Transcript Physiology and Pathology of Uterine Contractions

Physiology and Pathology of
Uterine Contractions
Michael G. Halaška, M.D.
Department of Obstetrics and Gynaecology
of 2nd Medical Faculty
Physiology
myometrium – smooth muscle
enlargment of the muscle cells
basal tonus
first contractions from 20thweek of gravidity
Braxton-Hick contractions
Physiology
Montevid Units
Montevid Units – addition of amlitudes of
contractions in 10 minutes
pacemaker – contraction wave – 2cm/s
amplitude of an contraction
1st stage – 40-60 mm Hg
 2nd stage – 80 mm Hg

closure of blood-vessels
veins : 20 mm Hg
 artery: 60 mm Hg

Physiology
basal tonus 10 mm Hg
1. stage of labour 30-40 mm Hg - 120 MU
2. stage of labour 50-60 mm Hg - 250 MU
resting time >30 s
Physiology
Proper shape of the contractions

1. stage

2. stage

3. stage
Physiology – starting factors
mechanical - ↑ pressure, ↓ volume
2. endocrine
1.



3.
estrogen - ↑ number of estro receptors,
↓ membrane potential, ↑ ATP in myocytes
oxytocine - ↓ membrane potential, ↑ PG
prostaglandins – preparing of cervix, contract.
neurogen


Fergusson reflex
Parasympaticus reflex
Recording the contractions
absolute – intrauterine
- intrauterine catheter
relative – external
- using piesoelectric
effect
Indications and contraindications
Type of
sensor
Conditions
Indications
Contraindicatio
ns
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
Pathology
1.
2.
3.
4.
5.
hypertonus
hyperactivity
hypoactivity
dystokia
failure of the abdominal muscle
Pathology
1.
2.
3.
4.
5.
hypertonus
hyperactivity
hypoactivity
dystokia
failure of the abdominal muscle
Pathology - hypertonus
etiology: macrosomy, multiple pregnancy,
premature separation of placenta
pathophysiology: ↑ basal tonus - ↑blood in
veins – hypoxy
clinics: palpable,
changes on CTG
treatment:
tocolysis
Pathology
1.
2.
3.
4.
5.
hypertonus
hyperactivity
hypoactivity
dystokia
failure of the abdominal muscle
Pathology - hyperactivity
> 390 MU, >7 contrac/min, resting time <30 s
etiology: hypersensitivity, overstimulation of
the uterus
clinics: CTG changes
therapy: less oxytocine, tocolysis
Pathology
1.
2.
3.
4.
5.
hypertonus
hyperactivity
hypoactivity
dystokia
failure of the abdominal muscle
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
Pathology
1.
2.
3.
4.
5.
hypertonus
hyperactivity
hypoactivity
dystokia
failure of the abdominal muscle
Pathology - dystokia
etiology: hypertonus of the cervix, failure of
pacemakers, exhaustion of uterus
clinics: CTG, no postup of the labour
therapy: tocolysis, S.C.
Pathology
1.
2.
3.
4.
5.
hypertonus
hyperactivity
hypoactivity
dystokia
failure of the abdominal muscle
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.