ABNORMAL UTERINEACTIONPRESENTED BYDr Pawan JhaltaMODERATOR DR Mamta
INTRODUCTION• Abnormal uterine action is one of the factors causing dystocia(difficult labor) in which uterine forces are insufficiently strong orinappropriately coordinated to efface and dilate the cervix (uterinedysfunction).• Pelvic contraction is often accompanied by uterine dysfunctionand the two together constitute the most common cause of dystocia.• Dystocia is the most common current indication for primarycesarean delivery.• Similarly, malpresentation or large fetal size (macrosomia) may beaccompanied by uterine dysfunction.
REVIEW OF NORMAL UTERINEACTION• Regular interval• Interval gradually shortens• Intensity gradually increases• Discomfort in the back and abdomen• Associated with cervical dilatation• Discomfort not relieved by sedation
REVIEW OF NORMAL UTERINECONTRACTIONSPOLARITY OF UTERUS: When upper segmentcontracts, lower segment relaxes.PACEMAKERS: Two pacemakers situated at each cornuaof uterus generating the contraction in co-ordinatedmanner.PATTERN OF CONTRACTIONS: uterine contraction startsat cornua, propagates towards lower uterinesegment with decrease in the duration and intensityof contraction as it moves away from pacemaker.
PARAMETERS OF UTERINECONTRACTION• BASAL TONE: 5-20mmHg.• PEAK PRESSURE: around 60 mm Hg pressure• FREQUENCY OF CONTRACTIONAdequate uterine contractions are 1 in 3minutes lasting for 45 seconds with goodrelaxation in between.
ASSESSMENT OF CONTRACTION• CLINICAL PALPATION• TOCODYNAMOMETER with externaltransducer- measures duration of contractionand interval between them but not strength.• INTRAUTERINE PRESSURE CATHETER:Measures the strength of contraction also.
Quantitative monitoringData measured most commonlyusing Montevideo units (MVU).Montevideo Unit the sum of theintensity of each contraction in a10 minute period (in mmHg).Adequate uterine activity contraction pattern that generates> 200 MVUs
DEFINITION OF ABNORMALUTERINE ACTION• Any deviation from normal pattern of uterinecontractions affecting the normal course oflabour is designated as abnormal uterinecontraction.Over all labour abnormalities occur in• 25%nulliparous• 10%multiparous
EXCESSIVE UTERINECONTRACTION• TACHYSYSTOLE :contractions more than once every 2minutes.• HYPERSTIMULATION: the above in response to oxytocin withFHR abnormality.• TETANIC UTERINE CONTRACTION: single contraction lastingfor more than 3 minutes .• HYPERTONIC UTERINE CONTRACTION: Elevated baselinepressure above 20mm Hg.
CLASSIFICATION• ABNORMAL UTERINE ACTION– N. POLARITY• HYPERTONIC DYSFUNCTION1.PRECIPITATE LABOUR: In the absence of obstruction2.TONIC CONTRACTION &RETRACTION(Bandls ring):in presence ofobstruction• HYPOTONIC DYSFUNCTION (UTERINE INERTIA)– ABNORM. POLARITY• SPASTIC LOWER SEGMENT• COLICK Y UTERUS• CONSTRICTION RING• GENERALISED TONIC CONTRACTION• C. DYSTOCIA
Precipitate laborDefinition:It is a labor duration less than 3 hours due tostrong coordinate uterine contractions in absenceof obstruction in the birth canal, and resistance ofthe soft tissues. The patient does not feelcotractions except the last contractions during theexpulsion of the fetus
DIAGNOSIS• It is a retrospective diagnosis as thepatient is usually seen in the 2nd or 3rdstages of labor. If seen during the firststage of the labor, the partogram will showrapid progress of cervical dilatation andeffacement. If seen afterdelivery, examination of the mother andinfant should be performed for thefollowing
Complications• Lacerations of the cervix, vagina and perineum predisposing to:postpartum hemorrhage and sepsis which is also predisposed to due todelivery in unsuitable surroundings.• * Atony: due to uterine exhaustion may lead to postpartum *hemorrhage,retained placenta and inversion of the uterus.• *Shock due to heamorrhage and/or pain.– Fetal:• * Intracranial hemorrhage: due to rapid compression anddecompression of the fetal head during delivery• * Fetal injuries• * Avulsion of the cord• Neonatal sepsis
Management• Prophylaxis:• A patient with past history of precipitate labor should be admitted to thehospital at the first perception of labor pains.• Rarely if the patient is seen during delivery, general anesthesia (inhalationby nitrous oxide and oxygen or sedation) may be given to slow down thecourse of delivery to prevent forcible bearing down.• If the patient is seen after delivery: exploration of the birth canal for anyinjury and manage accordingly.• Prophylactic antibiotics if delivery occurred in unsuitable conditions• Proper examination of the fetus for detection of any complications
TONIC UTERINE CONTRACTIONAND RETRACTIONPATHOLOGICAL ANATOMY OF UTERUS:Contraction increases in intensity ,duration and frequency withdecreased relaxation in betweenRetraction continuesProgressive thinning & elongation of lower uterine segmentDevelopment of circular groove b/n upper and lower segment-called BANDL’S RING.
In primigravidae further retraction ceases in response toobstruction and labour comes to a stand still-a state ofexhaustion.In multiparae retraction continues with progressive dilatationand thinning of lower uterine segmentBandl’s ring moves towards the umblicusRupture of lower uterine segmentFetal 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
UTERINE INERTIA• . Hypotonic Inertia:• Definition: Weak, infrequent and ineffective uterine contractions• Etiology: Not known but the following factors may be associated:• 1. General factors:• Primigravida especially elderly.• Anemia, chronic illness. (Antepartum hemorrhage leads toanemia that predisposes to inertia.• Hypertensive states with pregnancy
• . Local factors:• Overdistension of the uterus (e.g.: twins and polyhydramnios).• Anomalies in development of the uterus (eg: unicornuate,bicornuate and septate uterus).• Malpresentations and malposition•• Full bladder or rectum.• Uterine fibroids: Fibroids interfere with proper uterinecontractions.• Induction of premature labour
CLASSIFICATION• Primary inertia:• Poor uterine contractions from the start of labor.• Secondary inertia:• Uterine contractions become weaker after a period ofgood uterine contractions due to uterine exhaustion in cases ofcephalopelvic disproportion (act as a protective mechanism againstrupture uterus).
CLINICAL FEATURES• Labor is prolonged: at various stages of labor (detected clinically by partogram ase.g.: prolonged latent phase, protraction disorders and arrest of cervical dilatation).• Uterine contractions are weak, infrequent and have short duration. This can bedetected clinically by:• Examination: On feeling the contractions abdominally there is weak increase inthe uterine tone, uterine contractions in 10 minutes are less than 3 contractions andeach lasting less than 30 seconds.• Monitoring using:• External tocodynamometer: by external sensor over the abdomen.• The mother & the fetus are usually not seriously affected especially when themembranes remain intact, apart from prolonged labor.• If the inertia persists after delivery of the fetus, there is liability for retention of theplacenta (prolonged 3rd stage of labor) and atonic postpartum hemorrhage.
COMPLICATIONS• Mostly that of prolonged labor• A. Maternal:• In the 1st stage:• Nervousness, anxiety, exhaustion and starvation ketoacidosis.• In the 2nd stage:• prolonged 2nd stage, increase liability for instrumental delivery andcesarean section.• In the 3rd stage:• retention of the placenta and postpartum hemorrhage• Subinvolution of the uterus• Risks of abuse of uterine stimulants.• B. Fetal:• Usually no effect apart from fetal infection from prolonged prematurerupture of the membranes
MANAGEMENT• General measures:• Proper diagnosis that this patient is in active labor (and not in theprodroma of labor) by proper identification of true labor pains(rhythmic, increase in strength, frequency and duration andaccompanied by bulge of the bag of forewater and cervicaldilatation.• Exclusion of cephalopelvic disproportion and malpresentations so asto be managed accordingly.• Proper management of the 1st stage of the labor
• Oxytocin stimulation:• Aim:• To increase the strength, frequency and duration of the uterine• contractions.• Precautions before & during use of oxytocin:• There must be no contraindication to oxytocin. Exclusion of the following isessential:• Cephalopelvic disproportion.• Malpresentations (however oxytocin can be given in cases of breechprovided that the pelvis is adequate and there is no other contraindication).• Incoordinate uterine action.• Scar in the uterus.• Grand multipara.• Fetal distress.
• Close observation of the mother &the fetal heart sounds by continuous fetalmonitoring. If significant deceleration develops, stop the infusion.• Continuous automatic computer infusion pump: For proper calculation andadjustment of the doseTechnique of I.V. oxytocin administration:• Dissolve 2 units (2,000 mIU) in 500 ml of lactated ringer solution so 1ml contains 4 mIU of oxytocin.• Assessment of efficiency of uterine contractions:• a. Clinical:• The hand is applied on the patientsabdomen to detect frequency, regularity, duration and strength.• b. External tocography:• A tocodynamometer is applied on themothers abdomen to record uterine contractions.
• Operative interference• Artificial rupture of the membranes: may be effectiveespecially in cases of hydramnios (will relieve the overstretch of theuterine muscles).• Operative delivery indicated if labor is prolonged beyond 24hours or if there is fetal distress at any time.• One of the following may be done:• Vaginal delivery for example by forceps if the cervixis fully dilated and the conditions are suitable for vaginal delivery• Caesarean section: if fetal distress occurs before fulldilatation of the cervix
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 tothe presenting part
Clinical features• Patient in agony with unbearable pain• dehydration and ketoacidosis• Bladder is distended with often retention of urinePER ABDOMEN:• Uterine tenderness• Increased uterine contraction with poor relaxation in between• Palpation of fetal parts is difficult• fetal distress in the form of fetal tachycardia
• PER VAGINUM:cervix is thick loose edematoushanging like a curtain ; not well applied to thepresenting part.Absence of membranes and meconiumstained liquor may be there.
MANAGEMENT:Most of the patients need to be terminated bycaesarean section
CONSTRICTION RINGAlso called Schroeder’s ring.May appear in all stages of labour.Localized myometrial contraction forms a ring of circular musclefibers of the uterusSituated at the junction of upper and lower segmentUsually 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 ino first stage during –caesarean sectiono Second stage –forceps applicationo Third stage –manual removal of placenta
Delivery is usually by caesarean sectionRing usually passes of by deepening plane ofanaesthesia.In case of difficulties ring is cut vertically todeliver the baby.
• Localised incoordinateuterine contraction• Undue irritability ofuterus• Usually at the junctionof upper and loweruterine segment• Upper segmentcontracts and retractswith relaxation inbetween• Lower uterine segmentthick and loose• End result of tonic uterinecontraction and retraction• Following obstructed labour• Always at the junction ofupper and lower uterinesegment• Tonically contracted upperuterine segment• Lower uterine segmentthinned out• CONSTRICTION RING • RETRACTION RING
CERVICAL DYSTOCIA• Failure of progressive cervical dilatation.TYPES:a) Primaryb) Secondary
CERVICAL DYSTOCIA• PRIMARYI. First birth when ext osfails to dilateII. Rigid cervixIII. Insufficient uterinecontractionIV. Malpresentation andmalposition• SECONDARYI. Excessive scarring orrigidity of cervix fromprevious operation ordiseaseII. Post deliveryIII. Cervical cancer
MANAGEMENT:If only thin rim of cervix left behind- it is pushedup manually during contractionIf cervix is thinned out but only half dilated –Duhrssens’s incision is given at 2’oclock and10 o’clock position followed by forceps orventouse extraction
GENERALISED TONICCONTRACTION• Pronounced retraction occurs involving wholeof uterus up to internal os.No physiological differentiation of activeupper segment and the passive lower uterinesegment.Fetus is holded inside theuterus,usually there is no risk of ruptureuterus
CAUSE:-Cephalopelvic disproportion-obstruction-injudicious use of oxytocics
FEATURESPER 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 ofcases.