ABNORMAL UTERINE ACTION

NAZNEEN VAHORACLINICAL INSTRUCTOR,MTIN,CHARUSAT

BRIEF REVIEW OF NORMAL UTERINE CONTRACTIONS

POLARITY OF UTERUS: When upper segment contracts, lower segment relaxes.

PACEMAKERS: Two pacemakers situated at each cornua of uterus generating the contraction in co-ordinated manner.

PATTERN OF CONTRACTIONS: uterine contraction starts at cornua, propagates towards lower uterine segment with decrease in the duration and intensity of contraction as it moves away from pacemaker.

PARAMETERS OF UTERINE CONTRACTION• BASAL TONE: 5-20mmHg.

• PEAK PRESSURE: around 60 mm Hg pressure

• FREQUENCY OF CONTRACTION Adequate uterine contractions are 1 in 3

minutes lasting for 45 seconds.

DEFINITION

• Any deviation from normal pattern of uterine contractions affecting the normal course of labour is designated as abnormal uterine contraction.

Over all labour abnormalities occur in• 25%nulliparous• 10%multiparous

EXCESSIVE UTERINE CONTRACTION POLYSYSTOLE :contractions more than once

every 2 minutes.

HYPERSTIMULATION: the above in response to oxytocin

TETANIC UTERINE CONTRACTION: single contraction lasting for more than 3 minutes .

HYPERTONIC UTERINE CONTRACTION: Elevated baseline pressure above 20mm Hg.

ETIOLOGYCause is obscure but following conditions are

often associated:Elderly primigravidaeProlonged pregnancyOver distended uterus- twins, fibroidContracted pelvisMalpresentationObesityEmotional factor: anxiety and stressInjudicious administration of sedative,

analgesics, oxytotics

CLASSIFICATION

UTERINE INERTIA

May appear from the beginning of labour or may develop subsequently after variable period of effective contractions.

FEATURES:• Intensity of contractions- decreases• Duration –shortens• Interval – increases• Good relaxation• General pattern maintained

DIAGNOSISPatient feels less pain during contraction Per abdomen: -less hardening of uterus -easily indentable uterine wall -Fetal parts well palpable -Fetal heart rate normalPer vaginal examination -poor cervical dilatation -associated contracted pelvis,

malpresentation, malposition, deflexed head

MANAGEMENTGENERAL MEASURES:Keep up the morale Avoid supine positionEmpty the bladderMaintain hydration

ACTIVE MEASURES:Low rupture of membranes followed by

oxytocin drip in escalating doses until effective uterine contractions set up.

ROLE OF CAESAREN SECTION:-contracted pelvis-malpresentation-fetal or maternal distress

PRECIPITATE LABOUR

Combined duration of 1st and 2nd stage of labour is < 2 hours.

-common in multipara-Due to combined effect of hyperactive

uterine contractions and diminished soft tissue resistance

RISK MATERNAL• Extensive laceration

of cervix, vagina, perineum.

• PPH due to subsequent uterine hypotonia

• Inversion • Uterine rupture• Infection• Amniotic fluid

embolism

FETUS• Intracranial stress

and hemorrhage( as no time for moulding)

• Direct hit on the skull

• Bleeding from Torn cord

TREATMENT• Patient with prior history should be

hospitalized prior to labour.• Elective induction of labour by low rupture

of membranes.• Oxytocin augmentation to be avoided.• During labour the contractions may be

suppressed with ether or magnesium sulphate.

• Liberal episiotomy.• Controlled delivery.

TONIC UTERINE CONTRACTION AND RETRACTION

PATHOLOGICAL ANATOMY OF UTERUS: Contraction increases in intensity ,duration and

frequency with decreased relaxation in between Retraction continues

Progressive thinning & elongation of lower uterine segment

Development of circular groove b/n upper and lower

segment-called BANDL’S RING.

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In primigravidae further retraction ceases in response to obstruction and labour comes to a stand still-a state of exhaustion.

In multiparae retraction continues with progressive dilatation and thinning of lower uterine segment

Bandl’s ring moves towards the umblicus

Rupture of lower uterine segment

Fetal jeopardy and death

Clinical features• Patient is anxious looking• Features of exhaustion and ketoacidosis• Upper uterine segment is tender and hard• Lower uterine segment distended and

tender• Groove is seen between the two.

TREATMENT• Correction of dehydration & ketoacidosis• Adequate pain relief • Parenteral antibioticsEXCLUDE RUPTURE OF UTERUSCaesarean delivery in majority of cases

ABNORMAL UTERINE ACTION

FEATURES• Hypertonic uterine state • Appear in active stage of labour• New pacemakers appear all over the

uterus • Irregular and spasmodic contraction of

uterus• Increased frequency& duration of

contraction with decreased relaxation in between.

• Rise in the basal tone

Clinical featuresPatient in agony with unbearable paindehydration and ketoacidosisBladder is distended with often retention of

uterine

PER ABDOMEN:Uterine tendernessIncreased uterine contraction with poor

relaxation in betweenPalpation of fetal parts is difficultfetal distress in the form of fetal tachycardia

PER VAGINAL EXAMINATION:• Cervix –poor dilatation • Poor descent • Meconium stained liquor may be present

TREATMENT• Correction of dehydration • Adequate pain relief

• Empty the bladder

• Parenteral antibiotics

SPASTIC LOWER SEGMENT• Fundal dominance is lacking• Reverse polarity • Lower segment contractions are stronger• Inadequate relaxation in b/n the

contractions• Premature bearing down• Cervix loose, oedematus, not well applied

to the presenting part

MANAGEMENT:Most of the patients need to be terminated by

caesarean section

CONSTRICTION RING

Also called Schroeder’s ring.

May appear in all stages of labour.

Localized myometrial contraction forms a ring of circular muscle fibers of the uterus

Situated at the junction of upper and lower segment

Usually around constricted part of the fetus.

CAUSE:• Injudicious administration of oxytocin• Premature rupture of membranes• Premature attempt of instrumental delivery

FEATURES• Maternal condition not affected• Fetal distress may occur • Ring is not palpable during per abdomen• Felt in o first stage during –caesarean sectiono Second stage –forceps applicationo Third stage –manual removal of placenta

Delivery is usually by caesarean section

Ring usually passes of by deepening plane of anaesthesia.

In case of difficulties ring is cut vertically to deliver the baby.

CONSTRICTION RING Localised

incoordinate uterine contraction

Undue irritability of uterus

Usually at the junction of upper and lower uterine segment

Upper segment contracts and retracts with relaxation in between

Lower uterine segment thick and loose

RETRACTION RING• End result of tonic uterine

contraction and retraction• Following obstructed

labour• Always at the junction of

upper and lower uterine segment

• Tonically contracted upper uterine segment

• Lower uterine segment thinned out

CONSTRICTION RING• MATERNAL

condition Always unaffected unless labour is prolonged

• Ring is not felt on per abdomen

• Round ligament not felt

On per vaginal examination ring can be felt usually above head

RETRACTION RING• Maternal exhaustion

and sepsis appear early

• Ring is felt as a groove

Round ligament taut and tender

Can not be felt on per vaginal examination

CERVICAL DYSTOCIA

Failure of progressive cervical dilatation.TYPES:a)Primary b)Secondary

TYPES OF CERVICAL DYSTOCIA

PRIMARYI. First birth when

ext os fails to dilate

II.Rigid cervixIII.Insufficient

uterine contraction

IV.Malpresentation and malposition

SECONDARYI. Excessive

scarring or rigidity of cervix from previous operation or disease

II.Post delivery III.Cervical cancer

MANAGEMENT:If only thin rim of cervix left behind- it is

pushed up manually during contraction

If cervix is thinned out but only half dilated –Duhrssens’s incision is given at 2’oclock and 10 o’clock position followed by forceps or ventouse extraction

GENERALISED TONIC CONTRACTION

Also called uterine tetanyNo physiological differentiation between

active upper segment and passive lower segment.

Pronounced retraction occurs involving whole of the uterus up to the level of internal os.

Whole uterus undergoes a tonic muscular spasm holding the fetus inside

CAUSE:-Cephalopelvic disproportion -obstruction-injudicious use of oxytocics

FEATURES

PER ABDOMINAL EXAMINATION• Uterus is smaller in size, tense, tender• Fetal parts are not palpable• Fetal heart sounds not audiblePER VAGINAL EXAMINATION• Dry and oedematus vagina• Jammed head with a big caput

TREATMENT

• Tocolytic agents for e.g terbutalin 0.25mg S.C.

• Caesarean delivery is done in majority of cases.