Week 3: Normal and abnormal labor

Question 1

3 Ps of labor: Power

Answer 1

• force of uterine contractions: frequency, duration, amplitude
• measured in Montevideo units=avg. amplitude of contractions x # in 10 mins. (>200 is adequate)
• measured directly by Intrauterine pressure catheter (IUPC)
• can be measured indirectly by observation, palpation, external tocodynomometry

Question 2

3 Ps of labor: passenger

Answer 2

1. fetal size: measured by palpation or ultrasound. Concern for large fetus
2. lie: longitudinal axis of fetus relative to longitudinal axis of maternal spine-longitudinal or transverse (back down)
3. presentation: fetal part overlying pelvic inlet
   - cephalic (nl, occiput), breech (butt down), shoulder
   - funic: umbilical cord at inlet
   - compound: more than 1 fetal part over inlet
4. attitude: position of head, degree of flexion or extension. Nl=flexed (short head diameter)
5. position: relationship of fetal occipital to maternal sacrum
6. Station: measure of descent of presenting part of fetus through birth canal relative to ischial spines.

Question 3

3 Ps of labor: pelvis

Answer 3

1. Pelvic types
   - gynecoid: ideal, wide as it is deep
   - anthropoid: deep but narrow
   - platypelloid: wide but shallow
2. Clinical pelvimetry
   - assessment of adequacy of pelvis, measures pelvic inlet, mid pelvis, pelvic outlet
   - poor predictor of vaginal delivery
   - better predictor is hx of vaginal birth

Question 4

Define labor

Answer 4

• uterine contractions that result in cervical change
• Braxton-Hicks contractions=”false labor”, contractions not assoc. with cervical change
• cervical insufficiency: cervical dilation without contractions
• cervix: change in diameter and effacement is estimated

Question 5

List the stages of labor

Answer 5

1. Onset of labor until complete cervical dilatation
2. Complete cervical dilatation to expulsion of fetus
3. expulsion of fetus to expulsion of placenta

Question 6

First stage of labor

Answer 6

1. latent phase: early labor, onset of labor to onset of active phase
   - avg. 6.4 hrs for nullipara, 4.8 hrs for multipara
   - variable. Abn. if > 20 hrs for nullipara, and >14 hrs for multipara
2. Active phase: greater rate of cervical dilation, usually begins after 5-6 cm dilation
   - avg. 4.6 hrs nullipara, 2.4 multipara
   - protracted: slowed dilation rate
   - arrested: if >6cm dilated, but no cervical change for more than 4 hours or 6 hrs (w/ pitocin). Rx: amniotomy, pitocin, C-section

Question 7

2nd stage of labor: from active dilatation to expulsion of fetus

Answer 7

1. Normal
   - mean duration: 66 min nullipara, 20 min multipara
2. protracted
   - nullipara: 4 hrs with epidural, 3 hors without
   - multipara: 3 hrs with epidural, 2 hrs without
   - Rx: pitocin, amniotomy, support, positional changes, operative vaginal delivery, C-section
3. Precipitous labor
   - less than 15 mins

Question 8

3rd stage of labor

Answer 8

-delivery of placenta and membranes
Duration
-normal duration: < 5 mins
-abn: more than 30 mins