Table 7-1. Syphilis in Pregnancy
| Characteristic | Primary | Secondary |
| Classic lesion | Chancre | Condyloma lata (“money spots”) |
| Extent of disease | Localized | Systemic |
| Lab tests (VDRL, | VDRL (–) | VDRL (+) |
| Darkfield, | Darkfield (+) | Darkfield (+) |
| FTA-ABS) | FTA-ABS (+) | FTA-ABS (+) |
| Fetal infection rate | 60% | 60% |
| Treatment of choice | Penicillin | Penicillin |
Primary Syphilis
Localized — chancre
Secondary Syphilis
Systemic — condyloma lata
2/3
Latent Syphilis
Symptoms absent Physical findings absent
Positive: nonspecific tests Positive: Trep-specific tests
1/3
Tertiary Syphilis
Symptoms present: variable Gummas in CV, CNS, bone
Positive: blood tests Positive: CSF if CNS involved
Figure I-7-2. Maternal Syphilis
Prevention
• Vaginal delivery is appropriate with cesarean section only for obstetric indications.
• Follow the principles of avoiding multiple sexual partners, and promote use of barrier contraceptives.
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Chapter 7 l Perinatal Infections
Management. Benzathine penicillin 2.4 million units IM×1 is given in pregnancy to ensureadequate antibiotic levels in the fetus. Other antibiotics do not cross the placenta well. Even if the gravida is penicillin-allergic, she should still be given a full penicillin dose using an oral desensitization regimen under controlled conditions.
Follow serology titers at 1, 3, 6, 12, and 24 months. Titers should be decreased fourfold by 6 months, and should be negative in 12-24 months.
The Jarisch-Herxheimer reaction is associated with treatment and occurs in half of pregnant women. It starts in 1-2 hours, peaks in 8 hours, and resolves in 24-48 hours. It is associated with acute fever, headache, myalgias, hypotension, and uterine contractions. Management is supportive care.
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HEPATITIS B (HBV)
A 29-year-old multigravida was found on routine prenatal laboratory testing to be positive for hepatitis B surface antigen. She is an intensive care unit nurse. She received 2 units of packed red blood cells 2 years ago after experiencing postpartum hemorrhage with her last pregnancy.
Pathophysiology. Hepatitis B is a DNA virus that is spread by infected body secretions. Sharingcontaminated needles, having sexual intercourse with an infected partner, and perinatal trans-mission are the most common ways of transmission. Vertical transmission accounts for 40% of all chronic HBV infections. Most HBV infections are asymptomatic.
Significance
• Fetal infection—Transplacental infection is rare, occurring mostly in the third tri-mester. The main route of fetal or neonatal infection arises from exposure to or inges-tion of infected genital secretions at the time of vaginal delivery. There is no perinatal transmission risk if the mother is positive for HBV surface antibodies but negative for HBV surface antigen.
• Neonatal infection—Neonatal HBV develops in only 10% of mothers positive forHBsAg but in 80% of those positive for both HBsAg and HBeAg. Of those neonates who get infected, 80% will develop chronic hepatitis, compared with only 10% of infected adults.
• Maternal infection (3 types):
– Asymptomatic HBV. The majority of all infected patients fall into this category with no impact on maternal health. Hepatitis B surface antigen (HBsAg) is the screening test used for identifying existing infection and is obtained on all preg-nant women. A positive HBsAg test is followed up with a complete hepatitis panel and liver enzymes assessing for active or chronic hepatitis.
– Acute hepatitis. Acute and chronic HBV infections can result in right upper quadrant pain and lethargy varying according to the severity of the infection. Laboratory studies show elevated bilirubin and high liver enzymes. The majority of patients with acute hepatitis will recover normal liver function.
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– Chronic hepatitis. Cirrhosis and hepatocellular carcinoma are the most serious consequences of chronic hepatitis.
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USMLE Step 2 l Obstetrics
Prevention
• Vaginal delivery is indicated with cesarean section only for obstetric indications.
• Avoid scalp electrodes in labor as well as scalp needles in the nursery. Neonates of
HBsAg-positive mothers should receive passive immunization with hepatitis B immu-noglobulin (HBIg) and active immunization with hepatitis B vaccine. Breast feeding is acceptable after the neonate has received the active immunization and HBIG.
• HBsAg-negative mothers at high risk for hepatitis B should receive HBIg passive immunization. Active immunization is safe in pregnancy because the agent is a killed virus.
Management. There is no specific therapy for acute hepatitis. Chronic HBV can be treated withinterferon or lamivudine.
| Lifelong | Treatment/Delivery | |||
| Group b beta | Colonization | Penicillin G | ||
| streptococcus | ||||
| Vaginal | ||||
| Toxoplasmosis | Pyrimethamine | |||
| Delivery | ||||
| Immunity | Sulfadiazine | |||
| Rubella | None | |||
| Cytomegalovirus | Ganciclovir | Cesarean | ||
| Varicella/HSV | Acyclovir | Section | ||
| Latency | if active | |||
| Triple Rx antivirals
| ||||
| HIV | HSV or few | |||
| HIV | ||||
| Findings | Findings | ||
| Toxoplasmosis*+ | Intracranial | Chorioretinitis | |
| calcifications | |||
| Varicella+ | Zig zag lesions | Small eyes | |
| Rubella*+ | Deafness | Congenital heart disease | |
| Cytomegalovirus*+ | Petechiae | ↑ liver, spleen | |
| Syphilis+ | Hydrops | Macerated skin | |
| HSV, HIV, HBV | None | ||
*Associated with IUGR +Transplacental vertical transmission
Vaginal delivery vertical transmission
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| Obstetric Complications | 8 | |
CERVICAL INSUFFICIENCY
A 32-year-old primigravida at 18 weeks’ gestation comes to the maternity unit complaining of pelvic pressure and increasing vaginal mucus discharge. She denies any uterine contractions. On pelvic examination the fetal membranes are seen bulging into the vagina, and no cervix can be palpated. Fetal feet can be felt through the membranes. Two years ago she underwent a cervical conization for cervical intraepithelial neoplasia.
The terms “cervical insufficiency” and “cervical incompetency” have been used to describe the inability of the uterine cervix to retain a pregnancy to viability in the absence of contractions or labor. A diagnosis was made in the past on the basis of a history of painless cervical dilation after the first trimester with expulsion of a previable living fetus.
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Recent studies using ultrasound to examine cervical length suggest that cervical function is not an all-or-none phenomenon, but may be a continuous variable with a range of degrees of competency that may be expressed differently in subsequent pregnancies.
Etiology. Causes may include trauma from rapid forceful cervical dilation associated withsecond trimester abortion procedures, cervical laceration from rapid delivery, injury from deep cervical conization, or congenital weakness from diethylstilbestrol (DES) exposure.
Diagnosis
• Studies show the benefit of elective cervical cerclage with a history of 2 or more unexplained second-trimester pregnancy losses. The benefit of cervical cerclage place-ment is unclear in the following situations: sonographic findings of a short cervix or funneling, history of cervical surgery, DES exposure.
• Serial transvaginal ultrasound evaluations of the cervix after 16–20 weeks may be helpful.
Management
• Elective cerclage placement at 13–16 weeks’ gestation is appropriate after sonographic demonstration for fetal normality.
• Emergency or urgent cerclage may be considered with sonographic evidence of cervi-cal insufficiency after ruling out labor and chorioamnionitis.
• Cerclage should be considered if cervical length is <25 mm by vaginal sonography prior to 24 weeks and prior preterm birth at <34 weeks gestation.
• McDonald cerclage places a removable suture in the cervix. The benefit is that vaginal delivery can be allowed to take place, avoiding a cesarean.
OB Triad
Cervical Insufficiency
• Pregnant 18–22 weeks
• Painless cervical dilation
• Delivery of previable fetus
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USMLE Step 2 l Obstetrics
• Cerclage removal should take place at 36–37 weeks, after fetal lung maturity has taken place but before the usual onset of spontaneous labor that could result in avulsion of the suture.
• Shirodkar cerclage utilizes a submucosal placement of the suture that is buried beneath the mucosa and left in place. Cesarean delivery is performed at term.
OB Triad
Di–Di Di or Mono–Di–Di
Twins
• Twin pregnancy
• Gender same or unknown
• Two placentas seen
Mono–Mono–Di Twins
• Twin pregnancy
• Gender always same
• One placenta but two sacs
Mono–Mono–Mono Twins
• Twin pregnancy
• Gender always same
• One placenta and one sac
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MULTIPLE GESTATION
A 21-year-old primigravida at 15 weeks’ gestation is seen for a routine prenatal visit. At her last visit 4 weeks ago, her uterus was appropriate for size and dates. Today, her uterine fundus is palpable at the umbilicus.
Definition. This is a pregnancy in which more than one fetus is present. The fetuses may arisefrom one or more zygotes and are usually separate, but may be conjoined.
Risk Factors
• Dizygotic twins are most common. Identifiable risk factors include by race, geogra-phy, family history, or ovulation induction. Risk of twinning is up to 10% with clomi-phene citrate and up to 30% with human menopausal gonadotropin.
• Monozygotic twins have no identifiable risk factors.
Diagnosis. Obstetric sonogram demonstration of more than one intrauterine fetus.
Complications for all twin pregnancies include nutritional anemias (iron and folate), pre-eclampsia, preterm labor (50%), malpresentation (50%), cesarean delivery (50%), and post-partum hemorrhage.
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