Uterine, Fetal Cerebral Doppler and Oligohydramnios to Predict Abnormal Heart Rate Tracings in Postterm Pregnancies

Study Overview
=================
Brief Summary
-----------------
Objective: To estimate the value of uterine, fetal cerebral Doppler and oligohydramnios to predict abnormal fetal heart rate tracings in pregnancies at or beyond 41 weeks

Detailed Description
-----------------
This will be a nested case-control study that was conducted at University Hospital Dr. Jose E. Gonzalez after the approval of Institutional ethical committee. Women with low risk late term or postterm pregnancy (at least 41 weeks) with confirm gestational age who will be referred to our Maternal-fetal unit and admitted 1 to 2 days prior to induction of labour according institutional protocol will be recruited and constitute the cohort. Cases will be patients with abnormal intrapartum cardiotocogram (category III fetal heart rate tracing). For each case, four controls will be matched. The primary outcome will be to obtain odds ratios for the Doppler parameters (middle cerebral artery pulsatility index, mean uterine artery pulsatility index and Middle cerebral artery pulsatility index to mean uterine artery pulsatility index ratio) and amniotic fluid index that would be associated with intrapartum category III fetal heart rate tracing.

Official Title
-----------------
Clinical Utility of Uterine, Fetal Cerebral Doppler and Oligohydramnios to Predict Abnormal Heart Rate Tracings in Pregnancies at or Beyond 41 Weeks

Conditions
-----------------
Abnormality in Fetal Heart Rate or Rhythm, Ultrasound, Late Pregnancy

Intervention / Treatment
-----------------
* Diagnostic Test: Ultrasound and Doppler ultrasound


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Singleton pregnancy Gestational age of at least 287 days (41 weeks) Low risk pregnancy (defined as the absence of maternal or fetal complications other than postterm pregnancy) Exclusion Criteria: Twin or multiple gestation Uncertain gestational age Non vertex presentation Estimated fetal weight below the 10th percentile for gestational age (Hadlock´s formula) Fetal macrosomia (estimated fetal weight ≥ 4 Kilos) diagnosed by clinical measurement (Johnson´s technique) or ultrasound measurement (Hadlock´s formula). Fetal abnormalities found on routine anomaly scan. Maternal medical disorder (preeclampsia, chronic hypertension, diabetes, lupus, hyperthyroidism) Prelabour rupture of membranes Antepartum hemorrhage Any fetopelvic disproportion that could create dystocia during labor.
Sexes Eligible for Study
-----------------
Female

Accepts Healthy Volunteers
-----------------
Accepts Healthy Volunteers

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Cohort<br>This will be a nested case-control study. Women with low risk pregnancies at or beyond 41 weeks, who will be referred to our Maternal-fetal unit and admitted 1 to 2 days prior to induction of labour according institutional protocol will constitute the cohort. Then women with intrapartum abnormal fetal heart rate tracings (cases) will be identified and match with controls. The primary outcome will be to obtain odds ratios for the Doppler ultrasound parameters (middle cerebral artery pulsatility index, mean uterine artery pulsatility index and Middle cerebral artery pulsatility index to mean uterine artery pulsatility index ratio) and Ultrasound assessment of amniotic fluid index that would be associated with intrapartum category III fetal heart rate tracing. | Diagnostic Test: Ultrasound and Doppler ultrasound<br>* Assessment of fetal cerebral and maternal uterine pulsatility index using Doppler ultrasound. Measurement of amniotic fluid index according to four-quadrant technique.<br>* Other names: Amniotic fluid index;|
| Cases<br>Cases will be patients with abnormal intrapartum cardiotocogram (category III fetal heart rate tracing). Intervention: Ultrasound and Doppler ultrasound | Diagnostic Test: Ultrasound and Doppler ultrasound<br>* Assessment of fetal cerebral and maternal uterine pulsatility index using Doppler ultrasound. Measurement of amniotic fluid index according to four-quadrant technique.<br>* Other names: Amniotic fluid index;|
| Controls<br>Those will be patients with normal intrapartum cardiotocogram (category I fetal heart rate tracing) or category II that converted into category I after intrauterine resuscitation methods. Intervention: Ultrasound and Doppler ultrasound | Diagnostic Test: Ultrasound and Doppler ultrasound<br>* Assessment of fetal cerebral and maternal uterine pulsatility index using Doppler ultrasound. Measurement of amniotic fluid index according to four-quadrant technique.<br>* Other names: Amniotic fluid index;|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Category III fetal heart rate tracings | Absent baseline fetal heart rate variability and any of the following: recurrent late decelerations, recurrent variable decelerations, bradycardia, sinusoidal pattern | 24 hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Middle cerebral artery pulsatility index | The middle cerebral artery pulsatility index will be obtained in a transversal view of the fetal head, at the level of its origin from the circle of Willis. Measurements will be obtained during periods of fetal apnea, and the angle of insonation will be maintained as close to 0° as possible when interrogating the middle cerebral artery | 24 hours before delivery | 
| Mean uterine artery pulsatility index | The probe will be placed on the lower quadrant of the abdomen, angled medially, and again color Doppler imaging will be used to identify the uterine artery at the apparent crossover with the external iliac artery. Measurements will be taken approximately 1 cm distal to the crossover point. In all cases, once it had been ensured that the angle was less than 20◦, the pulsed Doppler gate will be placed over the whole width of the vessel. Angle correction was then applied and the signal updated until three to five similar consecutive waveforms had been obtained. Mean pulsatility index will be calculated as the average pulsatility index of right and left arteries. | 24 hours before delivery | 
| Middle cerebral artery pulsatility index to mean uterine artery pulsatility index ratio | The ratio between the pulsatility index of the middle cerebral artery and the mean pulsatility index value of both uterine arteries. | 24 hours before delivery | 
| Oligohydramnios | Amniotic fluid index (Assessed acording to four-quadrant technique) | 24 hours before delivery | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
Late term pregnancy, Doppler