Obstetrics Flashcards
(154 cards)
1
Q
A patient who is taking birth control pills presents with amenorrhea. What is the likely cause?
A
Pregnancy. No form of contraception is 100% effective (including tubal ligation), especially when patient compliance is required.
2
Q
List the symptoms and signs of pregnancy.
A
q2
3
Q
Which vitamin should all pregnant women take? Why?
A
Give all pregnant patients folate to prevent neural tube defects. Ideally, all women of reproductive age should take folate because it is most effective in the first trimester, before most women know that they are pregnant. Iron supplements frequently are given to pregnant women to help prevent anemia.
4
Q
Define macrosomia. What is the likely cause?
A
Macrosomia is defined as a newborn that weighs more than 4 kg (roughly 9 lb). The cause is maternal diabetes mellitus until proven otherwise.
5
Q
What routine tests should be obtained for all pregnant patients?
A
q5
6
Q
On every prenatal visit, listen to fetal heart tones and evaluate uterine size. When can these factors first be noticed? What constitutes a size/date discrepancy?
A
Fetal heart tones can be heard with Doppler ultrasound at 10 to 12 weeks and with a normal stethoscope at 16 to 20 weeks. At 12 weeks of gestation, the uterus enters the abdomen and is palpable at the symphysis pubis; at roughly 20 weeks, it reaches the umbilicus. Uterine size is evaluated by measuring the distance from the symphysis pubis to the top of the fundus in centimeters. At roughly 20 to 35 weeks, the measurement in centimeters should equal the number of weeks of gestation. A discrepancy greater than 2 to 3 cm is called a size/date discrepancy. Ultrasound should be done for further evaluation (e.g., intrauterine growth retardation, multiple gestations).
7
Q
When is ultrasound most accurate at estimating the fetal age?
A
At 16 to 20 weeks, the biparietal diameter (measured on ultrasound) gives the most accurate estimate of fetal age.
8
Q
What is a hydatiform mole? What are the clues to its presence?
A
A hydatiform mole is one form of gestational trophoblastic neoplasia, in which the products of con- ception basically become a tumor. Look for the following clues: ■ Preeclampsia before the third trimester. ■ An hCG level that does not return to zero after delivery (or abortion/miscarriage) or one that rises rapidly during pregnancy. ■ First- or second-trimester bleeding with possible expulsion of “grapes” from the vagina (grossly, the tumor looks like a “bunch of grapes”) and excessive nausea/hyperemesis. ■ Uterine size/date discrepancy. ■ “Snowstorm” pattern on ultrasound.
9
Q
Distinguish between complete and partial moles. How are hydatiform moles treated?
A
Complete moles have a karyotype of 46 XX (with all chromosomes from the father) and no fetal tis- sue. Incomplete moles usually have a karyotype of 69 XXY with fetal tissue in the tumor. Treat hydatiform moles with uterine dilation and curettage. Then follow with serial measurements of hCG levels until they fall to zero. If the hCG level does not fall to zero or rises, the patient has either an invasive mole or a choriocarcinoma (increasingly aggressive forms of gestational trophoblastic neoplasia) and needs chemotherapy (usually methotrexate or dactinomycin, both of which are extremely effective).
10
Q
How is intrauterine growth retardation (IUGR) defined? What causes it?
A
IUGR is defined as fetal size below the tenth percentile for age. Causes are best understood in broad terms as maternal (e.g., smoking, alcohol or drug use, lupus erythematosus), fetal (e.g., TORCH infections, congenital anomalies), or placental (e.g., hypertension, preeclampsia). For a discussion of TORCH infections, see question 36.
11
Q
When should ultrasound be used to evaluate the fetus?
A
The indications for ultrasound are now quite liberal. Order ultrasound for all patients who have a size/date discrepancy greater than 2 to 3 cm or risk factors for pregnancy-related problems (e.g., hypertension, diabetes, renal disease, lupus erythematosus, smoking, alcohol or drug use, history of previous pregnancy-related problems). Ultrasound also is used when fetal death, distress, or abortion or miscarriage is suspected (e.g., a baby that stops kicking, vaginal bleeding, slow fetal heartbeat on auscultation).
12
Q
How is fetal well-being evaluated?
A
A nonstress test is the easiest initial screen. It is performed with the mother at rest. A fetal heart rate tracing is obtained for 20 minutes. A normal strip has at least 2 accelerations of heart rate, each at least 15 beats per minute above baseline and lasting at least 15 seconds. A biophysical profile is slightly more involved and includes a nonstress test as well as a measure of amniotic fluid (to determine whether oligohydramnios or polyhydramnios is present), a measure of fetal breathing movements, and a measure of general fetal movements. If the fetus scores poorly on the biophysical profile, the next test is the contraction stress test, which looks for uteroplacental dysfunction. Oxytocin is given, and a fetal heart strip is monitored. If late decelerations are seen on the fetal heart strip with each contraction, the test is positive. In most cases of a positive contraction stress test, a cesarean section is performed.
13
Q
True or false: A biophysical profile often is used in high-risk pregnancies in the absence of obvious problems.
A
True. A biophysical profile may be done once or twice a week from the start of the third trimester until delivery to monitor for potential problems.
14
Q
True or false: Aspirin should be avoided during pregnancy.
A
True. Use acetaminophen instead. One important exception is in patients with antiphospholipid syndrome, in whom aspirin may improve pregnancy outcome (subcutaneous unfractionated heparin or low molecular weight heparin also can be used to treat antiphospholipid syndrome in pregnancy).
15
Q
Define postterm pregnancy. Why is it a major concern? How is it treated?
A
Postterm pregnancy is defined as more than 42 weeks of gestation. Both prematurity and postmatu- rity increase perinatal morbidity and mortality rates. With postmaturity, dystocia (or difficult delivery) becomes more common because of the increased size of the infant. In general, if the gestational age is known to be accurate and the cervix is favorable, labor is induced (e.g., with oxytocin). If the cervix is not favorable or the dates are uncertain, twice-weekly biophysical profiles are done. At 41 weeks, most obstetricians advise induction of labor. A 2012 meta-analysis demonstrated that routine labor induction at greater than 41 weeks compared with expectant management resulted in lower perinatal mortality and a lower rate of meconium aspiration syndrome.
16
Q
What two rare disorders are associated with prolonged gestation?
A
Anencephaly and placental sulfatase deficiency.
17
Q
What are the normal changes and complaints in pregnancy?
A
Normal changes in pregnancy include nausea or vomiting (morning sickness), amenorrhea, heavy (pos- sibly even painful) feeling of the breasts, increased pigmentation of the nipples and areolae, Montgomery tubercles (sebaceous glands in the areola), backache, linea nigra, melasma (chloasma), striae gravidarum, and mild ankle edema. Heartburn and increased frequency of urination are also common problems.
18
Q
What test is used to screen for neural tube defects? At what time during pregnancy is it measured? Explain the significance of a low or high alpha- fetoprotein (AFP) level in maternal serum.
A
Maternal AFP is most accurate when measured between 15 and 20 weeks of gestation. A low AFP may represent Down syndrome, fetal demise, or inaccurate dates. A high AFP may represent neural tube defects (e.g., anencephaly, spina bifida), ventral wall defects (e.g., omphalocele, gastroschi- sis), multiple gestation, or inaccurate dates.
19
Q
What should be done if the AFP is elevated?
A
Repeat the test. As many as 30% of elevated maternal serum AFP test results may be elevated but are normal upon repeat testing. The initial elevation is not associated with an increased risk of neural tube defects.
20
Q
What further testing should a patient undergo if the AFP remains elevated?
A
If the AFP remains elevated, the patient is advised first to undergo ultrasound to determine whether a neural tube defect or other anomaly is present. The ultrasound is also used to confirm gestational age, number of fetuses, and fetal viability. Further evaluation with amniocentesis may be required if the ultrasound findings are uncertain or there is a concern for nonvisualized neural tube defects (via elevated AFP level in amniotic fluid or detection of acetylcholinesterase in amniotic fluid). There is a small risk of miscarriage after amniocentesis.
21
Q
What prenatal tests are available to screen for Down syndrome?
A
The first trimester combined test, integrated tests, sequential testing, contingent testing, the quadruple test, and maternal plasma-based tests. The ACOG recommends that all women be offered screening before 20 weeks of gestation.
22
Q
What is the first trimester combined test? When is it performed?
A
The first trimester combined test is performed at 11 to 13 weeks of gestation. The test involves determination of nuchal translucency (NT) by ultrasound, combined with serum pregnancy-associated plasma protein-A (PAPP-A) and serum human chorionic gonadotropin (hCG). Chorionic villus sampling (CVS) is used for women who have this first trimester screening and test positive.
23
Q
Describe the integrated tests.
A
The full integrated test includes an ultrasound measurement of nuchal translucency at 10 to 13 weeks of gestation, PAPP-A at 10 to 13 weeks of gestation, and AFP, unconjugated estradiol (uE3), hCG, and inhibin A at 15 to 18 weeks of gestation. Results of the full integrated test are not available until the second trimester. The serum integrated test is the same as the full integrated test but without the ultrasound evalua- tion of nuchal translucency. This test is used in areas where expertise in the ultrasound measurement of nuchal translucency is not available. Results of the serum integrated test are not available until the second trimester.
24
Q
Describe sequential testing.
A
Step-wise sequential testing has been developed to provide a risk estimate during the first trimester. The first trimester portion of the integrated screen is performed. If the tests indicate a very high risk of having an affected fetus, CVS is offered. Those women whose results do not place them at very high risk of having an affected fetus go on to have the second trimester portion of the screening.
25
Describe contingent testing.
Contingent testing has not yet been proven efficacious in a prospective clinical trial and probably will not be tested on the USMLE; however, contingent screening is defined in terms of three risk cut-offs: (1) women at very high risk of having a fetus with Down syndrome after first trimester testing are offered immediate invasive prenatal diagnosis, (2) women at very low risk are provided with their risk estimate and require no additional testing, and (3) women at intermediate risk receive second trimester marker testing.
26
What is the quadruple test? For whom is it typically used? When is it performed?
The quadruple test includes the serum markers AFP, uE3, hCG, and inhibin A. The quadruple test is the best available test for women who receive prenatal care in the second trimester, but can be used for women who receive earlier prenatal care. It is performed at 15 to 18 weeks of gestation.
27
What is a maternal plasma-based test?
This is the newest option that is just becoming widely available and may someday make many of these other tests obsolete. This test, also called cell-free fetal DNA testing, detects fetal DNA in the circulation and has a detection rate more than 98% and a false-positive rate of less than 0.5% for Down syndrome and Edward syndrome (trisomy 18). It is used after 10 weeks of gestation. Cell-free fetal DNA testing is not yet validated in low-risk women, but can be used in higher risk women (i.e., women who will be older than 35 at the time of delivery; presence of sonographic findings associ- ated with fetal aneuploidy; history of previous pregnancy with fetal trisomy; or positive screening results on tests such as the first trimester combined test, the integrated test, or the quadruple test).
28
What is the next step if a woman has a positive screening test for Down syndrome?
Offer fetal karyotype determination. This is done by CVS in the first trimester and by amniocentesis in the second trimester.
29
Why is CVS done instead of amniocentesis in some cases?
CVS can be done at 9 to 12 weeks of gestation (earlier than amniocentesis) and generally is reserved for women with previously affected offspring or known genetic disease. It offers the advantage of a first-trimester abortion if the fetus is affected. CVS is associated with a slightly higher miscarriage rate than amniocentesis.
30
True or false: CVS can detect neural tube defects but not genetic disorders.
False. CVS can detect genetic or chromosomal disorders but not neural tube defects.
31
Specify the effects of Thalidomide on an exposed fetus.
Phocomelia (absence of long bones and flipperlike appearance of hands)
32
Specify the effects of Antineoplastics on an exposed fetus.
many
33
Specify the effects of Tetracycline on an exposed fetus.
Yellow or brown teeth
34
Specify the effects of Aminoglycosides on an exposed fetus.
Deafness
35
Specify the effects of Valproic acid on an exposed fetus.
Spina bifida, hypospadias
36
Specify the effects of Progesterone on an exposed fetus.
Masculinization of female fetus
37
Specify the effects of Cigarettes on an exposed fetus.
Intrauterine growth retardation, low birth weight, prematurity
38
Specify the effects of OCP on an exposed fetus.
VACTERL syndrome: Vertebral anomalies, imperforate Anus, Cardiac anomalies, TracheoEsophageal fistula, Renal anomalies, Limb anomalies
39
Specify the effects of Lithium on an exposed fetus.
Cardiac (Ebstein) anomalies
40
Specify the effects of Radiation on an exposed fetus.
Intrauterine growth retardation, CNS defects, eye defects, malignancy (e.g., leukemia)
41
Specify the effects of Alcohol on an exposed fetus.
Fetal alcohol syndrome
42
Specify the effects of Phenytoin on an exposed fetus.
Craniofacial, limb, and cerebrovascular defects; mental retardation
43
Specify the effects of Warfarin on an exposed fetus.
Craniofacial defects, intrauterine growth retardation, CNS malformation, stillbirth
44
Specify the effects of Carbamazepine on an exposed fetus.
Fingernail hypoplasia, craniofacial defects
45
Specify the effects of Isotretinoin on an exposed fetus.
CNS, craniofacial, ear, and cardiovascular defects
46
Specify the effects of Iodine on an exposed fetus.
Goiter, neonatal hypothyroidism
47
Specify the effects of Cocaine on an exposed fetus.
Cerebral infarcts, mental retardation
48
Specify the effects of Diazepam on an exposed fetus.
Cleft lip and/or palate
49
Specify the effects of Diethylstilbestrol on an exposed fetus.
Clear cell vaginal cancer, adenosis, cervical incompetence
50
List the teratogenic effects of maternal diabetes mellitus. What is the best way to reduce these complications?
q32
51
What other problems does maternal diabetes cause in pregnancy?
In the mother, diabetes can result in polyhydramnios and preeclampsia (as well as the complica- tions of diabetes). Problems in infants born to a diabetic mother (other than birth defects) include an increased risk of respiratory distress syndrome and postdelivery hypoglycemia (from fetal islet-cell hypertrophy caused by maternal and thus fetal hyperglycemia). After birth, the infant is cut off from the mother's glucose and the hyperglycemia resolves, but the infant's islet cells still overproduce insulin and cause hypoglycemia. Treat with intravenous glucose.
52
True or false: Oral hypoglycemic agents should not be used during pregnancy.
True. Use insulin to treat diabetes if diet and exercise cannot control glucose levels. Oral hypoglyce- mics, unlike insulin, may cross the placenta and cause fetal hypoglycemia.
53
What commonly used drugs are generally considered safe in pregnancy?
A short list of drugs that are generally safe in pregnancy includes acetaminophen, penicillins, cepha- losporins, erythromycin, nitrofurantoin, histamine-2 receptor blockers, antacids, heparin, hydralazine, methyldopa, labetalol, insulin, and docusate.
54
What are the TORCH syndromes? What do they cause?
TORCH is an acronym for several maternal infections that can cross the placenta and can cause intrauterine fetal infections that may result in birth defects. Most TORCH infections can cause mental retardation, microcephaly, hydrocephalus, hepatosplenomegaly, jaundice, anemia, low birth weight, and IUGR. T = Toxoplasma gondii: Look for exposure to cats. Specific defects include intracranial calcifica- tions and chorioretinitis. O = Other: Varicella-zoster causes limb hypoplasia and scarring of the skin. Syphilis causes rhini- tis, saber shins, Hutchinson teeth, interstitial keratitis, and skin lesions. R = Rubella: Worst in the first trimester (some recommend abortion if the mother has rubella in the first trimester). Always check antibody status on the first visit in patients with a poor immunization history. Look for cardiovascular defects, deafness, cataracts, and microphthalmia. C = Cytomegalovirus: Most common infection of the TORCH group. Look for deafness, cerebral calcifications, and microphthalmia. H = Herpes: Look for vesicular skin lesions (with positive Tzanck smears) and history of maternal herpes lesions.
55
True or false: With most in utero infections that can cause birth defects, obvious clues are present in the mother and/or fetus at birth.
False. Although the USMLE probably will give clues, the mother may be asymptomatic (i.e., she may have a subclinical infection), and the infant may be asymptomatic at birth, developing only later such symptoms as learning disability, mental retardation, or autism.
56
Describe therapy to reduce HIV transmission from an infected mother to the fetus. When should an infant born to an HIV-infected mother be tested?
In untreated HIV-positive patients, HIV is transmitted to the fetus in roughly 25% of cases. When three-drug therapy is given to the mother prenatally and zidovudine is given to the infant for 6 weeks after birth, HIV transmission is reduced to roughly 2%. A noninfected infant may still have a positive HIV antibody test at birth because maternal antibodies can cross the placenta. Within 6 to 18 months, however, the test reverts to negative. This is why infants of infected mothers are tested using a direct HIV DNA PCR (polymerase chain reaction) test at birth, at 4 to 6 weeks of age, and 2 months after the second test. Babies who have these three negative tests should have an HIV antibody test at 12 and 18 months of age. Cesarean section may reduce HIV transmission to the child.
57
What should you do if a pregnant woman has genital herpes?
A decision is generally made when the mother goes into labor (not beforehand). If, at the time of true labor, the mother has active, visible genital herpes lesions, do a cesarean section to prevent transmission to the fetus. If, at the time of true labor, the mother has no visible genital herpes lesions, the child can be delivered vaginally.
58
What should you do for the child if the mother has chronic hepatitis B or chickenpox?
If the mother has chronic hepatitis B, give the infant the first hepatitis B vaccine shot and hepatitis B immunoglobulin at birth. If the mother contracts chickenpox in the last 5 days of pregnancy or the first 2 days after delivery, give the infant varicella-zoster immunoglobulin.
59
How do you treat gonorrheal and chlamydial genital infections during pregnancy?
The treatment for gonorrhea remains unchanged because ceftriaxone is safe during pregnancy. For chlamydial infection, give azithromycin, amoxicillin, or erythromycin base instead of doxycycline or erythromycin estolate.
60
How is tuberculosis treated in pregnancy?
In a similar way as for a nonpregnant patient. Use isoniazid, rifampin, and ethambutol if the risk of a drug-resistant organism is low. Pyrazinamide should be used with caution because of a lack of data on the risk of teratogenicity. However, pyrazinamide should be added if a drug-resistant organism is suspected. Streptomycin, which is a rarely used second-line agent, should be avoided. Give vitamin B6 to pregnant patients treated with isoniazid to avoid a deficiency.
61
What are the signs of placental separation during delivery?
The signs of placental separation include a fresh show of blood from the vagina, lengthening of the umbilical cord, and a rising fundus that becomes firm and globular.
62
True or false: After cesarean section, a patient may have a vaginal delivery in the future.
It depends. After a classic (vertical) uterine incision, patients must have cesarean sections for all future deliveries because of the increased rate of uterine rupture with vaginal delivery. After a lower (horizontal) uterine incision (the incision of choice), a patient may deliver future pregnancies vaginally with only a slightly increased (i.e., acceptable) risk of uterine rupture.
63
Define lochia. When is it a problem?
For the first several days after delivery, some vaginal discharge (known as lochia) is normal. It is red for the first few days and gradually turns white or yellowish-white by day 10. If the lochia is foul smelling, suspect endometritis.
64
What treatment may be given to a woman who does not want to breastfeed?
Because the breasts can become engorged with milk and thus quite painful, you may prescribe tight- fitting bras, ice packs, and analgesia to reduce symptoms. Medications for the suppression of lacta- tion (e.g., bromocriptine, estrogens, oral contraceptive pills) are generally no longer recommended because of risks of thromboembolism and stroke.
65
List the common contraindications for breastfeeding.
■ Use of alcohol or illicit drugs (with a few caveats that won’t be tested on the USMLE) ■ HIV infection, although the World Health Organization recommends breastfeeding in developing countries if replacement feeding is not possible ■ Some medications, including antineoplastic agents, antimetabolic agents (cyclophosphamide, mercaptopurine), some anticonvulsants (topiramate), amiodarone
66
What is the preferred method of anesthesia in obstetric patients? Why?
Epidural anesthesia. General anesthesia involves a higher risk of aspiration and its resulting pneu- monia because the gastroesophageal sphincter is relaxed in pregnancy and patients usually have not refrained from eating before going into labor. There also is concern about the effect of general anesthetic agents on the fetus. Spinal anesthesia can interfere with the mother's ability to push and is associated with a higher incidence of hypotension than epidural anesthesia.
67
True or false: Asymptomatic bacteriuria, detected on routine urinalysis, should be treated during pregnancy.
True. Up to 20% of patients develop cystitis or pyelonephritis if untreated. This rate is much higher than in nonpregnant patients, who should not be treated for asymptomatic bacteriuria. In pregnancy, the gravid uterus can compress the ureters, and increased progesterone can decrease the tone of the ureters, increasing urinary stasis and the risk for urinary tract infection.
68
What do you need to know about vaginal group B streptococcal colonization and pregnancy?
Pregnant women should be tested for vaginal group B streptococci. Women who are carriers should be treated during labor with penicillin G or ampicillin. Earlier treatment (e.g., second trimester) is ineffective because group B streptococci frequently return—and usually they are dangerous only during labor and delivery. The reason for treating asymptomatic carriers is to prevent neonatal sepsis and endometritis, both of which are commonly caused by group B streptococci.
69
When does mastitis occur? How do you recognize and treat it?
Mastitis (inflammation of the breast) usually develops in the first 2 months postpartum. Breasts are red, indurated, painful, and nipple cracks or fissuring may be seen. Staphylococcus aureus is the usual cause. Treat with analgesics (e.g., acetaminophen, ibuprofen), warm and/or cold compresses, and continued breastfeeding with the affected breast(s) even though it is painful (use a breast pump to empty breast if needed) to prevent further milk duct blockage and abscess formation. An antistaphylococcal antibiotic (e.g., cephalexin, dicloxacillin) is usually given for more than mild symptoms. If a fluctuant mass develops or there is no response to antibiotics within a few days, an abscess is likely present and must be drained.
70
What are the diagnostic signs and symptoms of preeclampsia? When does it occur?
Preeclampsia causes hypertension, defined as a greater than 30-point increase in systolic or a greater than 15-point increase in diastolic blood pressure over baseline. Other signs and symptoms include proteinuria (2+ or more protein on urinalysis), oliguria, edema of the hands or face, head- ache, visual disturbances, or the HELLP syndrome (hemolysis, elevated liver enzymes, low platelets, and right upper quadrant or epigastric pain). Preeclampsia usually occurs in the third trimester.
71
What are the main risk factors for preeclampsia? How is it treated?
The risk factors (in decreasing order of importance) include chronic renal disease, chronic hyperten- sion, family history of preeclampsia, multiple gestations, nulliparity, extremes of reproductive age (the classic patient is a young woman with her first child), diabetes, and black race. The definitive treat- ment is delivery. This is the treatment of choice if the patient is at term. In a preterm patient with mild disease, the hypertension can be treated with hydralazine, labetalol, or methyldopa. Advise bed rest and observe. If the patient has severe disease (defined as oliguria, mental status changes, headache, blurred vision, pulmonary edema, cyanosis, HELLP syndrome, blood pressure greater than 160/110 mm Hg, or progression to eclampsia [seizures]), deliver the infant once the mother’s condition is stabilized. Otherwise, both mother and infant may die.
72
True or false: The combination of hypertension and proteinuria during pregnancy means preeclampsia until proven otherwise.
True
73
When is edema normal during pregnancy? When is it not?
Mild ankle edema is normal in pregnancy, but moderate-to-severe edema of the ankles or edema of the hands is likely to be preeclampsia.
74
What should you consider if preeclampsia develops before the third trimester?
The possibility of gestational trophoblastic disease (i.e., hydatiform mole, choriocarcinoma).
75
Distinguish between preeclampsia and eclampsia. How can eclampsia be prevented?
Preeclampsia plus seizures equals eclampsia. Eclampsia can be prevented by regular prenatal care so that you catch the disease in the preeclamptic stage and treat appropriately.
76
What should you use to treat seizures in eclampsia? What are the toxic effects?
Use magnesium sulfate for eclamptic seizures; it also lowers blood pressure. Toxic effects include hyporeflexia (first sign of toxicity), respiratory depression, central nervous system (CNS) depression, coma, and death. If toxicity occurs, the first step is to stop the magnesium infusion.
77
True or false: When eclampsia occurs, you must deliver the infant immediately, regardless of maternal status.
False. Do not try to deliver the infant until the mother’s condition is stable (e.g., do not perform a cesarean section while the mother is having seizures).
78
Why are preeclampsia and eclampsia so important?
Preeclampsia and eclampsia cause uteroplacental insufficiency, IUGR, fetal demise, and increased maternal morbidity and mortality.
79
True or false: Preeclampsia and eclampsia are risk factors for development of future hypertension.
False
80
What are the major causes of maternal mortality associated with childbirth?
In decreasing order: pulmonary embolism (PE), pregnancy-induced hypertension (preeclampsia/ eclampsia), and hemorrhage.
81
How do you recognize an amniotic fluid PE?
Look for a recently postpartum mother who develops sudden shortness of breath, tachypnea, chest pain, hypotension, and disseminated intravascular coagulation. Treatment is supportive.
82
Define oligohydramnios. What causes it? Why is it worrisome?
Oligohydramnios means a deficiency of amniotic fluid (
83
Define polyhydramnios. What causes it? Why is it worrisome?
Polyhydramnios means an excess of amniotic fluid (\>2 L or an amniotic fluid index \> 25). Causes include maternal diabetes, multiple gestation, neural tube defects (anencephaly, spina bifida), gastro- intestinal (GI) anomalies (omphalocele, esophageal atresia), and hydrops fetalis. Polyhydramnios can cause maternal problems, including postpartum uterine atony (with resultant postpartum hemor- rhage) and maternal dyspnea (an overdistended uterus compromises pulmonary function).
84
How early can a standard home pregnancy test diagnose pregnancy?
Roughly 2 weeks after conception (about the time when the woman realizes that her period is late).
85
Define the characteristics and duration of the normal stages of labor.
see q67
86
Distinguish between a protraction disorder and an arrest disorder. What should you do when either occurs?
A protraction disorder occurs once true labor has begun if the mother takes longer than the previous chart indicates, but labor nonetheless is progressing slowly. An arrest disorder (failure to progress) occurs once true labor has begun if no change in dilation is seen over 2 hours or no change in descent is seen over 1 hour. In either situation, first rule out an abnormal lie and cephalopelvic disproportion. If neither is pres- ent, the mother can be treated with labor augmentation (e.g., oxytocin, prostaglandin). If these steps fail, manage expectantly and do a cesarean section at the first sign of fetal distress.
87
What is the most common cause of protraction or arrest disorder?
Cephalopelvic disproportion, defined as a disparity between the size of the infant's head and the mother's pelvis. Labor augmentation is contraindicated in this setting.
88
Distinguish between true labor and false labor.
In true labor, normal contractions occur at least every 3 minutes, are fairly regular, and are associated with cervical changes (effacement and dilation). In false labor (Braxton-Hicks contractions), contrac- tions are irregular and no cervical changes occur.
89
What problems may be encountered when oxytocin is used to augment labor?
On the Step 2 examination, watch for uterine hyperstimulation (painful, overly frequent, and poorly coordinated uterine contractions), uterine rupture, fetal heart rate decelerations, and water intoxica- tion/hyponatremia (because of the antidiuretic hormone effect of oxytocin). Treat all of these compli- cations first by discontinuing the oxytocin infusion; the half-life is less than 10 minutes.
90
What problems are associated with the use of intravaginal prostaglandin and amniotomy?
Prostaglandin E2 (dinoprostone) or misoprostol may be used locally to induce the cervix (a process sometimes called “ripening”) and is highly effective in combination with (or before) oxytocin. It also may cause uterine hyperstimulation. Amniotomy (creating a manual opening in the amniotic membrane) also hastens labor but exposes the fetus and uterine cavity to possible infection if labor does not occur promptly.
91
What are the contraindications to labor induction or augmentation?
The list is almost the same as the list of contraindications to vaginal delivery: Placenta or vasa previa, umbilical cord prolapse, prior classic (vertical) cesarean section, transverse fetal lie, active genital herpes, cephalopelvic disproportion, and cervical cancer.
92
Define abortion.
Abortion is defined as the termination (intentional or not) of a pregnancy at less than 20 weeks of gestation or when the fetus weighs less than 500 g. Miscarriage describes a spontaneous abortion.
93
What are the different terms for an unintentional abortion?
Threatened abortion: Uterine bleeding without cervical dilation and no expulsion of tissue. Treat with bed rest and pelvic rest. Inevitable abortion: Uterine bleeding with cervical dilation and crampy abdominal pain and no tissue expulsion. Incomplete abortion: Passage of some products of conception through the cervix. Complete abortion: Expulsion of all products of conception from the uterus. Treat with serial test- ing of hCG level to make sure that it goes down to zero. Missed abortion: Fetal death with no expulsion of tissue (in some cases not for several weeks). Treat with dilation and curettage if less than 14 weeks of gestation, attempted delivery if more than 14 weeks of gestation. All of the above terms imply less than 20 weeks of gestation. Treat all abortions with intrave- nous fluids (and blood transfusions if necessary) and consider dilation and curettage (once the fetus is confirmed as dead or expelled). Give the mother RhoGAM if she has an Rh-negative blood type.
94
Define induced and recurrent abortions. What do recurrent abortions suggest?
see q76
95
True or false: hCG roughly doubles every 2 days in the first trimester.
True. An hCG level that stays the same or increases only slowly with serial testing indicates a fetus in trouble (e.g., threatened abortion, ectopic pregnancy) or fetal demise. A rapidly increasing hCG level or one that does not decrease after delivery may indicate hydatiform mole or choriocarcinoma.
96
When can ultrasound detect an intrauterine gestational sac? Why do you need to know this information?
At roughly 5 weeks after the last menstrual period (or when hCG is greater than 2000 mIU), evidence of intrauterine pregnancy can be detected by transvaginal sonography. A definite fetus and fetal heartbeat can be detected by transvaginal ultrasound at 5 to 6 weeks of gestation. Use this information when trying to determine the possibility of an ectopic pregnancy. For example, if the patient's last menstrual period was 4 weeks ago and a pregnancy test is positive, you cannot rule out an ectopic pregnancy with ultrasound. If, however, the patient's last menstrual period was 10 weeks ago with a positive pregnancy test and an ultrasound of the uterus does not show a gesta- tional sac, be suspicious of an ectopic pregnancy.
97
What are the risk factors for developing an ectopic pregnancy?
The major risk factor for ectopic pregnancy is a previous history of pelvic inflammatory disease (10-fold increase in ectopic pregnancy rate). Other risk factors include a previous ectopic pregnancy, history of tubal sterilization or tuboplasty, pregnancy that occurs with an intrauterine device in place, and a history of DES exposure, which can cause tubal abnormalities in women who were exposed in utero.
98
What are the classic symptoms and signs of a ruptured ectopic pregnancy?
A recent history of amenorrhea with current vaginal bleeding and abdominal pain. Patients also have a positive hCG pregnancy test. If you palpate an adnexal mass, it may be an ectopic pregnancy or a corpus luteum cyst.
99
What should you do if you suspect an ectopic pregnancy?
Order an ultrasound to look for a gestational sac or fetus. When the diagnosis is in doubt and the patient is doing poorly (e.g., hypovolemia, shock, severe abdominal pain, rebound tenderness), do a laparoscopy for definitive diagnosis and treatment, if necessary. Culdocentesis is rarely performed in a stable patient to check for blood in the pouch of Douglas (with a ruptured ectopic pregnancy) because it has a high false-negative rate.
100
How is symptomatic ectopic pregnancy managed?
Surgically. A tubal pregnancy, if stable and less than 3 cm in diameter, can be treated with salpingos- tomy and removal of the products of conception. The tube is left open to heal on its own; this strategy retains normal tubal function and fertility. If the patient’s condition is unstable or the ectopic preg- nancy has ruptured or is greater than 3 cm in diameter, a salpingectomy is required. In Rh-negative patients, give RhoGAM after treatment. Methotrexate (causes fetal demise) is an alternative treatment for small (
101
What are the problems with preexisting maternal hypertension in pregnancy?
Preexisting hypertension (present before conception) increases the risk for IUGR and preeclampsia.
102
What does a basic fetal heart monitoring strip contain?
The fetal heart rate and the uterine contraction pattern over time.
103
In fetal heart monitoring, what is the difference between early decelerations, late decelerations, and variable decelerations?
In early decelerations (Fig. 25-1), the peaks match up (nadir of fetal heart deceleration and peak of uterine contraction). This pattern signifies head compression (probably a vagal response) and is normal. Variable decelerations (Fig. 25-2) are so-called because fetal heart rate deceleration varies in relation to uterine contractions. This is the most commonly encountered type of decel- eration pattern and signifies cord compression. If it is seen, place the mother in the lateral decubitus position, administer oxygen by face mask, and stop any oxytocin infusion. If the fetal bradycardia is severe (
104
What other patterns of fetal distress may be seen on a fetal heart tracing? What is a normal fetal heart rate?
Loss of short-term (beat-to-beat) variability, loss of long-term variability (or normal baseline changes in heart rate over 1 minute), and prolonged fetal tachycardia (\>160 beats/min). The normal fetal heart rate is 120 to 160 beats/min.
105
What if the question gives you a value for fetal oxygen saturation or scalp pH?
Any fetal scalp pH less than 7.2 or abnormally decreased oxygen saturation is an indication for immediate cesarean delivery. If the pH is greater than 7.2 or oxygenation is normal, you can generally continue to observe the mother and fetus.
106
What should you do if shoulder dystocia or impaction occurs during vaginal delivery?
The first step is to try the McRoberts maneuver. Have the mother sharply flex her thighs against her abdomen, which may free the impacted shoulder. Other maneuvers include applying suprapubic pressure, Woods screw maneuver (rotates the fetus so the anterior shoulder emerges from behind the maternal symphysis), delivery of the posterior arm, and fracture of the clavicle (risky). If these maneuvers fail, options are limited. A cesarean section is usually the procedure of choice (after push- ing the infant's head back into the birth canal).
107
What causes third-trimester bleeding?
q89
108
True or false: The initial workup of third-trimester bleeding, like most conditions, requires a history and thorough physical examination, including a good pelvic examination.
False. You should do a history and partial physical examination, but always do an ultrasound before a pelvic examination.
109
Why do an ultrasound before a pelvic examination for third-trimester bleeding?
When placenta previa is present, disturbing the placenta may make the bleeding worse and turn a worrisome case into an emergency.
110
Define placenta previa. How does it present? How is it diagnosed and treated?
True placenta previa occurs when the placenta implants in an area where it covers the cervical opening (os). Predisposing factors include multiparity, increasing maternal age, multiple gestation, and a history of prior placenta previa. Always do an ultrasound before a pelvic examination for third-trimester bleed- ing. The bleeding is painless and may be profuse. Ultrasound is 95% to 100% accurate in diagnosis. Mandatory cesarean section is required for delivery, but patients may be admitted to the hospital for bed and pelvic rest and tocolysis if they are preterm and stable and if the bleeding has stopped.
111
Define abruptio placentae. How does it present? How is it treated?
Abruptio placentae is premature detachment of a normally situated placenta. Predisposing factors include hypertension (with or without preeclampsia), trauma, polyhydramnios with rapid decompres- sion after membrane rupture, cocaine or tobacco use, and preterm premature rupture of membranes. Patients can have this condition without visible vaginal bleeding; the blood may be contained behind the placenta. Usual symptoms include pain, uterine tenderness, increased uterine tone with a hyperactive contraction pattern, and fetal distress. Abruptio placentae also may cause disseminated intravascular coagulation if fetal products enter the maternal circulation. Ultrasound detects only a small percentage of cases. Treat with intravenous fluids (and blood if needed) and rapid delivery (vaginal preferred).
112
What factors predispose to uterine rupture? How does it present? How is it treated?
Predisposing factors include previous uterine surgery (especially prior cesarian section with vertical incision), trauma, oxytocin, grand multiparity (several previous deliveries), excessive uterine disten- tion (e.g., multiple gestation, polyhydramnios), abnormal fetal lie, cephalopelvic disproportion, and shoulder dystocia. Uterine rupture is very painful, has a sudden and dramatic onset, and often is accompanied by maternal hypotension or shock. Other classic signs are the ability to feel fetal body parts on abdominal examination and a change in the abdominal contour. Maternal distress usually is more pronounced than fetal distress (unlike abruptio placentae, in which fetal distress is greater). Treat with immediate laparotomy and delivery. Hysterectomy usually is required after delivery.
113
What causes fetal bleeding to present as third-trimester vaginal bleeding?
Visible fetal bleeding usually is caused by vasa previa or velamentous insertion of the cord, which occurs when umbilical vessels present in advance of the fetal head, usually traversing the mem- branes and crossing the cervical os. The biggest predisposing risk factor is multiple gestation (the greater the number of fetuses, the higher the risk). Bleeding is painless, and the mother’s condition is completely stable, whereas the fetus shows worsening distress (tachycardia initially, then bra- dycardia as the fetus decompensates). An Apt test performed on vaginal blood is positive for fetal blood (this test differentiates fetal from maternal blood). Treat with immediate cesarean section.
114
Explain the term “bloody show.” How is it diagnosed?
With cervical effacement, a blood-tinged mucous plug may be released from the cervical canal and heralds the onset of labor. This normal occurrence is a diagnosis of exclusion in the evaluation of third-trimester bleeding.
115
Describe the initial management of third-trimester bleeding.
For all cases of third-trimester bleeding, start intravenous fluids, give blood if needed, start the patient on oxygen, and start fetal and maternal monitoring. Then order a complete blood count, coagulation profiles, ultrasound, and drug screen if drug use is suspected because cocaine causes placental abruption. Give RhoGAM if the mother is Rh-negative. A Kleihauer-Betke test can quantify fetal blood in the maternal circulation and can be used to calculate the dose of RhoGAM.
116
Define preterm labor. How is it treated?
Preterm labor is defined as labor between 20 and 37 weeks of gestation. Put the mother in the lateral decubitus position, order bed and pelvic rest, and give oral or intravenous fluids and oxygen. In some cases these maneuvers stop the contractions. If they fail, you can give a tocolytic (beta2 agonist or magnesium sulfate) if no contraindications (heart disease, hypertension, diabetes, hemorrhage, ruptured membranes, cervix dilated more than 4 cm) are present. The mother can be managed as an outpatient with an oral tocolytic once she is stable.
117
What are tocolytics? When is it not appropriate to give them?
Tocolytics stop uterine contractions. Common examples are beta2 agonists (terbutaline, ritodrine) and magnesium sulfate. Do not give tocolytics to the mother in the presence of preeclampsia, severe hemorrhage, chorioamnionitis, IUGR, fetal demise, or fetal anomalies incompatible with survival.
118
What is fetal fibronectin? When is a test for this substance useful? Is the test more helpful when positive or negative?
Fetal fibronectin (an extracellular matrix protein that helps attach the amniotic membranes to the uterine lining) can be detected in the vaginal secretions of some women presenting with signs and symptoms of preterm labor. The test is most helpful when negative between 22 and 34 weeks of gestation because it indicates a very low likelihood of delivery in the next 2 weeks. Thus a more conservative, observational approach can be used. When fetal fibronectin is posi- tive in this setting, the woman remains at a higher risk for delivery in the next 2 weeks and a more aggressive approach to tocolysis and fetal lung maturity hastening is typically employed.
119
When should fetal lung maturity be evaluated?
Evaluation of fetal lung maturity is indicated before elective deliveries that are, or may be, less than 39 weeks’ gestation. Testing is not necessary for well-documented pregnancies that are 39 or more weeks’ gestation, pregnancies that are less than 32 weeks’ gestation (because fetal lung maturity is unlikely), or when delaying delivery because of fetal lung immaturity will place the mother or fetus at significant risk.
120
What tests can be used to assess fetal lung maturity?
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121
What is the role of steroids in preterm labor?
Often steroids are given with tocolytics (at 24 to 34 weeks of gestation) to hasten fetal lung maturity and thus decrease the risk of respiratory distress syndrome in the neonatal period.
122
Define quickening. When does it occur?
Quickening is the term used to describe when the mother first detects fetal movements, usually at 18 to 20 weeks of gestation in a primigravida and 16 to 18 weeks of gestation in a multigravida.
123
Give the order of fetal positions during normal labor and delivery.
q105
124
What subtype of maternal antibody can cross the placenta?
IgG is the only type of maternal antibody that crosses the placenta. This may be an important diag- nostic point: an elevated neonatal IgM concentration is never normal, whereas an elevated neonatal IgG often represents maternal antibodies.
125
Explain Rh incompatibility. In what situations does it occur?
Rh (or rhesus factor) blood-type incompatibility is of concern because it can lead to hemolytic dis- ease of the newborn. Rh incompatibility occurs when the mother is Rh-negative and her infant is Rh- positive. The boards assume an understanding of inheritance of the Rh factor. If both the mother and the father are Rh-negative, there is nothing to worry about because their infant will be Rh-negative. If the father is Rh-positive, the infant has a 50/50 chance of being Rh-positive.
126
How do you detect and manage potential hemolytic disease of the newborn?
If indicated by maternal and potential fetal blood type, check maternal titers of Rh antibody every month, starting in the seventh month of gestation. Give RhoGAM automatically at 28 weeks and within 72 hours after delivery as well as after any procedures that may cause transplacental hemor- rhage (see question 110).
127
True or false: The first child is usually the most severely affected by Rh incompatibility.
False. Previous maternal sensitization is required for disease to occur. In other words, if a nullipa- rous Rh-negative mother has never received blood products, her first Rh-positive infant will not be affected by hemolytic disease—except in the rare case of sensitization during the first pregnancy from undetected fetomaternal bleeding, which commonly occurs later in the pregnancy and in most instances can be prevented by RhoGAM administration at 28 weeks. The second Rh-positive infant, however, will be affected—unless you, the astute board taker, administer RhoGAM at 28 weeks and within 72 hours after delivery during the first pregnancy. Any history of blood transfusion, abortion, ectopic pregnancy, stillbirth, or delivery can cause sensitization.
128
How much RhoGAM should you give if the maternal Rh antibody titer is extremely high?
In this setting RhoGAM is worthless because sensitization has already occurred. RhoGAM administra- tion is a good example of primary prevention. Close fetal monitoring for hemolytic disease is required.
129
How do you recognize, monitor, and treat hemolytic disease of the newborn?
Hemolytic disease of the newborn in its most severe form causes fetal hydrops (edema, ascites, pleural and/or pericardial effusions) and death. Amniotic fluid spectrophotometry and ultrasound can help gauge the severity of fetal hemolysis. Treatment of hemolytic disease involves (1) delivery, if the fetus is mature (check lung maturity with a lecithin-to-sphingomyelin ratio); (2) intrauterine transfusion; and (3) phenobarbital, which helps the fetal liver break down bilirubin by inducing enzymes.
130
True or false: ABO blood group incompatibility can cause hemolytic disease of the newborn.
True. ABO blood group incompatibility can cause hemolytic disease of the newborn when the mother is type O and the infant is type A, B, or AB. This condition does not require previous sensitization because IgG antibodies (which can cross the placenta) occur naturally in mothers with blood type O—but not in mothers with other blood types. The hemolytic disease is usually less severe than with Rh incompatibility, but treatment is the same. In rare instances, other minor blood antigens also may cause a reaction.
131
When should RhoGAM be given?
To reiterate, give RhoGAM only when the mother is Rh-negative and the father is Rh-positive or his blood type is unknown. During routine prenatal care, check for Rh antibodies at the first visit. If the test is positive, do not give RhoGAM—you are too late. Otherwise, give RhoGAM routinely at 28 weeks and immediately after delivery. Also give RhoGAM after an abortion, stillbirth, ectopic preg- nancy, amniocentesis, CVS, and any other invasive procedure that may cause transplacental bleeding during pregnancy.
132
Define premature rupture of membranes (PROM). How is it diagnosed?
PROM is rupture of the amniotic sac before the onset of labor. Diagnosis of rupture of membranes (whether premature or not) is based on history, sterile speculum examination, and/or a positive nitrazine test. The sterile speculum examination shows pooling of amniotic fluid and a ferning pattern when the fluid is placed on a microscopic slide and allowed to dry. Nitrazine paper turns blue in the presence of amniotic fluid. Ultrasound should be done in cases of PROM to assess amniotic fluid volume as well as gestational age and any anomalies that may be present.
133
What usually follows membrane rupture? What should you do if it does not occur?
Spontaneous labor usually follows membrane rupture; for this reason, an amniotomy may be done in an attempt to induce labor if membranes do not rupture spontaneously. If labor does not occur within 6 to 8 hours of membrane rupture, the mother is term, and if the cervix is favorable, labor should be induced. Labor is induced because the main risk of PROM is infection, which may occur in the mother (chorioamnionitis) and/or the infant (neonatal sepsis, pneumonia, meningitis). The usual culprits are group B streptococci, Escherichia coli, or Listeria sp.
134
Define preterm premature rupture of membranes (PPROM). How is it managed?
PPROM is defined as premature rupture of membranes before 36 to 37 weeks of gestation. The risk of infection increases with the duration of ruptured membranes. Do a culture and Gram stain of the amniotic fluid. If it is negative, treatment simply involves pelvic and bed rest with frequent follow-up. If the culture is positive for group B streptococci, treat the mother with penicillin G or ampicillin, even if she is asymptomatic.
135
How does chorioamnionitis present and how is it treated?
Patients with chorioamnionitis have presenting symptoms of fever and a tender, irritable uterus, usually after delivery. Antepartum chorioamnionitis may occur in patients with PROM. Do a culture and Gram stain of the cervix and amniotic fluid, and treat with antibiotics such as ampicillin plus gentamicin while awaiting culture results.
136
Define postpartum hemorrhage. What are the common causes?
Postpartum hemorrhage is defined as a blood loss greater than 500 mL during vaginal delivery or greater than 1 L during cesarean section. The most common cause is uterine atony (75%-80% of cases). Other causes include lacerations, retained placental tissue, coagulation disorders, low placental implantation, and uterine inversion. Retained placental tissue results from placenta accreta (penetration of the placenta through the endometrium into the myometrium), increta (deeper penetration of the placenta into the myometrium), or percreta (penetration of the placenta through the myometrium to the uterine serosa); in all three conditions, the placenta grows more deeply into the uterine wall than it should. The major risk factor for this condition is previous uterine surgery or cesarean section, and the usual treatment is hysterectomy.
137
What causes uterine atony? How is it treated?
Uterine atony is caused by overdistention of the uterus (as a result of multiple gestation, polyhydramnios, or macrosomia), prolonged labor, oxytocin usage, grand multiparity (a history of five or more deliveries), and precipitous labor (too fast or less than 3 hours). Treat with a dilute oxytocin infusion, and use bimanual compression to massage the uterus while the oxytocin infusion is running. If this approach fails, use ergonovine (contraindicated with maternal hyperten- sion), prostaglandin f2-alpha, or misoprostol. If these strategies also fail, the patient may need a hysterectomy; ligation of the uterine vessels can be attempted if the patient wants to retain fertility.
138
What is the treatment for retained products of conception?
With retained products of conception (which is probably the most common cause of a delayed post- partum hemorrhage), remove the placenta manually to stop the bleeding. Next try curettage in the operating room under anesthesia. If placenta accreta, increta, or percreta is present, hysterectomy is usually necessary to stop the bleeding.
139
What causes uterine inversion? How is it treated?
When the uterus inverts, it usually can be seen outside the vagina. It is usually iatrogenic, a result of pulling too hard on the cord. If it occurs, put the uterus back in place manually; you may need to use anesthesia because of pain. Give intravenous fluids and oxytocin.
140
Define postpartum fever. What are the common causes?
Postpartum fever is defined as a temperature greater than 100.4°F (38°C) for at least 2 con- secutive days and is classically caused by endometritis. However, do not forget easy causes of postpartum fever, such as a urinary tract infection or atelectasis/pneumonia. Pulmonary problems are especially common after a cesarean section. Other causes include pelvic abscess and pelvic thrombophlebitis.
141
What should you do if a patient has postpartum fever?
Look for clues in the history and physical examination. For example, in a patient with a history of PROM and a tender uterus on examination, endometritis is almost certainly the cause of the fever. Next, get cultures of the endometrium, vagina, blood, and urine. Start empirical antibiotics if indicated. Clindamycin plus gentamicin is a good choice; add “big-gun” antibiotics if the patient is crashing.
142
. What should you do if postpartum fever does not improve with antibiotics?
If a postpartum fever does not resolve with broad-spectrum antibiotics, there are two main possibili- ties: progression to pelvic abscess or pelvic thrombophlebitis. A computed tomography (CT) scan will show a pelvic abscess, which needs to be drained, and sometimes demonstrates thrombophlebitis. Pelvic thrombophlebitis presents with persistent spiking fevers, lack of response to antibiotics, and no abscess on CT. Give heparin or low molecular weight heparin for a cure (and diagnosis in retrospect)
143
What should you consider if a postpartum patient goes into shock without evident bleeding?
■ Amniotic fluid embolism ■ Uterine inversion ■ Concealed hemorrhage (e.g., uterine rupture with bleeding into the peritoneal cavity)
144
List normal laboratory changes of pregnancy.
q126
145
What cardiovascular and pulmonary changes occur in a normal pregnancy?
Normal cardiovascular changes: Blood pressure decreases slightly, heart rate increases by 10 to 20 beats/min, stroke volume increases, and cardiac output increases (by up to 50%). Normal pulmonary changes: Minute ventilation increases because of increased tidal volume, but respiratory rate remains the same or increases only slightly; residual volume and carbon dioxide decrease. Collectively these changes cause the physiologic hyperventilation/respiratory alkalosis of pregnancy.
146
What is the average weight gain during pregnancy? What commonly causes weight gain to be more or less?
The average weight gain in pregnancy is roughly 28 pounds (12.5 kg). A larger weight gain may mean maternal diabetes. A smaller weight gain may mean hyperemesis gravidarum or psychiatric or major systemic diseases.
147
Define hyperemesis gravidarum. How do you recognize and treat it?
Hyperemesis gravidarum is intractable nausea and vomiting leading to dehydration and possible electrolyte disturbances. It presents in the first trimester, usually in younger patients with their first pregnancy and underlying social stressors or psychiatric problems. Treat with supportive care as well as small, frequent meals and antiemetic medications such as pyridoxine-doxylamine, diphenhydr- amine, meclizine, dimenhydrinate, prochlorperazine, metoclopramide, or ondansetron. Patients may need intravenous fluids and correction of electrolyte abnormalities.
148
Define cholestasis of pregnancy. How is it treated?
Cholestasis of pregnancy presents with itching (often severe) and/or abnormal liver function tests, usually in the second and third trimester. In rare cases, jaundice may coexist. The only known defini- tive treatment is delivery, but ursodeoxycholic acid or cholestyramine may help with symptoms.
149
What is acute fatty liver of pregnancy? How is it treated?
Acute fatty liver of pregnancy is a more serious disorder than cholestasis. It presents in the third trimester or after delivery and usually progresses to hepatic coma. Treat with intravenous fluids, glu- cose, and fresh frozen plasma to correct coagulopathies. Vitamin K does not work, because the liver is in temporary failure. If the patient survives with supportive care, liver dysfunction usually resolves on its own with time.
150
True or false: In terms of surgery, the usual rule of thumb is to treat the disease in a pregnant woman the same as you would treat it in a nonpregnant woman.
It definitely is true in the case of an acute surgical abdomen. Pregnant women can develop appen- dicitis, which may present with right upper quadrant pain caused by displacement of the appendix by the pregnant uterus. Just as in nonpregnant patients, a laparotomy or laparoscopy is perfectly appropriate when the diagnosis is unsure and the patient has peritoneal signs. For semiurgent conditions (e.g., ovarian neoplasm), it is best to wait until the second trimester to per- form surgery (when the pregnancy is most stable). Purely elective cases are avoided during pregnancy.
151
How do you manage fetal malpresentation?
External cephalic version can be used to rotate the fetus from the breech to the cephalic position. If this fails, whether to attempt vaginal delivery or do a cesarean section must be decided. Although under specific guidelines some frank and complete breeches may be delivered vaginally, it is acceptable to do a cesarean section for any breech presentation. With shoulder presentation or incomplete/footling breech, cesarean section is mandatory. For face and brow presentations, watchful waiting is best because most cases convert to vertex presentations. If they do not convert, do a cesarean section.
152
What is the “poor man's way” to distinguish between monozygotic and dizygotic twins?
If the sex or blood type is different, the twins are dizygotic (i.e., fraternal). If the placentas are monochorionic, the twins are monozygotic (i.e., identical). These three simple points differentiate monozygotic from dizygotic twins in 80% of cases. In the remaining 20%, human leukocyte antigen typing studies are required to determine the type of twins.
153
What are the maternal and fetal complications of multiple gestations?
Maternal complications include anemia, hypertension, premature labor, postpartum uterine atony, postpartum hemorrhage, and preeclampsia. Fetal complications include polyhydramnios, malpresentation, placenta previa, abruptio pla- centae, velamentous cord insertion/vasa previa, premature rupture of the membranes, prematurity, umbilical cord prolapse, IUGR, congenital anomalies, and increased perinatal morbidity and mortality. The higher the number of fetuses, the higher the risk of most of the conditions mentioned for both mother and offspring.
154
How are multiple gestations delivered?
With vertex-vertex presentations of twins (both infants are head first), you can try vaginal delivery for both infants, but with any other twin presentation combination or more than two infants, perform cesarean section.
