PRIMARY UTERINE INERTIA
The failure of the myometrium to ever establish a contractile pattern adequate to
expel neonates from the uterus
Cause: unknown. There could be a genetic predisposition to primary inertia, as it has been
documented in related bitches.
Incidence Rate:
Predisposing Factors
Over-distension of the uterus in certain conditions is associated with weak
pains.
Premature rupture of the membranes is undoubtedly associated with a high
percentage of cases of inertia, but it cannot be cited as a cause when artificial
rupture of the membranes is used as a means of inducing labor.
Malpresentations, such as persistent occipito-posterior positions, are common,
but the non-rotation of the occiput is probably the result of the inertia and not the
cause of it.
Hormnones.-Ther6leplayedbytheseisuncertain. Extract of the posterior lobe of
the pituitary gland stimulates contraction of uterine muscle, and cestrin under
experimental conditions sensitizes the uterine muscle to this substance, but there
is no evidence that any hormonic disturbance is responsible for inertia, although
it is possible that fear, with the liberation of adrenalin, may inhibit uterine
contraction.
Mechanical interference with dilatation of the cervix by fibrosis has been
suggested as a cause of the rigid cervix. Mr. Aleck Bourne and myself have had
sections cut of many rigid, as well as of many normal, cervices and can find little
evidence in support of this.
All that we know as to the cause of inertia is the clinical observation that the
majority of cases occur in women in their first confinement, and that the nervous
type of woman isespecially liable to this complication.
2 TYPES
HYPOTONIC UTERINE INERTIA
Definition
The uterine contractions are infrequent, weak and of short duration.
Etiology
x:
General factors:
o Primigravida particularly elderly.
o Anemia and asthenia.
o Nervous and emotional as anxiety and fear.
o Hormonal due to deficient prostaglandins or oxytocin as in induced labor.
o Improper use of analgesics.
Local factors:
o Overdistension of the uterus.
o Developmental anomalies of the uterus e.g. hypoplasia.
o Myomas of the uterus interfering mechanically with contractions.
o Malpresentations, malposition and cephalopelvic disproportion. The presenting
part is not fitting in the lower uterine segment leading to absence of reflex uterine
contractions.
o Full bladder and rectum.
Types
Primary inertia: weak uterine contractions from the start.
Secondary inertia: inertia developed after a period of good uterine contractions when it
failed to overcome an obstruction so the uterus is exhausted.
Signs and Symptoms
Labor is prolonged.
Uterine contractions are infrequent, weak and of short duration.
Slow cervical dilatation.
Membranes are usually intact.
The fetus and mother are usually not affected apart from maternal anxiety due to
prolonged labor.
More susceptibility for retained placenta and postpartum hemorrhage due to persistent
inertia.
Topography: shows infrequent waves of contractions with low amplitude.
Diagnosis
Tocodynamometry
Management
Medical Management:
o Examination to detect disproportion, malpresentation or malposition and manage
according to the case.
o Prophylactic antibiotics in prolonged labor particularly if the membranes are
ruptured.
o Oxytocin:
Providing that there is no contraindication for it, 5 units of oxytocin
(syntocinon) in 500 cc glucose 5% is given by IV infusion starting with 10
drops per minute and increasing gradually to get a uterine contraction
rate of 3 per 10 minutes.
Surgical Management
o Amniotomy:
o Providing that;
vaginal delivery is amenable,
the cervix is more than 3 cm dilatation and
the presenting part occupying well the lower uterine segment.
o Artificial rupture of membranes augments the uterine contractions by:
release of prostaglandins.
reflex stimulation of uterine contractions when the presenting part is
brought closer to the lower uterine segment.
o Vaginal delivery: by forceps, vacuum or breech extraction according to the
presenting part and its level providing that,
cervix is fully dilated.
vaginal delivery is amenable.
o Caesarean section is indicated in:
failure of the previous methods.
contraindications to oxytocin infuCOsion including disproportion.
fetal distress before full cervical dilatation.
Nursing Responsibilities
Assess uterine contractile pattern manually (palpation) or electronically via external,
or internal monitor with internal uterine pressure catheter (IUPC)
In the first hour after birth following a labor of hypotonic contractions, palpate the
uterus and assess the lochia every 15 minutes to ensure that there are no postpartal
hypotonic contractions and inadequate to halt bleeding.
Encourage nipple stimulation to produce endogenous oxytocin or initiate infusion of
exogenous oxytocin (Pitocin) or prostaglandins.
HYPERTONIC UTERINE INERTIA (Uncoordinated Uterine Action)
Types
Colicky uterus: incoordination of the different parts of the uterus in contractions.
Hyperactive lower uterine segment: so the dominance of the upper segment is lost.
Signs and Symptoms
The condition is more common in primigravidae and characterized by:
Labor is prolonged.
Uterine contractions are irregular and more painful. The pain is felt before and
throughout the contractions with marked low backache often in occipito-posterior
position.
High resting intrauterine pressure in between uterine contractions detected by
topography (normal value is 5-10 mmHg).
Slow cervical dilatation .
Premature rupture of membranes.
Fetal and maternal distress.
Management
Medical Management
o Administer analgesic and antispasmodic as pethidine.
o Epidural analgesia may be of good benefit.
Surgical Management
o Caesarean section is indicated in:
Failure of the previous methods.
Disproportion.
oetal distress before full cervical dilatation.
Nursing Responsibilities
Encourage bed rest to promote relaxation and reduce pain
Evaluate fetal tolerance to labor pattern
Asses for signs of maternal infection
Rule out disproportion and fetal malpresentation
Explain to woman/family about dysfunctional pattern
Mortality Rate: fetal death rate 40% and the maternal death-rate10%
https://www.gfmer.ch/Obstetrics_simplified/abnormal_uterine_action.htm
https://journals.sagepub.com/doi/pdf/10.1177/003591573302601201
