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risk factors of preterm labor (PTL)

preterm ROM; chorioamnionitis; multiple gestations; uterine anomalies such as a bicornuate uterus; previous preterm delivery; maternal prepregnancy weight less than 50 kg; placental abruption; maternal disease including preeclampsia, infections, intra-abdominal disease or surgery; and low SES.


prematurity increases risk of

respiratory distress syndrome (RDS) or hyaline membrane disease, intraventricular hemorrhage, sepsis, and necrotizing enterocolitis


only tocolytic FDA approved in the US

ritodrine—a beta-mimetic agent
(many others are used)


ritodrine and terb doses

Ritodrine is given as continuous IV therapy, whereas terbutaline is usually given as 0.25 mg SC, loaded Q 20 min × 3 dosages, and then Q 3 to 4 h maintenance


how does hydration act as a tocolytic?

decreases levels of ADH, the octapeptide synthesized in the hypothalamus along with oxytocin. Because ADH differs from oxytocin by only one amino acid, it may bind with oxytocin receptors and lead to contractions.


why does terbutaline have a black box warning?

may cause maternal death and cardiac events, including tachycardia, transient hyperglycemia, hypokalemia, cardiac arrhythmias, pulmonary edema, and myocardial ischemia


Mg sulfate dosing

loaded as a 6-g bolus over 15 to 30 minutes, and then maintained at a 2- to 3-g/hour continuous infusion. A slower infusion should be used in the case of renal insufficiency because magnesium is cleared via the kidneys.


risks at toxic levels of magnesium (> 10 mg/dL)

respiratory depression, hypoxia, and cardiac arrest, pulmonary edema


risks at magnesium levels less than 10 mg/dl

Deep tendon reflexes (DTRs) are depressed


adverse effects of indomethacin

premature constriction of the ductus arteriosus, pulmonary hypertension, and oligohydramnios secondary to fetal renal failure.
increased risk of necrotizing enterocolitis and intraventricular hemorrhage in extremely premature fetuses that had been exposed to indomethacin within 48 hours of delivery


Oxytocin antagonists can also be used as tocolytics, including



preterm ROM vs premature ROM (PROM)

preterm ROM: before week 37
PROM: ROM occurring before the onset of labor
may occur together: PPROM
prolonged rupture of membranes if ROM lasts longer than 18 hours before delivery


most common concern of PROM



test for ROM

pooling, nitrazine test, ferning, U/S, Amnisure test, tampon test


the vault is composed of what 5 bones?
can do what during labor?

two frontal, two parietal, and one occipital
the bones of the vault are not fused and can undergo molding to conform to the maternal pelvis in contrast to the bones of the face and base


factors associated with breech presentation

previous breech delivery, uterine anomalies, polyhydramnios, oligohydramnios, multiple gestation, PPROM, hydrocephaly, and anencephaly
complications: prolapsed cord, head entrapment


types of breech: frank, complete, incomplete/footling

frank: "folded"; flexed hips and extended knees
complete: "compact"; flexed hips, but one or both knees are flexed as well, with at least one foot near the breech
incomplete/footling: one or both of the hips not flexed so that the foot or knee lies below the breech in the birth canal.


three management options for breech

external cephalic version of the breech (manipulation into a vertex presentation), trial of breech vaginal delivery, and elective cesarean delivery


compound presentation
watch out for ?
tx is different for UE and LE

fetal extremity presenting alongside the vertex or breech
risk of umbilical cord prolapse
UE may be gently reduced
LE is considered footling/incomplete and calls for c section


types of breech: frank, complete, incomplete/footling

frank: "folded"; flexed hips and extended knees
complete: "compact"; flexed hips, but one or both knees are flexed as well, with at least one foot near the breech
incomplete/footling: one or both of the hips not flexed so that the foot or knee lies below the breech in the birth canal.


OP vs OT position, which one more common to deliver vaginally?

While OP position fetuses deliver vaginally in about 50% of cases, OT position fetuses rarely deliver vaginally in the OT position and must rotate to either OA or OP to deliver vaginally.
(may try to rotate manually or operatively with vacuum/forceps, otherwise C section)


etiologies of prolonged FHR decelerations include

preuterine (maternal PE, MI, AFE, seizure, epidural) uteroplacental (abruption, tetanic contraction, rupture) or postplacental (cord prolapse/compression, vasa previa)


prolonged deceleration vs bradycardia

prolonged decel: FHR below 100-110 bpm for >2 minutes
bradycardia: >10 minutes


C section if FHR decelerations are due to

cord prolapse, placenta previa, abruption


management of prolonged FHR deceleration

left or right lateral decubitus position (to reduce IVC compression)
oxygen via face mask
if maternal hypotension: aggressive IV hydration and ephedrine


Tetanic uterine contraction is treated with

nitroglycerin, usually administered via a sublingual spray, and/or terbutaline


maneuvers for shoulder dystocia

McRoberts, suprapubic pressure, Rubin maneuver, Wood's corkscrew maneuver, deliver of the posterior arm/shoulder
then: generous episiotomy, Zavanelli maneuver, symphysiotomy


risk factors for shoulder dystocia

fetal macrosomia (weight over 4,000 g), preconceptional and gestational diabetes, previous shoulder dystocia, maternal obesity, postterm pregnancy, prolonged second stage of labor, and operative vaginal delivery.


Rubin maneuver

pressure on an either accessible shoulder toward the anterior chest wall of the fetus to decrease the bisacromial diameter and free the impacted shoulder


Wood's corkscrew maneuver

pressure behind the posterior shoulder to rotate the infant and dislodge the anterior shoulder.


McRoberts maneuver

sharp flexion of the maternal hips that decreases the inclination of the pelvis increasing the AP diameter can free the anterior shoulder


Pregnant patients commonly have BPs around

90/50 mm Hg


Associated complications of uterine rupture

*prior uterine scar from myomectomy or C section*, uterine fibroids, uterine malformations, obstructed labor, and the use of oxytocin/PGEs


uterine rupture may present how?

“popping” sensation or sudden abdominal pain, fetus may be palpable in the extrauterine space, there may be vaginal bleeding, and commonly the fetal presenting part is suddenly at a much higher station than previously

immediate cesarean delivery and exploratory laparotomy.


Management of a Pregnant Patient with Seizures or in Status Epilepticus

Assess and establish airway and vital signs including oxygenation
Assess FHR or fetal status
Bolus magnesium sulfate, or give 10 g IM
Bolus with lorazepam 0.1 mg/kg, 5.0–10.0 mg at no more than 2.0 mg/min
Load phenytoin 20 mg/kg, usually 1–2 g at no more than 50 mg/min
If not successful, load phenobarbital 20 mg/kg, usually 1–2 g at no more than 100 mg/min
Laboratory tests include CBC, metabolic panel, AED levels, and toxicology screen
If fetal testing is not reassuring, move to emergent delivery


BPs much lower than the 80/40 mm Hg range is unusual and can lead to poor maternal and uterine perfusion. Common etiologies?

vasovagal events, regional anesthesia, overtreatment with antihypertensive drugs, hemorrhage, anaphylaxis, and AFE


tx of maternal hypotension

aggressive IV hydration and adrenergic medications to constrict peripheral vessels, and increase both the preload and the afterload.
consider Benadryl and epinephrine should be considered for a possible anaphylactic reaction


Vertex malpresentations include

face, brow, compound, and persistent OP.


If there is no sign of resolution of the FHR deceleration in 4 to 5 minutes, the patient should either be

delivered vaginally or moved to the OR for cesarean.