HUMAN IMMUNODEFICIENCY VIRUS (HIV)
A 22-year-old multigravida is a former IV drug user. She was diagnosed as HIV positive 12 months ago during her previous pregnancy. She underwent vaginal delivery of an infant who is also HIV positive. She is now pregnant again at 15 weeks’ gestation.
Pathophysiology. HIV is an RNA retrovirus that is spread by infected body secretions. Sharingcontaminated needles, having sexual intercourse with an infected partner, and perina tal trans-mission are the most common ways of transmission.
The infected patient develops acquired immunodeficiency syndrome (AIDS). The clinical course from HIV to AIDS is a gradual but relentless immunosuppression during a period of years, resulting in death caused by overwhelming infection from opportunistic diseases.
Significance
• Fetal infection—Transplacental infection occurs, but the major route of verticaltransmission is contact with infected genital secretions at the time of vaginal delivery. Without maternal azidothymidine (AZT) prophylaxis, the vertical transmission rate is 30%, but with AZT the infection rate is lowered to 10% with vaginal delivery. With elective cesarean section without labor and before membrane rupture, the perinatal infection rate may be <5%. The greatest benefit to the fetus of cesarean delivery is probably in women with low CD4 counts and high RNA viral loads, making infection through a vaginal delivery much more likely.
• Neonatal infection—At birth neonates of HIV-positive women will have positive HIVtests from transplacental passive IgG passage. HIV-infected breast milk can potentially transmit the disease to the newborn. Progression from HIV to AIDS in infants is more rapid than in adults.
• Maternal infection—Pregnancy in an HIV-positive woman does not enhance progres-sion to AIDS.
Prevention
• Antiviral prophylaxis—The U.S. Public Health Service recommends that HIV-infected pregnant women be offered combination treatment with HIV-fighting drugs to help protect their health and prevent passing the infection on to their babies. Infected pregnant women should take triple-drug therapy including the drug zid-ovudine (ZDV) as part of their drug regimen, starting at 14 weeks and continuing throughout pregnancy, intrapartum, and after delivery.
• Mode of delivery—Vaginal delivery should be planned at 39 weeks. The guidelinesfor vaginal delivery are 1) to avoid amniotomy as long as possible, 2) do not use scalp electrodes in labor, 3) avoid forceps or vacuum extractor operative delivery, and 4) use gentle neonatal resuscitation. Cesarean section is offered at 38 weeks without amniocentesis if viral load is > 1,000 copies/mL.
|
|
|
• Breast feeding—This is probably best avoided in HIV-positive women.
• Universal precautions—Pay careful attention to handling of all body fluids.
Treatment. All HIV-positive pregnant women should be on combination triple anti-viralHAART therapy. This includes 2 nucelotide reverse transcriptase inhibitors (NRTIs) with either an NNRTI or a protease inhibitor. An example would be zidovudine, lamivudine, or ritonavir.
58
| S2 OB-GYN.indb 58 | 7/8/13 6:35 PM | |||
GI
Chapter 7 l Perinatal Infections
SYPHILIS
A 34-year-old multigravida presents for prenatal care in the second trimester. She admits to a past history of substance abuse but states she has been clean for 6 months. With her second pregnancy she experienced a preterm delivery at 34 weeks’ gestation of a male neonate who died within the first day of life. She states that at delivery the baby was swollen with skin lesions and that the placenta was very large. She was treated with antibiotics but she does not remember the name or other details. On a routine prenatal panel with this current pregnancy she is found to have a positive VDRL test.
Pathophysiology. Syphilis is caused byTreponema pallidum, a motile anaerobic spirochetethat cannot be cultured. Syphilis does not result in either a state of immunity or latency. The infection can be eradicated by appropriate treatment, but reinfection can occur over and over again. It is spread as a sexually transmitted disease by intimate contact between moist mucous membranes or congenitally through the placenta to a fetus from an infected mother.
Significance
• Fetal infection—Transplacental infection is common with vertical transmission ratesof 60% in primary and secondary syphilis. The rate of fetal infection with latent
|
|
|
or tertiary syphilis is lower. Without treatment, manifestations of early congenital syphilis include nonimmune hydrops, macerated skin, anemia, thrombocytopenia, and hepatosplenomegaly. Fetal death rates are high, with perinatal mortality rates approaching 50%. The placenta is typically large and edematous.
• Neonatal infection—Late congenital syphilis is diagnosed after 2 years of age andincludes “Hutchinson” teeth, “mul berry” molars, “saber” shins, “saddle” nose, and 8th nerve deafness.
• Maternal infection (4 types):
– Primary syphilis is the first stage after infection. Papules become painless ulcers with rolled edges (chancres) which appear 2–3 weeks after contact at the site of infection, most commonly the vulva, vagina, or cervix. Darkfield microscopy of lesion exudate is positive for the spirochete, but the nonspecific serologic tests (Venereal Disease Research Laboratory [VDRL] or rapid plasma reagin [RPR] test) are not yet positive. Without treatment the chancre spontaneously disappears.
– Secondary syphilis is characterized by systemic spirochetemia. Two to three months after contact, fever, malaise, general adenopathy, and a maculopapular skin rash (“money spots”) are seen. Broad exophytic excrescences (condyloma lata) appear on the vulva. These physical findings also spontaneously disappear with-out treatment. Darkfield microscopy of condyloma exudate is positive for trepo-nema. The VDRL or RPR test will be positive, but a diagnosis of syphilis must be confirmed with a treponema-specific test, such as the fluorescent titer antibody absorption (FTA-ABS) or microhemagglutination assay for antibodies to T. palli-dum (MHA-TP). The treponema-specific tests do not correlate with disease activ-ity and remain positive in spite of treatment.
– Latent syphilis is characterized by absence of symptoms or physical findings. One third of cases proceed to tertiary disease. The nonspecific and treponema-specific tests remain positive.
|
|
|
– Tertiary syphilis is a symptomatic stage with symptoms dependent on which organ system is affected by the classic necrotic, ulcerative nodules (gummas). Lesion location may include the cardiovascular system (aortitis, saccular aneurysms),
59
| S2 OB-GYN.indb 59 | 7/8/13 6:35 PM | |||
GI
USMLE Step 2 l Obstetrics
CNS (meningitis, tabes dorsalis, dementia, ataxia), or bone (osteitis). Not only are the blood tests positive, but also the cerebrospinal fluid will be positive with CNS involvement.
Дата добавления: 2018-11-24; просмотров: 235; Мы поможем в написании вашей работы! |
Мы поможем в написании ваших работ!