LABOR PROGRESS AND DYSTOCIA


I. Assessment of Labor

  1. See also stage-specific information below
  2. Evaluation of uterine contractions
    1. External tocodynamometry (may have limited accuracy in obese pts)
    2. Internal tocodynamometry with intrauterine pressure catheter (IUPC)
      1. Often used if uterine contractions and/or labor progress is felt to be insufficient, particularly if cesarean delivery is being considered.
      2. Intrauterine vs. external tocodynamometry was not associated with any sig. diff. in incidence of cesarean delivery, time to delivery, antibiotic use, analgesic use, or adverse neonatal outcomes in a randomized study in pts at > 36wks with singleton pregnancies in cephalic position with no indication for induction or augmentation of labor, no h/o uterine incision, and no indications of maternal infection or fetal distress (NEJM 362:1849, 2010-AFP)
    3. Cervical exam (consistency, length, diameter)

II. Stage 1 (onset of contractions until complete dilation of cervix)--Data comes from studies of Friedman in 1950's

  1. Avg. total duration 12-17h primip, 6-10h multip
  2. Usually divided into "Latent" and "Active" phases
    1. Latent phase
      1. Arbitrarily defined as up to 3-4cm dilation
      2. Avg. duration phase 8.6h primip, 4-5h multip
      3. "Prolonged latent phase" = >20h primip, >14h multip
      4. Management of latent phase = emotional support, avoid hospital admission (increases risk of operative delivery), hydration, sedation if needed
    2. Active phase
      1. Minimal progression per Friedman = for cervical dilation: 1.2cm/h primip, 1.5cm/h multip; for descent = 1cm/h primip, 2cm/h multip (can be less w/epidural)
      2. Walking may shorten stage 1 of labor thus prevent Dystocia (see below)
        1. 1097 women randomized to walking-as-desired (only 75% actually walked) vs. "usual care" (labor in bed) during stage 1 at 36-41wks with vtx presentation, regular uterine ctx and 3-5cm cervical dilatation, ok multip or primip. All underwent amniotomy if membranes were intact; pit used if no cervical change in 2-3h and ctx shown to be inadequate with IUPC. There were no sig. differences in duration of stage 1 or 2, need for oxytocin augmentation, need for analgesia, frequency of episiotomy, use of forceps, c/s, risk of chorioamnionitis, or neonatal outcomes (NEJM 339:76, 1998--AFP/JW)
        2. But other randomized trials show decreased labor duration in women allowed to walk (Obs. Gyn. 67:727, 1986, cited in ALSO syllabus)
      3. Routine Amniotomy can shorten labor but increased rate of c/s for fetal distress in one randomized trial (Br. J. Obs. Gyn 104:548, 1997--abst)

III. Stage 2:

  1. "Prolonged" stage 2 = for nullips: >2h (>3h with epidural); multips > 1h (>2h with epidural) per ALSO 2002
  2. Used to say shouldn't allow to go on >2h but now considered ok with FHR monitor if some evidence of progress
  3. Same normal values for descent as for Stage 1 labor
  4. If pt has no urge to push in early stage 2, it may help prevent maternal exhaustion to have her wait to push until she gets the urge
    1. In a study in 325 nulliparous women with uncomplicated labors who had not received epidural anesthesia randomized to coached pushing vs.  no coaching, the coached pts had sig. shorter stage 2's (46 vs. 59 minutes) but no sig. diff. in incidence of prolonged second stage, Apgar score, umbilical artery pH, need for neonatal resuscitation, or perineal laceration.  Coached pts had sig. higher incidence of meconium staining of amniotic fluid (Am. J. Obs. Gyn. 194:10, 2006--JW)

IV. Stage 3

  1. "Active management" can reduce postpartum hemorrhage--See link for details
  2. In a study in 79 women with uncomplicated singleton pregnancies randomized to injection in the umbilical vein (after cord clamping) of oxytocin 20IU in 30mL of saline injected vs. saline placebo, incidence of placental retention at 15min wa ssig. lower in active-tx group, though there was no sig. diff. in mean time to placental delivery (Presented at the annual meeting of the Society for Maternal-Fetal Medicine--FP News 5/1/06)
  3. Retained placenta--Can treat with:
    1. Oxytocin 20U in 20cc NS in umbilical vein may result in detachment
    2. Manual removal of placenta--Hold fundus with abdominal hand; be on lookout for accreta; follow with digital exam of uterus with gauze to get all fragments

IV. Dystocia--usually only diagnosed after active labor is established

  1. Per ACOG, divided into two categories:
    1. "Protraction disorder" = cervical dilation or descent less than minimum figures above
    2. "Arrest disorder" = no progress in dilation in 2h or active labor or no progress in descent in 1h of active labor
  1. Causes--usually divided into 3 categories:
    1. "Power" = inadequate ctx, e.g. from infection, sedation, anesthesia
      1. Diagnosis = by intrauterine pressure catheter; contractions should be > 50mm Hg
      2. Note--I've heard it said if you can manually indent uterus during a ctx, it is <50mm Hg
    2. "Passage" = maternal pelvic anatomy
    3. "Passenger" = fetal macosomia, malposition, or malformation
  1. Treatment
    1. Treat malposition if present
    2. Amniotomy
    3. Oxytocin augmentation
      1. Consider if not progressing as expected despite amniotomy and there's evidence for inadequate contraction pattern (IUPC shows ctx peaks < 50mm Hg or ctx < Q3min or < 30sec duration)
      2. Same dosing parameters as for Induction--click on link for details
    4. Cesarean section if no progress with oxytocin and adequate contractions x 2-4h
    5. Propranolol--96 women with arrest of dilatations during active labor, vertex presentation, EFT 2.5-4.5kg. Excluded if mom with HTN, tachycardia, bradycardia, asthma, diabetes. Randomized (double-blind) to IV propanolol 2mg vs. placebo; oxytocin was also administered. Med (propanolol vs. placebo) repeated after 1h if necessary; those who didn't respond to 2nd dose underwent c/s. 2 groups were similar in age, race, parity, gestational age, and height/wt. Sig. lower c/s rate in propanolol group vs. placebo group (51% vs. 27%); persisted controlling for parity, birth weight, and use of epidural anesthesia. NO diff. in mat. morbidity, birth weight, Apgars, NICU admission, or cord gas values. (Obs. Gyn 88:517, 1996-AFP)
    6. Meperidine for Stage 1 dystocia
      1. Meperidine, in addition to being an analgesic, increases uterine contractility
      2. However, in a study in 407 women with term singleton pregnancies, vertex presentation, ruptured membraines, cervical dilation 4-6cm, and diagnosed with inadequate uterine contractility randomized to meperidine 100mg over 15min vs. placebo, time to delivery was not sig. different between the two groups but infants of meperidine recipients were sig. more likely to have lower Apgar scores, umbilical artery acidosis, and NICU admission (Am. J. Obs. Gyn. 191:1212, 2005--AFP)

V.  "Active Management" of labor starting in stage 1--Shortens labor but no consistent evidence as of 2001 that it decrease c/s rate or maternal or neonatal morbidity.  Consists of:

  1. Patient education
  2. Accurate diagnosis of labor
  3. Early amniotomy
  4. Oxytocin for non-progression
  5. Continuous labor support
  6. Postpartum review/audit of cases