Maternal Serum alpha fetoprotein level increases gradually during pregnancy to a peak level around the 30th week of gestation period. Alpha fetoprotein test is carried out between the 14th and 22nd weeks but is more accurate when performed between the 16th and 18th weeks.
In the case provided. The test was performed in the 15th week where it was found that the alpha fetoprotein was elevated (5.0 MoM) but the human chorionic gonadotrophin (1.2 MoM) and estriol (1.0 MoM) were normal. In the second prenatal visit at 18th week, the results from the previous test should be presented to a doctor initially to determine the next course of action. The steps likely to be taken are: checking the family history for similar cases, carrying out a second alpha fetoprotein test to rule out inaccuracy that could have resulted either from performing the test at the 15th week or from inaccurate dating of the pregnancy. If the results turn out with elevated alpha fetoprotein, then a thorough obstetric ultrasonography should be carried out to investigate for multiple gestation or placental abnormalities (Tomasi, 1977).
The next step would be to proceed with the invasive process of amniocentesis for investigation of foetal abnormalities such as neural tube defect including open spina bifida and anencephaly. This step should be discussed thoroughly between the mother and the doctor before being undertaken. In some cases, it is important to test for secondary causes of elevated alpha fetoprotein which include ovarian tumour and endodermal sinus tumour. The final step the doctor should carry out is genetic counselling if the screening test turns out positive (Jassam & Jones & Horner, 2006).
In conclusion, elevated alpha fetoprotein is mainly as a result of incorrect dates. This is due to the fact that in a normal pregnancy, alpha fetoprotein increases by gestational age. As a result, alpha fetoprotein levels should be interpreted per gestational age. Interpretation of alpha fetoprotein data should be carried systematically to avoid misdiagnosis and to rule out secondary causes of elevated alpha fetoprotein.