Relation between oligohydramnios and spinal flexion in the human fetus.
BACKGROUND
Oligohydramnios, a severe reduction in the volume of amniotic fluid, is associated with fetal lung hypoplasia but underlying processes are unclear. Studies in sheep suggest that oligohydramnios may lead to lung hypoplasia by causing increased flexion of the fetal spine, but this has not been demonstrated in the human, which has a different uterine anatomy.


OBJECTIVE
Our aims were to quantify spinal flexion in the human fetus and to determine the relationship between oligohydramnios and the degree of spinal flexion.


METHODS
In 35 pregnancies, we used ultrasonography to assess amniotic fluid volume and to image the fetal spine so as to provide an index of mean spinal radius between the upper thoracic and lumbar spine. In 17 pregnancies with evidence of oligohydramnios resulting from premature rupture of membranes (mean +/- SEM gestation 28.8 +/-1.4 weeks), the mean radius of fetal spinal curvature between the upper thorax and sacrum was compared with values from 18 control fetuses with normal amounts of amniotic fluid (at 28.9 +/- 1.6 weeks).


RESULTS
In each fetus, the spine could be imaged and the mean radius of curvature calculated. Oligohydramnios was associated with a significantly increased degree of fetal spinal flexion compared to controls.


CONCLUSIONS
In human pregnancy, oligohydramnios is associated with increased flexion of the fetal spine, which is likely due to reduced uterine volume. This could contribute to the development of fetal lung hypoplasia, fetal immobility and other fetal anomalies.
Deaconess Medical Center, Spokane, WA, USA.
Cheryl A
CA
Albuquerque
Karen R
KR
Smith
Therese E
TE
Saywers
Cherie
C
Johnson
Megan L
ML
Cock
Richard
R
Harding
D001034:Apgar Score; D001946:Breech Presentation; D005260:Female; D005315:Fetal Diseases / Q000209:etiology*; D005322:Premature Rupture of Fetal Membranes / Q000150:complications; D005865:Gestational Age; D006801:Humans; D008168:Lung / Q000002:abnormalities; D016104:Oligohydramnios / Q000150:complications*; D011247:Pregnancy; D011256:Pregnancy Outcome; D013121:Spinal Curvatures / Q000209:etiology*; D013131:Spine / Q000196:embryology*; D016216:Ultrasonography, Prenatal