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.
• If maternal syphilitic lesions are present at the time of delivery the infection will be transmitted to the baby.
• 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.

Pregnant women should be screened for syphilis and re-screened later in pregnancy if at risk for infection later in pregnancy.

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

Repeat syphilis testing is recommended at 28 to 32 weeks of pregnancy, and at delivery, 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.

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.
• 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.

• Involve Partner Notification Officers for partner notification. Partners must be contacted, tested and offered treatment with a single dose of 1.8 g of benzathine penicillin 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.