8: Ultrasound measurement of fetal adrenal gland enlargement: an accurate predictor of preterm birth (PTB)

Article Outline

• Objective
• Study Design
• Results
• Conclusion
• Copyright

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Objective 

We hypothesized that ultrasound evaluation of fetal adrenal gland volume (AGV) and fetal zone enlargement (FZE) predicts PTB better than cervical length (CL).

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Study Design 

Patients presenting with preterm labor (PTL) symptoms had ultrasound measurement of CL and fetal adrenal gland dimension. Using 3D ultrasound with VOCAL cAGV (AGV/ Estimated fetal weight), 2D depth of the whole-gland (D) and fetal zone (d) were measured. The d/D ratio was calculated as an index of FZE. The cAGV, d/D and CL were compared for prediction of PTB within 7 days.

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Results 

62 singletons with PTL at 23-37 wks′ gestation were studied. Measurement-to-delivery interval only correlated with cAGV and d/D (r=−0.32 p=0.011 and r=−0.47 p=0.001respectively) but not CL (p=0.83). 20 women had PTB at <7 days (Group A) while 42 (Group B) delivered >= 7 days from initial assessment. While CL was similar (p=0.5) cAGV and d/D were higher in group A (p<0.0001 for both). ROC area under the curve was significantly greater for cAGV and d/D than for CL (0.82, 0.91 and 0.59, p<0.01 and 0.001 respectively, fig) without any significant differences be tween adrenal gland measurements. Using ROC derived cutoffs PTB <7 days was best predicted by d/D and cAGV but not CL.

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Conclusion 

We describe a simple 2 dimensional measurement of the fetal zone of the adrenal gland that is highly effective in identifying women with symptoms of PTL that are at risk for PTB within 7 days. This method performs significantly better than CL measurement.