Parturition - Stages of labor

Question 1

Stages, end and beginning

Answer 1

• First stage
  
  • Starts with painful regular contractions (5 minutes apart for 1 hour, i.e. ≥ 12 contractions per hour)
  • Ends with cervical dilatation
• Second stage
  
  • Starts with 10 cm cervical dilatation
  • Ends with fetal delivery
• Third stage
  
  • Delivery of placenta and membranes

Question 2

Labor initiation is heralded by ____

Answer 2

Bloody show

Question 3

Contractions are painful possible because of:

Answer 3

1. Hypoxia to myometrium
2. Compression of the nerve ganglia
3. Cervical stretching during dilatation
4. Stretching of peritoneum overlying fundus

Question 4

What is the Ferguson reflex?

Answer 4

Mechanical stretching of the cervix enhances uterine activity

Question 5

T/F. The myometrium relaxes to its original length after contraction

Answer 5

False

Question 6

Explain the formation of physiologic retraction ring

Answer 6

• The upper uterine segment becomes progressively thickened throughout thr 1^st and 2^nd stage of labor
• The lower segment is thinning
  
  • Concommitant occurence causes physiologic retraction ring formation

Question 7

Explanation for the formation of pathological retraction ring (of Bandl)

Answer 7

Happens when the thinning of the lower uterine segment is extreme as in obstructed labor, the ring is prominent leading to formation of pathologic retraction ring

Question 8

Most important force in fetal expulsion

Answer 8

Pushing or maternal intraabdominal pressure

Question 9

Forces that cause cervical dilatation

Answer 9

• Centrifugal pull exerted on the cervix
• Hydrostatic action of the amniotic sac or presenting part (if membranes are present) dilates the cervical canal like a wedge

Question 10

The leading portion of fluid and amniotic sac located in front of the presenting part that is formed during the process of cervical effacement and dilatation

Answer 10

Forebag

Question 11

The pattern of cervical dilatation during preparatory and dilatational divisions of normal labor

Answer 11

Sigmoid

Question 12

Description of uterine contractions during the 2nd stage of labor

Answer 12

UC averages from 30-90 seconds, averaging around 1 minute, interval between contractions is around 1 minute or less

Question 13

____ curve is formed when the station of the fetal head is plotted as a function of labor duration

Answer 13

Hyperbolic

Question 14

Fetal and maternal structures used as references in measuring station

Answer 14

Fetal biparietal diameter in relation to a line drawn between maternal ischial spines

Question 15

Phase in the Friedman curve where increased rates of descent are observed in nulliparas

Answer 15

Phase of maximum slope

Question 16

Signs of placental separation (in order)

Answer 16

1. Uterus becomes globilar and firmer (Calkin’s sign)
2. Sudden gush of blood
3. Uterus rises in the abdomen
4. Lengthening of the cord

Question 17

How does blood ‘escape’ in Schultze vs Duncan mechanism?

Answer 17

• Schultze
  
  • blood from the placental site pours into the membrane sac and does not escape externally until after extrusion of the placenta
• Duncan
  
  • placenta separates first at the periphery and the blood collects between the membranes and the uterine wall and escapes from the vagina
  • Placenta descends sideways, maternal surface appears first