Congenital Syphilis
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Direct answer
Congenital syphilis is Treponema pallidum transmitted across the placenta from an infected mother to her foetus. Disease before two years of age is classed as early, and disease after that as late, with the Hutchinson triad, Clutton joints and saddle nose being the classic late stigmata. Screening every pregnant woman and treating infected mothers with penicillin are the main preventive measures.
What you must remember
- Transmission: the spirochaete crosses the placenta, and the risk is highest when the mother has untreated early syphilis.
- Early congenital syphilis: presents before two years with snuffles, hepatosplenomegaly, a rash on the palms and soles, and osteochondritis.
- Late congenital syphilis: presents after two years with interstitial keratitis, Hutchinson incisors, mulberry molars, saddle nose and sabre tibia.
- Hutchinson triad: interstitial keratitis, Hutchinson incisors (notched, peg-shaped central incisors) and eighth nerve deafness.
- Clutton joints: painless, symmetrical effusions of the knees in late disease, which are non-tender and non-warm.
- Parrot pseudoparalysis: early limb immobility from osteochondritis and periostitis, with the infant reluctant to move the limb.
- Diagnosis: maternal serology, comparison of the infant's non-treponemal titre with the maternal value, and long bone radiographs.
- Prevention: screening at the first antenatal visit and prompt penicillin treatment of the mother and partner.
A pathway from stigmata to diagnosis
A 9-year-old boy has corneal clouding, notched central incisors and bilateral deafness, and his mother cannot recall her antenatal serology. The steps below link these stigmata to a diagnostic and treatment plan.
- Take the obstetric history: Ask about maternal serology, antenatal care and the timing of any treatment, since untreated maternal infection is the strongest risk factor.
- Map the early stigmata: In infancy, look for snuffles, a rash on the palms and soles, hepatosplenomegaly and pseudoparalysis of a limb.
- Check the late features: Examine the eyes for interstitial keratitis, the teeth for Hutchinson incisors and mulberry molars, the nose for saddle deformity and the ears for deafness.
- Examine the joints and bones: Clutton joints present as painless effusions of both knees, and radiographs may show osteochondritis, periostitis or sabre tibia.
- Send serology: Compare the infant's non-treponemal titre with the maternal titre, add treponemal tests, and examine cerebrospinal fluid when neurological involvement is suspected.
- Treat and trace contacts: Penicillin-based treatment for the infant is directed by the paediatric team, and the partner and other contacts are assessed and treated.
Where the exam tries to catch you
Congenital syphilis questions reward precision about the age of onset and the classic triad.
- Trap: attributing Hutchinson incisors and interstitial keratitis to a viral infection. Correct: they form part of the Hutchinson triad of congenital syphilis, and eighth nerve deafness completes the set.
- Trap: labelling every case of congenital syphilis as early disease. Correct: disease after two years of age is late congenital syphilis, where saddle nose, Clutton joints and sabre tibia appear.
- Trap: assuming an asymptomatic newborn of an untreated mother needs no evaluation. Correct: such infants need evaluation and are often treated, because clinical signs can appear later.
- Trap: using an alternative antibiotic for syphilis in pregnancy. Correct: penicillin is the only recommended treatment, and penicillin-allergic women are desensitised rather than given another drug.
Frequently asked questions
Which three features make up the Hutchinson triad in congenital syphilis?
The Hutchinson triad consists of interstitial keratitis, Hutchinson incisors and eighth cranial nerve deafness. These late stigmata are described together because they are often seen in the same child with late congenital syphilis.
How do Clutton joints differ from septic arthritis?
Clutton joints are painless, symmetrical effusions of the knees seen in late congenital syphilis, with the joints neither hot nor tender. Septic arthritis is typically painful, warm and single-jointed, with pus cells on synovial fluid analysis.
Why is antenatal screening central to preventing congenital syphilis?
Congenital syphilis is preventable because maternal infection can be detected by serology and treated with penicillin before transmission to the foetus. Screening at the first antenatal visit identifies infected mothers early, and early maternal treatment greatly reduces the risk of infection in the foetus.
What is the drug of choice for syphilis in pregnancy?
Penicillin is the drug of choice for syphilis in pregnancy, and it is the only treatment recommended because alternative drugs are not considered adequate for the foetus. A penicillin-allergic pregnant woman needs desensitisation rather than another antibiotic, and her partner must also be treated.