6. Restricción del crecimiento intrauterino Flashcards
¿What is Intrauterine growth restriction or (IUGR)?
Lower than normal fetal growth characterized by an estimated fetal weight below the 10th percentile for a given gestational age.
¿What are the two types of IUGR?
Symmetrical and symmetrical
¿What are some causes of asymmetrical IUGR?
Extrinsic influences (most commonly placental insufficiency) that affect the fetus in the later stages of gestation
¿What are some causes of symmetrical IUGR?
Iintrinsic influences (early intrauterine infections, aneuploidy) that affect the fetus in the early stages of gestation.
¿How is IUGR diagnosed?
Serial ultrasound, which demonstrates decreased fetal growth and oligohydramnios.
What are some typical manifestations of asymmetrical IUGR?
Normal fetal head size with a disproportionately small body and limbs
What are some typical manifestations of symmetrical IUGR?
Global growth restriction of the head and body and can lead to an increased risk of neurologic sequelae.
What are some of the tests recommended to monitor fetal status and placental development in cases of IUGR?
- Nonstress test (NST)
- Contraction stress test (CST)
- Biophysical profile (BPP)
What is a Nonstress test (NST)?
A form of antepartum fetal surveillance in which cardiotocography is performed for a period of 20–40 minutes along with a recording of fetal movements.
It tests the reactivity of fetal heart rate to fetal movements.
What is a Contraction stress test (CST)?
A test to assess the response of the fetal heart rate to contractions indicated in high-risk pregnancies.
When do we consider a contraction stress test (CST) positive?
If >50% of contractions are followed by late decelerations in FHR. It may indicate adverse outcomes of the fetus.
What is a biophysical profile?
A noninvasive evaluation of fetal wellbeing. It consists of four parameters measured via ultrasound (fetal breathing, movement, tone, and amniotic fluid volume) and a nonstress test, which is optional if all ultrasound parameters are normal.
How is the biophysical profile score interpreted?
Each parameter receives a score of either 0 (abnormal) or 2 (normal) points. The maximum score is 10.
A score ≤ 4 indicates potential fetal compromise, which is often taken as an indication for delivery
When should we consider labor induction or cesarean delivery in cases of IUGR?
If the infant is close to term or if there are signs of nonreassuring fetal status.
What is a Nonreassuring fetal status?
The characteristic changes in the fetal heart rate (FHR) in response to fetal hypoxia and metabolic acidosis (usually secondary to placental insufficiency).
How do we detect a nonreassuring fetal status on cardiotocography?
- Fetal tachycardia (FHR > 160-180/min)
- Fetal bradycardia (FHR < 110/min)
- Loss of baseline variability
- Recurrent variable decelerations
- Late decelerations
What is the conduct to follow if there is a nonreassuring fetal status?
Either intrauterine resuscitation or immediate delivery (cesarean or, if imminent, vaginal delivery).
What are some maternal causes of IUGR?
- Substance use (alcohol, cigarettes, cocaine, heroin)
- Teratogenic drugs: ACE inhibitors, carbamazepine, phenytoin, warfarin
- Maternal phenylketonuria
- Systemic diseases resulting in placental insufficiency
What are some uteroplacental causes of IUGR?
- Placental insufficiency
- Placenta previa
- Multiple gestations
- Placental abruption
- Umbilical artery thrombosis/extensive infarction
- Uterine malformations (e.g., fibroids)
What is placental insufficiency?
A disorder of the fetomaternal circulation that causes inadequate blood flow to the placenta and impaired substance exchange (e.g., oxygen) between the mother and fetus, leading to metabolic compromise of the fetus.
Causes and risk factors
Maternal conditions (smoking during pregnancy, diabetes mellitus with vasculopathy, chronic hypertension, severe anemia, anorexia nervosa, antiphospholipid syndrome, SLE, sickle cell disease)
Pregnancy-related conditions (preeclampsia, Rh incompatibility)
Clinical features: depend on the underlying cause
Complications: IUGR, placental abruption, preterm labor, stillbirth, Potter sequence, oligohydramnios
