In the final weeks of pregnancy, babies often settle down in a head down position. However, in rare cases, the baby can be seen lying sideways or in a transverse position, known as malpresentation.
Although this is common in early pregnancy when the babies are more mobile, most babies turn into the head down position by the last trimester. When this does not happen, the malpresentation called transverse lie results.
According to studies, this presentation is rare and is found in only 1 in 400 cases.
Risk Factors for Transverse Lie
Women with the following conditions are at a high risk for transverse presentation:
- High ratio of amniotic fluid to fetus
- Uterine abnormality
- Placenta previa
- Fibroids in the uterus
- Factors preventing fetal head engagement in the mother’s pelvis
- Narrow or contracted pelvis
- More than 2 babies in the womb
Diagnosis of Transverse Presentation
Abdominal examination— In transverse position, the presenting part of the fetus is typically the shoulder. During abdominal examination, the head or the buttocks cannot be felt at the bottom of the uterus and the head is usually felt in the side.
Vaginal examination— A shoulder may be felt during a vaginal examination. An arm of the fetus may even slip forward and the hand or elbow may be felt during pelvic examination.
Confirmation - An ultrasound scan of the uterus confirms the transverse lie position.
Complications of Transverse Lie
Transverse presentation can cause serious complications during delivery. Some of the consequences are listed below:
- Obstructed labor
- Umbilical cord or hand prolapse
- Postpartum hemorrhage
- Birth trauma
- Rupture of the uterus
Delivering a Transverse Baby
It is almost impossible to deliver a transverse baby vaginally. So if a baby is still lying sideways at term or when labor begins, a C-section (caesarean) may be the safest option for delivering the baby.
If a transverse position is confirmed near term, the woman may be advised to be admitted to the hospital, as there is a minor risk of the umbilical cord slipping out of the uterus once water breaks.
This should be treated as a medical emergency and attended to immediately, as the cord may come out of the uterus before the baby and then the baby will need to be delivered quickly.
In some cases of transverse lie and shoulder presentation, the baby can be turned manually into the head down position using a process called external cephalic version.
In this process, a skilled medical professional applies pressure on the maternal belly and guides the head of the fetus into the correct position, all the while monitoring the fetal presentation on an ultrasound monitor. Although this procedure is largely painless, it can cause some discomfort to the mother.
This process should be tried only if there is no risk of membrane rupture. Although the fetus can be readily rotated to a head first presentation, it may easily turn back to the transverse position.
If external cephalic version is successful, the chance of a normal, vaginal birth is very high. If external cephalic version is not recommended due to some reason or if the procedure is unsuccessful, delivery needs to be performed via caesarean section.
If a woman goes into labor while the baby is in a transverse position, it can impact the shoulder of the fetus adversely. This is because, in such cases, the fetus in a folded position is under pressure to move down the birth canal.
An immediate C-section should be carried out in such cases, even if the fetus is not alive, as this can cause rupture of the uterus.
Reviewed by Yolanda Smith, BPharm