ultrasound diagnosis of fatal anomalies

SHORT FEMUR
Nicolaides KH, Snijders RJ, Gosden CM, Berry C, Campbell
S. Ultrasonographically detectable markers of
fetal chromosomal abnormalities. Lancet 1992; 340:
704–7.
Sairam S, Al-Habib A, Sasson S, Thilaganathan B. Natural
history of fetal hydronephrosis diagnosed on midtrimester
ultrasound. Ultrasound Obstet Gynecol
2001; 17: 191–6.
Snijders RJ, Sebire NJ, Faria M, Patel F, Nicolaides KH.
Fetal mild hydronephrosis and chromosomal defects:
relation to maternal age and gestation. Fetal
Diagn Ther 1995; 10: 349–55.
Short Femur
Definition and clinical significance: This is defined
as length of femur below the 5th percentile
for the gestational age, or a ratio of BPD to femur
that lies above the 95th percentile. In Down syndrome,
short femur appears statistically more
often than in the normal chromosomal set. In addition,
shortened femur may be the first sign of
skeletal dysplasia.
Incidence: According to the above definition, 5%
of all fetuses.
Caution: The femur is not shortened significantly
in all cases of chromosomal aberrations,
especially in Down syndrome, in comparison
with a healthy fetus. The biological range and
possible inaccuracies in measurement are so extensive
that shortening of the femur or a pathological
BPD/femur ratio cannot be relied on as a
marker for detecting chromosomal aberration. If
the suspected finding is mentioned to the
mother, it causes such uncertainty that reassurance
is very difficult if karyotyping has not
been done. The question is what value should be
considered relevant for detecting Down syndrome.
Very wide variations from the normal
value should alert the physician to carry out
detailed scanning of the other structures. Even
then, for methodological reasons, chromosomal
aberration cannot be definitively excluded. The
parents should be counseled using computerized
risk assessment (developed by Nicolaides)
and risk for Down syndrome due to maternal
age. Nyberg et al. reported shortening of the
femur in only 14% of fetuses (seven of 49 cases)
with Down syndrome, compared to 6% of fetuses
(35 of 572) with normal chromosomes.
References
Ashkenazy M, Lurie S, Ben Itzhak I, Appelman Z, Caspi B.
Unilateral congenital short femur: a case report. Prenat
Diagn 1990; 10: 67–70.
Benacerraf BR, Gelman R, Frigoletto FDJ. Sonographic
identification of second-trimester fetuses with
Down’s syndrome. N Engl J Med 1987; 317: 1371–6.
Campbell J, Henderson A, Campbell S. The fetal femur/
foot length ratio: a new parameter to assess dysplastic
limb reduction. Obstet Gynecol 1988; 72: 181–4.
Graham M. Congenital short femur: prenatal sonographic
diagnosis. J Ultrasound Med 1985; 4: 361–3.
Keret D, Timor IE. Familial congenital short femur: intrauterine
detection and follow-up by ultrasound: a
case report. Orthop Rev 1988; 17: 500–4.
LaFollette L, Filly RA, Anderson R, Golbus MS. Fetal
femur length to detect trisomy 21: a reappraisal. J Ultrasound
Med 1989; 8: 657–60.
Makino Y, Inoue T Shirota K, Kubota S, Kobayashi H,
Kawarabayashi T. A case of congenital familial short
femur diagnosed prenatally. Fetal Diagn Ther 1998;
13: 206–8.
Nyberg DA, Resta RG, Hickok DE, Hollenbach KA, Luthy
DA, Mahony BS. Femur length shortening in the detection
of Down syndrome: is prenatal screening
feasible? Am J Obstet Gynecol 1990; 162: 1247–52.
Pierce BT, Hancock EG, Kovac CM, Napolitano PG, Hume
RF Jr, Calhoun BC. Influence of gestational age and
maternal height on fetal femur length calculations.
Obstet Gynecol 2001; 97: 742–6.
Ranzini AC, Guzman ER, Ananth CV, Day-Salvatore D,
Fisher AJ, Vintzileos AM. Sonographic identification
of fetuses with Down syndrome in the third
trimester: a matched control study. Obstet Gynecol
1999; 93: 702–6.
Snijders RJ, Platt LD, Greene N, et al. Femur length and
trisomy 21: impact of gestational age on screening
efficiency. Ultrasound Obstet Gynecol 2000; 16: 142–
5.
Sohl BD, Scioscia AL, Budorick NE, Moore TR. Utility of
minor ultrasonographic markers in the prediction of
abnormal fetal karyotype at a prenatal diagnostic
center. Am J Obstet Gynecol 1999; 181: 898–903.
Twining P, Whalley DR, Lewin E, Foulkes K. Is a short
femur length a useful ultrasound marker for Down’s
syndrome? Br J Radiol 1991; 64: 990–2.
Vintzileos AM, Egan JF, Smulian JC, Campbell WA, Guzman
ER, Rodis JF. Adjusting the risk for trisomy 21 by
a simple ultrasound method using fetal long-bone
biometry. Obstet Gynecol 1996; 87: 953–8.
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