19. Uterine activity during labor. Characteristics of contractions, their anomalies. Treatment.

Question 1

how is abnormal labor classified?

Answer 1

protraction disorders (slower than normal progress) or arrest disorders (complete cessation of progress).

Question 2

abnormal labor can be caused by?

Answer 2

the 3 P’s:
(1) Passenger (fetus) → abnormal lie, presentation, position, fetal structure, or size
(2) Pelvis (mother) → small/abnormal/suboptimal pelvic anatomy
(3) Power → ineffective uterine contractions

Question 3

what is an abnormal (prolonged) latent phase of labor?

Answer 3

Cervical dilation ≤ 6 cm after 20 h’ for nulliparous women or 14 h’ for multiparous women

Question 4

what causes a prolonged latent phase?

Answer 4

1. dysfunctional labor (hypertonic/hypotonic contractions)
2. premature or excessive use of sedatives or analgesics
3. fetal malposition
4. abnormal fetal size

Question 5

management of prolonged latent phase

Answer 5

1. if caused by premature or excessive use of sedation or analgesia–> usually resolves spontaneously after the effects of the medication worn off. Therapeutic rest with morphine maybe effective
2. Augmentation of labor by oxytocin-if a definitive diagnosis of prolonged latent phase has been made and there are medical reasons to accelerate delivery.
3. maybe Amniotomy or artificial rupture of the membranes

Question 6

what causes Protraction or arrest of the active phase?

Answer 6

the 3 P’s:

Question 7

what is protraction disorder of the active phase?

Answer 7

≥6 cm cervical dilation with progression rate of less than 1.2 cm/h’ (nulliparous women) and 1.5 cm/h’ (multiparous women)

Question 8

what is arrest of dilation?

Answer 8

If a period of 2 hours (or more) elapses during the active phase of labor without progress in cervical dilation

Question 9

management of abnormalities of the active phase of labor

Answer 9

• Augmentation with oxytocin for hypotonic contractions.
• Analgesia for hypertonic contractions.
• C-section for arrested active phase.

Question 10

Uterine contractile anatomy may be divided into?

Answer 10

upper part (actively contracting, thickening), and a lower part (passive, thinning).

Strenuous pushing may cause a visible retraction ring (Bandl’s ring)- between the upper and lower parts.

Question 11

what are hypertonic contractions?

Answer 11

Labor with uterine contractions of poor quality that
are painful, are out of proportion to their intensity,
do not cause cervical dilation or effacement, and are
usually uncoordinated and frequent.
↑ frequency, ↑ intensity of contractions, pain,
↓↓ effectiveness of contractions.

Question 12

when do hypertonic contractions occur?

Answer 12

during latent phase of labor.

Question 13

risk during hypertonic contractions?

Answer 13

of fetal distress

Question 14

what do we give in case of hypertonic contractions?

Answer 14

morphine

Question 15

what do we give in case of hypotonic contractions?

Answer 15

oxytocin

Question 16

what are the risks in hypotonic contractions?

Answer 16

infection, maternal exhaustion, bleeding

Question 17

when do hypotonic contractions occur?

Answer 17

during active phase of labor

Question 18

what are hypotonic contractions?

Answer 18

Occurs with abnormally slow progress after the labor
has been established. The uterine contractions become
weak and inefficient and may even stop.

↓ frequency, ↓ intensity of contractions,
no progression of labor.

Question 19

how is labor defined?

Answer 19

progressive cervical effacement and dilatation resulting from regular uterine contractions that occur at least every 5 minutes and last 30-60 seconds.

Question 20

criteria for normal labor

Answer 20

1. Spontaneous expulsion
2. Of a single
3. Mature fetus (37-42 weeks gestation)
4. Presented by vertex
5. Through the birth canal (vaginal delivery)
6. Within a reasonable time
7. With no maternal complications
8. With no fetal complications

Question 21

why does the cervix soften before the onset of parturition (phase 1)?

Answer 21

increased water content and collagen lysis (breakage of disulfide bonds, induced by prostaglandins).

Question 22

what is effacement (thinning of the cervix) ?

Answer 22

the internal os of the cervix is taken up into the lower uterine segment

As a result of cervical effacement, the mucous plug within the cervical canal may be released.
The onset of labor may thus be noted by the passage of a small amount of blood-tinged mucus from the vagina (‘bloody show’).