Differential Diagnosis
- Single most likely diagnosis + Chromosomal abnormality, specifically Down syndrome (Trisomy 21): The combination of decreased maternal serum alpha-fetoprotein (MSAFP), increased β-hCG, decreased unconjugated estriol, and increased inhibin A is highly suggestive of Down syndrome. This pattern of markers is commonly seen in pregnancies affected by Down syndrome.
- Other Likely diagnoses + Other chromosomal abnormalities: While Down syndrome is the most likely, other chromosomal abnormalities such as Trisomy 18 or Trisomy 13 could also present with abnormal quadruple marker test results, although the specific pattern may vary. + Multiple gestation: Twin or multiple pregnancies can also affect the levels of these markers, potentially leading to abnormal results.
- Do Not Miss + Molar pregnancy or other gestational trophoblastic diseases: Although less likely given the initial ultrasound findings, these conditions can present with abnormal β-hCG levels and must be considered due to their potential for serious complications. + Fetal demise or missed abortion: Given the patient's history of cramping and vaginal bleeding, although she had evidence of a viable fetus at 8 weeks, it's crucial to confirm fetal viability and rule out a missed abortion, especially if there are any discrepancies in dating or if the patient's symptoms recur.
- Rare diagnoses + Intrauterine growth restriction (IUGR): While not typically diagnosed through the quadruple marker screen, significant IUGR can sometimes present with abnormal levels of these markers, particularly decreased unconjugated estriol. + Congenital infections or anomalies: Certain congenital infections or structural anomalies can affect the levels of these markers, although they are less common causes of the specific pattern seen in this patient.