Presentation on theme: "Samia Mohamad Eid Assist. Prof of Obs & Gyne. Al-Azhar university."— Presentation transcript:
Samia Mohamad Eid Assist. Prof of Obs & Gyne. Al-Azhar university
BPP is applying to detect prenatal asphyxia Doppler ultrasound is a modality for detecting fetal hypoxia and acidosis.
Hypoxia: decrease oxygen concentration in the tissue & blood. Acidosis increase concentration of H+ in tissue & blood. Asphyxia: hypoxia & metabolic acidosis. Ischemia: Drop in blood flow
The fetus uses oxygen to "burn" molecules and release energy. The reaction: glucose + oxygen >> carbon dioxide + water + energy Poor blood flow from the uterus and placenta causes the fetus to constrict blood vessels in nonvital peripheral areas in order to supply more blood flow to vital organs such as the heart and brain. How hypoxia leads to acidosis
With a limited supplies of oxygen (hypoxia) the peripheral tissues can only partially break down the sugar and converts it to lactic acid. Significant levels of acid in the blood (acidemia) may suppress the fetal nervous system and eventually lead to cardiovascular collapse. How hypoxia leads to acidosis
In 1980, Maning and Platt fashioned a method for Fetal surveillance in high risk pregnancy that combine FHR with various US variable
FHR monitoring Fetal breathing movement Fetal movement Fetal tone Amniotic fluid assessment Biophysical profile
Fetal movement and fetal tone develop between 7.5 and 9 weeks’ menstrual age Fetal breathing movements are detectable by, at least weeks’ gestation The non-stress test is most reliable between 32 weeks and term
So,BPP has a limited role for assessing fetal well being before 32 gestational weeks. Comment
Timeline for fetal hypoxia
So, Doppler ultrasound can predict fetal distress sooner than BPP comment
It involve the ability of the hypothalamus and medulla to maintain a variable, rather than smooth baseline and to increase the heart rate with fetal movement. Hypoxia or acidosis decrease beat-to-beat variability and accelerated FHR with fetal activity. FHR monitoring
Fetal breathing movements are detectable by, at least weeks’ gestation. After 30ws of gestation, the fetus will spend about 30%of his time making breathing motion. Fetal breathing
Action generated in the ventral surface of the 4 th ventricle. One episodes of 3oseconds during an observation period of up to 20 minutes. Prolonged hypoxia and/or acidemia blunt this activity. Fetal breathing
The fetal cortex generate the massage for the fetus to move his/her arms, legs, trunk. At least 3 trunk movements during 20 minutes observation period. Fetal movement Profound hypoxia and Acidemia will stop this for happening
Depends on intact cortex and subcortex. One episode of extension with a return to flexion during Is the last to go in a sequence of events ending in severe fetal compromise. Actually, fetal tone is the least useful variable since, By the time tone is lost, all of the other categories will have had scores zero (unless ?) Fetal tone
Amniotic fluid assessment Amniotic fluid relates indirectly to fetal brain Brain sparing concept Except post term pregnancy
Assessment of AF. AF volume rise linearly to about 33-34ws when the average is about 1000cc. After which it generally drops slowly to about 800cc at 40 ws and to 600cc at 42ws AF volume rise linearly to about 33-34ws when the average is about 1000cc. After which it generally drops slowly to about 800cc at 40 ws and to 600cc at 42ws
Basically there are 3 methods commonly used to assess the adequacy of AF: 1.Vertical pocket technique. 2.Amniotic fluid index. 3.subjective (eyeball) assessment. Assessment of AF
Vertical pocket technique 1 cm oligohydramnios 2cm oligohydramnios
As you know, oligohydramnios may be Mild AFI=5-8cm Moderate AFI=2-5cm Sever AFI<2cm only sever oligohydramnios is considered as an abnormal score.
It is not to obsess about subjective technique. I think that SA of AF by an experienced operator is at least a good as any other attempt since the aim is to determine if there is too little or too much. subjective (eyeball) assessment.
oligohydramnios IUGR Fetal renal abnormalities PROM IUGR Fetal renal abnormalities PROM 1 ST place to star would be fetal kidney. Kidneys circumstance should be 1/3 of AC. Texture should be mildly heterogeneously echogenic IPCK MDKD ++
oligohydramnios +IUGR = MCA Doppler Increased diastolic flow +AGA ? The fetal demands outstrips the placental ability to keep up & the circulatory cascade enfolds that is similar IUGR. These mothers often go into labor soon after Doppler change, +AGA ? The fetal demands outstrips the placental ability to keep up & the circulatory cascade enfolds that is similar IUGR. These mothers often go into labor soon after Doppler change,
Oligohydramnous PROM ?? Sometimes the history is equivocal or not helpful, in this case once renal anomalies excluded & normal MCA Doppler TVUS optimize axial section, the membrane can be seen over the cervix.
brainstem medullary Subcortica l Cortical hypothalamus How the BPP relates to fetal behavior
Under the influence of progressive hypoxia, the characteristic behavior pattern linked to these portion of the brain are lost in reverse order. NST become non reactive & the respirations are lost at roughly the same level of PO2 however FM slow & stops at lower PO2. The last to be affected is the fetal tone.
The non-stress test and fetal breathing movements are suppressed when the pH falls below 7.2. If the fetal pH falls below 7.10, fetal tone and fetal movements are abolished. Normal umbilical artery PH 7.27 ± 0.6
FST affects on fetal behavior especially HR, respirations & movements. 1.Quiet sleep (f %) ( min) 2.Active rapid eye movement (F %) 3.Quit awake sleep 4.Active awake sleep The fetal sleep states
The efficacy 0f bpd
NST indicates acute hypoxia AFI speaks for chronicity of the problem. Modified BPP