Differential Diagnosis for Fetal Ultrasound Findings
- Single most likely diagnosis
- Cytomegalovirus (CMV) infection: This is the most likely cause of the fetal ultrasound findings, including bilateral periventricular intracranial calcifications and intrahepatic calcifications, as well as the estimated fetal weight consistent with 16 weeks gestation, indicating growth restriction. CMV is a common cause of congenital infection and can lead to these specific findings.
- Other Likely diagnoses
- Toxoplasmosis: Although less common than CMV, toxoplasmosis can also cause congenital infection leading to intracranial calcifications and fetal growth restriction. The patient's exposure to her son and his playmates at daycare, where hygiene may be less strict, increases the risk of toxoplasmosis.
- Varicella-zoster virus (VZV) infection: Given the patient's recent history of fever and pharyngitis, and similar symptoms in her son and his playmates, varicella infection is a possibility. However, the specific ultrasound findings are less typical for VZV.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Syphilis: Despite the negative treponemal antibody absorption test, false negatives can occur, especially in early infection. The positive rapid plasma reagin (RPR) at 1:64 titer is significant and requires further investigation. Congenital syphilis can cause a range of fetal abnormalities, including growth restriction and organ damage.
- HIV: Although the patient's HIV-1/2 antibody test was negative, any risk of HIV exposure should be thoroughly evaluated due to the potential for vertical transmission and severe consequences for the fetus.
- Rare diagnoses
- Rubella: Although the patient has rubella antibody IgG, indicating past infection or vaccination, congenital rubella syndrome is a possibility if the infection occurred during pregnancy. However, the specific ultrasound findings are less typical for rubella.
- Herpes simplex virus (HSV) infection: Congenital HSV infection can cause severe fetal abnormalities, including growth restriction and organ damage. However, the patient's presentation and ultrasound findings are not typical for HSV, making it a less likely diagnosis.