Ob - Dystocia

DYSTOCIA

ANDREW ROULDAN B. BUIZON, M.D., FPOGS, FSGOP Assistant Professor De La Salle University – Health Sciences Institute

DYSTOCIA • Literally means “Difficult Labor” • Characterized by Abnormally SLOW Progress of Labor

Overview of the lecture I – Normal and Abnormal Labor II – Causes of Dystocia III – Complications of Dystocia

Factors that affect Labor • Power – First stage: uterine contractions – Second stage: uterine contractions + intraabdominal pressure

• Passenger – Fetal Attitude, Presentation, Position – Ability to adapt through Passage

• Passage – Birth canal • *For Normal Labor to take place – Normal 3P’s

Prognosis for Vaginal Delivery • Power – force of uterine contractions • Passenger: – Presentation and Position – Size of fetal head – Adaptability of fetal head

• Passage – size and shape of maternal bony pelvis

Stages of Labor First* -

regular uterine contractions  fully

Second*- full cervical dilatation  delivery baby Third

- delivery of baby  placental delivery

“Fourth” -immediate postpartum *Stages concerned with Dystocia

First Stage of Labor • Latent Phase • Active Phase – Acceleration Phase • Predictive of outcome of labor

– Phase of Maximum slope • Measure of efficiency of the “machine”

– Deceleration Phase • Reflective of fetopelvic relationship

History of the Partograph

Functional Divisions of Labor • Preparatory Division • Dilatational Division • Pelvic Division

Preparatory Division • Latent Phase and Acceleration Phase • Major event – cervical ripening – Softening: changes in ground substance – Effacement: obliteration of cervical canal

• Cervical dilatation – minimal • Fetal descent – minimal to absent • Sensitive to sedation and conduction analgesia

Preparatory Division

Functional Divisions of Labor • Preparatory Division • Dilatational Division • Pelvic Division

Dilatational Division • • • • •

Phase of Maximum Slope Major Event – cervical dilatation Cervical Dilatation – most rapid rate Fetal Descent – minimal Unaffected by sedation and conduction analgesia

Dilatational Division

Functional Divisions of Labor • Preparatory Division • Dilatational Division • Pelvic Division

Pelvic Division • • • • •

Deceleration Phase to Second Stage of labor Major Event – cardinal movements Cervical Dilatation – rapid rate Fetal Descent – maximal Minimally affected by sedation but ‘bearing down’ effort largely affected by conduction analgesia

Pelvic Division

Cervical Dilatation and Fetal Descent • The only characteristics of the parturient useful in assessing labor & its progression • Time vs. Cervical Dilatation – sigmoid curve • Time vs. Fetal descent – hyperbolic curve

Mechanical Forces of Labor • Factors responsible for progression and completion of each stage • First stage: – Uterine power – Cervical resistance – Forward pressure of the fetal head

• Second stage: – Mechanical relationship between fetal head and pelvic capacity

Diagnosis of Labor

Regularity Frequency Duration Intensity Effect of walking

True Labor

False Labor

(+) > 1 / 10 min > 10 seconds increasing

(-) no pattern variable no pattern

aggravates

no effect

Criteria for Diagnosis of Labor 1. Documented uterine contractions (at Least once in 10 minutes, or 4 in 20 min.) In the form of direct observation or Electronically using a cardiotocogram 2. Documented progressive changes in cervical dilatation and effacement, as Observed by one observer 3. Cervical effacement of greater than 75-80% 4. Cervical dilatation of greater than 3 cm

Diagnosis of Normal Labor LABOR PATTERN

NULLIPARA

MULTIPARA

Latent Phase

< 20 hours

< 14 hours

Cervical Dilatation

> 1.2 cm/hr

> 1.5 cm/hr

> 1 cm/hr

> 2 cm/hr

Fetal Descent

Diagnosis of Abnormal Labor LABOR NULLIPARA PATTERN Prolongation Disorder Latent Phase > 20 hours Deceleration Phase > 3 hours Protraction Disorder Dilatation < 1.2 cm/hr Descent < 1 cm/hr Arrest Disorder No Dilatation > 2 hours No Descent > 1 hour

MULTIPARA

> 14 hours > 1 hour < 1.5 cm/hr < 2 cms/hr > 2 hours > 1 hour

Prolonged Latent Phase • It is the only disorder diagnosable in the Preparatory Division of Labor • Criteria: – Nulli > 20 hrs – Multi > 14 hrs

Etiology of Prolonged Latent Phase • • • • •

False Labor = 50% of the time Excessive sedation Unfavorable cervix (thick, uneffaced, closed) Uterine / Labor dysfunction Unknown

Management of Prolonged Latent Phase • Therapeutic Rest – if no C/I to delay for 6-10 hrs – Strong sedatives – Upon waking, 85% = enter active phase 15% = false labor

• Amniotomy – will not accelerate latent phase

• Caesarean section – Not usually done unless with indications

Diagnosis of Abnormal Labor LABOR NULLIPARA PATTERN Prolongation Disorder Latent Phase > 20 hours Deceleration Phase > 3 hours Protraction Disorder Dilatation < 1.2 cm/hr Descent < 1 cm/hr Arrest Disorder No Dilatation > 2 hours No Descent > 1 hour

MULTIPARA

> 14 hours > 1 hour < 1.5 cm/hr < 2 cms/hr > 2 hours > 1 hour

Protraction Disorders • Protracted Active Phase • Protracted Descent • Etiology : – Malposition – Excessive sedation / conduction analgesia – Cephalopelvic disproportion

• Management: – Augment of labor – CS = 28% have CPD

Diagnosis of Abnormal Labor LABOR NULLIPARA PATTERN Prolongation Disorder Latent Phase > 20 hours Deceleration Phase > 3 hours Protraction Disorder Dilatation < 1.2 cm/hr Descent < 1 cm/hr Arrest Disorder No Dilatation > 2 hours No Descent > 1 hour

MULTIPARA

> 14 hours > 1 hour < 1.5 cm/hr < 2 cms/hr > 2 hours > 1 hour

Arrest Disorders • Criteria before diagnosing Arrest disorders: – Latent phase completed (Cx > 4 cms) – Intensity of Uterine contractions > 200 MvU x 2 h

• Etiology: – Cephalopelvic disproportion – Hypotonic uterine contraction – Malposition – Excessive sedation / anesthesia

• Management: – CS – Augment labor

• “2-hour rule” for diagnosis of arrest in active phase of labor has recently been challenged • 542 women included where CS delivery was not performed for labor arrest until there were at least 4 hours of a sustained uterine contraction of >200montivedeo units or a minimum of 6 hours oxytocin augmentation if the contraction pattern could not be achieved

• Protocol resulted in high rate of vaginal delivery (92%) w/ no severe adverse maternal or fetal outcomes • “Thus extending the minimum period of oxytocin augmentation for active arrest from 2 hours to 4 hours appears effective” ACOG Practice Bulletin, Compendium 2004

Management of Abnormal Labor Labor pattern

Preferred Treatment Prolongation Disorders Latent Phase Bed rest Protraction Disorders Dilatation Expectant / Support Descent Arrest Disorders Prol Decel Augment if no CPD 2o Arrest of Dil Arrest of Descent CS if + CPD Failure of descent

Exceptional Treatment Augment / CS CS for CPD / Augment Rest if exhausted CS

Abnormal Labor (Based on Friedman’s curve) Prolonged Deceleration Phase Failure of Descent Protracted Descent Arrest of Descent

Arrest in Cervical Dilatation Protracted Active Phase Prolonged Latent Phase

DYSTOCIA - Abnormal Labor • Other names: Dysfunctional labor, Ineffective labor, Failure to progress

• Worldwide - Accounts for 43% of all primary cesarean sections

• Philippines - it accounts for 38.85% Textbook of Obstetrics, 2002

Risk Factors for Dystocia • Associated w/ longer 2nd stage - epidural analgesia - occiput posterior position - longer 1st stage of labor - nulliparity - short maternal stature - birthweight - high station at complete cervical dilatation ACOG Practice Bulletin Compendium 2004

DYSTOCIA - Abnormal Labor Three categories causing Dystocia: (Abnormalities of 3Ps)

• POWERS – Expulsive powers: • Uterine dysfunction, or • inadequate voluntary muscle effort

• PASSENGER – Presentation, Position, or Development of the Fetus

• PASSAGE – Maternal Bony Pelvis (Pelvic Contraction) – Soft Tissues of the Reproductive Tract

Normal Uterine Contractions Parameter

Latent Phase

Frequency / Interval

3-5 mins

Active Phase to Second Stage 2-3 mins

Duration

30 – 40 secs

40 – 60 secs

Intensity

Mild to moderate

Moderate strong

Methods to Quantify Uterine Activity palpation external tocodynamometry internal uterine pressure sensors

Normal Uterine Contractions • Characterized by a gradient of myometrial activity: greatest and lasting longest at the fundus (fundal dominance) & diminishing toward the cervix

UTERINE DYSFUNCTION Hypotonic Uterine Dysfunction • More common • No basal hypertonus • Uterine contractions have a normal pressure gradient pattern (synchronous) • IUP < 25 mmHg insufficient to dilate cervix

UTERINE DYSFUNCTION Hypertonic Uterine Dysfunction • Also called incoordinate uterine dysfunction • Either basal tone is elevated or pressure gradient is distorted by contraction of the midsegment of the uterus with more force than the fundus or by complete asynchronism or a combination of both

CAUSES OF UTERINE DYSFUNCTION • • • •

Epidural analgesia Chorioamnionitis Maternal position during labor Birthing position in 2nd stage labor William’s Obstetrics, 21st ed.