Syphilis in pregnancy treatment guidelines

• Most congenital syphilis results from in utero rather than intrapartum transmission.
• The risk of fetal infection rises as pregnancy progresses, particularly beyond 18 weeks: 26% if treated by 24 weeks and 60% if not treated until the third trimester.
• Risk also increases with higher RPR titres.
• Risk to the fetus is greatest with primary and secondary syphilis and with latent infection of up to four years duration.
• If syphilis in pregnancy is untreated, the overall rate of stillbirth or prematurity is around 50%, with congenital syphilis in about half the remainder.
• Maternal infectious lesions at delivery are associated with a very high risk of neonatal infection and require urgent neonatal assessment.
• Untreated late latent syphilis leads to congenital syphilis in 2-10% of cases, with increased risk of perinatal death of around 10 times the background rate.

All pregnant women should undergo syphilis screening at the first antenatal visit and at 26-28 weeks and at 36 weeks or birth (whichever is earlier) according to current Australian Pregnancy Care Guidelines.

Women at increased risk should undergo additional testing during pregnancy.

Syphilis in pregnancy results in very high rates of fetal morbidity and mortality and should be treated as soon as practical after diagnosis.

Australia now recommends universal repeat screening during pregnancy, not only risk-based screening: 

• At first antenatal visit 
• At 26-28 weeks 
• At 36 weeks or birth (whichever occurs first) 
• In high-risk patients, additional testing may be indicated, including postpartum testing. 

Syphilis testing is also recommended in all women at risk of sexually transmissible infections, and in all women presenting with signs or symptoms of any other sexually transmissible infection.

Index patient: pregnant woman

Syphilis is notifiable to the Victorian Department of Health

Ensure the patient is not lost to follow up, with involvement of contact tracers if required.

Women diagnosed after 20 weeks gestation should undergo ultrasound assessment for evidence of fetal infection (e.g. hepatomegaly, placentomegaly, ascites, hydrops, polyhydramnios), although treatment should not be delayed while awaiting assessment. 

Communication with the Maternity care provider (ie Obstetric team, Midwifery team, Booking hospital)  is essential to ensure patient receives adequate follow up testing in pregnancy & in the post partum & early neonatal period.  

Follow up serology guidance 

Monitor maternal RPR titres after treatment to assess response and ensure appropriate follow up. 

• An adequate treatment response is generally shown by a fourfold decline in RPR titre (for example, from 1:32 to 1:8), in 6 months 
• Rising RPR titres or failure of titres to decline as expected should prompt assessment for reinfection or treatment failure.  
• Repeat syphilis testing during pregnancy should be performed as recommended to identify reinfection and reduce the risk of congenital syphilis.  
• Women diagnosed with syphilis in pregnancy should remain under specialist and obstetric follow-up throughout the pregnancy 
• No mother or infant should leave hospital without maternal syphilis status documented 

Penicillin allergy

• Penicillin-allergic pregnant women with syphilis pose additional management problems and should be managed in consultation with an Infectious Disease specialist.
• These women will be considered for oral penicillin desensitisation and subsequent IM benzathine penicillin treatment.
• Penicillin desensitisation carries a 3% risk of anaphylaxis. Both anaphylaxis and its treatment may have deleterious effects on uterine blood flow that could lead to premature delivery. Penicillin desensitisation and immediate treatment is safer than delaying treatment or avoiding penicillin.
• Consider ceftriaxone only if there is a concern that the patient may not follow-through with the recommendation to desensitise.
• In practice, treatment for syphilis in pregnancy is most common for latent infection of unknown duration often in women with low or non-reactive RPR titres and where there is no documented history of previous syphilis treatment prior to pregnancy. These are cases with a lower risk of congenital syphilis, where the risk of prematurity induced by anaphylaxis might be relevant.
• The Infectious Disease specialist may consider delaying desensitisation for a mother with a history of probable treated syphilis, RPR < 4, and a serious penicillin allergy. One would need to balance the risk of a serious outcome from anaphylaxis against the risk that she has not in fact been treated. If in doubt, the conventional approach is to treat early.

Management of the newborn

• Refer to the detailed information in the Australasian society for infectious diseases guidelines.
• All babies born to women with reactive syphilis serology should be examined for evidence of congenital syphilis by a paediatrician.
• All babies born to mothers diagnosed with syphilis in pregnancy will require follow up and testing overseen by a specialist paediatric clinic such as those at the Royal Children’s Hospital or the Monash Children’s hospital.
• To be considered adequate for prevention of congenital syphilis, maternal treatment should be completed at least 30 days before delivery. Infants born within 30 days of treatment require careful neonatal evaluation and management.
• All cases of syphilis in pregnancy require close cooperation between GPs, laboratories, and specialist clinics to ensure women and their babies are treated appropriately and not lost to follow-up. The Department’s Partner Notification Officers can assist with cases lost to follow up.
• Further assessment and management depends upon the newborn’s investigation results and the timing of treatment of the mother.
• The baby may still be infected if the mother is treated in the third trimester.
• Babies infected in late pregnancy may have negative serology at birth.
• For the newborn whose mother was treated during pregnancy, but at least a month before delivery, and whose RPR is less than 4 times the mother's RPR, a single dose of benzathine penicillin 50,000 U/kg is recommended.
• All cases of syphilis in pregnancy should be discussed with an experienced infectious diseases/sexual health physician and an obstetrician, with early involvement of neonatal/paediatric services.

• Involve Partner Notification Officers for partner notification. Partners must be contacted, tested and offered treatment with a single dose of Benzathine benzylpenicillin 2.4 million units IM without waiting for the results of serology which can be negative in early infection.
• Contacts who are penicillin allergic can be treated with doxycycline 100 mg, twice daily for 2 weeks.
• Individuals should abstain from sex with their partners until seven days after both have received treatment.