• Follow up of multiple gestation: Twin, triplet and higher order gestations are a unique set of pregnancies. It is important that any potential problem is discovered early so appropriate decisions are taken. The type of twin to twin placenta connection is important to taking decisions for the management of the pregnancy. This diagnosis is best made early hence women are advised to book early in pregnancy for their scans. This then forms the basis for subsequent ultrasound follow up especially if there is unequal growth of the babies.
  • Late ultrasound: Mothers are encouraged to carry out their first scans within the first 20 weeks of the pregnancy. Late scans become necessary as follow up of previous scans. However, some problems may have been suspected or detected by the woman’s care giver who then requires ultrasound confirmation. This could include conditions like bleeding from the vagina, excessive or inadequate growth of the womb, severe hypertension in the mother, and many others.
  • Basic ultrasound: This is the commonest type of obstetric ultrasound done in most centers. However, there is a shift away from this as it assesses just the basic features of the pregnancy. It is advised that, where feasible, women and health practitioners should opt for a detailed scan as the minimum.
  • Detailed ultrasound: This scan type goes beyond just checking the basic features of the baby. After checking how the baby is lying, where the placenta is, the amount of fluid around the baby and the age of the pregnancy, it checks in turn the various organs of the baby and assesses their normal growth and development. If there is any abnormality found, it then goes ahead to scan further to diagnose the cause and what remedies can be offered. These are the details that are done at the 18 – 22 week scan. However, the scan can be done at any time in the pregnancy. The drawback of poor timing of the scan is that the ease and clarity is diminished at certain other periods of the pregnancy hence limiting the information that one can get from the scan. Therefore, as much as is possible, detailed scan should be planned for the 18 – 22 weeks of pregnancy.
  • Chorionic Villus Sampling [CVS]: This is an ultrasound guided specialized procedure whereby developing placenta tissue is taken from within the uterus. The tissue is specially preserved and then sent for tests to determine the genetic make up of the fetus. The tests include test for the number and nature of chromosomes, test for sickle cell gene in the fetus and test for some enzyme abnormalities.
  • Amniocentesis: This is also a highly specialized ultrasound guided procedure in which a special needle is used to collect some of the liquor around the baby. This liquor is then sent for chromosomal, genetic and enzymatic tests.
  • Amniodrainage: In some pregnancies. The liquor around the baby becomes excessive. This may become uncomfortable for the mother requiring reduction of the fluid. In these circumstances, using ultrasound guidance, the fluid is gently drained form the womb until a tolerable amount of fluid is left. The fetus is then monitored closely until it is appropriate to deliver the baby.
  • Cervical assessment: Cervical assessment is especially important in women who are at risk for preterm delivery. The cervix is assessed using the transvaginal scan. The cervix can be assessed as open/closed or/and long/short and based on this, the risk of preterm delivery is calculated. Based on the risk, some treatment modalities may be instituted to improve fetal survival.
  • External cephalic version [ECV]: In this case, the pregnancy is almost 9 months but the fetus is not presenting with the head. The baby is either breech (coming with the buttocks first) or transverse (lying across the womb). Ultrasound scan is first done to rule out other complications (uterine fibroid, ovarian cyst, abnormality in the formation of the baby, abnormal movement of the baby, etc), to check the location of the placenta, to check the amount of liquor around the baby and to estimate the weight of the baby. A CTG examination (test to see if the heart beat of the baby is normal) is then carried out. If every other thing is normal, the baby is then turned to present with the head which thereby increases the chance of a vaginal delivery.

ECV is generally a safe procedure. Nevertheless, it is not a 100% successful. In close to a third of cases, turning the baby may not work. In such cases, depending on the policy of the hospital, the mother is either allowed to go into labour as breech (if transverse, delivery is by caesarean section) or has a caesarean section without the option of going into labour. Another drawback of ECV worth noting is that, in rare instances, the baby may develop an emergency like fetal distress (the heart beat becoming abnormal) or there may be placenta abruption (abnormal separation of the placenta before delivery of the baby). These can be detected when a CTG is done after the procedure. If present, the baby will need to be delivered immediately by emergency caesarean section. It is good to know that ECV is not carried out if there has been an operation on the womb previously as in previous Caesarean section. Also, in placenta praevia, severe preeclampsia (see below), very big babies, twins and some other conditions, ECV is not done.
It is therefore important that ECV is carried out by a qualified and properly trained personnel with the necessary back up including a functional theater.

  • Pre and post cervical cerclage: This special scan is important for those mothers who are deemed to have high risk of having preterm delivery or miscarriage due to the mouth of the womb not being tight enough to hold the baby inside the womb for 9 months as there could be in cervical incompetence. In these women, a scan is advised at about 12 weeks to accurately date the pregnancy and to check if the baby is healthy and sometimes to also measure the mouth of the womb. After this, the cerclage stitch is then put in by her doctor at about 14 weeks. Thereafter, she is advised to repeat the scan to see the position of the stitch and if any space is still present in the mouth of the womb. In some women, the doctor is not sure if she really has cervical incompetence. In these women and in those who refuse cerclage at the beginning, it is advisable to have regular measurement of the mouth of the womb to see if its opening at any time. If it is, then a cerclage can still be inserted much later to increase the chance of a live birth.
  • Screening for preeclampsia: This is a more recent ultrasound based screening test. It determines the risk of a woman having preeclampsia in the current pregnancy by putting together a lot of factors. It makes use of Doppler measurements mainly of the mother’s uterine arteries and combines this with factors in the history, etc. In those with high risk, factors in the management of the pregnancy can be adjusted to cater for this.
  • Placenta problems especially in those with previous caesarean section: For women who have had previous CS delivery/ies, there is an increased chance that the placenta being located in the lower part of the womb (placenta praevIA) or that the placenta has infiltrated into the body of the womb (placenta accreta). Placenta accreta is very dangerous as terrible bleeding can occur during delivery which is difficult to stop. Based on this, it is safer to have a high level scan to determine the chance of infiltration. If this is found, special surgical techniques are then planned or the patient is referred to a hospital where she will have more advanced care to minimize the risk from this condition.

 

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