News and views on FETAL MUSCULOSKELETAL EVALUATION : :  How many of us really read and interpret   at the report page of USG  ON Foetal foot length ?? 

Q.1: What is the importance of FL in USG?  Ans.  It  is the measurement of the ossification center of the femoral diaphysis.  FL is ordinarily included in routine obstetric sonography to assist in a) determining gestational age and b) growth between ultrasound examinations because it reliably corresponds to menstrual age.

An abnormal FL or configuration is often the c) first clue to a fetal musculoskeletal abnormality. Careful sonographic measurement of the femoral diaphyseal ossification center is needed to obtain accurate femur measurement and configuration assessment.

Q,2: Caution :--Proper ultrasound technique must avoid obliquity and exclude the cartilaginous epiphyses.

Q.3: what are the common pitfalls?   Common pitfalls such as a mildly curved appearance of the femur when imaging from the medial aspect of the femoral diaphysis should not mistaken for a limb abnormality. Charts correlating FL with other parameters of gestational age assessment head circumference can be used to determine whether there is limb shortening . Measurements of other long bone diaphyseal ossification centers is useful for selected cases at risk for limb length abnormality either generalized or non generalized.

Q.4: When to consider Limb shortening in the second trimester? Ans:  Limb shortening in the second trimester should raise suspicion of a fetal abnormality . Mild shortening of the femur or the humerus may be indicative of a chromosomal aberration or a syndrome .

Point 1: On Femur”  If mild femoral shortening  is present there is a 1 % risk of trisomy 21  in a high risk population and a 3% risk of trisomy 21 in a low risk population .

Point 2: On Humerus:  Mild humeral shortening is even more specific than femoral shortening in predicting trisomy 21. If mild humeral shortening is identified there is a 3% risk of trisomy 21 in a high risk population  and a 1% to 2% risk of trisomy 21 in a low risk population.

Point 3: May be normal variant in the third Trimester if slight shortening  : In the third trimester one should remember that the femur is subject to the same biologic variability as other biometric markers. It is not unusual on occasion for the FL measurement to be slightly less than other biometric markers in the absence of a morphologic abnormality. This is particularly true if the remainder of the sonographic evaluation of the fetus is normal.

Q.5:  How many of us really lookat the report page OF usdg ON Foetal foot length ??  What we should remember while interpreting Foetal foot length??  Ans : We know that  the fetal foot length is approximately equal to the FL throughout gestation . So Foot length   may be useful in detection of a fetus with skeletal dysplasia. Fetal foot length correlates with gestational age and FL . It is certain that FL :  Foot length ratio should be 1. If this ratio is <0.9 skeletal dysplasia is possible . If it is 0.9 to 1.0 it may represent a constitutionally small fetus or symmetric IUGR.

Evaluation of fetal posture and fetal movements are very important in prenatal ultrasound. Abnormal posture or movement may be the first clues to either a focal or generalized fetal musculoskeletal abnormality . Contractures or abnormal fetal movements may provide definitive diagnosis of affected fetuses for genetically transmitted muscular or musculoskeletal disorders such as some of the arthrogryposis syndromes , Pena shokeir syndrome congenital myotonic dystrophy and amyoplasia