Obstetrics Flashcards
What is the linea nigra?
a hyperpigmented streak appearing below the umbilicus
What is chloasma?
reddish hyperpigmentation over the bridge of the nose and cheeks during pregnancy
Chadwick’s sign?
bluish discoloration of vulva and vagina. Sign of pregnancy.
Hegar’s sign?
softening of the cervix. Sign of pregnancy.
Premature menopause?
Before age 40
True labor and its parts
True labor is defined as progressive cervical dilation with uterine contractions. Effacement, the process of thinning of the cervix, occurs before and during labor. Traditionally, labor has been defined as occurring in three stages:
First stage is divided into latent (1–20 hours) characterized by milder and less frequent contractions and active (averaging 5 hours in multiparas and 8 hours in primaparas), where the cervix dilates from 4 cm to complete (10 cm) characterized by stronger, regular contractions lasting 60 seconds or more.
Second stage begins when dilation is complete and ends with the birth of the baby and averaging 20 minutes in multiparas and 50 minutes in primaparas.
Third stage is from the delivery of the baby to delivery of the placenta (up to 30 minutes is considered normal).
At what hCG level do you expect to see a gestational sac on TVUS?
1500mIU/ml
Timeline for trimesters?
First - 1-13 weeks
Second - 14 - 27
Third 28-term
Term- 37-42
Factors that lead to transverse lie?
Predisposing factors for transverse lies include multiparity, placenta previa, hydramnios, and uterine anomalies.
Tests to order if APH?
Baseline laboratory tests
include hematocrit, platelet count, fibrino
gen level, coagulation studies, blood type,
and antibody screen. Women who are Rh
negative should receive Rho(D) immune
globulin (Rhogam); a KleihauerBetke test
should be performed to determine the appro
priate dose.
Placenta previa
- Def’n
-Placenta previa is a placental implantation that
overlies or is within 2 cm (0.8 inches) of the internal cervical os.
- The placenta is described as a complete previa when it covers the os and as a marginal previa when the edge lies within 2 cm of the os. When the edge is 2 to 3.5 cm (1.4 inches) from the os, the placenta may be described as low lying
Placenta previa
- Risk factors
Chronic hypertension Multiparity Multiple gestations Older age Previous cesarean delivery Tobacco use Uterine curettage
Placenta previa
-presentation
-Placenta previa is a common incidental
finding on second trimester ultrasonogra
phy. It is evident on approximately 4 percent
of ultrasound studies performed at 20 to
24 weeks’ gestation12 but is present at term in
only 0.4 percent of pregnancies.
- Symptomatic placenta previa usually man
ifests as vaginal bleeding in the late second or
third trimester, often after sexual intercourse.
The bleeding typically is painless unless labor
or placental abruption occurs. This initial
sentinel bleed usually is not sufficient to pro
duce hemodynamic instability or to threaten
the fetus in the absence of cervical instru
mentation or cervical digital examination
Placenta previa
- management
-Women with bleeding from placenta previa
generally are admitted to the hospital for an
initial assessment.15 Because most neonatal
morbidity and mortality associated with pla
centa previa results from complications of
prematurity, the main therapeutic strategy is
to prolong pregnancy until fetal lung maturity
is achieved16 (Figure 3). Tocolytic agents may
be used safely to prolong gestation if vaginal
bleeding occurs with preterm contractions.
Corticosteroids should be administered to
women who have bleeding from placenta pre
via at 24 to 34 weeks’ estimated gestation
-Because placenta previa may resolve close
to term, it is recommended that no decision
on mode of delivery be made until after ultra
sonography at 36 weeks.25 Women whose
placental edge is 2 cm or more from the
internal os at term can expect to deliver vagi
nally unless heavy bleeding ensues.4
Women whose placenta is located 1 to 2 cm (0.4 to 0.8 inches) from the os may attempt vagi
nal delivery in a facility capable of moving
rapidly to cesarean delivery if necessary.4
Women with a nonbleeding placenta previa
may have amniocentesis at 36 to 37 weeks
to document pulmonary maturity before a
scheduled cesarean delivery
If over cesarean scar should be evaluated for accreta (U/S)
Risk factors for placental abruption?
Chronic hypertension Multiparity Preeclampsia Previous abruption Short umbilical cord Sudden decompression of an overdistended uterus Thrombophilias Tobacco, cocaine, or methamphetamine use Trauma: blunt abdominal or sudden deceleration Unexplained elevated maternal alpha fetoprotein level Uterine fibroids cocaine smoking
Placental abruption
- definition
Placental abruption is the separation of
the placenta from the uterine wall before
delivery. Abruption is the most common
cause of serious vaginal bleeding, occur
ring in 1 percent of pregnancies. Neonatal
death occurs in 10 to 30 percent of cases.
Presentation of placental abruption
Placental abruption typically manifests as
vaginal bleeding, uterine tenderness or back
pain, and evidence of fetal distress. Preterm
labor, growth restriction, and intrauterine
fetal death also may occur. The fundus
often is tender to palpation, and pain occurs
between contractions. Bleeding may be com
pletely or partially concealed or may be
bright, dark, or intermixed with amniotic
fluid. Disseminated intravascular coagulation
may result from the release of thromboplastin
into the maternal circulation with placental
separation. This occurs in about 10 percent
of abruptions and is more common with fetal
death. A chronic form of abruption may
manifest as recurrent vaginal bleeding with
episodic pain and contractions.
Management of abruption
Initial management
includes rapid stabilization of maternal car
diopulmonary status and assessment of fetal
wellbeing.
- Do not wait to get fetus out
- If fetal demise then goal is vaginal delivery
Vasa previa - definition
Vasa previa is the velamentous insertion of
the umbilical cord into the membranes in
the lower uterine segment resulting in the
presence of fetal vessels between the cervix
and presenting part.
Risk factors for vasa previa
In vitro fertilization Low-lying and second trimester placenta previa Marginal cord insertion Multiple gestation Succenturiate-lobed and bilobed placentas
Presentation of vasa previa
Vasa previa typically manifests as onset
of hemorrhage at the time of amniotomy
or spontaneous rupture of membranes. The
hemorrhage is fetal blood, and exsanguina
tion can occur rapidly because the average
blood volume of a term fetus is approxi
mately 250 mL. Rarely, vessels are palpated
in the presenting membranes, prohibiting
artificial rupture and vaginal delivery
Risk factors for preterm delivery?
Maternal characteristics Black race Interpregnancy interval of less than six months Physically strenuous or stressful work Prepregnancy body mass index ≤ 19 kg per m2 Pregnancy history Previous preterm delivery Pregnancy characteristics Bacterial vaginosis, Chlamydia infection Cocaine or heroin use History of cervical cone biopsy or loop electrosurgical excision procedure Intrauterine infection Maternal abdominal surgery Maternal medical disorders such as thyroid disease, diabetes mellitus, or hypertension Multiple gestation Nongenital tract infection (asymptomatic bacteriuria, pneumonia, appendicitis) Periodontal disease Polyhydramnios or oligohydramnios Shortened cervix (< 3.0 cm) Tobacco use Uterine anomalies Vaginal bleeding caused by placental abruption or placenta previa
Prevention of preterm birth
Smoking cessation, progesterone, screening and treatment of BV in high risk women
Effective interventions for preterm birth?
The three antenatal interventions that have been proven effective in premature labor are transfer to a facility with a NICU, maternal corticosteroid administration, and antibiotic
prophylaxis for group B streptococcus (GBS)
Assessing for true labour in preterm patients
- Assess for rupture of membranes - sterile spec, pooling, ferning, nitrazine test, Ultrasound for oligohydramnios ,Amnioinfusion of indigo carmine (if above tests are nondiagnostic)
- fetal fibronectin - high NPV for delivery in 14 days. The test should not be done if the patient had a vaginal examination, sexual intercourse, or endovaginal ultrasonography within the previous 24 hours.40 Other confounders to fetal fibronectin testing include vaginal bleeding, rupture of membranes, abnormal vaginal flora, and use
of vaginal lubricants or disinfectants - Cervical U/S - Patients with a cervical length of
at least 3.0 cm are unlikely to deliver within seven days - Abolishment of contractions with a single subcutaneous 0.25 mg dose of terbutaline decreased time to discharge from five to four hours when compared to observation alone
Management of preterm labour
Management of preterm labor consists of corticosteroids to improve fetal outcomes, antibiotics for prophylaxis of GBS infection, and limited tocolysis.
The use of tocolytics decreases the odds of delivery within 48 hours, but has not consistently been shown to improve neonatal and perinatal outcomes. Basically use for time to administer steroids and/or transfer mom. General contraindications to tocolysis include fetal distress, chorioamnionitis, and maternal instability
Dose of steroids for preterm birth?
betamethasone (two 12-mg intramuscular doses 24 hours apart) or dexamethasone (6 mg intramuscularly every 12 hours for four doses)
When to treat GBS?
For those at less than 37 weeks’ gestation who
have not yet been screened, a rectovaginal culture or rapid streptococcal test should be obtained, and prophylaxis should be started. Full antibiotic prophylaxis is indicated in patients who are culture-positive for GBS, who had GBS bacteriuria prenatally, or who had a prior newborn infected
with GBS
If GBS status is unknown at time of presentation, intrapartum chemoprophylaxis should be administered to women with duration of membrane rupture > 18 hours, or temperature > 100.4ºF (> 38ºC).
Treatment options for GBS?
Recommended prophylaxis
Penicillin G: initial dose of 5 million units IV, then
2.5 million units IV every four hours until delivery
-Alternative prophylaxis Ampicillin: initial dose of 2 g IV, then 1 g IV every four hours until delivery
For patients who are allergic to penicillin
Not at high risk of anaphylaxis
Cefazolin: initial dose of 2 g IV, then 1 g IV every eight hours until delivery
At high risk of anaphylaxis and GBS susceptible to clindamycin (Cleocin) and erythromycin Clindamycin: 900 mg IV every eight hours until delivery or Erythromycin: 500 mg IV every six hours until delivery
At high risk of anaphylaxis and GBS resistant to clindamycin or erythromycin, or GBS susceptibility unknown Vancomycin: 1 g every 12 hours until delivery
Indocid
- dose, when to use, contraindications, side effects (maternal and fetal)
Indomethacin (Indocin; class: NSAIDs)
Loading dose: 50 mg rectally or 50 to 100 mg orally
Maintenance dosage: 25 to 50 mg orally every four hours for 48 hours. Total 24-hour dose should not be greater than 200 mg
NSAIDs theoretically intervene more proximally in the labor cascade than other agents; effectiveness similar to other agents
Maternal adverse effect profile is favorable
Other NSAIDs (sulindac [Clinoril], ketorolac [formerly Toradol]) may be used
May be optimal choice for tocolysis before 32 weeks’ gestation
Contraindications: maternal renal or hepatic impairment, active peptic ulcer disease, oligohydramnios
Maternal adverse effects: nausea, heartburn
Fetal adverse effects: constriction of the ductus arteriosus (not recommended after 32 weeks’ gestation), pulmonary hypertension, reversible decrease in renal function with oligohydramnios, intraventricular hemorrhage, hyperbilirubinemia, necrotizing enterocolitis
MgSO4
- dose, when to use, contraindications, side effects (maternal and fetal)
Magnesium sulfate
4- to 6-g bolus intravenously over 20 minutes, then
1 to 2 g per hour (3 g per hour
maximum)
In widespread use in the United States, although metaanalysis fails to demonstrate improvement in outcomes; comparison studies demonstrate similar effectiveness to other agents in delay of delivery
Contraindication: myasthenia gravis
Maternal adverse effects: flushing, lethargy, headache, muscle weakness, diplopia, dry mouth, pulmonary edema,cardiac arrest
Newborn adverse effects: lethargy, hypotonia, respiratory depression,demineralization with prolonged use
Nifedipine
- dose, when to use, contraindications, side effects (maternal and fetal)
Nifedipine (Procardia; class: calcium channel blockers)
30-mg loading dose orally, then 10 to 20 mg every four to six hours
May offer the best outcomes of the tocolytic agents
May prolong pregnancy for seven days; delivery after 34 weeks’ gestation is also increased
Decreased incidence of neonatal respiratory distress syndrome, necrotizing enterocolitis, intraventricular hemorrhage,
and jaundice
Neonatal mortality not affected
Contraindication: maternal hypotension
Maternal adverse effects: flushing, headache, dizziness, nausea, transient hypotension
No fetal adverse effects noted
Terbutaline
- dose, when to use, contraindications, side effects (maternal and fetal)
Terbutaline (formerly Brethine; class: beta mimetics)
0.25 mg subcutaneously every 20 to 30
minutes for four to six doses
Appropriate as the first-line agent
Beta mimetics may delay delivery for 48 hours, but neonatal outcomes are variable and maternal adverse effects common
Maternal contraindications: heart disease, poorly controlled diabetes mellitus, thyrotoxicosis
Maternal adverse effects: cardiac arrhythmias, pulmonary edema, myocardial ischemia, hypotension, tachycardia, hyperglycemia,
hyperinsulinemia, hypokalemia, antidiuresis, altered thyroid function, physiologic tremor, palpitations,
nervousness, nausea, vomiting, fever, hallucinations
Fetal and newborn adverse effects: tachycardia, hypoglycemia, hypocalcemia, hyperbilirubinemia, hypotension, intraventricular hemorrhage
What is most important risk factor for preterm labour?
Previous preterm labour. In general the risk is increased by a factor of 2.5.
How does progesterone prevent PTL?
The mechanisms by which progesterone prevents PTL include reduction of gap junction formation,
oxytocin antagonism, maintenance of cervical integrity and anti-inflammation.
When to use progesterone to prevent PTL?
The American College of Obstetricians and Gynecologists recommends that progesterone supplementation be offered to patients with a history of PTD as well as for those with serendipitously noted ultrasonic cervical length < 15 mm.
How to diagnose BV clincally
Amsel’s Criteria for Diagnosis of Bacterial Vaginosis
Diagnosis requires three of four findings
Homogenous, white, non-inflammatory discharge that smoothly coats the vaginal walls
Presence of clue cells on microscopic examination
pH of vaginal fluid > 4.5
Fishy odor of vaginal discharge before or after addition of 10 percent KOH
Treatment of BV
CDC Recommendations for Treatment of Bacterial Vaginosis in Pregnancy
Metronidazole 500 mg orally twice a day for seven days
Metronidazole 250 mg orally three times a day for seven days
Clindamycin 300 mg orally twice a day for seven days
Initial evaluation for patients with suspected PPROM?
Accurate dating is critical: Review dating criteria as management choices are determined by
gestational age.
• Sterile speculum examination: If rupture of membranes is suspected, digital examination should be avoided as it shortens the latency period before onset of labor and increases the risk of infection.
A sample of amniotic fluid may be obtained for fetal lung maturity evaluation if between 32 and 34 weeks
• Ultrasound evaluation: Oligohydramnios supports the diagnosis of membrane rupture. Oligohydramnios will also decrease the accuracy of fetal weight and gestational assessment. Low amniotic volume increases the likelihood of cord compression and other complications.
• Assessment of fetal lung maturity: Vaginal amniotic fluid may be tested for phosphatidyl glycerol, the presence of which indicates fetal lung maturity between 32 and 34 weeks’ gestation,
although this is not commonly done. Amniocentesis allows collection of fluid for fetal pulmonary maturity testing as well as for evaluation of infection.
• Screen for infection: Cervical cultures for sexually transmitted infections or vaginal/rectal culture for group B streptococcus may be obtained.
• Fetal monitoring: Electronic fetal heart rate and uterine contraction monitoring during initial
assessment may identify cord compression and asymptomatic contractions.
Antibiotic therapy for PPROM?
- advantages
- doses
At gestations between 24 and 32 weeks, treatment with antibiotics prolongs pregnancy, decreases fetal morbidity, decreases chorioamnionitis and maternal infection
Initial therapy:
Ampicillin 2 grams intravneously every six hours for 48 hours or
Erythromycin 250 mg intravenously every six hours for 48 hours
Followed by:
Amoxicillin 250 mg orally every eight hours for five days
Erythromycin base 333 mg orally every eight hours for five days
