Abnormal Uterine Contraction 156w4c

ABNORMAL UTERINE CONTRACTION PREPARED BY: NISHA DWA

DEFINITION: Any deviation of the normal pattern of uterine contractions affecting the course of labour is designated as disordered or abnormal uterine contraction.

The criterion of effective uterine contraction is progressive dilatation of the cervix with descent of the presenting part withing the specified time limit.

ETIOLOGY: As the physiology of normal uterine contraction is not fully understood, the cause of its disordered action remains obscure. The following are the associated causes: I. Primigravida with advancing age of mother. II. Prolonged pregnancy (Post term pregnancy) III. Over distension of the uterus due to twins and/or hydramnious

IV. Contracted pelvis V. Malpresentation and deflexed head VI. Full bladder VII.Injudicious istration analgesics and oxytocics.

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VIII.Premature attempt at vaginal delivery or attempted instrumental vaginal delivery under light anaesthesia.

NORMAL UTERINE CONTRACTION:  There exists polarity in uterus i.e. when the upper segment contracts the lower segment relaxes  There are two pacemakers situated at each cornua of uterus  The intensity of contraction diminishes from top to bottom of the uterus.

 The contraction wave starts at the pacemaker and propagates to the lower segment.  The duration of contraction diminishes progressively as the wave moves away from the pacemaker

TYPES OF ABNORMAL UTERINE ACTION: 1) Hypotonic dysfunction(Uterine inertia) 2) Hypertonic dysfunction(Excessive contraction)  Precipitate labour  Tonic uterine contraction and retraction(Bandl’s Ring)

3) Inco-ordinate uterine action  Spastic lower segment  Colicky uterus  Asymmetry uterine contraction  Constriction ring  Generalized tonic contraction  Cervical dystocia

NOTE: The uterine space maker is situated at the cornua of the uterus and this generates uterine contractions. Effective uterine contraction, starts at he cornua and gradually sweep downwards over the uterus.

Primary dysfunctional labour is defined when the cervix dilates less than 1cm/hr following a normal latent phase of labour. In a primary dysfunctional labour, uterine activity instead of being governed by a single dominant space maker, is shifted to less efficient contractions due to emergence of other pacemaker foci.

HYPOTONIC UTERINE DYSFUNCTION(UTERINE INERTIA):  This is a common type of abnormal uterine contraction, which may present from the beginning of labour or may develop subsequently after a variable period of effective contractions.  In uterine inertia, the pattern of the uterine contraction is normal but the cervical dilatation is slow.  The intervals between contractions are long, the duration of contraction is short and the intensity is weak.

SIGNS AND SYMPTOMS:  Patient feels less pain during uterine contraction.  Palpation reveals less hardening of the uterus.  Uterine wall is easily indentable at the acme of pain.  Uterus becomes relaxed after the contraction; fetal parts are well palpable and fetal heart rate remains good.

 Internal examination reveals:  Poor dilatation of the cervix (<1cm/hour beyond 3cm dilatation)  Membranes usually remain intact.  Associated presence of contracted pelvis, malposition, deflexed head or malpresentation may be evident.

COMPLICATIONS:  Maternal exhaustion and/or fetal distress are unusual and appear late.  Prolonged labour  Infection  Possibility of Postpartum Haemorrhage due to atonic uterus.

MANAGEMENT:  Careful evaluation of the case is to be done:  To be sure that the patient is in true labour.  To exclude D and malpresentation.  To plan out the management protocol.  In normal condition prepare for vaginal delivery.  Plan for caesarean section if mother have contracted pelvis, malpresentation or evidence of fetal and maternal distress.

GENERAL MANAGEMENT:  Reassure the mother to keep up the morale and prevent psychological depression.  Change posture of woman(avoid supine position)  Empty the bowel by enema and encourage mother to frequently empty the bladder. If fails to empty by herself, catheterization should be done.

 Maintain hydration by infusion of Ringer’s solution.  Adequate pain relief by intramuscular pethidine 100mg or combination of pethidine 75mg and Sparine 50mg.

ACTIVE MANAGEMENT:  Acceleration of uterine contractions can be brought about by low rupture of membranes followed by oxytocin drip.  If labour does not progress and there is sign of maternal and/or fetal distress, caesarean section should be done.  Keep keen and constant observation on maternal and fetal condition.

 If head is low forceps or vacuum delivery is indicated.  Continue the oxytocin drip till one hour after the delivery of baby to prevent PPH.

HYPERTONIC UTERINE DYSFUNCTION (EXCESSIVE CONTRACTION):  It is the condition in which the tone of the uterus is high during and between contractions with severe backache.  The higher tonic state of the uterine segments, colicky uterus, asymmetrical uterine contraction, constriction ring or generalized tonic contractions of the uterus and all these states are collectively called incoordinate uterine action.

 In the absence of obstruction, the hypertonic uterine action results in precipitate labour whereas it results in Bandl’s ring formation in the presence of any obstruction.

PRECIPITATE LABOUR:  A labour is called precipitate when the combined duration of the first and second stage is less than 2 hours.  This is an overactive labour in which the baby is expelled soon after the start of labour.

 Rapid expulsion is due to the combined effect of hyper active uterine contractions associated with diminished soft tissue resistance.  Labour is short as the rate of cervical dilatation is 5cm/hr or more.  It is common in multiparae and may be repetitive.

COMPLICATIONS: a) Maternal Risk:  Extensive laceration of the cervix, vagina and perineum  Postpartum haemorrhage due to uterine hypotonia that develops subsequently  Inversion of uterus  Infection  Uterine rupture  Amniotic fluid embolism

b) Fetal Risk:  Intracranial stress and haemorrhage because of rapid expulsion without time for moulding of the head  Fetal hypoxia because of strong, frequent uterine action  Skull fracture  Rupture of cord

MANAGEMENT:  The patient having previous history of precipitate labour should be hospitalized prior to labour.  During labour, the uterine contraction may be suppressed by istering ether or magnesium sulphate during contractions.  Delivery of the head should be controlled but not prevented.

Episiotomy should be done liberally. Elective induction of labour by low rupture of membranes and careful conduction of controlled delivery may be advantageous. Oxytocin augmentation should be avoided.

TONIC UTERINE CONTRACTION AND RETRACTION (BANDL’S RING):  This type of uterine contraction is predominantly due to obstructed labour.  The pattern of uterine action is normal, the upper uterine segment actively while the lower segment remains ive.  There is gradual increase in intensity, duration and frequency of uterine contraction.

 The relaxation phase becomes less and less; ultimately a state of tonic contraction develops. Retraction, however, continues  The lower segment, elongates and becomes progressively thinner to accommodate the fetus driven from the upper segment.  A circular groove encircling the uterus is formed between the active upper segment and the distended lower segment called pathological retraction ring(Bandl’s ring).

In primigravidae, further retraction ceases in response to obstruction and labour comes to a stand still – a state of uterine exhaustion. Contractions may recommence after a brief period of rest with renewed vigour.

But in multiparae, retraction continues with progressive circumferential dilatation and thinning of the lower segment. There is progressive rise of the Bandl’s ring; moving nearer and nearer to the umbilicus and ultimately, the lower segment ruptures.

CLINICAL FEATURES:  Patient is in agony from continuous pain and discomfort and becomes restless.  Features of exhaustion and keto acidosis

 Abdominal palpation reveals:  Upper segment is hard and tender. Lower segment is distended and tender.  The pathological retraction ring is placed obliquely between umbilicus and symphysis pubis and rises upwards in course of time.  Fetal parts may not be well defined.  FHS is usually absent.

Internal examination reveals:    

Dry, hot vagina with offensive discharge. Cervix fully dilated Membranes are absent Cause of obstructed labour is revealed.

PREVENTION: The abnormality either due to age or enger should be ruled out in antenatal period and plan for appropriate treatment.

TREATMENT:  Rupture of membrane is excluded.  Correction of dehydration and ketoacidosis by infusion of Ringer’s solution.  Adequate pain relief measures must be used.

 Parenteral antibiotic is given (Ceftriaxone 1gm IV).  Caesarean delivery is done in majority of the cases.  Rupture of uterus must be excluded before attempting destructive operation.

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INCO-ORDINATE UTERINE ACTION:  It is a type of abnormal uterine action in which the two poles of the uterus do not function rhythmically i.e. there is inco-ordination between the two poles.  It is a state of uterine dysfunction in which the contractions are usually strong, painful and/or may be frequent but cervix dilates slowly.  It usually appears in active stage of labour.

SPASTIC LOWER SEGMENT:  This is a common type of abnormal uterine action in the primigravida.  The pain comprises mainly severe backache, intensified during contractions  The cervix is thick edematous and is poorly applied to the presenting part.

 There is reversal of uterine action, increased tone in lower uterine segment and weakly acting upper uterine segment.  Fundal dominance is lacking and often there is reversed polarity.  Inadequate relaxation in between contractions.

CLINICAL FEATURES:  The patient is in agony with unbearable pain referred to the back.  There are evidences of dehydration and keto acidosis.  Bladder is frequently distended and often there is retention of urine; distension of the stomach and bowels are visible.  There are premature attempts to bear down.

 Abdominal palpation reveals:  Uterus is tender and gentle manipulation excites hardening of uterus with pain which precedes and out lasts the uterine contraction.  Uterus remains tense and tender even after the contraction es off.  Palpation of the fetal parts is difficult.  Fetal distress appears early.

 Internal examination may reveal:  Cervix which is thick, oedematous, hangs loosely like a curtain, not well applied to the presenting part.  Inappropriate dilatation of the cervix.  Absence of membranes.  Varying degree of caput.  Meconium stained liquor amnii.

MANAGEMENT:  Caesarean section is done in majority of cases.  Prior correction of dehydration and ketoacidosis must be achieved by rapid infusion of Ringer’s solution.  There is no place of oxytocin augmentation.

COLICKY UTERUS:  In colicky uterus various parts of uterus contract independently with feeling of pain at fundus and lower segment.  There is lack of polarity and uterus contracts strongly.  The contractions are very painful and felt predominantly in the hypogastrium region.

 The uterus has high resting tone, is irritable and tender.  The cervix is thick, unaffected and poorly applied to the presenting part.

CONSTRICTION RING:  It is one form of inco-ordinate uterine action where there is localized spastic constriction of a ring of circular muscle fibres of the uterus.  It is usually situated at the junction of the upper and lower segment around a constricted part of the fetus usually around the neck in cephalic presentation.  It may appear in all stages of labour.

 It is usually irreversible and complete.  The constriction ring usually results from abnormal uterine activity, which usually are not effective to dialte cervix, or cause rupture of uterus.

CAUSES:  Hypertonic lower uterine segment.  Injudicious use of oxytocics.  Premature application of instrumental delivery.  Premature rupture of membrane.

DIAGNOSIS:  Diagnosis is difficult.  Constriction ring is suspected when descent of fetus is arrested for no obvious reason.  The ring is not palpable per abdomen.  Maternal condition is not much affected but the fetus is in jeopardy because of hypertonic state.

 It is revealed during:  Caesarean section in first stage.  During forcep application in second stage.  Manual removal in third stage (hour glass formation)

MANAGEMENT: Management is based on the stage of labour at which diagnosis is made:  First stage: The diagnosis is made during caesarean section after opening the uterine cavity. The ring may have to be cut vertically to deliver the baby.

 Second stage: Failure to deliver head even after correct and judicious application of forcep suspicious of constriction ring. The confirmation is made by palpating the ring after removing the forceps blade.  Third stage: The diagnosis is made during attempted manual removal. Deepening the plane anesthesia is usually effective. Alternatively, adrenaline may be istered.

GENERALIZED TONIC CONTRACTION(UTERINE TETANY):  It is the condition in which there is pronounced retraction involving whole of the uterus upto the level of internal os resulting in no physiological differentiation of active upper segment and ive lower segment of the uterus.  The uterine contraction ceases and the whole uterus undergoes a sort of tonic muscular spasm holding the fetus inside.  New pacemakers appear all over the uterus.

CAUSES:  Failure to overcome the obstruction by powerful contractions of the uterus.  Irritation caused by repeated unsuccessful attempt at assisted delivery.  Injudicious istration of oxytocics.

CLINICAL FEATURES:  Prolonged labour with continuous and severe pain.  Evidences of dehydration and ketoacidosis.  Abdominal palpation reveals somewhat small sized uterus which is also tense and tender.

 Fetal parts are neither well defined nor is FHS audible.  Per vagina reveals jammed head with big caput formation, dry and edematous vagina.

MANAGEMENT:  Adequate pain relief.  Correction of dehydration and ketoacidosis by rapid infusion of Ringer’s solution.  Antibiotic istration as per need.

 Oxytocin infusion is stopped and hyper contractility induced by oxytocics can be managed by tocolytics istration.  Caesarean delivery is done in majority of the cases where the obstruction is suspected.

CERVICAL DYSTOCIA:  The rigid cervix is the condition in which the cervix fails to dilate despite of normal uterine contraction.  Progressive cervical dilatation needs an effective stretching force by presenting part.

CAUSES:  Inefficient uterine contraction  Malpresentation, Malposition  Spasm of the cervix

Cervical dystocia may be:  Primary cervical dystocia  Secondary cervical dystocia

Primary cervical dystocia: It is commonly observed during the first birth where the external os fails to dilate due to ineffective uterine contraction. The non dilatation may be due to the presence of excessive fibrous tissue or spasm of circular muscles firms surrounding the os. The characteristic feature of this condition is the state of the cervix. The cervix is effaced and well applied to the engaged head but it has firm ring and does not dilate normally.

Secondary cervical dystocia: This type of cervical dystocia results usually due to excess scarring or rigidity of cervix from the effect of previous operation or disease. The cervix does not dilate due to previous obstetric injury or gynecological operation such as amputation of the cervix.

MANAGEMENT:  In the presence of associated complications as malpresentation and malposition, caesarean delivery is performed  If the head is sufficiently low down with only thin rim of cervix left behind, the rim is pushed up manually during contraction or traction is given by ventouse.  If the cervix is thinned with half dilatation ventouse extraction is quite safe and effective.

DIFFERENCE BETWEEN CONSTRICTION RING AND RETRACTION RING: CONSTRICTION RING RETRACTION RING NATURE It is manifestation of localized It is an end result of tonic uterine inco-ordinate contraction.

uterine contraction and retraction.

CAUSE Undue irritability of the uterus. Following obstructed labour. SITUATI Usually at the junction of upper Always situated at the junction and lower segment but may of upper and lower segment. The ON occur in other places. The position progressively position does not alter. upwards.

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UTERUS Upper segment contracts and Upper segment is tonically retracts with relaxation in contracted with no relaxation. between; lower segment The wall becomes thicker; lower remains thick and loose. segment becomes distended and thinned out.

CONSTRICTION RING MATERNAL CONDITION

RETRACTION RING

Almost unaffected unless Features of maternal exhaustion, the labour is prolonged. sepsis appear early.

ABDOMINAL a. Uterus feels normal and a. Uterus is tense and tender. not tender. b. Not easily felt. EXAMINATIO b. Fetal parts are easily c. Ring is felt as a groove felt N felt. obliquely. c. Ring is not felt. d. Taut and tender d. Round ligament is not ligaments are felt. felt e. Usually absent. e. FHS is usually present.

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a. The lower segment is a. Lower segment is very much VAGINAL not pressed by the pressed by the forcibly driven EXAMINATIO presenting part. presenting part. N b. Ring is felt usually b. Ring cannot be felt vaginally. above the head. c. Features are present. c. Features of obstructed labour are absent.

CONSTRICTION RING END RESULT

RETRACTION RING

a. Maternal a. Maternal exhaustion exhaustion is a late and sepsis appear early. feature. b. Fetal anoxia and even b. Fetal anoxia death are usually early. usually appear late. c. Rupture uterus in c. Chance of uterine multigravidae is rupture is absent. common.

PRINCIPLE OF To relax the ring To relieve the obstruction followed by delivery by safe procedure after TREATMENT of the baby or to cut excluding rupture uterus. the ring during caesarean section.

REFERENCES:  D.C. Dutta, “Text Book of Obstetrics(2004)”, 6 th edition, New Central Book Agency (P) LTD, Pg. no. 357 – 364  Durga Subedi, Saraswoti Gautam, “Midwifery Nursing Part II (2010),” 1st edition, Medhavi Publication, Kathmandu, Pg. no. 195 – 202  Roshani Tuitui, “Manual of Midwifery II(Intrapartum Care) (2012),” 8th edition, Vidyarthi Pustak Bhandar, Kathmandu, Pg. no. 290 - 299

 Retrieved from: URL:  www.gfmer.ch/Obstetrics_simplified/abnormal _uterine_action.htm  nursingcontentbank.blogspot.com/2013/03/abn ormal-uterine-actions.html?m=1

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