DYSTOCIA DURING LABOR

DIFFICULT LABOR

Prof dr Made Kornia Karkata, SpOG(K)

Morning lecture for ObGyn students.

DYSTOCIA

Dystocia is defined as a difficult labor, the opposite of eutocia, an easy normal labor. It may associated with various abnormalities or pathologies that prevent or deviate from the normal labor and delivery. In general this condition will result in prolonged labor and if not treated well will end with neglected-labor which compromised both mother and baby outcome. It is considered normal if labor finish in, at least 24 hours, so every woman in labor should not experience two sunrise or two sunset. Prolonged labor is labor that last more than 24 hours or if there is prolongation of the phase of labor. Neglected labor is prolonged labor with complications for both mother and baby during birth process. Dystocia can happen at latent phase, active phase and second stage of labor.  The causes of dystocia are classified into 3 general categories that are often interrelated : factor of power, passage or passenger. Some also add the factor of mismanagement can influence the sequence of labor.

Factor of power :

            It is about the power of uterine contraction (his) to start labor and the power of bearing down at the second stage of labor. This include the ineffective contraction of the uterus, whether hypertonic, hypotonic or discoordinated uterine contraction and , at the second stage of labor may be because of lack of “pushing down” power..

Factor of the passage

            Abnormalities of the passage constitute pelvic dystocia and it is because of  aberration of pelvic architecture and its relationship to the presenting part of the baby (passenger). Such abnormalities may be caused by the size and configuration of bony pelvis, traumatic pelvic fracture, xyphotic and scoliotic pelves, inlet contraction, midpelvic-outlet contraction, and soft tissue abnormalities of the birth canal, ovarial tumor or blockage by placental location. Study by Caldwell and Maloy, classified the 4 major types of adult pelves: gynecoid pelvis is the most typically “female” type, android pelvis, anthropoid pelvis and platypelloid pelvis.

            To evaluate passage as a factor-causing dystocia can be done by doing clinical measurement and by X-ray pelvimetry. Suspicion of pelvic dyastocia can happen in short height mother ( low than 150 cm) , and mothers with bad obstetric histories. Once a mother successfully give normal vaginal birth a term baby with more than 2.5 kg , the pelvis is considered normal.

            Other anatomic abnormalities of the reproductive tract may cause dystocia. So-called soft tjssue dystocia may be caused by congenital anomalies, scarring of the birth canal, pelvic mass tumor and low implantation of the placenta..

Abnormalities of the passenger

            Known as fetal dystocia include fetal size, mal-positions (fetal lie), congenital anomalies, multiple pregnancies, compound presentation etc. Fetal head presentation is not a guarantee of successful labor. Face presentation, brow presentation and vertex presentation, compound presentation (ex: fetal head and part of extremity lay beside) can give a difficult labor. Abnormal fetal lie such as : breech presentation, transverse and oblique lie will result in abnormal labor. And obviously major fetal malformations can result in dystocia such as: hydrocephalus, fetal hydrops, Siamese twin and others.  

Abnormal patterns of labor.

            Labor is a dynamic process characterized by uterine contractions that increase in regularity, intensity and duration to cause progressive effacement and dilatation of the cervix and followed by descent of the fetus through the birth canal. To evaluate the progress of labor clinician use two methods: curve of Friedman and/or  partograph of WHO that widely used all over the world.

            By using “partograph WHO”, will prevent the incidence of prolonged labor and (of course) neglected labor. Neglected labor is prolonged labor with complications happened to both mother and child. Partograph itself is a very simple tool, easy to apply, and all of important information for mother and child are available, there is an “alert line” and “action line” to decide when to take intense observation and when the time to take action or to refer the patient to higher center.

Should the “opening line” cross the “alert line” the parturient should be monitored closely and soon the opening line cross the “action line”, the action should be taken by first considering which of the 3 factors as a cause of dystocia.

            Depend on its causes several actions could be taken such as:

·        Transverse lie can be changed by doing external version as there is no contraindication.

·        Hypotonic contraction can be fixed by breaking the amniotic membrane (amniotomy) or augmented by oxytocin induction with strict precaution considering indication, contraindication, the procedure of closed monitoring for possible dangers of fetal distress and potential uterine rupture for the mother.

·        Should dystocia happened at second stage of labor, as far as no contraindications and evidence fulfill the criteria of safe vaginal delivery then operative vaginal deliveries should be taken such as vacuum or forcepal extraction, manual delivery of breech etc.

·         If there is no way to make correction or it is considered dangerous to be delivered vaginally then cesarean section should be carried out.

Dystocia in the second stage usually of inadequate expulsive efforts because of conduction anaesthesia, oversedation, exhaustion or neurologic dysfunction such as paraplegia or hemiplegia and outlet foceps delivery may be effected in selected cases. For the shake of the baby the difficult mid and high forceps are abandoned and cesarean section is more preffered.

By using Friedman curve the progress of abnormalities labor consist of : prolonged latent phase, protracted active phase, secondary arrest of dilatation and prolonged second stage.

PROLONGED LATEN PHASE

            The duration of the latent phase averages 6.4 hours in nulliparas and 4.8 hours in multiparas. It considered prolonged if it lasts more than 20 hours in nulliparas or 14 hours in multiparas and stated as more than 8 hours in WHO partograph.

Causes consist of : a labor with low Bishop score , uterine dysfunction characterized by weak, irregular, uncoordinated and ineffective uterine contractions and also because of feto-pelvic disproportion.

PROTRACTED ACTIVE PHASE.

            Protracted cervical dilatation in the active phase of labor, meaning there is constrain in speed of opening and tend to prolonged. The “secondary arrest” meaning there is a stop in opening at active phase of labor after 2 hours or more by same examiner.

MANAGEMENT

            The clinical signs of dystocia will appear in the form of prolongation of labor such as:: prolonged latent phase, protracted active phase, secondary arrest, opening line crossed the action line or prolonged second stage. After all  the three Ps should be reevaluated to confirm the cause of dystocia. The cause of power may be responded by augmentation with amniotomy or oxytocin induction as far as no contra-indication. If certain criteria matched to vaginal operative procedures then it should be applied with strict careful handling. And should there is no possibility to give vaginal birth or in the case of emergency due to fetal distress or threatened uterine rupture with incomplete opening of the cervix, then the cesarean section is mandatory.

            It is nice to know the indication, criteria, contra-indication and procedure to apply amniotomy, oxytocin stimulation, forcepal or vacuum extraction, cesarean section etc.

MATERNAL-FETAL EFFECTS OF DYSTOCIA

            Dystocia  will result in higher morbidity and mortality for both mother and child. Prolonged labor and (much more) neglected labor will appear in exhaustion, dehydrated, vulvar-edema, cervical edema, intra-uterine infection, general peritonitis and even pathologic retraction ring and uterine rupture. For long term it will give pelvic floor injury and fistula formation .For babies, complicated dystocia may give caput  succedaneum, fetal head molding and complication due to the action of operative vaginal deliveries, chorioamnionits, neonatal sepsis, severe fetal distress and even fetal death in utero and also cerebral palsy in later life.. Manipulated deliveries can complicate with skull fracture, cerebral palsy, deep nerve paralyse, clavicular fracture etc.

            Management of fetal compromised during labor several actions should be taken include : a change of the mother’s position on her side, correct maternal hypotension  by intravenous fluid drip, decrease uterine activity by stopping the administration of oxytocin or change to tocolytic agent and administer oxygen mask.

            If the situation worsen, immediate delivery is mandatory. Obstetric judgment  must decide how the delivery will be accomplished in relation with the presentation, station, position and dilatation of the cervix and presumed fetal status.

The indication for cesarean section have been broadened with its increased safety ( anesthesia, laboratory, blood bank and neanotology). Thus the use of cesarean section may justifiably increased for fetal distress, big sized baby, contracted pelvic inlet, fetopelvic disproportion , previous uterine scar, placenta previa, abruption placenta, abnormal presentation and maternal complication such as vesico-vaginal fistula, severe cardiac disease etc.

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References :

Cunningham FG, Leveno KJ, Bloom SL, Hauth JC. Gilstrap III LC, Wenstrom KD (Eds): Williams Obstetrics, 22^nd Edition 2005, Chapter 20, Dystocia, Abnormal Labor : 495-521.