Mechanisms of labor Dr F Mostajeran Mechanisms of

Mechanisms of labor Dr. F Mostajeran

Mechanisms of labor q Lie presentation q Attitude and position Fetal lie: § Longitudinal § Oblique

F. Presentation q Cephalic q Breech q Shoulder (preria-septum)

q. Relationship head and body classified q. Chin contact thorax vertex, occiput presentation occiput and back contact , face presentation F. head position between these partially flexed , fontanel (bregma) , sinciput presentation partially extended , brow

Breech presentation q Frank q Complete q Footling

q Fetal attitude or posture q Fetus forms an avoid q Back q Head q Legs q Arms

Position : q Presenting part q Vertex → occiput q Face →mentum q Breech →sacrum q Lo Ro o. A o. P

Diagnosis presentation – position Abdominal palpation: q. Leopold maneuvers üFirst maneuver üSecond maneuver fetal fole üThird maneuver thumb – fingers , movable üFourth maneuver q. First three fingers q. Direction of axis pelvic inlet

q V. E xamination ü Sutures ü Fontanels

q Auscultation reinforce q V. S q Radiography

q Labor with occiput presentation q vertex presentation q 40% LOT q 20% ROT q 20% OP OP (placenta anterior –narrow fore pelvis)

q Cardinal morement of labor q Engagement q Descent q Flexion q Internal rotation q Extension q External rotation q Expulsion

q Changes in shape of the head q Caput succedaneum Vertex → head change shape → labor forces ü Fetal scalp → forming swelling ü prevent differentiation sutures fontanels

q. Molding q. Head shape change → external compressive forces possibly → Braxton hicks cont

Admission procedures q. Urged to report early in labor q. Early admittance to labar , delivery unit qespecially high risk pregnancy qaccurat diagnosis of labar q. Falsely diagnosed , inappropriate in terrention q. Not diagnosed (remot from medical personnel medical facilities)

Definition of labor q. Uterine contractions that bring effacement and dilatation of cervix. q. Painful contractions become regular qonset of labor as beginning at the time of admission to the labor unit q. Admission for labor based on dilatations accompanied by painful contractions.

D. Diagnasis between false and true labor is difficult q. Contractions of true labor q. Regular intervals q. Intervals gradually shorten q. Intensity gradually increases q. Discomfort back , abdomen q. Cervix dilates q. Discomfort is not stopped by sedation

Contractions of false labor q. Irregular intervals q. Intervals long q. Intensity unchanged q. Discomfort lawer abdomen q. Cervix not dilate q. Relieved by sedation

q. Pregnant woman who is having Cantractions q. Emergency condition q. Labor is defined as process of childbirth beginning q. Latent phase delivery placenta

Electronic admission testing q. Recommend NST or CST on all patient q(labar – delivery unit) q. Fetal admission test q identify unsuspected cases

Vaginal examination 1. Amnionic fluid effacement 2. Cervix dilatation position 3. Presenting part 4. Station 5. Pelvic architecture

Detection of ruptured membranes q. Leakage of fluid q. Prolapse cord q. Labor occur q. Serious intra uterine infection q. Nitrazine paper (PH= 7. 0 – 7. 5) q. Arborization or ferning q. Alpha – fetoprotein q. Injection various dyes

q. Vital signs and review of pregnancy record q. Physical examination q. Preparation of vulva and perineum q. Inspection and cleaning of the vulva , perineum , mini – shave enema

Friedman q. Three functional divisions of labor q. Preparatory division: Little cervical dilatation Considerable change q. Dilatational division : Most rapid rate qpelvic division: Deceleration phase of cervix dilatation Cardinal fetal movements

Cervical dilatation q. Latent phase (14 -20 h) q. Active phase: acceleration , phase of maximum slope , deceleration phase

Management first stage of labor q. Remainder of general physical exam is completed q. HCT HB protein - glocose qaverage duration first stage of labor q 7 hours in nulliparous w q 4 hours in parous w

q. Fetal monitoring during labar q. Contractions and response FH q. Suitable stethoscopc , doppler ultrasonic devices q. FH should be checked after contractions qevery 30 minutes (15) q. Second stage every 15 minutes (5) q. Cantinous electronic monitoring

MATERNAL MONITORING q. Vital signs q. T , pulse , BP every 4/h q. PROM temprature every 1/h q 18 h of PROM antimicrobial

Subsequent vaginal examinations q. When membrans rupture if head was not Defenetly engaged qfetal H immediately and during the next uterine contraction q(occult umbilical cord compression) qperiodic examinations at 2 -3 hours interval

Oral intake q. Gastric emptying time prolanged (food – medication remain in the stomach – not absorbed may be vomited) q. Food should be withheld q. Intravenous fluids q. Infusion system routine early labar (IV line) q. Longer labors glucose sodium water 60120 ml/hr

q. Maternal position during labor qnormal laboring woman q. Not be confined to bed q. Comfortable chair q. In bed position most comfortabl (lateral recumbend)

Analgesia q. Is initiated on the basis of maternal discomfort qvaginal examination befor administration of analgesia (delivering a depressed infant) q. Timing , method and size of initial and subsequent dose , interval of time until delivery

Amniotomy q. There is a great temptation q. Benefits: rapid labor detection of meconium staining q. Internal fetal M q. Aseptic technique q. Head must be well applied to the cerxin

Urinary bladder function q. Bladder distention avoid q. Abstracted labor q. Subsequent bladdes hypotonia, infection q. Suprapubic region shauld be visualized , palpated detect filling bladder q. If could not void on a bedpan q. Intermittent catheterization

Management of second stage labor q. Full dilatation of the cervix q. Begins to bear dawn q 50 minutos in nulliparous q 20 minutos in multiparous

q. Higher parity 2 -3 expulsive efforts may suffice Complete the delivery of the infant q. FHR q. Low – risk 15 H. risk 5

q. Fetal H. R q. Contraction – maternal expulsive efforts q FHR are not consequence of head compression q. Descent fetus and reduction in uterine volume q some degree of premature separation placenta

qtighten a loop or loops of umbilical cord q. Around the fetus umbilical blood flow q. Prolonged uninterrupted maternal expulsive efforts dangerous to the fetus

Preparation for delivery q. Variety of positions q. Dorsal lithotomy position q. For beter exposure legholders stirrups q. Cramps in the legs (brief massage – changing position) q. Preparation for delivery entails vulvar and perineal cleansing

Spontaneous delivery q. Delivery of the head q. Contraction perineum bulges q. Vulvovaginal opening becomes more dilated q. Gradually circular opening q. This encirclement of the largest head q. By the vulvar ring is known as

q. Perineum is extremely thin q. Episiotomy , laceration q. Episiotomy risk tear external anal – rectum q. Episiotomy - anterior tear urethra , labia

Ritgen manover q. Vaginal introitus 5 cm q. Towel – draped , gloved hand forward pressure qon the chin of the fetus qother hand exerts pressure superiorly against occiput

q. Cleaning the nasopharynx q. Minimize aspiration AF – debris , blood qonce thorax is delivered q face quickly wiped nause , mouth are aspirated

q. Following delivery of anterior shoulder q. Finger should be passed to the neck q. Nuchal cords 25% + q. Drawn down , loose – slipped over the head q. Clamping the cord q 4 -5 cm , 2 -3 cm fetal abdomen two clamps q. Plastic cord clamp

Timing of cord clamping q. Infant is placed at or below vaginal interoitus 3 , 80 ml of blood shifted from placenta to infant q 80 ml 50 mg Iron , Iron deficiency anemia q. Maternal alloimmunization qour policy after cleaning airway 30" cord clamp

Management of the third stage q. After delivery of the infant q. Height uterine fundus q. Uterus firm , no unusual bleeding q. Waiting until placentac separat – no massage q. Hand rest on the fundus (atonic – filled with blood)

Signs of placental separation 1. uterus becames globular firm 2. Sudden gush of blood 3. Uterus rises (placenta separated , passes dawn to lower u-segment 4. Its balk pushes uterus upward 5. Umbilical cord protrudes forther out

delivery of the placenta q. Traction on the umbilical cord must not be used inversion q. Manaol removal of placenta qoccasionally placenta will not separat q. At any time brisk bleeding and , placenta can not be delivered q. Active management of the third stage q 5 units oxytocin +0. 5 ergometrine q reductian in the length of third stage

Fourth stage of labor q. Exam placenta , membranes , umbilical cord q. Completeness , anomalies q. Hour immediately fallowing delivery q. Critical fourth stage of labor quterine atony , BP , pulse every

Oxytocic Agents q. Oxytocin (pitocin , syntocinon) q. Methylergo novine maleat (methergine) q. Reduce blood loss by stimuloting myometrial contraction q. Iml 10 IU half – lifc IV 3 q. Inapropriate dose kill the fetus , rupture uterus

Cardiovascular effects q. Deleterious effects follow IV bolus q. Antidiuresis qrare maternal convulsion antidiuretic action q. Water intoxication (20, 40 mu/minut ) q. Concentration should be increared rather than rate of flow q. Normal saline are lactated ringer solution

q. Ergonovine and methylergonavine q. IV – IM – orally no differenc in actions q. Sensitivity of pregnant uterus is very great q. In pregnancy 0. 1 my IV , 0. 25 my oral tetanic Uterine contraction q. Tetanic effect prerention , control PPH q. IV administration sometimes tram sient , severe hypertension

Prostaglandins q. Not used routinely q. Manage ment PPH q. PG F 2 x 250 ng IM (15 -90" ) 8 does 88% successful q 20% side effects diarrhea , hypertension vomiting , Fever , flushing , tachycandia q. PG E 2 20 -mg suppositories

Lacerat ons of the Birth canal q. Classified q. First fourchette , perineal skin vaginal mucous q. Second fascia and muscles of perineal body q. Third anal sphincter q. Fourth retal mucosa

Episiotomy and repair q. Incision of pudenda q. Perineotomy incision of perineu q. Episiotamy synonymously with penineotomy q. Begin in midline : q. Directed laterally mediolateral q. Directed down ward midline

Timing of episiotomy q. Perform when head is visible during contraction 3 -4 q. After application of blades q. Timing of repair q. Most common practice repair until placenta delivered q. Technique q. Hemostasis q. Anatomical restoration without excessive suturing q. Chromic catgut 3 -0

Fourth – degree laceration q. Various techniques remcommend q. Esential approximat torn edges rectal mucosa q. With muscularis sutures 0. 5 cm apart q. Muscular layer covered with a layer of fascia

Labor with occiput presentations q 95% fetus occiput or vertex presentation q. Most commonly ascertained ab – exam q. Confirmed V. Examination before or at the onset of labor q. Sagitlal suture in the transrevse pelvic diameter q. LOT , ROT , LOA , ROA q. ROP , LOP (narrow forepelvis , anterior placentation

OCCCIPUT ANTERIOR PRESENTATION q. Irregular shape pelvic canal q. Large dimensions fetal head q. Adoptation or accommodation of suitable q. Portions of head to the varius segment of the pelvis is required

Cardinal movements of labar q. Engagement q. Descent q. Flexion q. Internal rotation q. Extension q. External rotation expulsion

q. Concomitantly , uterine cantractions q. Important modifications in fetal attitude qstraightening of the fetus loss dorsal convexity , closer application of the extremities to the body , fetal ovoid cylinder

Engagement q. Biparietal diameter – greatest transverse diameter F. Head passes thraugh the pelvic inlet q. Lost few weeks of pregnancy q. Until after cammencement of labor q. In many multiparous , some nulliparous q. At onset of labor head freely movable above inlet q. Referred “floating”

Asynclitism q. Sagittal suture remaining parallel to transverse axis may not lie exactly midway q. Between symphysis and sacral promontory q. Sagitlal suture deflected posteriorly or anteriorly

q. Asynclitism anteror or posterior q. Moderat degree of asynclitism are the rule in normal labor q. Severe asynclitism may lead to cephalopelvic disproportion even with an normal – sized pelvis

DESCENT q. First requisit for birth infant q. In nulli parus take place befor the onset of labor q. Further descent until onset of the second stage q. In multiparous descent usually begins with engagement

1. 2. 3. 4. Descent is brought by one or more of four forces Pressure of amnionic fluid Direct pressure of fondus with cont ractions Bearing down efforts abdominal muscles Extension and straightening of fetal body

FLEXION q. As soon as descending head meets resistance q. Cervix , walls of the pelvis , pelvic floor q. The chin is braught into more intimate contact Fetal thorox qsuboccipitobreg matic occipitafrontal

Internal rotation qocciput gradually moves from original position toward symphysis pubis q. Less commonly posteriorly q. Internal rotation essential completion of labor q. It always associated with descent and acomplished after engagement

Extension q. After in-rotation sharply flexed head reaches the vulva q. Undergoes extension which essential to birth q. Vulvar outlet directed upward , for ward q. Extension must occur before head can pass through it

q. Head born by further extension qocciput , bregma , fore head , nose mouth q. Finally chin pass q. Head drops down ward chin lies over anal region

External rotation qdelivered head under goes restitution qocciput toward the left rotates left ischial tuberosity qocciput toward the right rotates right ischial tuberosity q. Bisacromial diameter in to relation anteroposterior diameter of the pelbic outlet shoulders (anteriar – posterior)

Expulsion q. Immediatly after external rotation q. Anterior shoulder under symphysis pubis q. Posterior shoulder distended perineum q. After delivery of the shoulders q. Rest of body quickly extruded