Altitude
In obstetrics, the height describes the position of the preceding part of the unborn child (head or rump) in the maternal pelvis . It is usually given in + or - cm.
At birth, the head performs three movements when it passes through the pelvis: stepping down (change in height), flexion (change in posture) and rotation (change in position). In total, the head must cover about 12 cm from the pelvic entrance to the pelvic floor.
Basics and meaning
The repeated determination of the height is important for the assessment of the birth process and forms one of the decision-making bases for the question of whether vaginal-operative or caesarean deliveries must be used. Other obstetric decisions, such as the type of induction , are usually also made taking into account the height. In addition to assessing the amount subject also to gestational age , the parity , any existing labor , the condition of the cervix and the fetal position (location, position, attitude and setting) considered.
The four important levels that the head goes through within the pelvis during pregnancy and childbirth are:
- Head over pool entrance :
- Head in the pool entrance : The control center has crossed the terminal level.
- The head is low and firm in the pool entrance : the head has exceeded the terminal level with its greatest circumference.
- Head stands on the pelvic floor : The head sits firmly on the pelvic floor muscles, the head stands with its greatest circumference in the mid-level of the pelvis (middle posterior wall of the symphysis, middle of the third sacral vertebra).
Most textbooks describe altitude in relation to a skull position. Even with a breech position , the term height is used. However, this does not play the same role here as with the position of the skull, since the child's rump is usually located here for a very long time (sometimes until shortly before birth) above the pelvic entrance and the head (the part of the child with the greatest circumference and therefore the more relevant) is very much passes through the birth canal quickly after the birth of the rump. During pregnancy , the height is important in that it comes to the 36th week of pregnancy, the lowering of the child in the womb. In the case of primiparous women, it is considered to be prognostically favorable if the child then has a connection to the pelvis, while in the case of multiparous women it is often the case that the child only gets a connection to the pelvis during labor or after the rupture of the bladder .
A distinction is made between two methods of determining the height: the external and the internal (vaginal) examination.
Determination of the height by external examination
The 3rd and 4th Leopold handles are usually used to determine the height by external examination .
As long as the head or another preceding part is still above the pelvic entrance, you can still feel it completely above the pelvis and it is easy to move. When performing the 3rd Leopold move, the previous part can be made to swing back and forth ( balloting or ballottement ). When using the 4th Leopold handle, the tip of the finger can be used to penetrate between the head and the bevel ring.
If the head is placed on the pelvis, it has entered the pelvis with the smallest segment , then its mobility becomes less and it goes from "freely movable via the pelvic entrance" to "difficult to move in the pelvic entrance". Most of the head can still be felt from the outside.
If the head is difficult to move in the pelvic entrance, the entered head segment is larger than with a movable head. The head can still be felt from the outside. At this height, during a vaginal examination, the head of a multiparous woman could still be pushed out of the pelvis, whereas this usually no longer succeeds in a primiparous woman.
If the head is low and firmly in the pelvic entrance, it can hardly be felt from the outside at all. The height in the middle of the pelvis is the only one that cannot be determined by external hand movements. If the head is on the pelvic floor , it fills the entire pelvic cavity and sits firmly on the pelvic floor muscles; you can feel it from below. There are two steps to do this:
- Schwarzenbach handle : If you press the tip of the four fingers of one hand, coming from the sacrum, into the area between the tip of the tailbone and the anus , the "back perineum", you can clearly feel the head resting on the pelvic floor as a hard, broad resistance.
- De Leescher handle : If you press two fingers down the sides of a large labia , you can feel the big, hard head standing there.
If the head is in the pelvic outlet, it becomes visible in the vulva or in the depth of the vagina .
Determination of the height by internal examination
If the height is determined with the help of the vaginal examination, three basic things must be observed. First, the probing finger must be exactly in the guide line of the arched birth canal (the midpoints of all straight diameters of the small pelvis and the soft tissue path connected downwards form an axis = guide line). If you examine too far ahead, you can get too easy to get to the head and appreciate it too deeply. The bony control point, the lowest point of the previous section, is also the reference point on the head. If there is a birth tumor , it must be deducted. In extreme cases, this lump can already be visible in the vulva while the head with its greatest circumference has not yet entered the pelvis. Thirdly, it must be noted that all information always applies to the physiological flexion positions and not to the deflexion positions, such as the face position or the forehead position . In the vaginal examination, a distinction is made between three methods, each with different reference points, for determining the height.
Description of height in relation to the pool areas
The height is determined based on the ratio of the functional head circumference in relation to the pelvic spaces. As a rule, three pelvic spaces - pelvic entrance, pelvic center and pelvic exit - are described, although other names are common (e.g. pelvic cavity instead of pelvic center). The functional head circumference, which is important for stepping deeper into the pelvic area in relation to the mechanics of childbirth, is also referred to in some textbooks as the "largest child head circumference", "passage planum" or "head circumference effective in terms of birth mechanics".
Parallel planes according to Hodge
This altitude description comes from the American gynecologist Hughes Lennok Hodge (1796–1873). This classification relates to the relationship between the control center and the parallel levels of the maternal pelvis. The control point corresponds to the lowest point of the previous child's part, i.e. the point that the finger first encounters in the guide line during the vaginal examination. The small basin is divided into four parallel levels. They are each about four centimeters apart and are based on prominent bone sites:
- O-level : upper level of the edge of the lap joint, this runs from the upper edge of the symphysis to the promontory , the preceding part has no relation to the pelvic entrance space at this height, it is movable above the small pelvis
- U-level : lower joint edge level, this runs parallel to the O-level at the level of the lower edge of the symphysis,
- I-level : Interspinal level , this runs parallel at the level of the two ischial spines
- B-level : pelvic exit level , this runs parallel to the not bent coccyx
Altitude diagnosis according to de Lee
This altitude description goes back to the American gynecologist Joseph Olivar de Lee (1869–1942). The interspinous plane - an imaginary connecting line between the ischial spines (spinae ischiadicae) - is the reference point, which corresponds to the zero point. The height of the child's preceding part is given in centimeters above or below the interspinal plane. The small pelvis is divided into eight centimeters. So it will give a value from I-4 to I + 4.
Practical use
The determination of the height and above all the information are not always clear in practice. It is advisable to agree on a uniform description within a delivery room team . The German Society for Gynecology and Obstetrics recommends in its AWMF guidelines, the height level according to de Lee for the procedure for vaginal-operative delivery.
swell
- Christine Mändle, Sonja Opitz-Kreuter, Andrea Wehling: The midwifery textbook of practical obstetrics. Schattauer, Stuttgart / New York 1997, ISBN 3-7945-1765-2 .
- B. Petersen: The tricky thing with the high altitude. In: Midwives Forum. No. 3, 2010, pp. 178-181.
- Pschyrembel: Practical obstetrics. 22nd, enlarged and corrected edition. de Gruyter, Berlin 2019, ISBN 978-3-11-065031-0 .