Placenta Previa
Placenta Previa is a condition where the placenta embeds itself in such a way that it partially or completely covers the cervix. In such a case, the placenta lies low in the uterus and is at risk of separation from the uterine wall during labor contractions. When a pregnant woman experiences painles vaginal bleeding during the third trimester, the doctor may conduct an ultrasound to check for placenta previa. Other symptoms that might indicate placenta previa are a large uterine size, breech or transverse position of the baby or premature contractions.
Usually placenta previa is detected during routine ultrasound scans of the growing fetus. Women who are over 35 years or have had multiple pregnancies are at higher risk of placenta previa. If a woman is diagnosed with placenta previa, she will need to take bed rest. Often hospitalization is necessary. Travel must be avoided and pelvic examination by the doctor is not advisable. Instead the doctor will resort to ultrasounds and MRI.
Placenta previa can cause growth retardation in the fetus due to irregularly placed placenta. This can lead to increased chances of congenital anomalies. The expectant mother is at risk for hemorrhage. Blood transfusion is resorted to in cases of severe bleeding.
Chorionic Villus Sampling
The diagnostic procedure of taking out a sample tissue (Choroinic Villi) from the placenta to detect congenital abnormalities in a fetus is known as Chorionic Villus Sampling (CVS). With the guidance of ultrasound, the position of placenta is first determined. There are two methods - trans-cervical and trans-abdominal to perform this test. The position of the placenta helps the physician choose a suitable method. For trans-cervical CVS, parameters like the position of the uterus, the size of the gestational sac and the position of the placenta inside the uterus are first determined using abdominal ultrasound. Using a good antiseptic, the vulva, vagina and the cervix are cleansed. The abdomen is also cleansed for trans-abdominal procedure.
Trans cervical procedure: A thin plastic tube is inserted through the vagina and cervix for the trans-cervical procedure to reach the placenta. A tiny sample of chorionic villus tissue is taken out after locating the exact position of the placenta.
Trans-abdominal procedure: This procedure is similar to the earlier one, but a needle is inserted through the abdomen in this test to reach the uterus and then to the placenta. The chorionic villus sample tissue is drawn into the syringe, while the needle is guided by ultrasound.
This sample is then taken to the laboratory for evaluation. This procedure can be conducted even earlier than amniocentesis to detect any congenital defects present in the fetus. It is done at around 10 to 12 weeks after the last menstruation. Study of the DNA, chromosomes and enzymes of the fetus can be conducted using the sample taken out during the test. Results are available within a week or two. If there are any abnormalities found in the fetus, it is easy to conduct a therapeutic abortion, in case it is necessary. Pregnant women over the age of 35 who are at risk for giving birth to a baby with Downs Syndrome or those who have had birth defects in an earlier pregnancy are advised this test. For detecting neural tube defects and the Rh-incompatibility, amniocentesis is a better option. Hemoglobinopathies and Tay-Sachs disease can be detected through Chorionic Villus Sampling.
The risk involved in using CVS is slightly higher when compared to amniocentesis. Some complications like rupture of the amniotic membrane, miscarriage, infection, bleeding, Rh-incompatibility in the mother if she is Rh-negative and contamination of the sample with maternal cells can occur. When CVS is performed after 10 weeks of gestational period, there is a risk for limb defects in the fetus. If the mother's blood is Rh-negative, she has to receive RhoGAM to avoid Rh incompatibility. After the CVS, it is advised to have an ultrasound done after about two or four days to ensure the fetus is fine.
Placental Abruption
The placenta usually separates from the uterus after the birth of the baby.
Placental abruption is a condition where the placenta separates from the uterine wall during the pregnancy. Placental abruption is a serious condition and can put the baby at risk. This is a medical emergency. Hypertension can sometimes lead to placental abruption. Women who have blood-clotting disorders may experience placental abruption. Women suffering from diabetes or abusing drugs are also at higher risk for placental abruption. Those women who have had multiple pregnancies are also at higher risk for placental abruption.
A pregnant woman suffering from placental abruption is likely to have abdominal and back pain. There might be rapid uterine contractions. There is tenderness in the abdomen. Uterine bleeding is often noticed. Placental abruption can occur anytime after the 20th week of pregnancy.
An ultrasound can help in locating any possible blood clot behind the placenta. It can also help in checking for any signs of fetal distress. Fetal monitoring is essential since the placenta supplies nutrients to the growing fetus. There may be decreased fetal movements. The extent of placental abruption decides the course of treatment to be followed. Partial placental abruption needs adequate bed rest and close monitoring. In cases of total placental abruption, delivery of the infant is undertaken. This is either with vaginal delivery or cesarian section. But there is a risk of premature birth and fetal death. The newborn baby could suffer brain damage due to low levels of oxygen in the blood.
Bibliography / Reference
| 