1. Physiology and Pathology of Uterine Contractions
Michael G. Halaška, M.D.
Department of Obstetrics and Gynaecology
of 2nd Medical Faculty

2. Physiology myometrium – smooth muscle enlargment of the muscle cells
basal tonus
first contractions from 20thweek of gravidity
Braxton-Hick contractions

3. Physiology

4. Montevid Units
Montevid Units – addition of amlitudes of contractions in 10 minutes
pacemaker – contraction wave – 2cm/s
amplitude of an contraction
1st stage – mm Hg
2nd stage – 80 mm Hg
closure of blood-vessels
veins : 20 mm Hg
artery: 60 mm Hg

5. Physiology basal tonus 10 mm Hg
1. stage of labour mm Hg MU
2. stage of labour mm Hg MU
resting time >30 s

6. Physiology
Proper shape of the contractions
1. stage
2. stage
3. stage

7. Physiology – starting factors
mechanical - ↑ pressure, ↓ volume
endocrine
estrogen - ↑ number of estro receptors,
↓ membrane potential, ↑ ATP in myocytes
oxytocine - ↓ membrane potential, ↑ PG
prostaglandins – preparing of cervix, contract.
neurogen
Fergusson reflex
Parasympaticus reflex

8. Recording the contractions
absolute – intrauterine
- intrauterine catheter
relative – external
- using piesoelectric
effect

9. Indications and contraindications
Type of sensor
Conditions
Indications
Contraindications
External
anytime
non-ivasive
as CTG
none
not recommended
- obesity
Internal
cervix dilatated at least 2-3 cm,
ruptured membranes,
tonus of the uterus
mostly scientific use
placenta praevia,
face presentation,
intraovulatory infection

10. Pathology hypertonus hyperactivity hypoactivity dystokia
failure of the abdominal muscle

11. Pathology hypertonus hyperactivity hypoactivity dystokia
failure of the abdominal muscle

12. Pathology - hypertonus
etiology: macrosomy, multiple pregnancy,
premature separation of placenta
pathophysiology: ↑ basal tonus - ↑blood in veins – hypoxy
clinics: palpable,
changes on CTG
treatment:
tocolysis

13. Pathology hypertonus hyperactivity hypoactivity dystokia
failure of the abdominal muscle

14. Pathology - hyperactivity
> 390 MU, >7 contrac/min, resting time <30 s
etiology: hypersensitivity, overstimulation of the uterus
clinics: CTG changes
therapy: less oxytocine, tocolysis

15. Pathology hypertonus hyperactivity hypoactivity dystokia
failure of the abdominal muscle

16. Pathology - hypoactivity
< 100 MU, < 30 mm Hg, < 2 contract/min
type: primary – from the beginning
secondary – during the labour
etiology: primary: hypoplasia of U., dystokia
secondary: prolonged labour, overstimulation by oxytocine, exhaustion of the mother
clinics: CTG, no postup of the labour
therapy: oxytocine, tocolysis, rest

17. Pathology hypertonus hyperactivity hypoactivity dystokia
failure of the abdominal muscle

18. Pathology - dystokia
etiology: hypertonus of the cervix, failure of pacemakers, exhaustion of uterus
clinics: CTG, no postup of the labour
therapy: tocolysis, S.C.

19. Pathology hypertonus hyperactivity hypoactivity dystokia
failure of the abdominal muscle

20. Pathology - failure of abd. muscle
etiology:
disease of the muscle or inervation
disease which unables higher activity ( heart, eyes .. )
epidural anesthesia
exhaustion of the mother
obesity
not cooperating mother
therapy: forceps, VEX, S.C.