Abnormal Labor

8 Interesting Facts of Abnormal Labor 

1. Abnormal labor refers to a deviation in the progression or duration of labor from that observed in women who have a normal, spontaneous delivery 
2. In most cases, no signs or symptoms alert the birth attendant to impending arrest or protraction disorder of labor
3. Diagnosis of protracted labor or arrest disorder is made based on a deviation in progression or duration of active labor at term from established norms
4. Inducing labor by using oxytocin (or by placing cervical/vaginal prostaglandin when cervix is unfavorable) is recommended when rupture of membranes is not followed by start of labor 
5. Treat protracted labor or labor arrest with augmentation of labor using oxytocin 
6. Vaginal delivery is anticipated for most patients, although instrument-assisted or cesarean delivery may be necessary for fetal well-being
7. Complications of protracted labor or arrest disorder may affect the pregnant patient (eg, perineal trauma, endometritis, amnionitis, postpartum hemorrhage) and/or the neonate (eg, decreased Apgar scores, infection)
8. With proper maternal and fetal monitoring, excellent outcomes are anticipated

Pitfalls

• Do not use misoprostol to induce labor (nor allow exposure to it during the third trimester) in women who have had previous cesarean delivery or major uterine surgery owing to the risk of uterine rupture 

Clinical Clarification

• Abnormal labor refers to a deviation in the progression or duration of labor from that observed in women who have a normal, spontaneous delivery 
• Described as protraction (slowing) or arrest of labor 
• Abnormal labor (also referred to as dystocia) is common and affects 20% of all pregnancies 

Classification

• Characteristics of abnormal labor by stage of labor
  • First stage (from initiation of labor to full cervical dilation)
    • Arrested labor 
      • Complete cessation of labor progression at 6 cm or more of cervical dilation with membrane rupture and 1 of the following:
        • More than 4 hours without cervical change with adequate contractions (eg, more than 200 Montevideo units [internal uterine pressure])
        • More than 6 hours without cervical change with inadequate contractions
    • Protracted labor
      • Friedman definition
        • Latent phase (from maternal perception of regular contractions to 4 cm cervical dilation) 
          • Nulliparous: more than 20 hours
          • Parous: more than 14 hours
        • Active phase (from 4 cm dilation to 10 cm complete dilation) 
          • Nulliparous: less than 1.2 cm/hour cervical dilation
          • Parous: less than 1.5 cm/hour cervical dilation
      • Modern definition 
        • Protracted labor is defined by labor duration beyond 95th percentile of established norms 
        • Latent phase (from maternal perception of regular contractions to 6 cm cervical dilation) 
          • Nulliparous latent labor: mean of 7.3 to 8.6 hours (95th percentile, 17-21 hours) 
          • Multiparous latent labor: mean of 4.1 to 5.3 hours (95th percentile, 12-14 hours) 
          • Progress from 4 cm to 5 cm dilation may require more than 7 hours and progress from 5 cm to 6 cm may take longer than 3 hours, regardless of parity 
        • Active phase (from 6 cm dilation to 10 cm complete dilation) 
          • Duration of labor by parity (median hours)
            • Dilation from 6 to 7 cm
              • Nulliparous: 0.6 hours (95th percentile, 2.2 hours)
              • Primiparous: 0.5 hours (95th percentile, 1.9 hours)
            • Dilation from 7 to 8 cm
              • Nulliparous: 0.5 hours (95th percentile, 1.6 hours)
              • Primiparous: 0.4 (95th percentile, 1.3 hours)
            • Dilation from 8 to 9 cm
              • Nulliparous: 0.5 hours (95th percentile, 1.4 hours)
              • Primiparous: 0.3 hours (95th percentile, 1 hour)
            • Dilation from 9 to 10 cm
              • Nulliparous: 0.5 hours (95th percentile, 1.8 hours)
              • Primiparous 1: 0.3 hours (95th percentile, 0.9 hours)
  • Second stage (full cervical dilation and descent of fetus to birth) 
    • Friedman definition
      • Arrested descent
        • Nulliparous
          • With epidural analgesia: more than 4 hours without further fetal descent
          • Without epidural analgesia: more than 3 hours
        • Parous
          • With epidural analgesia: more than 3 hours
          • Without epidural analgesia: more than 2 hours
      • Protracted descent
        • Nulliparous
          • Less than 1 cm/hour rate of descent
          • With epidural analgesia: more than 3 hours
          • Without epidural analgesia: more than 2 hours
        • Parous
          • Less than 2 cm/hour rate of descent
          • With epidural analgesia: more than 2 hours
          • Without epidural analgesia: more than 1 hour
    • Modern definitions of second stage of labor 
      • Protracted labor is defined by labor duration beyond 95th percentile of established norms
      • Second stage with epidural analgesia (median hours)
        • Nulliparous: 1.1 hours (95th percentile, 3.6)
        • Primiparous: 0.4 hours (95th percentile, 2)
      • Second stage without epidural analgesia
        • Nulliparous: 0.6 hours (95th percentile, 2.8)
        • Primiparous: 0.2 hours (95th percentile, 1.3)
      • Consensus documents from the National Institute of Child Health and Human Development, the Society for Maternal-Fetal Medicine, and the American College of Obstetricians and Gynecologists define second stage arrest as follows:
        • Nulliparous women
          • Without epidural analgesia: no progress in descent or rotation for 3 hours or more 
          • With epidural analgesia: no progress in descent or rotation for 4 hours or more 
        • Multiparous women
          • Without epidural analgesia: no progress in descent or rotation for 2 hours or more 
          • With epidural analgesia: no progress in descent or rotation for 3 hours or more 
          • Managing labor based on these definitions has reduced the rate of first cesarean deliveries, with a small rise in instrumental deliveries and no change in early neurologic outcomes in neonates 
  • Third stage (time that elapses between delivery of neonate and delivery of placenta) 
    • Arrested delivery
      • Placenta is not delivered spontaneously or by assisted extraction within 30 minutes
    • Protracted delivery
      • Placenta is not delivered spontaneously or by assisted extraction within 15 minutes
• Precipitous labor
  • Interval from onset of regular uterine contractions to delivery of fetus lasting less than 3 hours 

Diagnosis

Clinical Presentation

• 4 types of pelvic bones. – (A) Android. (B) Anthropoid. (C) Gynecoid. (D) Platypelloid.

History

• If there is no history of abnormal labor, no patient signs or symptoms are reliably predictive of abnormal labor

Physical examination

• Include the following on examination for admission to labor and delivery:
  • Pelvis (using standard digital vaginal examination)
    • Cervical dilation (in centimeters) 
      • 1 fingerbreadth inserted into cervix is approximately 1 cm
      • 2 fingerbreadths inserted is approximately 3 cm
      • Complete dilation is 10 cm
    • Pelvimetry (clinical) 
      • Convergent, divergent, or straight ischial spinal processes
      • Biischial pelvic diameter greater than 8 cm is normal
      • Sacral promontory to symphysis pubis depth more than 12 cm is normal
    • Pelvic type (defined on vaginal examination)
      • Gynecoid (round inlet, short ischial spines; best suited for delivery)
      • Android (heart-shaped inlet, prominent spines; more difficult to deliver and may prolong labor)
      • Platypelloid (kidney-shaped inlet, narrow anteroposterior diameter; if head will engage, delivery may occur but prolonged labor is likely)
      • Anthropoid (oval-shaped inlet, large anteroposterior diameter, smaller transverse diameter than gynecoid; delivery may occur if head engages)
  • Fetus (using abdominal examination and standard digital vaginal examination)
    • Position
      • Right and left occipitotransverse position is common in early labor; rotation to occipitoanterior position is common as fetus descends
      • Fetal position can arrest in occipitotransverse position, usually caused by cephalopelvic disproportion (head or body is too large for passage through pelvis)
    • Presentation
      • Occipitoanterior (preferred)
      • Face
      • Brow
      • Occipitoposterior
      • Breech
    • Estimated weight
      • Performed by abdominal palpation and measurement of fundal height, which requires experience to judge when it is appropriate to obtain an ultrasonographic study that more accurately estimates fetal weight
      • Both clinical assessment and ultrasonography have a large degree of error in determining fetal weight
    • Suspected fetal macrosomia (fetal weight more than 4500 g in diabetic women or exceeding 5000 g in nondiabetic women) 
      • Suspected on basis of fundal height, palpation of the fetus, and/or ultrasonographic findings
  • Uterine contractions
    • Palpate gravid abdomen to detect contractions while monitoring fetal heart rate with handheld Doppler ultrasonographic device to detect any changes in fetal heart rate in relation to contractions
    • Fetal heart rate tracings are created by using a fetal heart rate monitor attached to a tocometer belt placed on the mother’s abdomen; the monitor also detects uterine contractions
    • Frequency and intensity (measured in Montevideo units) of contractions can be determined if needed by placing an internal pressure monitor (after admission and rupture of membranes)

Causes

• In most cases, abnormal labor is the result of problems with passenger, passage, and power (the 3 Ps):
  • Passenger (ie, fetus)
    • Nonreassuring fetal heart tracing (indicates fetal acid-base imbalance)
    • Macrosomia or cephalopelvic disproportion (fetal weight exceeds 4000-4500 g) 
      • Incidence of shoulder dystocia (obstructed labor with shoulder unable to easily pass under the pubic symphysis) increases with macrosomia
      • Odds ratio of shoulder dystocia with birthweight of 4000 to 4199 g reported as 22.4; with birthweight of 4200 g or more is 76.1 
    • Malposition (any head position other than occipitoanterior)
    • Malpresentation (presentation of any body part but the head)
    • High station in the active phase of labor, including:
      • Ballotable presenting part
      • Not engaged in the pelvis
      • Higher than station −1 (ie, more than 1 cm proximal to the spinous processes) 
  • Passage (ie, pelvic size, shape, and adequacy)
    • Bandl ring (muscular band between the upper and lower uterine segments; may contract and cause obstruction)
    • Uterine abnormality (eg, fibroids and anomalies such as septate, bicornuate, unicornuate, or didelphys uterus)
    • Nongynecoid pelvis
  • Power (ie, uterine contractility)
    • Anesthesia/analgesia (causes decreased uterine contractility or decreased maternal effort)
    • Inadequate contractions
      • Less than 200 Montevideo units (as measured by intrauterine pressure catheter) 
    • Abruptio placentae (premature separation of placenta from uterus)
    • Chorioamnionitis
    • Postdatism (gestation beyond 42 weeks) 
      • Increases risk of macrosomia and nonreassuring fetal heart rate tracing, leading to higher risk of cesarean delivery

Risk factors and/or associations

Age

• Increased maternal age (older than 35 years) 

Genetics

• Genetic predisposition has been suggested but not defined or confirmed 
• Nongynecoid shape of pelvis could be the inherited factor

Other risk factors/associations

• Prelabor rupture of membranes (preterm) occurs in 2% to 3% of pregnancies in the United States 
  • Typically results in longer labor and increased risk of decreased uterine contractility as labor lengthens
  • Risk of intrauterine infection increases as duration of membrane rupture increases
• Nulliparity
  • Particularly associated with prolongation of labor phases
• Multiparity
  • Particularly associated with precipitous delivery (approximately 22% incidence in parous women compared with 7% in nulliparous women) 
• Obesity
  • Longer gestation, increased risk of postdate pregnancy, increased risk of stillbirth, diabetes mellitus, and delivery by cesarean section associated with higher maternal BMI in the first trimester (35 kg/m² or higher) 
• Maternal height less than 150 cm 
• Increased cervical length in midtrimester
• Previous cesarean delivery 
• Pregnancy complications (eg, high blood pressure, low-lying placenta, gestational diabetes) 

Diagnostic Procedures

Primary diagnostic tools

• Arrest and protraction disorders of active labor are diagnosed based on results of serial digital cervical examinations compared with known normal durations of the stages of labor 
  • Typically, cervical examinations occur every 2 hours during active phase of labor to determine cervical change
  • Examination findings are graphically represented on a partogram to allow comparison with established norms
• Uterine contractions can be monitored externally with a tocometer belt on the gravid abdomen or internally with an intrauterine pressure catheter 
  • Intrauterine pressure catheter may be especially helpful for obese patients, for whom palpation or external monitoring may not detect contractions as well
    • Useful when there is lack of progress in labor and adequacy of uterine contractions is in question
• Fetal heart rate can be monitored externally by a belt on the gravid abdomen, by telemetry, or by handheld Doppler device, or internally with an electrode placed on the fetal scalp 
  • Internal monitoring is usually only necessary if the external monitor might be inadvertently detecting maternal heart rate, if there is possible arrhythmia and a clearer tracing is required, and if it is twin gestation 
    • Used often in patients who are obese, for whom it may be difficult to determine fetal heart rate with an external monitor
    • In twin deliveries, internal monitoring of presenting twin is often recommended

• No specific laboratory studies are used to diagnose abnormal labor; however, patients with unknown group B streptococcal status who present for delivery have rectovaginal swab samples tested by nucleic acid amplification for group B streptococcus, if available 
• Use amniotic fluid pH test and ferning to confirm rupture of membranes (if needed) 
• Use soaked pad or vaginal fluid from speculum examination
  • Nitrazine test strip indicates neutral pH for amniotic fluid (7.1-7.3), as opposed to vaginal secretions, which are acidic
  • Ferning is visible on microscopic examination of amniotic fluid

Imaging

• Bedside ultrasonography can be used to estimate fetal size and confirm fetal position; not typically required during normal labor 
  • Fetal size 
    • Reference range: weight less than 4990 g in women without diabetes, and weight less than 4491 g in women with diabetes
      • Fetal weight: 50th percentile is 3402 g and 95th percentile is 5171 g 
    • Fetal macrosomia may lead to abnormal labor
  • Lie (longitudinal axis of fetus relative to longitudinal axis of the uterus)
    • May be longitudinal, transverse, or oblique
    • Longitudinal alignment of fetus is essential for progress of normal labor
    • Aids assessment for assisted delivery
  • Cephalic presentation
    • Occipitoanterior (fetus facing the mother’s spine) is most common presentation
    • Occipitoposterior presentation (fetus facing forward) is associated with longer labor and seen in 10% to 13% of patients
  • Attitude
    • Optimal attitude is flexion of the head and neck with fetal chin pointed down into chest
    • Deflexion or asynclitism may self-correct in early labor
      • Asynclitism is lateral flexion of fetal head; parietal bones precede the sagittal suture, which is not central in the pelvis
    • Aids the assessment for instrumental delivery
  • Cervical length
    • Probability of a cesarean delivery increases by approximately 10% with each increase of 1 mm in cervical length above 20 mm at time of labor
      • However, odds of a cesarean delivery are 75% lower in multiparas than in nulliparas with the same cervical length

Functional testing

• Fetal heart rate monitoring 
  • External monitors use Doppler technology; internal monitors read R-R intervals through an electrode placed on fetal scalp
  • Review fetal heart rate tracing approximately every 30 minutes in first stage of labor and every 15 minutes in second stage of labor
  • Fetal heart rate tracing provides information that reflects acid-base status of fetus
  • Defined by category
    • Category I: normal tracings; no specific action required
      • Baseline heart rate: 110 to 160 beats per minute
      • Beat to beat variability: moderate
      • Accelerations of heart rate with fetal movement: present or absent
      • Early decelerations of heart rate with uterine contractions: present or absent
      • Late decelerations: absent
    • Category II: tracings do not predict abnormal fetal acid-base status; continue to monitor
      • May require ancillary tests to ensure fetal well-being (eg, acoustic stimulation and expected fetal heart rate acceleration)
      • May require intrauterine resuscitation measures (eg, fluid bolus, maternal position change, supplemental oxygen, treatment of uterine tachysystole if present)
      • Baseline rate
        • Bradycardia (not accompanied by absent baseline variability): fewer than 110 beats per minute
        • Tachycardia: more than 160 beats per minute
      • Baseline fetal heart rate variability
        • Absent baseline variability with no recurrent decelerations
        • Minimal baseline variability
        • Marked baseline variability
      • Accelerations
        • Absence of induced acceleration with fetal stimulation
      • Periodic or episodic decelerations
        • Recurrent variable decelerations accompanied by minimal or moderate baseline variability
        • Prolonged deceleration for more than 2 minutes but less than 10 minutes
        • Recurrent late decelerations with moderate baseline variability
        • Variable decelerations with other characteristics (eg, slow return to baseline, overshoots)
    • Category III: tracings are associated with abnormal fetal acid-base status
      • Requires expeditious response (eg, intrauterine resuscitation, assisted delivery)
      • Baseline variability is absent and any of the following are present:
        • Recurrent late decelerations
        • Recurrent variable decelerations
        • Bradycardia
      • Sinusoidal pattern

Treatment Goals

• Decrease duration of labor
• Avoid assisted or operative delivery
• Prevent maternal and fetal morbidity and mortality

Disposition

Admission criteria

Admit all pregnant patients (gravida I, gravida II, and so on) who are in active labor to a labor and delivery unit

• Spontaneous contractions; at least 2 per 15 minutes with at least 2 of the following:
  • Complete cervical effacement
  • Cervical dilation of 3 cm or more on first cervical examination
  • Spontaneous rupture of membranes
    • Determine presence of amniotic fluid discharge by identifying pooling within vagina and confirm with a pH test and by ferning of discharge that is allowed to dry on a glass slide

Admission may be delayed for women in latent phase, providing maternal and fetal status is reassuring 

• Offer frequent contact and support as well as nonpharmacologic pain management

Criteria for ICU admission

• Single or multiorgan system failure
• Uterine rupture in the mother
• Maternal hemorrhage
• Cardiac disease requiring telemetry at time of delivery

Recommendations for specialist referral

• Refer to an anesthesiologist for epidural analgesia if patient desires
• Consult an obstetrician or experienced obstetrics provider, especially if:
  • Management of abnormal labor is beyond training and experience
  • Assistance is required for operative or cesarean delivery
  • Assistance is required to manage postpartum hemorrhage
• Postpartum referrals may include:
  • Obstetrician for those who present without obstetric care
  • Pediatrician for newborn care
  • Lactation consultant for breastfeeding support

Treatment Options

When protraction of labor or an arrest disorder is suspected or diagnosed, reevaluate the 3 Ps and ensure maternal and fetal well-being before stimulating labor 

• A consensus document developed by the American College of Obstetricians and Gynecologists and the Society of Maternal-Fetal Medicine suggests allowing 2 hours of pushing for multiparous women and 3 hours of pushing for nulliparous women before diagnosing arrest of labor in the second stage (providing fetal/maternal status remains reassuring) 
• Artificial rupture of membranes can be done when they do not rupture spontaneously in a pregnancy at term, if the fetal head is well-engaged in the pelvis
• Augmentation of labor using oxytocin is indicated when uterine contractions are not adequate to establish or continue labor, before or after rupture of membranes 
  • Oxytocin is the only FDA-approved medication to augment labor
  • An intrauterine pressure catheter is sometimes placed to monitor the strength of contractions and monitor for uterine tachysystole (overstimulation)
    • Not required while undergoing oxytocin augmentation (or induction) of labor
    • Placed when little progress of labor occurs, despite presence of an adequate contraction pattern, to better determine strength of contractions and guide oxytocin use

If membranes have ruptured before the start of labor at term, both induction of labor and expectant management are viable options

• American College of Obstetricians and Gynecologists recommends inducing labor in women who experience rupture of membranes at term but no onset of spontaneous labor near time of presentation 
  • Both options result in similar rates of neonatal infection and cesarean delivery 
    • However, induction of labor with IV oxytocin lowers risk of maternal infection and is recommended by the American College of Obstetricians and Gynecologists 
• May offer expectant management for 12 to 24 hours after membrane rupture if there are no other reasons to expedite delivery 
  • Do not delay prophylaxis for group B streptococcus while awaiting labor if patient has had previous positive culture/nucleic acid amplification test results; immediate induction may be preferable 
• May use oxytocin to induce labor
  • A thickened, undilated cervix at term is considered unfavorable to induction and is treated by softening or ripening the cervix, typically with a prostaglandin preparation
• Prostaglandins are more effective than oxytocin at inducing (not augmenting) labor within 24 hours of rupture of membranes; however, prostaglandins are associated with increased risk of chorioamnionitis 
  • Misoprostol, a prostaglandin, is FDA-approved for cervical ripening and labor induction; dinoprostone is alternate option for prostaglandin cervical ripening and labor induction
    • Do not use misoprostol to induce labor in women who have had previous cesarean delivery or major uterine surgery owing to risk of uterine rupture; avoid exposure to this drug during third trimester 
  • Treat failed induction (ie, no labor ensues within 24 hours of prostaglandin placement) with high-dose oxytocin infusion for up to 12 hours
    • Do not administer oxytocin less than 4 hours after the last placement of misoprostol, 6 to 12 hours after placement of dinoprostone gel, or 30 to 60 minutes after removal of a sustained-release form of dinoprostone
  • As long as the patient is making progress, even slowly, cesarean delivery is not indicated 
• Allow at least 12 to 18 hours of latent labor before considering induction to have failed; this can help reduce necessity of cesarean delivery

If fetal presentation is not occipitoanterior, manual rotation can be helpful if cervical dilation is more than 7 cm, although best results are achieved at full dilation 

Instrumental (operative) delivery is indicated for arrest, fetal distress, or maternal exhaustion in second stage of labor

• Consider antibiotic prophylaxis to reduce perineal wound infection and other infectious complications in women undergoing operative vaginal deliveries 
• The role of routine episiotomy for instrumental vaginal birth is unclear
  • ACOG recommends against routine episiotomy for operative delivery owing to reported poor healing and discomfort with mediolateral incisions and increased risk of injury to the anal sphincter and extension into the rectum with midline incisions 
  • Australasian guidelines suggest considering episiotomy in women having their first vaginal birth assisted by forceps or vacuum extraction as this practice is associated with reduced rate of obstetric anal sphincter injuries, particularly when forceps are used 

Cesarean delivery is indicated for: 

• Labor arrest in the second stage, when instrumental delivery is not an option (eg, arrest at high station)
• Labor arrest in first stage
• Fetal malpresentation that preempts vaginal delivery

Begin intrapartum group B streptococcal prophylaxis at time of admission or rupture of membranes and continue every 4 hours until delivery in the following patients: 

• Those with positive vaginal-rectal culture for group B streptococcus at 36 to 38 weeks of gestation or those who have had group B streptococcal bacteriuria during any trimester
• Those who have previously given birth to an infant with early-onset group B streptococcal disease
• Those with unknown group B streptococcus status when labor starts and any of the following:
  • Risk of preterm birth
  • Preterm premature rupture of membranes
  • Rupture of membranes for 18 hours or more at term
  • Intrapartum fever (38 °C or higher)
  • Intrapartum positive nucleic acid amplification test results for group B streptococcus
  • Positive culture for group B streptococcus in a previous pregnancy

Appropriate antibiotics for group B streptococcal prophylaxis include penicillin G or ampicillin if patient is not truly penicillin allergic 

Drug therapy

• Oxytocin 
  • Indicated for labor augmentation
  • Consider augmentation with oxytocin if there is protracted or arrested first-stage labor (assuming fetal monitoring is reassuring) with 6 cm or more of cervical dilation lasting: 
    • 4 or more hours with ruptured membranes and adequate contractions (eg, internal pressure catheter shows intrauterine pressure of more than 200 Montevideo units) and no cervical change 
    • 6 hours or more of inadequate contractions and no cervical change 
  • Low-dose regimen is used to augment labor
    • Oxytocin Solution for injection; Adult females: 0.5 to 1 milliunit/minute via continuous IV infusion initially. May slowly increase (e.g., 1 to 2 milliunits/minute increments at 30 to 60-minute intervals) until the desired contraction pattern has been established. Once the desired frequency of contractions is obtained and labor has progressed to 5 to 6 cm dilation, the dose may be reduced by similar increments.
  • Can be used after initial treatment with intravaginal misoprostol or dinoprostone for labor induction if necessary 
    • High-dose regimen is indicated to induce labor
      • Oxytocin Solution for injection; Adult females: Various protocols are reported in the literature. 6 milliunits/minute via continuous IV infusion is a common initial infusion rate. May increase (e.g., 3 to 6 milliunits/minute increments at 15 to 60-minute intervals) until the required contraction pattern is established. A reduced incremental increase should be used if there uterine hyperstimulation occurs. Suggested Max: 40 milliunits/minute.
  • Adverse effects may include uterine hypertonicity, known as tachysystole (more than 5 contractions per 10 minutes, averaged over a 30-minute window), which can further lead to fetal heart rate decelerations 
    • Treat by reducing or discontinuing oxytocin infusion; may be improved by subcutaneous terbutaline 
• Tocolytic agent
  • Terbutaline
    • Indicated for off-label use to improve hypertonicity (tachysystole) and fetal heart rate decelerations induced by oxytocin use 
      • Terbutaline Sulfate Solution for injection; Pregnant females: 0.25 mg subcutaneously injected into the lateral deltoid area every 15 to 30 minutes as needed. Total dose within 4 hours should not exceed 0.5 mg. Hold for pulse more than 120 beats/minute. If the patient fails to respond, use other measures (eg, sublingual nitroglycerin).
• Prostaglandins
  • Misoprostol vix and induce labor
    • Inducing labor is appropriate in the setting of membrane rupture, when labor has not yet begun
      • Misoprostol Oral tablet; Adult females: 25 mcg vaginally (inserted  into the posterior vaginal fornix) every 3 to 6 hours is considered effective for cervical ripening and induction of labor. Most off-label protocols limit duration of use to 24 hours (roughly 5 doses). The use of higher dosages (50 mcg every 6 hours intravaginally) to induce labor may be appropriate in some situations, although an increased risk of complications has been reported with doses greater than 25 mcg/dose in term pregnancies. High doses (200 to 400 mcg vaginally inserted every 4 to 12 hours) to induce labor are reserved for patients of less than 28 weeks gestation with intrauterine fetal demise.
  • Dinoprostone 
    • Indicated to ripen cervix and induce labor
    • An advantage of dinoprostone is its availability as a sustained-release form that can be removed from the vagina should uterine tachysystole occur
      • Dinoprostone Vaginal gel; Adult females: 0.5 mg gel placed into the cervical canal (endocervical application). If the desired response is obtained, the recommended interval before giving oxytocin IV is 6 to 12 hours. If there is no cervical/uterine response to the initial dose, a repeat dose may be given (0.5 mg gel every 6 hours). Max cumulative dose: 1.5 mg (7.5 mL of gel)/24 hours.
      • Dinoprostone Vaginal insert; Adult females: One 10 mg vaginal insert administered high into the vagina and placed transversely in the posterior fornix. The insert delivers 0.3 mg/hour of dinoprostone over a 12-hour period. Remove the insert upon onset of active labor or 12 hours after insertion. Remove at least 30 minutes prior to administering an oxytocic agent. Also remove prior to an amniotomy, occurrence of uterine tachysystole, uterine hypersystole/hypertonicity, or fetal distress.
• Inhaled analgesia
  • Nitrous oxide with oxygen 
    • 30% to 60% admixture
    • Self-administered using a facemask or mouthpiece; patient inhales 30 to 60 seconds before each contraction
    • Maximum 8-hour time-weighted average concentration of 25 ppm
  • Fluorane derivatives with oxygen (available but not used commonly in the United States) 
    • Enflurane Inhalation vapour, solution; Adults: 0.25% to 1% delivered via inhalation produces analgesia during vaginal delivery similar to that produced by 30% to 60% nitrous oxide.
    • Other fluoranes effective for labor analgesia
      • Desflurane 1.4% to 5%
      • Isoflurane 0.2% to 0.75%
      • Sevoflurane 0.7%
• Opioids
  • Fentanyl Citrate Solution for injection; Adults females: 50 to 100 mcg IM or slow IV over 1 to 2 minutes. The dose may be repeated in 1 to 2 hours, as needed. 
• Local anesthetic for episiotomy
  • Lidocaine 1% to 2% infiltrated locally 
  • Prilocaine 0.5% infiltrated locally 
• Antibiotics
  • Appropriate antibiotics for group B streptococcal prophylaxis include penicillin G or ampicillin if patient is not truly penicillin allergic 
    • Penicillin G Sodium Solution for injection; Pregnant females: 5 million units IV load initiated at the time of labor or rupture of membranes, followed by 3 million units IV every 4 hours until delivery.
    • Ampicillin Sodium Solution for injection; Pregnant females: 2 g IV load initiated at the time of labor or rupture of membranes, followed by 1g IV every 4 hours until delivery.
  • If patient reports allergy to penicillin but did not experience angioedema, anaphylaxis, respiratory distress, or urticaria, cefazolin is indicated
    • Cefazolin Sodium Solution for injection; Pregnant females: 2 g IV load initiated at the time of labor or rupture of membranes, followed by 1 g IV every 8 hours until delivery.
  • If patient has true allergy to penicillin or cephalosporins (ie, experiences angioedema, anaphylaxis, respiratory distress, urticaria with exposure), and isolate is known to be susceptible to clindamycin or erythromycin, then clindamycin is indicated; otherwise, may use vancomycin
    • Clindamycin Phosphate Solution for injection; Pregnant females: 900 mg IV every 8 hours initiated at the time of labor or rupture of membranes and continued until delivery.
    • Vancomycin Hydrochloride Solution for injection; Pregnant Females: 20 mg/kg/dose (Max: 2 g/dose) IV every 8 hours intrapartum.

Nondrug and supportive care

Positioning and ambulation

• Laboring women may choose the position for labor that is the most comfortable and are encouraged to ambulate during the first stage 
  • Upright positioning includes kneeling, sitting, semirecumbent (trunk tilted 30° backward), or squatting; any of these positions are used for labor
  • Upright positioning has been found in some studies to decrease risk of cesarean delivery and need for epidural analgesia

Continuous 1-on-1 support 

• Vaginal birth is more likely with at least 1 companion (eg, doula) providing emotional support, in addition to regular nursing care, throughout labor

Pain relief

• Relaxation techniques 
  • Hypnosis during labor has shown some benefit 
  • Breathing techniques and massage
  • Meditation and yoga
  • Water immersion 
• Nonepidural analgesia, inhaled  or opioid 
• Epidural analgesia
  • Can be offered at any stage of labor at patient’s request 

Oral hydration 

• IV fluids or placement of IV access are not routine unless patient is unable to maintain adequate hydration with oral fluids
• IV fluid infusion is helpful before epidural analgesia to help prevent hypotension

Maternal oxygen 

• Used to improve fetal oxygenation when fetal heart rate pattern is concerning

Easily digestible food and fluid intake as requested by the patient 

• Light meals, juices, and soups

Assisted (instrumented) or cesarean delivery may be necessary when prompt delivery is indicated 

Manual delivery of the placenta is performed when the norms of the third stage of labor are exceeded, typically if the placenta remains undelivered after 30 minutes

• Involves removal by hand and curettage under appropriate anesthesia
• Some authors advocate for waiting a shorter period (15 minutes) before intervention, owing to decreased risk of hemodynamic compromise 

Procedures

Artificial rupture of membranes (amniotomy) 

General explanation

• An amnio hook (crochet hook–like instrument) is used to snag and rupture the bag of waters, thereby stimulating labor (when spontaneous rupture of membranes does not occur in a pregnancy at term)
• Only perform if the head is well engaged in the pelvis and there is no concern for umbilical cord prolapse
• Rupture membranes before second stage of labor to evaluate amniotic fluid for possible meconium passage
  • If meconium is present, a neonatal practitioner is often present at delivery to help prevent meconium aspiration

Indication

• Not routinely indicated 
• Spontaneous rupture of membranes fails to occur by second stage of labor
• Internal fetal or uterine monitoring is required (eg, during oxytocin infusion)

Contraindications

• Fetal head is not well engaged in pelvis
  • Fetus may turn to breech position, making birth more difficult
• Concern for umbilical cord prolapse
  • Cord compression can compromise blood flow to fetus

Epidural analgesia

General explanation

• Injection of local anesthetic within the epidural space of the lower spine 
  • Requires an anesthesiologist
  • Analgesia may not be adequate in some cases
• Adverse effects include muscle weakness, nausea, shivering, itching, headache, fever, fluid retention, temporary motor blockade after birth, and hypotension 
• Epidural analgesia with low concentration infusions of bupivacaine does not increase probability of cesarean delivery; earlier association with increased likelihood of operative delivery and longer duration of second stage of labor is not seen in recent studies involving modern approaches to epidural analgesia 
• Women who use epidural analgesia are also more likely to need labor contractions stimulated with oxytocin 

Indication

• Patient request for pain relief during active labor 

Contraindications 

• Hemorrhage
• Coagulopathy
• Moderate to severe thrombocytopenia
• Concerns for increased intracranial pressure
• Infection

Manual rotation 

General explanation

• In the setting of abnormal labor, application of manual pressure to gravid abdomen to turn a fetus from a malpresentation to occipitoanterior presentation
  • Patient, with bladder emptied, lies in a dorsal recumbent position
  • When uterus is relaxed, gently place 2 fingers or, if possible, the entire hand behind the fetal ear (right ear for left positions and left ear for right positions)
  • Use the right hand for left occipitoposterior and occipitotransverse positions, and the left hand for the right occipitoposterior and occipitotransverse positions
  • While the patient is pushing, during a uterine contraction, apply pressure to rotate the anterior fetal head
  • May be repeated if unsuccessful

Indication

• Fetal malposition during active phase of labor

Contraindications

• Vaginal birth is not anticipated
• If fetal bradycardia occurs or procedure is too uncomfortable for mother, abandon attempt

Interpretation of results

• Attempting external cephalic version at term does not appear to increase perinatal morbidity or mortality compared with expectant management 

Instrumental vaginal delivery 

General explanation

• A vacuum-assisted suction cup or metal forceps is applied to the fetal head to extract fetus from birth canal

Indication

• Protraction or arrest disorder during the second stage of labor 
• Immediate or potential fetal compromise during the protracted second stage of labor
• Maternal exhaustion
• Maternal cardiac condition preempting hard straining at delivery

Contraindications 

• Unengaged fetal head
• Unknown fetal position
• Malpresentation
• Suspected cephalopelvic disproportion
• Fetus known or strongly suspected to have a bone demineralization condition or a bleeding disorder
• Vacuum extraction has been discouraged when gestational age is less than 34 weeks (relative contraindication)

Episiotomy 

General explanation

• Second-degree tear by definition
  • Administer local anesthesia
  • Use large, straight Mayo scissors to make the incision
  • Mediolateral episiotomy
    • Incision is placed at 45° angle from the midline
    • Extended approximately 4 cm in the direction of the right ischial tuberosity
  • Midline or median episiotomy
    • Vertical incision from midline of the posterior fourchette towards the rectum
    • Cut is approximately one-half the length of the perineum

Indication

• Short perineum (shorter than 3 cm)
• Shoulder dystocia
• Operative delivery
• Need to expedite delivery owing to nonreassuring fetal heart rate tracing

Contraindications

• Coagulopathy

Cesarean delivery 

General explanation

• Fetus is delivered through abdominal and uterine incisions

Indication

• Active phase arrest in first stage of labor in a patient whose cervix has dilated to at least 6 cm
• Protraction or arrest disorder of second stage of labor
• Fetal distress
• Maternal exhaustion with fetal head at high stage in pelvis
• Active genital herpes
• Fetal malpresentation preempting vaginal delivery
• Previous uterine scar
• Placenta previa
• Uterine rupture

Comorbidities

• Preexisting infection (eg, group B streptococcus)
  • Treat with antibiotics (ie, penicillin, ampicillin, cefazolin, clindamycin)
• Gestational diabetes
  • Suspect fetal macrosomia and advise cesarean delivery if diagnosis is confirmed
• Obesity
  • Suspect fetal macrosomia and advise cesarean delivery if diagnosis confirmed
  • Epidural analgesia may be less effective

Monitoring

• Maternal
  • During first 24 hours postpartum 
    • Beginning in the first hour postpartum, regularly assess the following:
      • Vaginal bleeding
      • Uterine contraction
      • Fundal height
      • Temperature and heart rate
    • Measure blood pressure shortly after birth and again in 6 hours
    • Document urine voiding within 6 hours after birth
  • Beyond the first 24 hours postpartum 
    • Enquire about general well-being and assess the following:
      • Micturition and urinary incontinence
      • Healing of any perineal wounds
      • Bowel function
      • Fatigue
      • Headache
      • Back pain
      • Perineal pain and hygiene
      • Breast pain
      • Uterine tenderness
      • Lochia
    • Assess breastfeeding progress at every postnatal contact
    • Assess emotional well-being and family and social support
      • Encourage all women and family or partners to report any mood or behavior change
    • Discuss sex
      • Advise her to refrain from sexual intercourse at least until perineal wound heals
      • Explain that she can become pregnant as soon as 4 weeks after delivery; discuss and provide contraception as desired
    • Discuss hygiene and washing to prevent infection
  • At 4 to 6 weeks postpartum, evaluate mother to assess recovery from pregnancy and birth 
    • Perform pelvic and perineal examination for uterine involution (return to pregravid state) and perineal healing
    • Evaluate for medical complications (eg, urinary incontinence, thyroid disorders)
    • Provide breastfeeding support
    • Screen for postpartum depression (use of standardized screening tool is recommended)
    • Again discuss and provide appropriate contraception
• Newborn
  • Provide postnatal care to newborns in the birthing facility for at least 24 hours postpartum 
    • Further pediatric assessment is needed if any of the following are present:
      • Cessation or lack of development of adequate feeding
      • Seizures
      • Tachypnea (60 or more breaths per minute)
      • Severe chest retractions
      • Lack of spontaneous movement
      • Fever (37.5 °C or higher)
      • Low body temperature (below 35.5 °C)
      • Jaundice developing within the first 24 hours of life
      • Jaundice involving palms or soles at any age

Complications

• Prolonged first stage of labor is associated with an increased risk of maternal fever, postpartum transfusion, prolonged second stage, higher-order perineal lacerations, cesarean delivery in the second stage of labor, operative vaginal delivery, respiratory distress syndrome, and neonatal sepsis 
• Prolonged second stage of labor is associated with an increased risk of postpartum hemorrhage, chorioamnionitis, endometritis, postpartum fever, obstetric anal sphincter injury, neonatal intensive care admission, and neonatal sepsis 
• Maternal complications
  • Uterine tachysystole
    • Defined as more than 5 contractions every 10 minutes, averaged over 30 minutes 
    • Attempt intrauterine resuscitation with the following common techniques: 
      • Maternal repositioning and/or alteration in second-stage labor maternal pushing efforts
      • Treat maternal hypotension; administer oxygen or an IV fluid bolus to the mother
      • Amnioinfusion with room temperature normal saline through an intrauterine pressure catheter 
    • Administer tocolytic medications (eg, terbutaline) to reduce uterine activity
  • Perineal trauma
    • Tearing due to edema of perineal tissue with prolonged labor, especially during the second stage
    • Third- or fourth-degree perineal tear presents in 5% of all deliveries; fourth-degree tear presents in 1.7% of deliveries 
    • Relative risk of this complication is approximately 4 times higher in instrument-assisted deliveries 
  • Endometritis
    • Most common infection in puerperal period
      • Occurs in 1% to 3% of uncomplicated vaginal deliveries 
      • Relative risk of this complication is 1.2 in instrumental deliveries (95% confidence interval, 1-1.5) 
      • Usually develops on second or third postpartum day
    • Presents with foul smelling lochia; fever and abdominal pain indicate a more severe infection
    • Related to prolonged rupture of membranes, prolonged second stage of labor, intrauterine monitoring, frequent vaginal examinations, operative delivery, and lack of prenatal care
    • Primary treatment options include IV therapy with combination of gentamicin and clindamycin 
  • Amnionitis (infection of fetal membranes, chorion, and amnion)
    • Most commonly seen in cases of prolonged labor or premature rupture of membranes, of multiple cervical examinations, or with internal fetal monitoring
      • Occurs in 1.9% of all deliveries 
      • Relative risk of this complication is 1.2 in instrumental deliveries (95% confidence interval, 1-1.5) 
    • Presents with foul smelling fluid on rupture of membranes, fever, uterine tenderness, and fetal and maternal tachycardia
    • Primary treatment options include IV therapy with combination of ampicillin, gentamicin, and clindamycin or IV piperacillin-tazobactam 
  • Uterine rupture
    • Associated with congenital uterine anomalies, previous cesarean section or myomectomy, fetal macrosomia, labor induction, and uterine instrumentation
    • Occurs in 1.4% of patients undergoing induction who have had a previous cesarean delivery 
    • Relative risk of this complication is 1.2 in assisted (instrumental) deliveries (95% confidence interval, 1-1.5) 
  • Postpartum hemorrhage 
    • Loss of more than 500 mL of blood within the first 24 hours after vaginal birth (or loss of more than 1000 mL with a cesarean delivery)
    • Can be diagnosed if vaginal bleeding is greater than expected (ie, soaks more than 1 pad in 5 minutes)
    • Often due to uterine atony from prolonged labor
      • Finding of boggy uterus on bimanual examination is diagnostic
      • Initial action is to compress and massage the uterus
        • Evaluate vaginal vault and cervix for lacerations and repair if needed to arrest bleeding
        • Evaluate for hematomas and drain if enlarging, suturing the incision; may have to pack vagina with gauze to prevent reforming hematoma and to stop bleeding
      • Continued bleeding from the uterus requires use of uterotonic medications, such as:
        • Oxytocin
        • Methylergonovine
        • 15-methyl PGF₂α (avoid in patients with asthma)
        • Dinoprostone (avoid in patients with hypotension)
        • Misoprostol
      • If uterotonics fail to control bleeding, packing or tamponade of the uterus is indicated:
        • Pack with gauze from 1 cornu to the other, back and forth, until uterus is packed and gauze extends through the cervical os
          • Use 2.54-cm gauze soaked in 5000 units of thrombin in normal saline
        • Tamponade balloons are also available; additionally, 1 or more Foley catheters can be placed, instilling each bulb with 60 to 80 mL of saline
      • Continued bleeding after packing requires surgical management (eg, bilateral uterine artery ligation)
  • Genitourinary infection
    • Occurs in 2.7% of all deliveries 
    • Relative risk of this complication is 1.4 in instrumental deliveries (95% confidence interval, 1.1-1.8) 
  • Episiotomy complications 
    • Possible risk of further injury to the perineum, rectum, or anal sphincter
    • Urinary and fecal incontinence
    • Dyspareunia
  • Operative delivery complications 
    • Urinary and fecal incontinence for months to years postpartum
    • Severe blood loss
    • Hematomas
• Fetal/newborn complications
  • Decreased Apgar scores 
  • Fetal hypoxia (birth asphyxia)
  • Respiratory morbidity with possible meconium aspiration
    • Lower risk in vaginal delivery compared with cesarean delivery
  • Birth injuries, including intracranial hematomas and fractures
  • Neonatal infection

Prognosis

• Prognosis is excellent in most cases if appropriate steps are taken in a timely fashion to hasten the progress of labor
  • Minimal neonatal morbidity and mortality
    • 1 death per 1600 live births by vaginal delivery 
    • Risk of neonatal mortality for vaginal delivery is one-half that of primary cesarean delivery 
  • Minimal maternal morbidity and mortality
    • 1 death per 10,000 live births by any method of delivery 
    • Risk of severe maternal morbidities in vaginal delivery is one-third that of cesarean delivery (0.9% versus 2.7%, respectively) 
      • Higher risk of complications when second stage exceeds 2 to 3 hours 
      • Relative risk of maternal morbidity is 1.3 for assisted (instrumental) deliveries 

Screening

At-risk populations 

• Pregnant patients with a contracted pelvis (ie, 1 or more of the diameters is smaller than reference range, interfering with normal mechanisms of labor)
• Advanced maternal age (older than 35 years)
• Pregnant patients shorter than 150 cm 
• Gestational age more than 41 weeks
• Pregnant patients with a history of abnormal labor
• Interval between receipt of epidural analgesia and full cervical dilation longer than 6 hours
• High fetal station when cervix is fully dilated (eg, fetal station at more than −2 cm [2 cm distal to ischial spines])
• Occipitoposterior fetal position, as determined at presentation

Screening tests 

• History and physical examination at time of presentation for delivery, particularly bimanual pelvic examination and digital examination of the cervix, provide information that allows discernment of patients at risk for labor protraction or arrest

Prevention

• There is no evidence that abnormal labor can be prevented 
  • However, maternal freedom of movement and position during labor and birth and continuous care throughout have been shown to increase likelihood of achieving a normal birth 

Sources

1: Zhang J et al: Contemporary patterns of spontaneous labor with normal neonatal outcomes. Obstet Gynecol. 116(6):1281-7, 2010

Cross Reference