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Obstetric & Perinatology

Some of this material is particularly dated.

Beta Strep Management - Antenatal and Infant

rev. 1994 eg. ancient!

Antenatal

Infant: Committee on infectious diseases and committee on fetus and the newborn. Guidelines for prevention of group B streptococcal (GB) infections by chemoprophylaxis. Pediatr 1992 Nov ;90(5):775-8.

Lower Vaginal Culture: 1-2 before 32 w GA

Culture taken as single swab of lower vagina. Used to be done at 26-28 weeks GA, but CDC has changed to later @35-37 weeks. Some swab anorectum as well.

a) positive vaginal or urine culture: antibiotics > 4h prior delivery

• Ampicillin 2gm IV then 1-2 gm q4-6h
• Clindamycin:
• Erythromycin:

b) negative culture: prophylaxis per obstetric indications

Beta Strep: Management of Infants of Treated Mothers

a) symptomatic infants: culture & treat as septic (pending cultures)

• culture +: usual therapy
• culture - at 48-72 h: d/c therapy

b) asymptomatic infants

1. GA >= 38 weeks: no therapy
2. GA 34-38 weeks: individualize based on age, other risk factors
3. GA <=34 weeks: culture and empiric therapy (?IM ampicillin only?)
   • culture +: usual therapy
   • culture - at 48-72 h: d/c therapy

First trimester bleeding: ab vs. ectopic

Common Errors

1. Always confirm pregnancy with qualitative serum test before initiating major evaluation. History may be unreliable or initial test might be a false positive.

Evaluation

ultrasound and quantitative B-HCG: at 5w U/S should show sac and B-HCG should be > 6500. Vaginal probe should show sac as early as 3.5 weeks with B-HCG of 15 (?).

• B-HCG < 1000: expectant management
• B-HCG > 6500
  • sac: normal IUP
  • no sac: ectopic (laparotomy)
• B-HCG < 6500 and > 1000:
  • sac: missed ab or other problem?
  • pelvic mass: ectopic
  • neither sac nor mass: recheck in 48 hours
    • B-HCG doubles: normal pregnancy
    • no change: ectopic, LAP
    • falls: do D&C
      • D&C positive: Ab
      • D&C negative: laparotomy

Hyperemesis

• elevated FTI in 40-73% (false positive hyperthyroid)
• low risk rx: bendectin-equivalent: Unisom (doxylamine) + Pyridoxine (Vitamin B6 30 mg/day)
• higher risk: compazine (cat C), Zofran (cat C, less experience) meclizine (cat B), Reglan (cat B)

Infection - Maternal

• Varicella
  • maternal infection
    • between 0-12 weeks of gestation: 0.4% congenital varicella syndrome
    • between 13-20 weeks gestation: 2% congenital varicella syndrome
    • after 20 weeks: may have later zoster but less likely to show disease at birth
    • 5 days before delivery to 2 days after: child varicella risk, potentially fatal.
  • If maternal exposure to varicella then give VZIG within 96 hours.
  • Varicella vaccine is a live attentuated vaccine
• Herpes: if active lesions do C-SXN.
• HIV: consultation. C-SXN and Zidovudine
• toxoplasmosis
  • 15% rate of serious fetal injury/malformation with 1st trimester infection but problems throughout.
• Beta Strep Management - Antenatal and Infant

Labor and Delivery Notes

Delivery

• both dictate and write (SFH)
• document: labor course, EBL, placenta and cord, inspection of cervix and sidewalls (prior to placental delivery), Apgars

FHM

• early decel esp. if tracks with pressure: vagal, head compression (theory)
• late decel esp. with late recovery and consistent: anoxia
• variable: cord compression, hard to interpret
• prolonged decel: HR decr for  >= 30 bpm for >= 2.5 min, often reversible (oxygen, change position, decr oxytocin)
• sinusoidal: ominous if persistent

Labor Dysfunction

• estimated fetal weight
• pelvimetry
• judgement of cause of delay
• why expect vaginal birth

Misc

Ectopic pregnancy management with oral methotrexate

• hCG < 15,000 mIU/ml
  • if < 1,000 and falling expectant management is an option
• otherwise healthy liver, kidney, lung, immune, etc
• typical dose: 50 mg/m2
• reevaluate 3-4 days, if hCG rising then laparoscopy with salpingostomy

Molar pregnancy

• serum hCG q2wk until level is normal, then q1-2 mo for 1 year. Methotrexate if hCG rises
• avoid pregnancy for 1 yr post resolution

Imaging

• CNS teratogenesis interval is 10 - 17 wk GA -- avoid non-urgent radiologic testing.
• accepted cum dose is 5 rad: an IVP delivers 1.4 rad and CT pelivmetry 0.25 rad.

Premature Rupture of Membranes

Thu, Apr 15, 1993 (eg. ancient)

key decisions: infection vs. immaturity

The use of pulmonary surfactant (less RDS), and of prostaglandin gel, have yet to be “digested” by the medical literature. Surfactant makes delay of delivery and steroids less important in premies. PG gel makes delay of delivery less important in term infants with an unripe maternal cervix. Beta strep screening also may change management. Factoring these in a rough guess is:

< 32 weeks: immaturity > infection as cause of mortality.

> 32 weeks: infection > immaturity as cause of mortality.

• deliver or wait
• if deliver: how?
• antibiotics or not
• steroids or not (probably not)

initial considerations and standard evaluation

a) confirm diagnosis: are membranes ruptured? (see speculum exam)

• pooling (keep lying down with torso up for 20-40 minutes)
• Valsalva or fundal pressure if no fluid seen
• Nitrazine testing: avoid cervix, cervical pool. Also test urine. Low false negative (3-5%), false positive (1-17%)
• ferning: allow fluid to dry. Examine on slide

b) establish gestational age. Femur length and abdominal circumference are more reliable than HC if oligohydramnios present.

c) establish if infection present (fever, ?WBC)

d) establish if fetal distress present

e) establish if active labor by monitoring and speculum exam

f) avoid digital exam (see below)

g) alert pediatrician, consultation if needed (local vs. distal)

h) establish fetal lung maturity if 32-36 weeks

These recommendations are of less importance in the surfactant era. We should discuss with our referral center in Green Bay as to whether they would like us to obtain a fluid sample and transport it with the patient.

(1) PG testing from vaginal pool

(2) if PG negative L/S ratio on amnio. If do amniocentesis obtain cultures and Gram stain.

speculum exam

• a) ferning, nitrazine (see diagnosis)
• b) culture: GC, chlamydia, beta strep
• c) inspect cervix (changing? dilation?)
• d) PG sample? (see above)

digital exam

• a) Digital examination precipitates labor and increases the risk of ascending infection. This probably occurs because of disruption of the cervical mucous by the examining finger.
• b) Do in active labor only; establish that labor is occurring by speculum exam and monitoring.

indications for delivery and associated management issues

Careful monitoring required, esp. for cord compression.

C-SXN reserved for usual obstetrical indications, there is increased maternal risk if chorioamnionitis present. May do c-sxn however if suspect very virulent infection.

labor

Active labor is the most common indication for delivery. Tocolysis doesn’t seem to work in PROM especially with a preterm infant.

antibiotics (assuming absence of chorioamnionitis)

• Indications for use: GA < 37 weeks, ruptured membranes > 18 hours, fever, colonization with Group B Strep, or a prior infant with Group B Strep.
• Main benefit is likely for infection with group B strep. Ampicillin 2 gm IV with the onset of labor then 1 gm IV q4h. Mezlocillin?

chorioamnionitis

• temp > 38 in absence of any other explanation. WBC of limited utility.
• fetal tachycardia and decreased variability to be expected, uncertain prognostic value.
• antibiotic therapy
  • amipicillin and +/- gentamicin, change to oral post-delivery for few days.
  • infant management?

fetal distress

no labor, no choriamnionitis, no fetal distress

A 48 hour delay in delivery appears to promote fetal lung maturation.

therapeutic options (general)

antibiotic regimens for expectant management

Main benefit is likely for infection with group B strep. Choice of antibiotic, dosing, and mode of administration varies (see also antibiotics in labor, above). The following regimens were described in articles on expectant management.

• Intravenous ampicillin, gentamicin, and clindamycin for 24 hours, followed by amoxicillin plus clavulanic acid orally for 7 days. [Christmas JT, Cox SM, Andrews W, Dax J, Leveno KJ, Gilstrap LC. Expectant management of preterm ruptured membranes: effects of antimicrobial therapy. Obstet Gynecol 1992 Nov;80(5):759-62.]
• ampicillin 1 gm IV q6h for 24 hours, then 500 mg PO q6h until delivery, then ampicillin 1 gm IV q6h until delivery.
• ampicillin 2 gm IV q6h until cultures negative then stop.

induction when indicated (see below)

monitoring for expectant management

• NST daily +/- biophysical profile
• maternal temperature q4h
• maternal WBC qD

management by dates

post-term (>41 weeks)

• Use PG gel if cervix unfavorable.
• Generally delivery within 24 hours.
• see term (below)

term (36-41 weeks)

• standard evaluation (see above)
• close monitoring: 12-24 hours continuous
• cervical assessment (based on speculum exam)
  • favorable: induce as convenient
  • questionable: wait up to 24 hours for onset of labor or use PG gel.

pre-term, viable (25-35 weeks)

Management of PROM without labor in infants from 25-35 weeks is changing quickly. Probably can divide into two subgroups. The following is highly speculative. Antibiotic administration should involve consultation with a perinatologist. These women are likely admitted and/or transferred.

late pre-term (32-35 weeks)

• standard evaluation
• possibly assess pulmonary maturity (see PG and LS ratios, above)
• if choose expectant management: Temp, WBC, NST, monitor, biophysical profile.
• antibiotic administration per consultation.

early pre-term (24-32 weeks)

• standard evaluation
• likely attempt to delay delivery.
• antibiotic administration per consultation.

preterm, non-viable (<25 weeks)

• standard evaluation
• antibiotic administration per consultation.
• ultrasound to assess fluid quantity (baseline)
• observe for 3-4 days (check temp TID, ?WBC)
• repeat U/S at 3-4 days
  • fluid increasing or reasonable: bedrest until reaccumulates (10-30% viable?)
  • fluid absent: high risk pulmonary hypoplasia. Discuss termination: PGE2 suppositories or oxytocin.

management of the infant

• chorioamnionitis: treat as if infected.
• maternal GrpB Strep colonization only (no symptoms) and GA > 34w: observe. If any symptoms culture and treat as below.
• maternal GrpB Strep colonization and GA < 34w, or ROM >18h, or maternal fever: culture and treat as if infected irregardless of symptoms. If cultures negative at 72 hours stop.

Screens

See AAFP MOM Care and especially Laboratory-Parameters - MOM Care

Seizure Disorders in pregnancy

1. to prevent neonatal Vit K deficiency: Vitamin K1 10 mg PQ qD from 36w onwards. (Am J Obstet Gynecol, Mar 1993)