Hematology and Immunology
What causes physiologic anemia of pregnancy?
Plasma volume expansion.
Physiologic anemia of pregnancy results from an expansion of plasma due to increased renal filtrate absorption that is not fully compensated by the increase in red blood cell production that occurs in pregnancy. This mismatch results in normocytic anemia.
A 34-year-old gravida 1, para 0, at 28 weeks of gestation presents for a routine prenatal visit. Her pregnancy is notable for chronic hypertension that is well controlled with medication. On examination, her blood pressure is normal, but there is a size-versus-dates discrepancy on the fundal height check. At what fundal height to weeks of gestational age discrepancy, in cm, would there be concern for fetal growth restriction?
Screening for fetal growth restriction begins with assessing risk factors with a thorough review of medical history and obstetric history. Fundal height examination should begin at 24 weeks of gestation as part of routine prenatal care. It has been recommended that a fundal height to weeks of gestational age discrepancy of greater than or equal to 3 should increase your clinical suspicion for fetal growth restriction. This screening method can be limited by the presence of maternal obesity, leiomyomas, and multifetal gestation. In those circumstances or in the presence of risk factors, the preferred screening method is ultrasound.
What is the most accurate method to establish or confirm gestational age?
Ultrasound measurement of the embryo or fetus in the first trimester (up to and including 13 6/7 weeks of gestation) is the most accurate method to establish or confirm gestational age.
Most common symptom of cervical cancer in pregnancy
(Postcoital) bleeding
In the United States, which tocolytic has benefit beyond a 48 hour period?
None.
Maintenance therapy with tocolytics is ineffective for preventing preterm birth and improving neonatal outcomes and is not recommended for this purpose. Tocolytic therapy may provide short-term prolongation of pregnancy, enabling the administration of antenatal corticosteroids and magnesium sulfate for neuroprotection, as well as transport, if indicated, to a tertiary facility. However, no evidence exists that tocolytic therapy has any direct favorable effect on neonatal outcomes or that any prolongation of pregnancy afforded by tocolytics translates into a statistically significant neonatal benefit.
A 33-year-old woman, gravida 3, para 2002 at 37 weeks of gestation with no prenatal care, undergoes an uncomplicated vaginal delivery. Her prenatal labs reveal she is O negative and has a negative antibody screen. After her delivery, a Kleihauer-Betke test was performed, revealing a fetomaternal hemorrhage of approximately 50 mL of fetal red blood cells. How many vials of Rhogam should be administered within 72 hours of delivery?
4 vials.
A prophylactic dose of 300 micrograms of anti-D immune globulin can prevent Rh D alloimmunization after exposure to up to 30 mL of Rh D-positive fetal whole blood or 15 mL of fetal red blood cells. The dosing calculation is number of vials = (volume of fetal RBCs in mL/15 mL) + 1 extra vial. In this patient, four vials would be needed for 45.1–60 mL of fetal RBCs. Importantly, anti-D immune globulin doses given to susceptible Rh D-negative women within 72 hours of delivery reduced the rate of Rh D alloimmunization by 80–90%.
A 26-year-old gravida 1, para 0, at 12 weeks of gestation presents for her initial prenatal visit. She notes a recent history of international travel. She was in a remote area in West Africa and is concerned about exposures. What type of infection accounts for the majority of cases of fetal growth restriction worldwide?
Malaria
When is a pregnancy without a prior ultrasound confirmation considered suboptimally dated?
After 22w0d
A 25-year-old para 1001 woman at 11 weeks' gestation with a long-standing history of asthma comes to the clinic for worsening wheezing. In her last pregnancy, she did not have any problems with her asthma; however, over the last few weeks, she has been experiencing daily symptoms that have been waking her up at least once a week. She is responsive to the inhaled medications she has been prescribed, but she is wondering if she can take anything else. Which of the following is the preferred add-on controller therapy for pregnant women with moderate persistent asthma that is not well controlled with moderate-dose inhaled corticosteroids?
A long-acting β2-agonist is the preferred add-on controller therapy in pregnant women whose asthma is not well controlled on moderate-dose inhaled corticosteroids.
What is the appropriate placement of the center of a vacuum extractor on the fetal head relative to the fontanelles? (All answers are centered on the sagittal suture.)
Proper placement of the cup over the flexion point is a key step in safe and successful vacuum extraction. The flexion point is centered along the sagittal suture, approximately 3 cm anterior to the posterior fontanelle. The distance between posterior and anterior fontanelles is approximately 9 cm, so the flexion point is approximately 6 cm from the anterior fontanelle. As vacuum cups are 5–6 cm in diameter, when the cup is centered on the flexion point, the rim of the cup is 3 cm from the anterior fontanelle and abuts the posterior fontanelle.
A 27-year-old woman, gravida 2, para 1001, at 14 weeks of gestation, presents for her routine prenatal visit. Her initial prenatal labs show a positive antibody screen for Kell antibody with a titer of 1:32. After you discuss additional evaluation, the patient asks about the mechanism by which alloimmunization with Kell can cause hemolytic disease of the newborn. How do you explain this?
Kell antibody destroys red blood cell precursors and maturing erythrycytes in bone marrow.
Name the specificity and sensitivity of fundal height measurement in identifying FGR? What factors may limit its accuracy?
A single fundal height measurement at 32–34 weeks of gestation has been reported to be approximately 65–85% sensitive and 96% specific for detecting the growth-restricted fetus.
A 31-year-old patient presents with three consecutive early pregnancy losses. As part of the workup for recurrent pregnancy loss, the provider recommends parental karyotype. What percent of couples with recurrent pregnancy loss are found to have cytogenetic abnormalities identified on parental karyotype?
Recurrent pregnancy loss (RPL) is a distinct disorder defined by two or more failed clinical pregnancies. The workup for recurrent pregnancy loss includes parental karyotypes, as 2–5% of couples will have balanced reciprocal translocations or Robertsonian translocations. Other common causes of recurrent pregnancy loss are included in the table below.
Treatment options for Bell's Palsy?
An oral corticosteroid regimen (prednisone, 50 to 60 mg per day for five days followed by a five-day taper) is the first-line treatment for Bell palsy. Combination therapy with an oral corticosteroid and antiviral may reduce rates of synkinesis (misdirected regrowth of facial nerve fibers manifesting as involuntary co-contraction of certain facial muscles). Recommended antivirals include valacyclovir (1 g three times per day for seven days) or acyclovir (400 mg five times per day for 10 days).
Name the 10 pre-requisites for operative vaginal birth
The prerequisites for OVB are as follows: cervix fully dilated and retracted, membranes ruptured, engagement of the fetal head, position of the fetal head has been determined, fetal weight estimation performed, pelvis thought to be adequate for vaginal birth, adequate anesthesia, maternal bladder has been emptied, patient has agreed after being informed of the risks and benefits of the procedure, and willingness to abandon trial of OVB and backup plan in place in case of failure to deliver.
For a patient with Hb S disease who is indicated for a transfusion, what is the goal Hemoglobin concentration? Goal Hb S concentration?
the objective is to lower the percentage of Hb S to approximately 40% while simultaneously raising the total hemoglobin concentration to about 10 g/dL.
In addition to fetal growth restriction, ACE inhibitors can also cause what developmental anomaly?
Angiotensin-converting enzyme inhibitors are contraindicated in pregnancy and can cause growth restriction and calvarium maldevelopment.
Which cells are analyzed in pre-implantation genetic diagnosis? What is the false negative rate?
To remove material from an oocyte or embryo, an opening in the zona pellucida is created using a laser, acid Tyrode's solution, or a sharpened glass needle. The polar body or blastomere(s) then may be extracted using a small suction pipette or by gently compressing the oocyte or embryo to extrude material through the opening. For maternally inherited mutations, genetic analysis can be performed on the oocyte by removing the first and, sometimes, the second polar body and by inferring the genetic composition of the oocyte from the result (2, 3). Genetic analysis usually is performed on one or two nucleated blastomeres removed three days after fertilization. The decision to remove one or two blastomeres depends on the quality of the embryo and the disease of interest. The embryo then may remain in culture up to the blastocyst stage or be cryopreserved until such time as the results of the genetic analysis can be completed. Alternatively, mural trophectoderm cells can be removed from the embryo for analysis at the blastocyst stage.
The estimated risk of transferring an affected embryo mistakenly identified as normal by PGD is approximately 2% for recessive disorders and 11% for dominant disorders
How does cardiac function change in the second stage of labor?
During stage 2 contractions, cardiac output decreased by 32%, stroke volume decreased by 44%, heart rate increased by 52%, systemic vascular resistance increased by 88%, and systolic arterial pressure increased by 36% compared to baseline. During stage 1 contractions, haemodynamic changes were less profound and less uniform than during stage 2.
Name 3 indications for prophylactic antibiotics after a vaginal birth.
Operative delivery with episiotomy
Manual extraction of placenta
OASIS injury
How does natural killer cell activity change throughout pregnancy?
These findings indicate that the increased NK activity in the first trimester and at 1 month postpartum is induced by increased cytotoxic activity of individual NK cells, and that the decreased NK activity in late pregnancy is induced by a decrease in the numbers of NK cells. These physiological changes may play an important role in implantation in early pregnancy, protection of the fetal allograft in late pregnancy and in the natural defense against infection during the puerperal period.
True or false, antiphospholipid antibodies are associated with fetal growth restriction
Intrauterine growth restriction (IUGR) complicates pregnancies in women with APS, occurring in 15–30% in most series. Although APS is associated with IUGR, there is conflicting evidence of the link between antiphospholipid antibodies alone and IUGR. Although some studies have not found a correlation between antiphospholipid antibodies and IUGR, this discrepancy may result from the inclusion of some women with low-positive test results for antiphospholipid antibodies.
Name 3 medications which should be avoided or limited in those using ondasetron?
Antihistamines (hydroxyzine)
Analgesics and sedatives (methadone, oxycodone, and chloral hydrate)
Diuretics
Anticholinergics
Antiarrhythmics (amiodarone, sotalol, quinidine, procainamide, and flecainide)
Antipsychotics (thioridazine, haloperidol, chlorproma- zine, and clozapine)
Tricyclic and tetracyclic antidepressants (amitriptyline, imipramine, and clomipramine)
Macrolide antibiotics (erythromycin and azithromycin)
Trazodone
Fluoxetine
Antimalarials (chloroquine, mefloquine, and quinine)
Metronidazole
Human immunodeficiency virus (HIV) protease inhibitors
A 24-year-old G0 presents for a preconception visit. The patient has a past medical history significant for systemic lupus erythematosus, and would like to find out if there is anything she needs to know regarding pregnancy and her disease before conceiving. In a patient with systemic lupus erythematous, pregnancy outcome has been found to be improved if the disease is quiescent for a minimum of how long before conception?
Preconception counseling is an important opportunity for obstetricians to counsel patients about maintaining a healthy lifestyle and minimizing health risks in an upcoming pregnancy. Ideally, disease should be quiescent for 6 months prior to systemic lupus erythematosus (SLE) patients attempting conception.
What tocolytic has been shown to be superior as maintenance therapy over placebo in prolonging pregnancy?
Atosiban