Filly's 7th Law
One lethal anomaly per customer.
This “law” is especially directed to those who are involved in prenatal diagnosis. I realize that this “law” sounds a bit odd, but I assure you that I have seen this mistake many times. For the sake of illustration, let us assume you see a fetus with a skeletal dysplasia. It is immediately obvious that it is associated with severe shortening. If the diagnosis is thanatophoric dysplasia or osteogenesis imperfect type II (the two most common skeletal dysplasias encountered in utero), then the outcome is universally fatal. DO NOT spend your time trying to document a ventricular septal defect. Spend every moment of the fetal survey making every effort to conclusively prove one or the other of these two likely diagnoses. If the diagnosis is osteogenesis imperfect type II, then it matters not a whit that the fetus also has a ventricular septal defect. ONE LETHAL ANOMLY PER CUSTOMER!
An even better example is bilateral renal agenesis. This anomaly is associated with profound oligohydramnios (indeed, anhydramnios). The scanning difficulties in this circumstance are significant. Spend your time documenting bilateral “lying down adrenals” and obtaining the best images you can of the renal fossae. Proving conclusively that there is a small omphalocele is a complete waste of time and does not serve your patient.