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33 Cards in this Set

  • Front
  • Back
Cardinal movements of fetus during delivery
1. Engagement
2. Descent
3. Flexion
4. Internal rotation (to OA position ideally)
5. Extension (delivery of head)
6. External rotation; head rotates in line with shoulders
7. Expulsion (delivery of shoulders and body)
Definition and types of feta lies
Orientation of the long axis of the fetus with respect to the long axis of the uterus
- Longitudinal
- Transverse
- Oblique
Definition and types of fetal presentation
Fetal presentation at pelvic outlet
- Vertex : occiput
- Breech : sacrum
- Mentum : face


Normal, fetal head enters maternal pelvis and engages in OT position
Subsequently rotates to OA position or OP (in a small percentage of cases)

* Occiput Anterior (OA) : most common presentation - left OA most common
* Occiput Posterior (OP) : most rotate spontaneously to OA; may cause prolonged second stage of labour
* Occiput Transeverse (OT) : leads to arrest of dilatation
Definition and types of fetal attitude
FlexionéExtension of fetal head realtive to shoulders
- Brow presentation : head partially extended (requires C/S)
- Face presentation : head fully extended
* mentum posterior always requires C/S, mentum anterior will deliver vaginally
Definition and types of fetal station
Position of presenting part relative to ischial spines - determined by vaginal exam

- at ischial spines = station 0 = enganged
- cm above (-5 = -1) or cm below (+1 = +5)
Cervix dilatation
Latent phase : 0-3 cm
Active phase : 4-10 cm
Definition of effacement
Thinning of the cervix by percentage or length of cervix
Definition of labour
Regular painful contractions associated with progressive dilatation and effacement of cervix and descent of presenting part, or station
Definition of Baxton-Hicks contractions
Irregular, occur throughout pregnancy and not associated with any dilatation, effacement or descent.
Bishop score
Stages of labour
First stage (6-18 hours) (2-10 hours)
- Latent phase
* uterine contractions typically infrequent and irregular
* slow cervical dilatation (usually 3-4 cm) and effacement
- Active phase
* rapid cervical dilatation to full dilatation (nulliparous 1.2 cm/h, multiparous 1.5cm/h)
* phase of maximum slope on cervical dilatation curve
* painful, regular contractions Q2min, lasting 40-60 seconds

Second stage (30 min - 3 hours) (5-30 minutes)
- From full dilatation to delivery of the baby
- Mother feels a desire to bear down and push with each contraction
- Women may choose a comfortable position that enhances pushing efforts and delivery
* upright (semi-sitting, squatting)
- Progress measured by descent

Third stage (5-30 minutes)
- Separation and expulsion of placenta
- Can last up to 30 minutes before intervention indicated
- Strat oxytocin IV drip or give 10 U IM after delivery of anterior shoulder in anticipation of placental delivery
- Routine oxytocin administration in third stage of labour can reduce the risk of PPH by > 40%

Fourth stage of labour
- First postpartum hour
- monitor vital signs and bleeding
- repair lacerations
- ensure uterus is contracted (palpate uterus and monitor uterine bleeding)
- inspect placenta for completeness and umbilical cord for presence of 2 arteries and 1 vein.
- 3rd and 4th stages of labour are the most dangerous to the mother (i.e. hemorrhage)
Signs of placental hemorrhage
1. Gush of blood
2. Lengthening of cord
3. Uterus becomes globular
4. Fundus rises
Definition of induction of labour
Artificial initiation of labour before its spontaneous onset for the purpose of delivery of the fetus and placenta
Prerequisites for labour induction
- Capability for C/S if necessary
- Maternal
+ short, thin, soft, anterior cervix with open os
+ if cervix is not ripe, use prostaglanding vaginal insert (cervidil), prostaglandin gel (Prepidil) or Foley catheter

- Fetal
+ reassuring fetal heart tracing
+ cephalic presentation
+ adequate fetal monitoring available

- Likelihood of success determined by Bishop Score
+ cervix considered unfavourable if < 6
+ cervix favourable if > 6
+ score of 9-13 associated with high likelihood of vaginal delivery
Bishop score characteristics
Position
Consistency
Effacement (%)
Dilatation
Station of fetal head
Indications for induction of labour
- Post date pregnancy
- Maternal factors
+ significant antepartum hemorrhage
+ gestational HTN
+ other medical problems e.g. diabetes, renal or lung disease
- Maternal-fetal factors
+ isoimmunization, PROM, chorioamnionitis

- Fetal factors
+ suspected fetal jeopardy as evidenced by biochemical or biophysical indication
Risks associated with induced labour
Failure to achieve labour / vaginal birth
Uterine hyperstimulation and fetal compromise
Uterine rupture
Uterine atony and PPH
Maternal side effects to medications
Contraindications for the induction of labour
Maternal
- prior classical or inverted-T incision or uterine surgery (e.g. myomectomy)
- unstable maternal condition
- gross COPD
- active maternal genital herpes
- invasive cervical carcinoma
- pelvic structure deformities

Maternal-Fetal
- Placenta Previa or Vasa previa
- Cord presentation

Fetal
- Fetal distress
- Malpresentation
- Preterm fetus without lung maturity
Induction stages
1. Cervical ripening
2. Induction of labour
Cervical ripening in induction
Definition : use of medications or other means to soften, efface and dilate cervix to increase likelihood of induction success (Bishop score)

Methods
- Intravaginal prostaglandin PGE2 gel : Prostin (long and closed cervix with no ROM)
- Intravaginal PGE2 : Cervidil (long and closed cervix, may use if ROM)
- Misoprostol : synthetic methylated PGE1 (not commonly used)
- Foley catheter placement to mechanically dilate the cervix
- Hydroscopic dilators, osmotic dilators (laminaria)



Meta-analysis has shown that :
- the use of oxytocin to ripen the cervix is not effective
- since the best dose and route of misoprostol for labour induction with a live fetus are not known and there are concers regarding hyperstimulation, misoprostol's use for induction of labour should be within clinical trials only or in cases of intrauterine fetal death to initiate labour
Induction of labour
Amniotomy
- artificial rupture of membranes to stimulate PG synthesis and secretion; may try this as initial measure if cervix is dilated
- amniotomy plus intravenous oxytocin : more women delivered vaginally at 24 hours than amniotomy alone ( RR = 0.03) and had fewer instrumental vaginal deliveries


Oxytocin
Augmentation of labour
Augmentation of labour is used to promote adequate contractions when spontaneous contractions are inadequate and cervical dilatation or descent of fetus fails to occur.

Oxytocin (0.5-2 mU/min IV increasing by 1-2 mU/minutes Q20-60 minutes
Etiology of preterm labour
Maternal
- infection (recurrent pyelonephritis, untreated bacteriuria, chorioamnionitis)
- genital infection (bacterial vaginosis )
- HTN, DM, chronic illness
- mechanical factors
- previous obstetric/gynecological/abdominal surgeries
- socio-environmental factors

Maternal-Fetal
- PPROM
- Polyhydramnios
- Placenta abruptio or previa
- Placental insuffisicency

Fetal
- multiple gestations
- congenital abnormalities
- fetal hydrops

Uterine
- incompetent cervix
- excessive enlargement, malformations
Risk factors and prediction of preterm labour
Most important risk factor is prior history of spontaneous PTL

Maternal risk scoring using etiologies fails to identify up to 70% or PTL

Cervical length
- measured by TVUS; cervical length >30mm has high negative predictive value for PTL before 34 weeks

Identification of bacterial vaginosis and ureaplasma urealyticum infections

Fetal fibronectin : a glycoprotein in amniotic fluid and placental tissue functionning to maintain integrity of chorionic-decidual interface in asymptomatic women, a positive fetal fibronectin in cervicovaginal fluid (>50 ng/ml) at 24 weeks gestation predicted spontaneous PTL at <34 weeks (i.e. Sn 23%, Sp 97%, PPV 25%, NPV 96%)

In symptomatic women fetal fibronectin is most effectively combined with U/S detecting cervical length; if cervical length is not short and fetal fibronectin is negative, preterm labour is highly unlikely, thus preventing unnecessary admissions or transfers to higher level facilities.
Management of preterm labour
Initial
- Hydration
- Bed rest at LLDP
- Sedation (morphine)
- Avoid repeated pelvic exams (increased infection risk)
- U/S examination of fetus (for GA, BPP, position, placenta location, estimated fetal weight)

Suppression of labour - Tocolysis
- does not inhibit PTL completely, but may buy time to allow Celestone use
- requirements (all must be met)
+ preterm labour
+ live, immature fetus, intact membranes, cervical dilatation of < 4 cm
+ absence of maternal or fetal contraindications

Enhancement of fetal pulmonary maturity
- Celestone (betamethasone) 12 mg IM Q24H x 2 or dexamethasone 6 mg IM Q12H x 4
+ 28-34 weeks : reduces incidence of RDS
+ 24-28 weeks : reduces severity of RDS, overall mortality and rate of intraventricular hemorrhage

Cervical cerclage
- definition : placement of cervical sutures, wires or synthetic tape at the level of the internal os, usually at the end of the first trimester and removed in T3
- in particular indications
Contraindications to tocolysis
Maternal
- bleeding (placenta previa or abruption)
- maternal disease : HTN, diabetes, heart disease
- preeclampsia
- chorioamnionitis

Fetal
- erythroblastosis fetalis
- severe congenital anomalies
- fetal distress / demise
- IUGR
- Multiple gestation
Tocolytic procedure
If no contraindications present, agent used depends on clinical situation

- Calcium channel blockes : Nifedipine
+ prostaglandin synthesis inhibitors (2nd line) : indomethacin
+ B mimetics : ritodrine, terbutaline (rarely used)


No proven efficacy
- nitroglycerin patch : vasodilator and smooth muscle relaxant that may delay delivery by 24-48 hours
- magnesium sulfate (if diabetes or cardiovascular disease present)
Contraindications to celestone use for increasing fetal pulmonary prematurity
Active TB
Viral keratosis
Maternal DM
Indications for cervical cercling
Cervical incompetence : cervical dilation and effacement in the absence of increased uterine contractility

Dx of CI
- obstetrical Hx : silent cervical dilation
- ability of cervix to hold an inflated Foley catheter during a hysterosonogram

Proven benefit in the prevention of PTL in women with primary structural abnormality of the cervix.
Definition of :
- premature rupture of membranes
- prolonged rupture of membranes
- preterm rupture of membranes
- preterm premature rupture of membranes
Premature : rupture of membranes prior to labour at any GA
Prolonged : > 24 hours elapse between rupture of membranes and onset of labour
Preterm : before 37 weeks
PPROM : rupture of membranes before 37 weeks and prior to onset of labour
Risk factors for premature rupture of membranes
Maternal
- multiparity
- cervical incompetence
- infection (cervicitis, vaginitis, STI, UTI)
- family history of PROM
- low socioeconomic class / poor nutrition

Fetal
- congenital anomaly
- multiple gestation

Other risk factors associated with PTL
What can turn nitrazine paper blue?
Amniotic fluid
Blood
Urine
Semen
Management of premature rupture of membranes
Admit and monitor vital signs Q4H, daily BPP and WBC count
Avoid introducing infection with P/E (do not do a bimanual exam)
Cultures (cervix for GC, lower vagina for GBS)
Assess fetal lung maturity by L/S ratio of amniotic fluid
- consider administration of celestone to accelerate maturity if < 32 weeks and no evidence of infection

Weigh degree of prematurity vs. risk of amnionitis and sepsis by remaining in utero
- < 24 weeks : consider termination
- 24-26 weeks : expectant management as prematurity complications are significant
- 34-36 weeks : "grey zone" where risk of death from RDS and neonatal sepsis is the same
- > 36 weeks : induction of labour since the risk of death from RDS and neonatal sepsis is the same