The use of ossification centers in predicting gestational age and maturity

The use of ossification centers in
predicting gestational age and maturity

The distal femoral epiphysis (DFE) is rarely seen with ultrasound before 33 weeks, when it appears as a thin disk-
like collection of echoes. By 36 weeks, it becomes a thickechogenic spot, which is seen just below the end of the os-
sified shaft of the femur. Using the axial resolution, one canprecisely measure the thickness of this epiphyseal center
in the north/south axis .The proximal tibial epiphysis (PTE) is rarely seen be-
fore 36 weeks, when it appears as an echogenic dot at theproximal end of the tibial shaft. The last longbone epiphysis to appear in utero is the proximal
humeralepiphysis, which rarely shows up before 37 weeks.
These observations can be used to advantage in unregistered patients entering the labor and delivery suite withlittle or no documentation of dating. Not infrequentlythe average ultrasound age is discordant with the patient’s
dates and often in the late or no care patients, there are noreliable dates. When the fetus is smaller than expected, theepiphyseal centers can help in
deciding whether to stop labor, if the fetus appears to be premature, or even to inducelabor if the fetus is growth restricted.
Let’s take a typical scenario occurring at least once everyfew days on a busy labor and delivery service. The patient
enters in preterm labor with a history of being 37 weeksby menstrual dates alone. The average ultrasound age is
determined to be 33 weeks, but a thick DFE is seen anda PTE is visualized. The fetus most likely is mature andperhaps growth restricted. This would also
suggest thepatient’s dates to be correct, and there would be no need
to stop her labor.