This is most likely non-immune hydrops (NIH). There is a high risk of intrauterine demise and perinatal mortality. Appropriate investigations to correctly identify the cause are important as some conditions are amenable to intrauterine treatment which can improve outcome. If the condition is recurrent or carries a very poor prognosis appropriate counseling for this and future pregnancies can be done. Targeted investigations will be done based on History and preliminary investigations.
The patient should be referred to tertiary level facilities for detailed investigations and l a fetal medicine expert are available. A detailed ultrasound looking for structural defects is required. These include cystic hygroma, cardiac, CNS and skeletal survey. Sites and degree of effusions will be noted. Although detection rate for cardiac structural abnormalities is less than fifty percent, hypo plastic left heart and AV canal defects will be sought. Tachyarrhythmias can lead to cardiac failure, which precede hydrops. Bradyarrhythmias will prompt investigating for anti-ro and anti-la antibodies in maternal serum. Fetal echocardiogram will be done. If skeletal dysplasia is suspected a detailed look at long bones, hands, feet and thorax will be done. Peripheral shunting can lead to high output failure and hydrops. Sacrococcygeal teratomas and placental chorioangiomas can produce this effect and will be sought. Doppler insonation of middle cerebral arteries can detect almost all cases of fetal anemia and will be done. This condition exists with Parvo B19 infection. Twin pregnancy and possible twin-to-twin transfusion syndrome will be excluded at this time.
Fetal Blood sampling will be done for complete blood count (anemia and thrombocytopaenia seen with viral infection especially ParvoB19), liver function tests, infection screen, detection of viral DNA, enzyme level for metabolic disorders will be done if necessary. Karyotyping must be done for chromosomal and genetic abnormalities. Although karyotyping can be done via amniocentesis, which carries a lower risk of fetal wastage even when the fetus is hydropic, fetal blood sampling is the superior investigation since a more comprehensive study is possible.
Maternal blood must be tested for other red cell antigens. Kell antigen can provoke an antibody response producing a rapidly progressing hydrops out of proportion to the degree of anemia. Infection screen and a Kleihauer-Betke test to quantify fetomaternal haemorrhage can also be done, if necessary.
Prognostic factors include the cause and degree of hydrops, and risks associated with invasive procedures used for diagnosis or treatment. Chromosomal abnormalities and genetic conditions may not be treatable. Anemia secondary to infection can be treated with intravascular transfusions, which carry a fifty to sixty percent success. Pleural effusions can be shunted. Arrhythmias can be treated with anti-arrhythmics either to mother or directly to fetus. All invasive procedures carry a risk of preterm labour and miscarriage. Perhaps the single worst prognostic factor is NIH, which carries a perinatal mortality of up to ninety percent.
