14. Dysfunctional Labor Flashcards
Describe the physiologic changes that occur to the uterus during labor
- Uterus is a large organ made up of __________
- Contractile smooth muscle cells
- When intracellular Ca2+ increases => actin-mysin elements form
- Oxytocin increases formation
- During gestation = contractions occur in localized areas. During labor = ENTIRE uterus contracts d.t gap junctions
During labor, 2 distinct segments of the uterus are formed, what is the function of each?
- Upper segment: actively contracts and retracts to expel fetus
- Lower segment: becomes thinner and passive
Uterus:
How is relaxation and contraction maintained?
- Relaxation = increase cAMP
- Contraction = increase in intracellular Ca2+ => actin-myosin => contraction
Describe the physiologic changes that occur to the cervix during labor?
Collagen and smooth muscle undergo collegenolysis:
- ↑ in hylauronic acid
- ↓ in dermaan sulfate
- => ↑ water content => cervix changes from firm, intact sphincter => soft, pliable and dilatable.
The active phase of the 1st stage of labor starts when the cervix is dilated how far?
6 cm
What is labor?
Contraction of the uterus that is sufficient enough to cause effacement and dilate the cervix.
What is the 4th stage of labor?
12-24 hours after delivery where there is an increase chance of post-partum hemorrhage.
What is the latent phase of the 1st stage of labor?
Cervix softens and effaces, with LITTLE dilation (less than 6cm)
What are the normal limits of the latent phase for nulliparous and multiparous women (hours)?
- Nulliparous = up to 20 hours
- Multiparous = up to 14 hours
In general how are abnormalities of the latent phase managed?
[Admit for therapeutic rest (sleep)] + [morphine (15-20mg)]
Most of the time, they will progress to active phase :)
For all phases of labor (EXCEPT latent phase), what abnormalities can you see in labor?
- Protraction = slower rate than NL
- Arrest = complete cessation of dilation or descent
Has labor began if in arrested latent phase?
No, labor has not began.
What is “dysfunctional labor”?
Rates of dilation and descent exceed NL times.
What is a prolonged latent phase and what outcome does it have on perinatal mortality?
- Longer than NL latent phase
- Outcome has LITTLE effect on perinatal mortality.
What are causes of prolonged latent phase?
- Enter labor without change in cervix
- Excessive use of sedatives or analgesics
- Fetal malposition
Pt comes in and is miserable: contracting, lots of pain, but NO dilation?
- Admit for therapetuic rest + morphine
What are the NL limits of the active phase for cervical dilation (cm/hr) in nulliparous vs. multiparous woman?
- Nulliparous = 1.2 cm/hr
- Multiparous = 1.5 cm/hr
What are the NL limits of the active phase for fetal descent (cm/hr) in nulliparous vs. multiparous woman?
- Nulliparous = 1 cm/hr
- Multiparous = 2 cm/hr
What is protaction dilation/protraction descent?
- Protraction dilation = cervical dilates less than NL active phase
- Protraction descent = fetus descends less than NL active phase
What is arrest of dilation/arrest of descent?
- Arrest of dilation => 2 or more hours with no dilation of cervix.
- Arrest of descent => no change in descent/station 1 hour within an arrest.
What effects do abnormalities of active phase have on perinatal mortality?
- Increase risk of perinatal mortality
What can cause active phase abnormalities?
- Inadequate uterine activity
- Cephalopelvic disproportion
- Fetal malposition
- Anesthesia
Dystocia or “difficult labor” is labor that is not progressing properly due to abnormalities of the three P’s, which are?
- Power = contractions or maternal expulsive forces
- Passenger = fetus position, size, or presentation
- Passage = maternal pelvic bone contractures
Diagnosis of dystocia should NOT be made before what?
Trial of labor has been tried
What is augmentation?
Patient starts to have contraction, but you want to make them stronger because they are NOT causing dilation or descent.
Methods of augmentation.
- Pitocin
- Rupture of membranes
At which contraction rate and/or intensity should you consider augmentation of labor?
Less than 3 contractions/10 minutes and/or intensity < 25 mmHg
ACOG recommends giving oxytocin in [protraction & arrest disorders] after assessing what 4 things?
- Moms pelvis
- Station and position of the fetus
- Maternal and fetal status
Placing an IUPC to assess “power”/MVU requires rupture of membranes, what 2 situations would you NOT want to do this?
- If the station is really high.
- Babies head is ballotable (floating upward) upon palpation.
Rupture of membranes risks and benefits
-
Benefits:
- Augment labor
- Assess status of meconium
-
Risks
- Cord prolapse
- Prolonged rupture can cause chorioamnionits
NL effective uterine activity is described as ____ contractions in a ____ period, averaging ______mmHg above baseline.
3 contractions in 10 minute, averaging 25 mmHg above baseline.
How long should we monitor IUPC when measuring strength of contractions?
>200 MVU in a 10 minute period for at least 2 hours.
Before doing a C-section, we should note adequate contractions for at least ______.
At least 4 hours
If MVU is not >200 in a 10 minute time period for at least 2 hours, what do we do?
-
Pitocin [0.5m - 30 mIU/min] for 20-30 minutes to see full effects.
- ONLY approved med for stimulating labor
Nulliparous women who present in labor with an unegaged fetal head indicates an increased likelihood of what?
Cephalopelvic disproportion (CPD) = disparity between size of moms pelvis and bbs head
What pelvis shapes have GOOD prognosis for delivery?
- Gynecoid
- Anthropoid
What presentation is the ONLY normal one in a patient in labor?
- Vertex occiput anterior (OA)
How does the fetal head change during labor?
- Enters and engages pelvis in OT
- THEN => rotates and flex to OA
- however, it can get stuck in OT or rotate to OP
Dystocia can be caused by what fetal abnormalities?
- Macrosomnia
- 2. Shoulder dysoticia
- 3. Fetal anomalies
What is transverse arrest of descent?
- Persistant OT position with arrest of descent for 1hr or more due to deflexion causing the occiputofrontal diamter (11 cm) to be the presenting diameter.
Which diameter of the fetal head becomes the presenting diameter during transverse arrest of descent?
Occipitofrontal diameter
What is appropriate management of persistent occipitotransverse (OT) position if pelvis is adequate, infant is not macrosomic and contractions are inadequate?
- Oxytocin
- Manually rotate using Keilland forceps
If a patient has persistant OT position, when is a C-section performed?
- Inadequate pelvis
- Macrosomnic bb
The course of labor if fetal head is in stuck in OP position is usually normal, but may see what 2 abnormalities?
- Prolonged 2nd stage
- Assoc. w/ considerably MORE back discomfort***
What is appropriate management of persistent OP fetal head position?
- Observation: if labor is progressive and FHR is normal
- If not => vacuum or forceps (operational delivery)
What is macrosomnia?
BB weighs more than 4500g.
When is a BB considered LARGE for GESTATIONAL AGE (LGA)?
Birth weight is equal than or greater than 90%.
Diagnosis of macrosomnia is imprecise if we use ______.
US
What are abnormalities that can affect the “passenger” and cause dystocia?
- 1. Abnormalities of fetal anomaly
- Hydrocephalus => big head seen on US that can make vaginal delivery impossible
- 3. Fetal ascites or elnargement of organs (liver) cause dystocia due to big abdomen
- 4. Conjoined twins, locked twins (bb A = breech, bb B = vertex)
Most common cause of enlarged fetal abdomen leading to dystocia is what?
Immune hydrops - Rh isoimmunization
After assessing the 3 P’s => _________ => may proceed with C-section.
- Place IUPC and rupture membranes => not adequate contractions => pitocin => doesnt work => Csection,
What are primary risks to mother associated with macrosomia?
- Primary risk = ↑ risk for C-section
- If deliver vaginally => postpartum hemorrhage and vaginal lacerations
What are the fetal risks associated with macrosomia during delivery?
- Shoulder dystocia
- Fracture of clavicle
- Damage to brachial plexus: especially C5-C6 (Erb’s palsy)
Risk factors for Macrosomnia
- Maternal DB, obesity, birth weight, height, <17YO
- Previous hx of macrosomnia
- Multiparity
- Gestational age >40 weeks
- Male fetus
Most common brachial plexus injury during birth is what?
- Erb-Duschenne (upper arm palsy (C5-C6))
Which brachial plexus injury is more common with shoulder dystocia?
Klumpke’s palsy (low arm palsy = C8 and T1); but Erb’s is still most common
Due to risk of death for infants and mothers with macrosomia, ACOG recommends prophylactic C-section at what weights for non-diabetic and diabetic patients?
- >5000g in NON-diabetic
- >4500g in diabetic (these babies often have ↑ AP diameter of their chest! = > increase chance of shoulder dystocia)
If you suspect shoulder dystocia what should you do immediately?
- Obstetric emergency! CALL FOR HELP (anesthesiologist and NICU)
- Initial maneuvers: McRoberts with suprapubic pressure
What causes shoulder dystocia?
- Anterior fetal shoulder is stuck behind the moms pubic symphysis
- Posterior shoulder is stuck on sacral promontory.
What is sign of shoulder dystocia?
Turtle sign => delivered fetuses head retracts against moms perineum
What is first line and last resort managment of Shoulder Dystocia; what can be done after?
- McRobert’s Maneuver —> Hyerflexion and ABduction moms hips
- Suprapubic pressure
- Zavanelli maneuver (cephalic replacement) is last resort –> will need C-section
Other: rotational maneuvers, deliver posterior arm, fracture clavicle
What should we be cautious of when applying suprapubic pressure to dislodge the stuck anterior shoulder?
DO NOT APPLY PRESSURE ON FUNDUS
How is Zavanelli procedure performed for shoulder dystocia?
Manually return the fetus head back to pre-restitution position using an upward, steady position => deliver via c-section.
What is appropriate management of persistent occipitotransverse (OT) positionif pelvis is inadequate, infant is macrosomic and contractions are inadequate?
C-section: perform is bb is macrosomnic or pelvis is inadequate
