterine contractions, therefore qualitative rahter than quantitative. Allows accurate correlation of FHT pattern with uteirne activity, does not allow measurement of ctx intensity or basal intrauterine tone. IUPC - Most precise. Come at a cost—require membrane rupture, risk of uterine perforation, infection

Mechanics of Labor Passenger Fetal size Lie Presentation Abdominal palpation or Ultrasound Macrosomia (>4500g) associated w/ failure to progress Lie Longitudinal axis of fetus relative to longitudinal axis of uterus Longitudinal*, transverse or oblique Presentation Fetal part that directly overlies pelvic inlet Cephalic, breech, or shoulder Compound – presence of >1 fetal part overlying the pelvic inlet Funic – umbilical cord presenting at pelvic inlet Malpresentation – any presentation that is not cephalic with occiput leading Fetal size calculations subject to large degree of error Malpresentaiton – 5% of term labors

Mechanics of Labor Passenger (cont) Attitude Position Position of head with regard to fetal spine (ie: degree of flexion or extension) Flexion allows smallest diameter of fetal head to present at pelvic inlet Position Relationship of a nominated site of presenting part to denominating location on internal pelvis Example: cephalic presentation Position – cephalic presentation, nominated site is the occiput. Breech presentation, nominated site is the sacrum Malposition = any position NOT ROA, OA, or LOA

Mechanics of Labor

Mechanics of Labor Passenger (cont.) Station Multifetal Pregnancy Measure of descent of presenting part of the fetus through the birth canal. Multifetal Pregnancy Increase probability of abnormal lie and malpresentation in labor Station – ischial spines mark mid-point (0 station)

Mechanics of Labor Passenger (cont.) Leopold’s maneuvers #1 – Correct dextrorotation of the uterus with the back of one hand and delineate the fundus with the other to determine gestational age and/or appropriate size. #2 – Run hands down maternal abdomen on either side of fetus to determine fetal lie, identifying small parts and fetal spine #3 – Firmly grasp upper and lower poles of fetus by placing fingers at uterine fundus and above symphysis to determine presentation and fetal size. #4 – Move hands in bilaterally from anterior superior iliac crests to determine whether or not the presenting part of the fetus is engaged in maternal pelvis. Head regarded as unengaged if examiner’s hands are see to converge below fetal head. #1 - Dextrorotated b/c of sigmoid colon position #3 -Breech is oftern larger, softer, less well defined

Mechanics of Labor Passenger (cont.)

Mechanics of Labor Passage Bony pelvis + soft tissues X-ray pelvimetry now rarely used, having been replaced by a trial of labor 4 types of the female bony pelvis Bony pelvis = sacrum, ilium, ischium, and pubis Soft Tissue = 1st stage of labor  cervix 2nd stage of labor  pelvic floor muscles Gynecoid – preferred; oval shaped, far-space ischial spines Anthropoid – exaggerated oval shape to the inelt with alrgest diameter being A-P. More often associated w/ occiput deliveries. Android – male pattern, heart-shaped, prominent sacral promonitory and ischial spines. Increased risk of CPD. Platypelloid – Broad, flat, exaggerated oval-shaped inlet

Normal Labor and Delivery In order to maximize the patient’s chance at a vaginal delivery it is important to understand the basics of labor and delivery: Stages of labor Mechanics of labor Cardinal movements of labor Delivery

Cardinal Movements of Labor Engagement Passage of widest diameter of presenting part to level below the plane of the pelvic inlet 0 station Occurs earlier in nulliparous women (36 wks) Descent Downward passage of presenting part through the pelvis. Flexion Occurs passively as the head descends due to the shape of the bony pelvis and resistance of pelvic floor soft tissues Allows smallest diameter of fetal head to pass through the pelvis.

Cardinal Movements of Labor Internal Rotation Rotation of presenting part from original position (transverse) to anteroposterior position Extension Occurs once fetus has descended to the level of the introitus Base of occiput in contact with inferior margin of symphysis pubis External Rotation Return of fetal head to correct anatomic position in relation to the fetal torso Expulsion Delivery of rest of fetus Anterior shoulder delivered first with rotation under the symphysis pubis

Cardinal Movements of Labor

Normal Labor and Delivery In order to maximize the patient’s chance at a vaginal delivery it is important to understand the basics of labor and delivery: Stages of labor Mechanics of labor Cardinal movements of labor Delivery

How to effectively deliver a baby Prepare for the delivery taking into account parity, progression of labor, presentation of fetus, complications of labor When head crowns and delivery is eminent, protect the perineum + downward pressure to keep head flexed Ritgen’s maneuver my help if delay in delivery of the fetal head Sterile towel used to palpate fetal chin through the rectum to apply upward pressure to facilitate extension of fetal head After delivery of head Allow for external rotation (restitution). Reduce nuchal cord Suction fetal mouth and nares After clearing fetal airway Place a hand on each parietal eminence to apply downward traction to deliver anterior shoulder Followed by upward traction to deliver posterior shoulder With traction, avoid perineal injury and brachial plexus

How to effectively deliver a baby After complete delivery of infant Cradle in a single arm below the perineum to allow maximal blood transfer to infant Delivery of the placenta 3 classic signs of placental separation: Lengthening of the umbilical cord Gush of blood from vagina Change in shape of the uterine fundus to a more globular appearance Active management of 3rd stage has been shown to reduce total blood loss Brandt-Andrews Maneuver: abdominal hand secures the uterine fundus to prevent uterine inversion while the other hand exerts sustained downward traction on umbilical cord Crede maneuver – cord is fixed with lower hand while the uterine fundus is secured and sustained upward traction is applied using abdominal hand

How to effectively deliver a baby Inspect the placenta Abnormalities of lobulation Site of insertion of umbilical cord into the placenta Marginal insertion –inserts into edge of placenta Membranous insertion – vessels course through the membranes prior to attaching to placental disk Length (50-60cm) 2 arteries and 1 vein Single umbilical artery associated with 20% risk of other structural anomalies.