Abnormal uterine contraction

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