vertex presentation

vertex presentation

The Importance of Vertex Presentation in Childbirth

1. Understanding Vertex Presentation

Degree of Flexion: This refers to the chin of the fetus being in contact with the fetal chest. Full flexion is necessary for a normal vaginal delivery. If the degree of head flexion is abnormal, it is an extension which is termed brow or face presentation.

Attitude: This is the relationship of the fetal body parts to each other. Often it is described by fetal head flexion or extension.

Presentation: This refers to the part of the fetus that enters the maternal pelvis.

Lie: The lie is the relationship of the long axis of the fetus to the long axis of the mother. The normal lie is longitudinal, although transverse lie is common early in pregnancy and also just prior to term.

Understanding of the fetal lie, presentation, attitude, and degree of flexion is important in clinical practice as it has a direct implication on the mode of delivery and maternal and fetal morbidity.

2. Benefits of Vertex Presentation

The vast majority of malpresentations are cephaloidal but are divided into brow, face, and mentum presentations. These are thought to be associated with cephalic abnormalities and abnormalities in the cervico-fetal relationships. These presentations have increased incidence of operative delivery and antenatal death and are classed as fetopelvic presentations.

Since fetuses are passive in presentation, factors which determine malpresentation are related to the shape of the uterus and maternal posture. It has been thought that fetal size, abnormalities in the number of amniotic sacs, and fetal anomalies have been the causative factors for malpresentation but no clear links have been found. Uterine and pelvic factors are thought to be the major cause of malpresentation. For example, grandmultiparity has been associated with increased occipito-posterior positions and transverse lies. Abnormalities in the fetus with regard to malpresentation have an increased incidence of prolonged pregnancy and increased fetal mobility.

One of the primary concerns for both physician and mother in childbirth is the position of the baby. Since time immemorial, fetal malpresentation has been a significant cause of maternal and fetal morbidity and mortality. It is estimated that malpresentation occurs in 3-4% of all term pregnancies and is the commonest indication for perceived difficult labour.

Introduction

Friday, August 25, 2006

3. Common Challenges and Solutions

Bracket Edt Al. (1998) define the occipito-posterior position of the head as being the single most important problem in obstetrics with less than 5% of women continuing in labour to have a normal vaginal delivery, risk factors include nulliparity and high BMI. Factors causing the above problems include mal-presentation, malposition of the head, multiparity and failure to descend of the fetal head. Often these problems can be resolved with careful assessment of the position of the head and appropriate management, but sometimes a decision will be made for a caesarean section delivery.

There are a number of challenges that can arise in vertex presentation, but the majority are related to the position of the baby. Flexion of the head is essential as it allows the smallest diameter of the presenting part to enter the pelvis. Asynclitism is when the fetal head becomes angled on the neck and the majority of the pressure is then on one side of the cervix as opposed to the whole presenting part. Deep transverse arrest occurs when the fetal head fails to descend or rotate and is unable to negotiate the pelvic curve, the head will become deeply impacted above a narrow part of the pelvis. Posterior presentation can lead to a prolonged and dysfunctional labour. Extension of the head can occur after rotation resulting in the face or brow becoming the presenting part.

4. Techniques for Promoting Vertex Presentation

Instructions given to pregnant women for restoring a transverse lie, or avoiding one, may promote a posterior position. This means that it is difficult to give a clear recommendation on techniques to encourage vertex presentation. Measures that have been suggested include sitting in a comfortable chair with a firm seat and with the back tilted slightly backwards, avoiding sitting in a semi-recumbent position or sitting with the knees higher than the hips. Avoiding crossing the legs, and adopting positions on ‘all fours’ or kneeling may also be helpful. It is important that women with a breech presentation do not spend too much time lying on their back because this may discourage the baby from turning. This can make it difficult to recommend a best position for sleeping as individual comfort is an important consideration. Some authors may recommend lying on the side favorable for fetal position with a wedge-shaped pillow supporting the upper leg and compresses containing cold or frozen peas placed at the fundus or the baby’s back. However, there is no evidence to support the use of any of these measures. Further research is necessary in this area. On the basis of the theories of fetal molding and pelvic constraint, Barnett has suggested teaching women to habitually adopt a pelvic tilt position to counteract the tendency to a posterior position and the assumption that inadequate uterine space is a major factor in malpresentation has led to recommendations for the conservative management of twins with the aim to encourage both babies to lie head down. Any clinical trials to assess these interventions must evaluate not only effects on fetal presentation and labor but also assess adverse effects and maternal compliance. Randomized trials should be well-designed and adequately powered to detect clinically important differences. Data should be presented in a format that allows its inclusion in systematic reviews and meta-analysis including assessment of the quality of available evidence.

5. Conclusion: Embracing Vertex Presentation for a Smooth Delivery

With a greater understanding of vertex presentation and the assurance that it is not a mythical or rare event, a positive step can be made towards dealing with the persistent issue of informed consent. It’s 2017, and yet there are still mothers unaware of why they received certain types of obstetric care or what the medications and procedures given entail. There is a considerable amount of misinformation about childbirth, including the very steps and processes of normal birth physiology. While it may appear that a firm understanding of fetal presentation is basic knowledge for any birth attendant, it’s quite surprising how unfamiliar medical personnel can be with the conditions for the positions and how this lack of knowledge can affect the course and outcome of childbirth. The author herself has been asked by doctors, “Do you have a small pelvis?” after being informed of an ultrasound confirming her baby to be in a breech position. Knowledge says that a pelvis and its dimension have no bearing on the ability to give birth to a breech baby, but it is not the topic to be discussed here.

Supported by evidence from various sources, the aspirations for a normal and natural birthing experience are verified to be attainable for mothers with vertex presentations. To dream of an undisturbed childbirth is no longer a far-fetched fantasy. It is predominant knowledge that interventions often snowball from one to another, having adverse effects on the rest of labor and birth. Therefore, it is opportune for medical personnel and mothers to know the conditions that may lead to interventions and what strategies and precautions can be taken to prevent them from occurring. With knowledge of vertex presentation and its usual course of occurrence, mothers can be well prepared, and medical personnel can largely decrease their rates of PP interventions with a simple hands-off policy when monitoring the position of the baby.

Primary proponents advise that knowledge is power and to have successful and healthy childbirth, an expectant mother should be well informed of all possible scenarios that may arise during labor. Maximize the power and pursue that knowledge, in particular, that pertaining to the normal birthing process beginning with fetal presentation. Understanding the normal and knowing when to expect the abnormal is of great advantage and perhaps the most important step in avoiding unnecessary interventions. When interventions can be avoided, they should be. This should be the attitude of medical personnel, and mothers must take responsibility for their own education to be able to make informed decisions regarding their care. With regards to vertex presentation, this beginning step poses a usually smooth course for the rest of labor. As family physician Sarah J. Buckley states in her article, “If a mother is to have a physiological or natural (undisturbed) birth, then this is the ideal position.” But what makes it an ideal position, and is an undisturbed birth truly out of the realm of possibility for all vertex presentations?