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Abnormal uterine action Prepared by :
Nirsuba GurungAssistant Lecturer
MSON
Normal uterine action Normal labour is characterized by coordinated uterine contractions(interval
gradually shortens and intensity gradually increases)
associated with progressive dilatation of the cervix (Normal labour is associated with cervical dilatation ≥ 1cm \ hour in a nulliparous woman )
descent of the fetal head.
Polarity of uterus: When upper pole contracts lower pole relax
Pacemakers : Two pace makers are situated at each cornua of the uterus generating contraction in co-ordinated manner
Pattern of contraction : uterine contraction starts at cornua and propagate towards lower uterine segment with decrease in duration and intensity as it moves away from the pacemaker
Parameter of uterine action Basal tone : 5- 20 mm Hg Peak pressure : 60 -80 mm Hg Frequency of contraction :adequate
uterine contractions are 1 in every 3 mints lasting for about 45 sec with good relaxation in between
Assessment of contraction Abdominal palpation
Tocodynamometer :with the help of external trasducers
Intrauterine pressure catheter
Abnormal uterine action Any deviation of the normal pattern of
uterine contractions affecting the course of labour is designated as disordered or abnormal uterine action.
Overall labour abnormalities occur in about 25% of the nulliparous women
and 10% of multiparous women.
Classification of abnormal uterine activity Inefficient uterine activity
Hypoactive states/uterine inertia Hyperactive, incoordinate states
Hyperactive lower uterine segment Colicky uterus Constriction ring
Cervical dystocia Overefficient uterine activity
Precipitate labour Tetanic uterine activity
ETIOLOGY Prevalent in primi with advancing age of the mother Prolonged pregnancy Over distension of the uterus due to twins and or
ployhydramnios Psychologic factor Contracted pelvis, malpresentation and deflexed
head. All these lead to ill fitting of the presenting part into the lower uterine segment. This probably results in inhibition of the local reflex which is needed to produce effective contraction of the upper segment.
Full bladder and loaded rectum reflexly inhibit uterine contraction
Injudicious administration of sedatives, analgesics and oxytocics
Premature attempt at vaginal delivery or attempted instrumental vaginal delivery under light anaesthesia.
Uterine inertia Weak ,infrequent ,inefficient uterine
action Uterine contraction: the intensity is
diminished; duration is shortened; good relaxation in between contractions and the intervals are increased. General pattern of uterine contractions of labour is maintained but intrauterine pressure during contraction hardly rises above 25mm Hg
Etiology Elderly primi Anemia or other chronic illnes Hypertensive state in pregnancy Overdistension of uterus such as in twin or
polyhydraminous Malpresentation and malposition Full bladder Uterine fibroid Premature induction of labour
Types Primary inertia :weak uterine
contrations from the begining Secondary inertia :interia developed
after a period of good contraction probably as the result of contracted pelvis as protective mechanism .
Sign and symptom 1.Patient feels less pain and discomfort
during uterine contraction2.Hand placed over the uterus during
uterine contraction not only reveals hardening of the uterus before the patient feels pain but the contraction also outlasts the pain.
3.Uterine wall is easily indentable at the acme of a pain.
4.Uterus becomes relaxed after the contraction; fetal parts are well palpable and fetal hearts rate remains good.
Diagnosis Internal examination reveals; Poor dilatation of the cervix Membranes usually remain
intactCervix well applied to the
presenting part Associated presence of
contracted pelvis, malposition, deflexed head or malpresentation may be evident.
Complication Effect on mother:
Prolonged laborMaternal distress, dehydration
and psychological depressionIncreased risk for infection Increased risk of PPHSubinvolution
Fetal complication Fetal distress if membrane
ruptures early
Management Careful evaluation of the case is to
be done: To be sure that the patient is in
true labourTo exclude cephalopelvic
disproportion or malpresentationTo plan out the management
protocol
Detected in first stage:Place of caesarean section:
Presence of contracted pelvisMalpresentationEvidences of fetal or maternal
distress
Vaginal delivery General measures:
To keep up the morale of the patient To empty the bowel by enema and
bladder by encouraging the patient to empty at intervals, failing which catheterization is to be done
To maintain nourishment by infusion of 5% dextrose
Adequate sedation is ensured by intramuscular Pethidine 100 mg
Active measures Acceleration of uterine contraction can be
brought about by low rupture of the membranes followed by Oxytocin drip if not contraindicated. An infusion of 2 unit of Oxytocin dissolved in 500ml 5% dextrose is started. The drip rate should be slow at first and is to be gradually increased until effective contractions are set up. Close watch of the maternal and fetal conditions and nature of uterine contractions is mandatory. The drip is to be continued till 1 hour after delivery; if, however, cervical dilatation remains unsatisfactory and \ or fetal distress appears, Caesarean section is the best alternative.
Detected in second stage If the case is first seen at this
stage, careful evaluation of the case is to be done to exclude contracted pelvis, malpresentation and to determine station of the head in relation to ischial spines and fetal condition.
Place of caesarean section In presence of contracted
pelvis or malpresentation where vaginal delivery is found unsafe and fetal condition remains good, caesarean section may be preferred even at this stage.
Vaginal delivery Head low down – Forceps or ventouse
deliveryHead not sufficiently low down
· Stimulation of uterine contraction by oxytocin drip or
Ventouse extraction. Difficult forceps should be avoided
Craniotomy – If the baby is dead
Third stage
Active management of the third stage is advocated
HYPERTONIC UTERINE ACTION It is defined as either a series of
single contractions lasting 2 minutes or more or a contraction frequency of five or more in 10 minutes.Uterine hyperstimulation may result in fetal heart rate abnormalities, uterine rupture, or placental abruption
Example Spastic lower uterine segment Colicky uterus Asymmetrical uterine contraction Constriction ring Generalised tonic contraction
All these states are collectively called as incordinate uterine action
Inco-ordinate uterine actionStrong and painful uterine
contractionHigh frequency Slow cervical dilatation Two pole of uterus doesn’t
functions rhythmically
Clinical feature Labour 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 tocography (normal value is 5-10 mmHg).
Slow cervical dilatation . Premature rupture of membranes. Foetal and maternal distress.
Management CPD- C/SVital monitoring I/V therapy I/O charting FSH every 15 min PartographFetal distress-C/S
Colicky uterus Various parts of uterus contracts
independently
Hyperactive lower uterine segment Fundal gradient is lost , reverse gradient
of the uterine activity starts from the lower uterine segment goes toward fundus and cervix
CONSTRICTION (CONTRACTION) RING It is a persistent localised annular spasm
of the circular uterine muscles. It occurs at any part of the uterus but
usually at junction of the upper and lower uterine segments.
It can occur at the 1st, 2nd or 3 rd stage of labour.
AetiologyUnknown but the predisposing factors are: Malpresentations and malpositions. Premature rupture of membrane Premature attempt of instrumental
delivery Intrauterine manipulations under light
anaesthesia. Improper use of oxytocin e.g.
use of oxytocin in hypertonic inertia. IM injection of oxytocin.
Diagnosis The condition is more common in primigravidae
and frequently preceded by colicky uterus. The exact diagnosis is achieved only by feeling the
ring with a hand introduced into the uterine cavity.
Complications Prolonged 1st stage: if the ring occurs at the level
of the internal os. Prolonged 2nd stage: if the ring occurs around the
foetal neck. Retained placenta and postpartum haemorrhage:
if the ring occurs in the 3rd stage (hour- glass contraction).
Management Exclude malpresentations, malposition and
disproportion. In the 1st stage: Pethidine morphine may be of
beneficial . In the 2nd stage: Deep general anaesthesia and
amyl nitrite inhalation are given to relax the constriction ring: If the ring is relaxed, the foetus is delivered
immediately by forceps. If the ring does not relax, caesarean section is
carried out with lower segment vertical incision to divide the ring.
In the 3rd stage: Deep general anaesthesia and amyl nitrite inhalation are given followed by manual removal of the placenta
Pathological Retraction Ring (Bandl’s ring)Physiological Retraction Ring It is a line of demarcation between the upper
and lower uterine segment present during normal labour and cannot usually be felt abdominally.
Pathological Retraction Ring (Bandl’s ring) It is the rising up retraction ring during
obstructed labour due to marked retraction and thickening of the upper uterine segment while the relatively passive lower segment is markedly stretched and thinned to accommodate the foetus.
The Bandl’s ring is seen and felt abdominally as a transverse groove that may rise to or above the umbilicus.Clinical picture: is that of obstructed labour with impending rupture uterus (see later).Obstructed labour should be properly treated otherwise the thinned lower uterine segment will rupture.
DIFFERENCE BETWEEN CONSTRICTION RING AND
RETRACTION RINGCONSTRICTION RING RETRACTION RING
Nature It is a manifestation of localised inco-ordinated uterine contraction.
It is an end result of tonic uterine contraction and retraction
Cause Undue irritability of the uterus. Following obstructed labour
Situation Usually at the junction of upper and lower segment but may occur in other places. The position does not alter.
At the junction of upper and lower segment. The position progressively moves upwards
Uterus Upper segment contracts and retracts with relaxation in between lower segment remains thick and loose.
Upper segment is tonically contracted with no relaxationThe wall becomes thicker, lower segment becomes distended and thinned out
Maternal condition
Almost unaffected unless the labour is prolonged
Maternal exhaustion, sepsis appear early
Abdominal Examination
oUterus feels normal and not tenderoFetal parts are easily feltoFHS is usually felt
o Uterus is tense and tendero Not easily felto Ring is felt as a groove placed obliquely
Vaginal examination
o The lower segment is not pressed by the presenting parto Ring is felt usually above the heado Features of obstructed labour are absent
o Lower segment is very much pressed by the forcibly driven presenting parto Ring cannot be felt vaginallyo Features are present
End result o Maternal exhaustion is a late featureo Fetal anoxia usually appear lateo Chance of uterine rupture is absent
o Maternal exhaustion and sepsis appear earlyo Fetal anoxia and even death are usually earlyo Rupture uterus in multi gravidae is common
Clinical feature Mother becomes tired and restless due to continue
pain and discomfort Features of maternal distress and keto-acidosis Abdominal palpation
Upper segment hard ,uniformly convex and tender
Retraction ring obliquely placed between umblicus and symphysis pubis
Fetal part may not be well defined FHS usually absent
Vaginal examination Dry hot vagina with offensive discharge Cervix fully dilated Causes of obstruction is revealed
Management Provide supportive therapy
Analgesic and sedation Hydration Prophylactic antibiotic
Definitive treatment Destructive surgery if fetus is dead Fetus alive-C/S
CERVICAL DYSTOCIADefinition
Failure of the cervix to dilate within a reasonable time in spite of good regular uterine contractions.
Types Organic (secondary) due to:
Cervical stances as a sequel to previous amputation, cone biopsy, extensive cauterisation or obstetric trauma.
Organic lesions as cervical myoma or carcinoma. Functional (primary):
In spite of the absence of any organic lesion and the well effacement of the cervix, the external os fails to dilate.
This may be due to lack of softening of the cervix during pregnancy or cervical spasm resulted from overactive sympathetic tone or excessive fibrous tissue .
Etiology Ineffective uterine contractions Malpresentation, Malposition (abnormal
relationship between the cervix and the presenting part)
Spasm (contractions) of the cervix
Management Organic dystocia:
Caesarean section is the management of choice.
Functional dystocia: Pethidine and antispasmodics: may be
effective. Caesarean section: if
medical treatment fails or foetal distress developed.
GENERALIZED TONIC CONTRACTION (UTERINE
TETANY) In this condition pronounces retraction occurs
involving whole of the uterus upto the level of internal os. Thus there is no physiological differentiation of the active upper segment and the passive lower segment of the uterus. As there is no thinning of the lower segment, there is no chance of rupture of the uterus. The uterine contraction ceases and the whole uterus undergoes a sort of tonic muscular spasm holding the fetus inside (active retention of the fetus)
Causes
Failure to overcome the obstruction by powerful contractions of the uterus
Injudicious administration of oxytocics Irritation caused by repeated unsuccessful
attempt of instrumental delivery
Clinical Features The patient is in prolonged labor
having severe and continuous pain. Abdominal examination revels the uterus to be somewhat smaller in size, tense and tender. Fetal parts are neither well defined, nor is the fetal heart sound audible. Vaginal examination reveals jammed head with big caput; dry and oedematous vagina.
Management Correction of dehydration and keto
acidosis: by rapid infusion of Ringer’s solution
Antibiotics : To control infection Adequate pain relief