Obstetric

Question 1

what are factors that predict successful TOLAC?

what are factors that predict unsuccessful TOLAC?

Answer 1

Factors that tend to predict a successful TOLAC include the following:

Prior VBAC

Younger maternal age

TOLAC during spontaneous labor without augmentation or induction

Advanced cervical dilation on presentation

Lower prenatal BMI

White race/ethnicity

Non-recurrent indication for the initial cesarean section such as breech positioning or fetal bradycardia

Factors that tend to predict an unsuccessful (failed) TOLAC include:

Prior cesarean section for anatomic issues such as dystocia, cephalopelvic disproportion, or failed induction

The need for augmentation or induction

Post-term gestational age

No history of vaginal delivery

Geriatric mothers (age > 35 years)

Non-white race/ethnicity

Prenatal maternal obesity

Fetal macrosomia (> 4000 g estimated fetal weight)

Question 2

when is amniocentesis safer? week wise

Answer 2

Risks of the procedure include spontaneous abortion, fluid leakage, and infection. Pregnancy loss, ROM, club foot, and amniocyte culture failure are more common when the procedure is performed early, before 15 weeks. It is recommended that if karyotyping is needed, chorionic villus sampling should be performed if the fetus is still less than 15 weeks gestation. Amniocentesis can be performed under ultrasound guidance, which allows a safe place for needle placement, preferably away from the face and umbilical cord, and without passing through the placenta.

Question 3

what is carboprost?

What is misoprostol?

what is methergine?

Answer 3

Carboprost is a synthetic prostaglandin F2-alpha. It should be carefully administered to patients with a history of reactive airway disease as it can trigger bronchoconstriction but is safe in patients with mild, asymptomatic cases. Other adverse effects include nausea, vomiting, and diarrhea.

Misoprostol is a synthetic prostaglandin E1 uterotonic. Misoprostol commonly causes diarrhea. Unlike carboprost, however, this prostaglandin does not cause bronchoconstriction.

Methylergonovine is an ergot alkaloid that constricts vascular smooth muscle to cause uterine constriction. This may concomitantly increase systemic blood pressure and thus is relatively contraindicated in patients with hypertensive disorders.

Question 4

Define early, late, variable, and sinusoidal decelarations?

Answer 4

Early deceleration: deceleration starts at the same time as and mirrors a uterine contraction. This is indicative of head compression and is not associated with fetal distress.

Late deceleration: deceleration starts after the onset of a uterine contraction with a nadir >30 seconds after the onset of contraction. This is most likely due to uteroplacental insufficiency. The severity is determined by the magnitude of the deceleration.

Variable deceleration: deceleration starts at variable times in relation to the uterine contraction. This is due to cord compression. The compression of the umbilical cord results in a sudden increase in fetal blood pressure resulting in a reflex bradycardia. The severity of a variable deceleration is determined by its duration.

Sinusoidal FHR pattern: a smooth sine wave (no variability present). It is rare, however, is associated with high rates of fetal morbidity and mortality. This pattern is indicative of severe fetal anemia.

Question 5

what is a reactive non-stress test for pregnancy?

Answer 5

Fetal accelerations are defined by an abrupt increase (onset to peak less than 30 seconds) with a peak of 15/min or more above fetal heart rate baseline and a duration of 15 seconds or more from onset to return in a fetus of at least 32 weeks gestation. Reactive stress tests have ≥2 accelerations within a 20-40–minute time period. A nonreactive stress test does not have sufficient fetal heart rate accelerations during a 40-minute time period.

Question 6

Which of the following values on an arterial blood gas measurement is MOST LIKELY INCREASED in a healthy pregnant patient compared with a healthy nonpregnant patient? CO2 O2 Base excess Bicarbonate

Answer 6

Partial pressure of O2 To meet the increased metabolic demands during pregnancy, a woman’s minute ventilation increases over the course of pregnancy to approximately 145% of normal nonpregnant minute ventilation (primarily due to increased tidal volume from 450 to 600 with a small contribution from increased respiratory rate by 1-2 breaths/min). This is driven by the respiratory stimulant effects of progesterone, which shifts the carbon dioxide–ventilatory response curve to the left. The result is that respiratory alkalosis as the arterial partial pressure of carbon dioxide (PaCO2) is decreased by approximately 10 mm Hg (from 40 to 30 mm Hg) by the end of the first trimester.

Question 7

what are risk factors for umbilical cord prolapse?

Answer 7

fetal malpresentation, long umbilical cord, low birth weight, multiparity, multiple gestations, and artificial rupture of membranes

Question 8

what can be done to help prevent meconium aspiration?

Answer 8

Using the earliest gestational age for estimating delivery is recommended to help prevent meconium aspiration. Gestational age is the largest risk factor when considering the passage of meconium.

Question 9

how does lambert-eaton work?

Answer 9

Lambert-Eaton syndrome involves autoantibodies targeting presynaptic calcium channels to inhibit calcium ion influx and thus prevent acetylcholine release.

Question 10

why do pregnant patients have a decrease in O2 sats so quickly?

Answer 10

Increased O2 consumption and decreased FRC

Question 11

what coagulation factors increase the most during pregnancy?

which factors decrease?

Answer 11

fibrinogen and factor VII increase the most

Factors XIII and XI decrease

Question 12

when do postdural puncture headaches usually occur?

what is the likelihood of an pdph if wet tapped?

Answer 12

Postdural puncture headache typically presents 6-72 hours after dural puncture and is commonly accompanied by nausea and neck stiffness, as well as ocular and auditory manifestations. The incidence is approximately 50% when the dura is accidentally punctured with the epidural needle, but only in the low single digits if using a spinal needle, particularly when using a small-diameter pencil-tip needle.

Question 13

what aspect of pregnancy increases the likelihood of PE?

Answer 13

Uterine caval compression (DVT)

hypercoagulable state

parturients have vascular injury during vaginal or c/s deliveries

Question 14

what is the definition of preeclampsia withot severe features?

with severe features?

Answer 14

Preeclampsia occurs when hypertension develops after 20 weeks’ gestation. It is unique to human pregnancies and is characterized by diffuse endothelial dysfunction. The cause of the disease is unknown. It is broken into ‘preeclampsia without severe features’ and ‘severe preeclampsia’. Preeclampsia without severe features is diagnosed when the BP is greater than 140/90 mmHg AND some degree of proteinuria. The newer guidelines do not require specific degrees of proteinuria to be present. Severe preeclampsia is BP greater than 160/110 mmHg PLUS thrombocytopenia (platelet count less than 100k), increasing serum creatinine (> 1.1 mg/dL or 2 times the baseline serum creatinine), pulmonary edema, new-onset cerebral or visual disturbances, and/or impaired liver function. Eclampsia is severe preeclampsia plus significant central nervous system involvement (seizures). HELLP syndrome occurs when hemolysis, elevated liver enzymes, and low platelet count in a woman with preeclampsia. The definitive treatment for all the above disorders is delivery of the fetus.

Question 15

what are normal fetal heart rate ranges?

Answer 15

Normal FHR ranges from 120-160 beats per minute (BMP). If the FHR is tachycardic or bradycardic for a sustained period of time, it becomes concerning for fetal distress.

Normal FHR can vary from beat to beat, and is referred to as “short-term variability” or “beat to beat variability.” The variation from one beat to another can range from 5-25 BPM. Variability in the FHR is a sign of a healthy autonomic nervous system, chemoreceptors, baroreceptors, and cardiac responsiveness. FHR becomes non-reassuring if the variability is < 5 or > 25. A decrease in FHR variability can be due to fetal sleep state, fetal acidosis, or maternal sedation from drugs.

Question 16

1. When does pregnancy CO return to normal post-delivery? 2. Does red blood cell mass increase or decrease? 3. Are response to adrenergic agents blunted during pregnancy?

Answer 16

1. takes about 2 weeks 2. The effects of adrenergic agents and vasoconstrictors (e.g. phenylephrine) are blunted during pregnancy. 3. Red blood cell mass increases 45%. Meanwhile, plasma volume increases 55% to result in physiologic anemia due to hemodilution. In fact, total blood volume reaches 90 mL/kg

Question 17

what accounts for the most pregnancy related deaths in the US?

Answer 17

cardiovascular disease

Question 18

how much is the o2 consumption increased in the second stage of labor?

Answer 18

75%

Question 19

what happens to the pao2, paco2, bicarb, and ph during pregnancy?

Answer 19

Question 20

The National Institute for Occupational Safety and Health (NIOSH) recommends a maximum exposure of nitrous oxide to healthcare providers of ___ parts per million

Answer 20

25 parts per million

Question 21

what is the pathophysiology of autoimmune thrombocytopeni purpura?

what is the treatment?

Answer 21

The pathophysiology involves immunoglobulin G (IgG) antibodies directed at platelet antigens with subsequent phagocytosis in the spleen

Corticosteroids are the first-line treatment and are indicated if the platelet count is < 30,000/μL before the onset of labor or < 50,000/μL during labor. High-dose intravenous immunoglobulin (IVIG) is indicated only if there is no response to corticosteroid therapy.

Question 22

why are pregnant patients at a greater risk for aspiration?

what is the primary cause of aspiration pneumonitis?

Answer 22

1. . Once aspiration occurs, the risk of pneumonitis is increased by aspirate pH < 2.5 because this causes a granulocytic reaction that continues beyond the acute phase.
2. . Once aspiration occurs, the risk of pneumonitis is increased by aspirate pH < 2.5 because this causes a granulocytic reaction that continues beyond the acute phase

pregnant patients have similar gastric ph and also have normal gastric emptying(except in advanced labor).

Question 23

Whats the range of a normal umbilical artery PH? Whats the normal range of abg for umbilical vein?

Answer 23

Artery away from baby (carries venous blood).. The normal average values of an umbilical artery blood gas sample are approximately: pH 7.2-7.3, PaCO2 50-55 mm Hg, PaO2 18-25 mm Hg, bicarbonate 22-25 mEq/L, base excess -2.7 to -4.7 mEq/L. umbilical vein ( 7.35/41/33/24//-1)

Question 24

fetal blood gas normalities??what isthe trick for Pco2 and Po2

Answer 24

Question 25

A 25-year-old pregnant woman with a past medical history significant for a spinal cord injury at the T5 level presents in labor. There are several medical complications secondary to spinal cord injury, which of the following is TRUE regarding this patient?

Answer 25

Any patient with injury T11 or higher has increased risk of preterm labor. Injuries >T6 and pregnancy has autonomic hyperreflexia in >85% of pregnancies

Question 26

what are the components of the biophysical profile?

Answer 26

non-stress test and observation of fetal breathing, fetal movement, fetal tone, and amniotic fluid volume

Question 27

how long must an acceleration or deceleration last to change the baseline FHR?

Answer 27

10 minutes

Question 28

what are some common teratogenic medications that we use?

Answer 28

Nitrous oxide is usually avoided in obstetric patients due to inhibition of methionine synthase, which is involved in folate metabolism and DNA synthesis. Significant DNA synthesis occurs in early embryogenesis during the first few weeks of life. Nitrous oxide has been associated with increased rates of miscarriage in obstetric patients as well as healthcare providers. According to the CDC and NIOSH, “Working with anesthetic gases could increase your chances of having a miscarriage if the gases are not properly controlled.” Animal studies have shown teratogenicity with prolonged exposure to concentrations of greater than 50% nitrous oxide. Human studies have not demonstrated the same effects, but nitrous is generally avoided in the first trimester and used in limited duration during non-obstetric surgery. These effects do not apply to the use of nitrous oxide in labor anesthesia.

Benzodiazepines are pregnancy category D and as their chronic use is associated with cleft lip, although some studies contest this. Cocaine is associated with growth retardation. Tetracyclines may inhibit fetal skeletal formation and cause tooth enamel hypoplasia. ACE inhibitors during pregnancy are associated with fetolethality. Warfarin can cause mental retardation and skeletal malformation.

Question 29

sprotte and whitacre are what type of needles?

2. a quincke needle is what type?

Answer 29

1. pencil point
2. cutting

Question 30

what is the definition of thrombocytopenia? (Platelet count)

Answer 30

<80k

Question 31

what is the diagnosis of chronic htn?

Gestational Htn?

Answer 31

Chronic hypertension occurs when the systolic pressure is above 140 mmHg or the diastolic pressure is above 90 mmHg before pregnancy or before 20 weeks’ gestation.

gestational: Gestational hypertension is the most frequent cause of hypertension. It presents with an elevated blood pressure after 20 weeks’ gestation without proteinuria. It will resolve within 12 weeks postpartum.

Question 32

what does progesterone do to lower esophageal sphincter tone?

Answer 32

Progesterone is also associated with decreased lower esophageal sphincter tone, which increases the risk of reflux as well as nausea and vomiting.

Question 33

is it ok to do neuroaxial anesthesia on a patient with severe mitral stenosis?

when is a strenuous time for mitral stenosis patients in obstetrics?

Answer 33

Mitral stenosis almost always occurs secondary to rheumatic disease; it is the most frequently acquired valvular lesion in pregnant patients. Severe mitral stenosis is defined with a valve area less than 1.0 cm^2. Mitral stenosis often becomes symptomatic during pregnancy due to the increase in maternal blood volume and heart rate. Poor functional status increases the risk for adverse outcomes and thus, it is ideal to treat the valve disease prior to conception. Vaginal delivery is generally assisted because the Valsalva maneuver may result in a sudden increase in central venous pressure. Cesarean delivery is typically reserved for obstetric indications. Regardless of the type of delivery, hemodynamic compromise and pulmonary edema immediately after delivery is a risk due to autotransfusion. Neuraxial anesthesia for labor and cesarean delivery can safely be performed. Ideal hemodynamic goals are a low-normal heart rate with sinus rhythm, avoidance of decreases in preload by avoiding aortocaval compression, and maintenance of venous return along with maintaining SVR.

Question 34

is it bette rto have surgery during the first or second trimester?

Answer 34

delaying surgery til the second trimester will help reduce the risk of preterm/miscarriage

Question 36

what is the normal fetal oxygen saturation?

Answer 36

35-65%

Question 37

what is sickle cell disease?

how do you manage these patients in the OR?

Answer 37

Patients with sickle cell disease (SCD) are often living longer, more fulfilling lives due to advances in medical technology. Encountering an obstetric patient with SCD has become more common in the last 2 decades. Special consideration must be given to these patients to help ensure favorable outcomes. Sickle cell disease occurs when there is a genetic defect that causes an abnormal hemoglobin variant to be substituted for the normal hemoglobin molecule. This variant is called hemoglobin S (HbS), and it has a single nucleotide polymorphism transversion (A to T). There are 2 main types: homozygous and heterozygous. Sickle cell trait carriers have 1 copy of the normal beta-globin gene and 1 sickle variant. The abnormal hemoglobin can cause distortion of the hemoglobin molecule when low oxygen tension is encountered. This results in the potential for vaso-occlusion, hemolysis, ischemia, and infarction. Oddly, the severity of the disease varies between individuals and is not always dependent on the percentage of HbS.

The tenets of care for pregnant SCD patients are the same as for those who are not pregnant: avoidance of hypercarbia, hypoxemia, acidosis, dehydration, and hypotension. Additionally, proper pain management can help decrease the stress response and potentially the sickling risk.

Question 38

what pressures define pulmonary htn?

Answer 38

Pulmonary hypertension is defined as mean pulmonary artery pressure over 25 mm Hg at rest or 30 mm Hg with exercise.