Should a pregnant patient continue benzathine penicillin G (deep intramuscular) for treatment of syphilis or rheumatic fever prophylaxis?

Benzathine Penicillin G During Pregnancy: Continue Treatment

Yes, absolutely continue benzathine penicillin G deep IM during pregnancy—it is the only proven effective treatment for syphilis in pregnancy and is essential for preventing congenital syphilis and adverse pregnancy outcomes. 1, 2, 3

Why Continuation is Mandatory

Penicillin is non-negotiable for syphilis treatment in pregnancy. There are no acceptable alternatives to penicillin for treating syphilis during pregnancy, as it is the only antimicrobial proven to reliably prevent maternal-to-fetal transmission and cure fetal infection. 1, 2, 3

• Benzathine penicillin G provides sustained treponemicidal concentrations necessary to cross the placenta and treat both maternal and fetal infection effectively. 3
• Treatment during pregnancy should use the penicillin regimen appropriate for the stage of syphilis identified. 1, 2
• Stopping treatment would place the fetus at extremely high risk for congenital syphilis, stillbirth, prematurity, and perinatal death. 4, 5, 6

Treatment Regimens by Stage

Primary, Secondary, or Early Latent Syphilis

• Standard regimen: Benzathine penicillin G 2.4 million units IM as a single dose. 2, 7
• Enhanced regimen (recommended by many experts): A second dose of benzathine penicillin G 2.4 million units IM one week after the initial dose, particularly for women in the third trimester or with secondary syphilis. 1, 2, 3, 7
• This enhanced approach addresses concerns about treatment failure with single-dose therapy, especially when delivery occurs soon after treatment. 4, 5

Late Latent or Unknown Duration Syphilis

• Benzathine penicillin G 7.2 million units total: administered as three doses of 2.4 million units IM each, given at weekly intervals (weeks 0,1, and 2). 2, 3, 7
• Each injection must be spaced exactly 7 days apart to ensure adequate treponemicidal coverage. 3

Critical Timing Considerations

Treatment must be completed >4 weeks before delivery for optimal prevention of congenital syphilis. 1, 2

• Research demonstrates that treponemicidal coverage of ≤3 weeks results in significantly worse outcomes, including decreased birth weight (2,748 vs 3,130 g), increased prematurity (RR 8.5), and increased perinatal mortality (RR 20.5). 4
• Women who deliver <4 weeks after receiving only one injection have outcomes comparable to untreated syphilis. 4
• Multiple doses provide superior protection: Each additional dose of benzathine penicillin reduces the risk of perinatal mortality (adjusted OR 0.63 per additional dose). 5

Management of Penicillin Allergy

If the patient reports penicillin allergy, desensitization is mandatory—not optional. 1, 2, 3, 7

• Pregnant women with documented penicillin allergy must undergo skin testing followed by penicillin desensitization, then receive the appropriate penicillin regimen. 1, 3, 7
• Desensitization can be performed safely using a four-hour intravenous protocol in a monitored setting. 8
• Never substitute non-penicillin antibiotics: Erythromycin does not reliably cure fetal infection, and tetracyclines/doxycycline cause maternal hepatotoxicity and fetal bone/tooth staining. 1, 3, 7
• Azithromycin and ceftriaxone are inadequate alternatives because they do not reliably prevent congenital infection. 2, 6

Monitoring and Follow-Up

Serologic Monitoring

• Repeat quantitative nontreponemal titers (RPR or VDRL) in the third trimester and at delivery. 1, 2, 7
• For women at high risk of reinfection or in high-prevalence areas, check titers monthly until delivery. 1, 7
• Treatment success is defined as a ≥4-fold (two-dilution) decline in nontreponemal test titers. 2

Jarisch-Herxheimer Reaction Precautions

• Warn the patient to seek immediate obstetric care if she experiences fever, uterine contractions, or decreased fetal movements within 24 hours after treatment. 1, 3, 7
• For pregnancies >20 weeks gestation, consider fetal and uterine-contraction monitoring for 24 hours after initiating therapy, especially if ultrasound suggests fetal infection. 1, 3
• Do not delay treatment due to fear of this reaction—untreated syphilis poses far greater risk to the fetus than the Jarisch-Herxheimer reaction itself. 1, 3, 7

Ultrasound Evaluation

• When feasible, perform pretreatment ultrasound in viable pregnancies, particularly after 20 weeks gestation. 1, 7
• Ultrasound signs of fetal syphilis (hepatomegaly, hydrops, placentomegaly) indicate greater risk for fetal treatment failure and warrant consultation with obstetric specialists. 1, 6

Additional Screening Requirements

• All pregnant women should be screened for syphilis at the first prenatal visit. 1, 2, 7
• In high-risk populations or high-prevalence areas, repeat screening at 28-32 weeks gestation and at delivery. 1, 2, 7
• Any woman who delivers a stillborn infant after 20 weeks gestation must be tested for syphilis. 1
• No newborn should be discharged without documentation of maternal syphilis screening at least once during pregnancy. 1, 2, 7

Partner Management and Co-Infection Testing

• Presumptively treat sexual partners exposed within 90 days preceding diagnosis, even if seronegative. 2, 3
• All patients diagnosed with syphilis should be offered HIV testing, as co-infection increases the risk of perinatal HIV transmission. 1, 2, 3

Common Pitfalls to Avoid

• Never discontinue penicillin treatment during pregnancy—there is no safe alternative. 1, 2, 3
• Do not use erythromycin, tetracyclines, azithromycin, or ceftriaxone as substitutes; they do not prevent congenital syphilis. 1, 2, 3, 7
• Do not compare RPR and VDRL titers directly—they are not interchangeable and sequential testing should use the same method and ideally the same laboratory. 2
• If a weekly dose is missed, pregnant women must repeat the entire three-dose course to ensure adequate treatment. 2
• Do not discharge a newborn without documented maternal syphilis screening status. 1, 2, 7