Fetal Adrenal Gland Volume Estimation in Prediction of Preterm Birth

Three - Dimensional Ultrasound Estimation of Fetal Adrenal Gland Enlargement Compared to Assessment of Cervical Changes Alone & Prediction of Impending Preterm Birth

If we could prove that three -dimensional ultrasound measurement of fetal adrenal gland volume can accurately predict the likelihood of preterm birth in patients having symptoms and signs of PTL , we would be able to use it as a valuable component for assessment and early management of high risk pregnant women for PTB which can be positively reflected on the risk of neonatal morbidity and mortality in those patients.

Preterm birth ( PTB) is one of the leading causes of neonatal morbidity and mortality (Goldenberg et al., 2008) Early PTB (≤ 34 weeks' gestation) carries a 7-fold increased risk of Neonatal death . Following PTB, survivors can experience significant long term cognitive, behavioral, emotional, sensory, and motor deficits. Hence, there is growing interest in the identification of women who are at Risk for spontaneous PTB. Many biophysical and biochemical markers have been discovered to identify those women who are at risk for spontaneous PTB.

(Honest et al., 2009)

Unfortunately, none of the various maternal and fetal biomarkers such as:

cytokines, CRH, C-reactive protein, fetal fibronectin ,…. etc. are sufficiently sensitive or specific to be used alone or in combination to help decrease the rate of preterm births. (Ozhan et al., 2007) Obviously, there's a need for an accurate method with high sensitivity and specificity for prediction of preterm labor. So that an appropriate management or referral to a higher center can be done to women likely to have PTB. Whereas unnecessary tocolytic therapy can be avoided in women who are unlikely to have PTB. (Rengaraj et al., 2009) Convincing data have shown that 2-dimensional (2D) ultrasound measurement of cervical length (CL) can identify women at risk for PTB.

Accordingly, CL is now widely used in clinical practice for risk estimation. ( Crane et al., 1997) However, as understanding of the mechanisms of preterm labor (PTL) have evolved, obstetricians have learned that, in some women, cervical shortening is a phenomenon that carries no increased risk for prematurity. Therefore, the search for early and accurate markers that distinguish between physiologic processes and abnormal activation of the labor cascade has been ongoing.

Literature has suggested that activation of the fetal hypothalamic-pituitary-adrenal axis play a crucial rule in commencement of labor. (Norwitz et al, 1999) A previous study demonstrated that three -dimensional ultrasound measurement of fetal adrenal gland volume (AGV) may identify women at risk for impending PTB. (Turan et al, 2007) In a more recent study receiver operator characteristics (ROC) curve analysis revealed that three -dimensional ultrasound measurement of (AGV) was superior to two-dimensional ultrasound measurement of (AGV) for anticipation of PTB within 7 days of the scan. (Turan et al, 2012) The aim of this study is to investigate the utility of 3D fetal adrenal gland volume measurement in the early prediction of PTB and to determine whether these measurements could be combined with 2D ultrasound cervical assessment to improve the early prediction of PTB.

Inclusion Criteria:

- 1. Age : 18 - 40 years 2. Gestational age : 26 - 35 weeks , which is going to be calculated according to the date of last menstrual period & confirmed by first trimester ultrasonography .

3 - Women who are diagnosed as having threatened preterm labour based on the American college of obstetricians and gynaecologists guidelines (ACOG,2003) :

• Presence of uterine contractions ( at least 4 in 20 minutes or 8 in 60 minutes )

• Cervical dilataion >1cm, &/or

• Cervical effacement ≥ 80% 4. Women having one or more of the following:

  • Multifetal pregnancy .
  • Previous preterm labor or premature birth, particularly in the most recent pregnancy or in more than one previous pregnancy .

Exclusion Criteria:

• 1 - Suspected fetal growth restriction . 2- Preterm premature rupture of the membranes : confirmed by visualization of amniotic fluid vaginal pooling at the time of sterile speculum examination .

  3- Patients with antepartum haemorrhage ( due to placental abruption &/or placenta previa ) .

  4 - Presence of fetal anomalies incompatible with life. 5 - Patients who are not sure of dates .