Pelvic presentation of the fetus

Breech presentation of the fetus is a position of the fetus that is characterized by the location of the pelvic end of the fetus relative to the plane of the entrance to the small pelvis.

In breech presentations, the fetus is in a longitudinal position, the breech end is presented, and the head is in the area of the fundus of the uterus. The frequency of breech presentation is 3-3.5% of the total number of births, and in premature pregnancy, every fifth birth occurs in gas presentation.

Breech presentation is the usual position of the fetus at the end of the second trimester of pregnancy. However, due to the relatively large volume of the pelvic end compared to the head, most fetuses acquire a cephalic presentation in the third trimester.

The causes of breech presentation during full-term pregnancy may be: polyhydramnios, multiple pregnancy, tumors of the uterus and ovaries, decreased muscle tone of the uterus, developmental anomalies of the uterus, placenta previa, narrow pelvis, developmental anomalies of the fetus.

The most common presentation is breech presentation - 63-75% of all cases of breech presentation. Mixed presentation - 20-24%, foot presentation - 11-13%. The position of the fetus in breech presentations is determined in the same way as in cephalic presentations.

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Classification of breech presentation

Breech presentation (flexed):

• incomplete or purely breech - the fetus's buttocks are present;
• full or mixed breech - the fetus's buttocks are presented together with the feet;

Foot presentation (extension:

• incomplete (one leg of the fetus is present);
• complete (both legs of the fetus are presented);
• knee presentation.

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Diagnosis of breech presentation

The diagnosis of breech presentation is based mainly on the ability to palpate the fetal head from the buttocks.

During external obstetric examination it is necessary to use Leopold's techniques:

• at the first appointment, a round, dense, balloting head is detected in the area of the fundus of the uterus;
• in the third case, above the entrance or at the entrance to the small pelvis, the irregularly shaped presenting part of the fetus of soft consistency, which does not ballot, is palpated.

During auscultation, the fetal heartbeat is heard depending on the position to the right or left above the navel. A high position of the uterine fundus may be observed.

Diagnosis of breech presentation usually causes difficulties in cases of severe tension in the muscles of the anterior abdominal wall and increased tone of the uterus, obesity, twins, and anencephaly.

During a vaginal examination during pregnancy, a voluminous, soft-textured presenting part of the fetus is palpated through the anterior fornix, which differs from the denser and rounded head. 

During an internal obstetric examination during labor (during dilation of the cervix), palpation of various parts is possible depending on the presentation:

• In case of breech presentation, the soft voluminous part of the fetus is palpated, the gluteal tubercles, sacrum, anus, and genitals are determined.

Additionally:

• in case of incomplete gluteal deflection, the inguinal flexure can be determined;
• for complete gluteal pain - a foot or two feet that lie next to the buttocks;
• the gluteal tubercles and the anus are located in the same plane;
• With foot palpation, the foot is palpated, which is distinguished by the following features: the heel bone, the toes are straight, short, the big toe is not abducted to the side and has limited mobility, and is not brought to the sole.

Ultrasound is the most informative diagnostic method. This method of examination allows determining not only the breech presentation, but also the weight of the fetus, the position of the head (flexed, extended).

Based on the angle between the cervical spine and the occipital bone of the fetus, there are four possible positions of the head, which is essential for determining the tactics of labor management in the case of breech presentation:

• head bent, angle greater than 110; - head slightly extended" "military pose"
• I degree of head extension, angle 100-110°; - head is moderately extended
• II degree of extension, angle 90-100°; - excessive extension of the head, "the fetus looks at the stars"
• III degree of head extension, angle less than 90°.

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The course and management of pregnancy in breech presentation

The course of pregnancy with breech presentation is no different from that with cephalic presentation, but complications are quite common. The most common and unfavorable in its consequences is early or premature rupture of membranes. In most cases, this occurs with foot presentation.

When conducting labor in a women's clinic, a preliminary diagnosis of breech presentation of the fetus is established at 30 weeks of pregnancy, and the final diagnosis is established at 37-38 weeks.

At 30 weeks of pregnancy, measures are taken to promote the fetus's self-rotation onto its head. The following is recommended for this:

• position on the side opposite to the position of the fetus;
• knee-elbow position for 15 minutes 2-3 times a day.

From the 32nd to the 37th week, a set of corrective gymnastic exercises is prescribed according to one of the existing methods (I.F. Dikan, I.I. Grishchenko).

Basic elements of corrective gymnastics:

• tilting the pregnant woman's body towards the back of the fetus;
• flexion of the lower limbs at the knee and hip joints with simultaneous flexion of the torso towards the fetal position;
• arching the back with support on the wall bars;
• arching the back in a knee-elbow position;
• bending the lower limbs at the knee and hip joints while lying on the back, pulling the knees to the stomach, half-turning the pelvis with bent limbs towards the fetal position.

Contraindications to performing gymnastic exercises:

• threat of termination of pregnancy;
• placenta previa;
• low placenta previa;
• anatomically narrow pelvis II-III degree.

Taking into account the peculiarities of the course of pregnancy with breech presentation of the fetus, at the stage of observation of these pregnant women in the antenatal clinic, it is necessary to comprehensively assess the condition of the fetus and the placental complex using modern diagnostic methods (ultrasound, Doppler, CTG).

External prophylactic cephalic version of the fetus is not performed in antenatal clinics due to the high risk of complications:

• premature detachment of the placenta;
• rupture of amniotic fluid;
• premature birth;
• uterine rupture;
• acute fetal distress;
• fetal trauma.

If the breech presentation of the fetus persists at 37-38 weeks of pregnancy, hospitalization in an obstetric hospital is carried out according to the following indications:

• presence of a complicated obstetric and gynecological history;
• complicated course of this pregnancy;
• extragenital pathology:
• the possibility of performing external cephalic version of the fetus.

In case of a full-term pregnancy in a level III hospital, an external cephalic version of the fetus may be performed before labor begins, provided the pregnant woman has given informed consent. Before the version, an ultrasound is performed, the condition of the fetus is assessed (BPP, Doppler if necessary), and the woman's body's readiness for labor is determined.

External cephalic version of the fetus

Indications:

• incomplete breech presentation in full-term pregnancy with a living fetus.

Conditions:

• estimated fetal weight < 3700.0 g;
• normal pelvic dimensions;
• empty bladder of a pregnant woman;
• the possibility of conducting ultrasound monitoring of the position and condition of the fetus before and after the turn;
• satisfactory condition of the fetus with BPP and the absence of developmental anomalies;
• normal fetal motor activity, sufficient amount of amniotic fluid;
• normal uterine tone, intact amniotic sac;
• readiness of the operating room to provide emergency care in case of complications;
• the presence of an experienced qualified specialist who is proficient in turning techniques.

Contraindications:

• complications during pregnancy at the time of the decision to perform external version (bleeding, fetal distress, preeclampsia);
• burdened obstetric and gynecological history;
• polyhydramnios or oligohydramnios;
• multiple pregnancy;
• anatomically narrow pelvis;
• the presence of cicatricial changes in the vagina or cervix;
• III degree of head extension according to ultrasound data;
• placenta previa;
• severe extragenital pathology;
• uterine scar, adhesive disease;
• hydrocephalus and tumors of the fetal neck;
• developmental abnormalities of the uterus;
• tumors of the uterus and appendages.

Technique of external cephalic version of the fetus:

• the woman's position on her side, with a 30-40° tilt towards the back of the fetus;
• the fetus's buttocks are moved away from the entrance to the small pelvis with the doctor's palms inserted between the pubis and the fetus's buttocks;
• carefully move the fetus's buttocks towards the fetus's position:
• shift the fetal head to the side opposite to the position;
• The rotation is completed by moving the fetal head toward the entrance to the small pelvis and the buttocks toward the bottom of the uterus.

If the first attempt at rotation was unsuccessful, performing a second one will be inappropriate. Taking into account the high percentage of failures of preventive rotation, the risk of serious complications, it is necessary to clearly define the indications and contraindications for performing rotation.

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Course and management of urgent labor in breech presentation

The peculiarities of the course of labor in breech presentations are the high risk of possible complications. In the first period of labor, the following are possible: premature and early rupture of amniotic fluid, prolapse of small parts of the fetus, umbilical cord, weakness of labor, fetal distress, endometritis during labor. In the second period - throwing back of the fetal arms, formation of a posterior view, spasm of the cervix, fetal injury, injury to the birth canal.

There are three degrees of arm throwing: I - the arm is in front of the ear; II - at the ear level; III - behind the ear of the fetus. Most often in these cases severe fetal distress occurs as a result of the prolonged birth of the head.

The period of expulsion deserves special attention, as improper management of it can lead to severe birth injuries or even death of the fetus.

During breech birth, there are four stages:

1. birth of the fetus up to the navel;
2. birth of the fetus to the lower angle of the shoulder blades;
3. birth of handles;
4. birth of the fetal head.

The biomechanism of childbirth in breech presentation of the fetus consists of the following points:

• the first moment is the insertion and lowering of the buttocks, while their transverse size of the buttocks is inserted into one of the oblique dimensions of the small pelvis;
• the second moment is the internal rotation of the buttocks, which move from the wide part to the narrow part and are set at the bottom of the gas in a straight size, the front buttock approaches the pubic symphysis, the back to the sacrum;
• the third moment is the lateral bending of the spine in the lumbosacral region. A fixation point is formed between the lower edge of the symphysis and the edge of the ilium of the anterior buttock. The posterior buttock is born first, then the anterior one. After the birth of the pelvic end, the torso straightens, the fetus is born to the navel, then to the lower angle of the shoulder blades, turning back forward;
• the fourth moment is the internal rotation of the shoulders (the transition of its transverse size from an oblique size to a straight one), the anterior shoulder is fixed under the pubic symphysis by the acromial process;
• the fifth moment is lateral flexion of the spine in the cervicothoracic region. The fixation point is between the lower edge of the symphysis and the acromial process of the fetal scapula. The birth of the posterior shoulder occurs, and then the anterior one in the direct size of the plane of exit from the small pelvis;
• the sixth moment is the internal rotation of the head. The sagittal suture passes into the direct size of the outlet from the small pelvis, the suboccipital fossa is fixed under the pubis;
• the seventh moment is the bending of the head around the point of fixation and its birth.

In the case of foot presentation, the biomechanics of labor is the same, only the legs, not the buttocks, emerge first from the genital slit.

In order to prevent complications in an obstetric hospital for women in labor with a breech presentation of the fetus, it is necessary to determine a plan for managing the birth, that is, after conducting a study, the issue of optimal delivery is decided on an individual basis, which depends on:

• age of the pregnant woman;
• pregnancy period;
• concomitant extragenital and genital pathology;
• obstetric complications;
• the mother's body's readiness for childbirth;
• pelvic dimensions;
• the condition of the fetus, its weight and sex;
• types of breech presentation;
• degree of extension of the fetal head.

Favorable obstetric situations in which childbirth can be carried out through the natural birth canal include:

• satisfactory condition of the pregnant woman and the fetus;
• complete ratio of the sizes of the maternal and fetal pelvis;
• sufficient biological readiness of the mother's body for childbirth;
• the presence of pure breech or mixed breech presentation;
• bent fetal head.

In conservative management of labor it is necessary:

• evaluate the indications, make sure that all the necessary conditions are in place for a safe delivery through the natural birth canal, and that there are no indications for a caesarean section;
• monitor the course of the first stage of labor by keeping a partogram and recording CTG for 15 minutes every 2 hours;
• in case of rupture of the membranes, urgently conduct an internal obstetric examination to exclude prolapse of the umbilical cord;
• the second stage of labor should be carried out with a mobilized vein for intravenous administration of 5 BD oxytocin in 500 ml of isotonic sodium chloride solution (up to 20 drops per 1 min) in the presence of an anesthesiologist and neonatologist;
• performing an episiotomy according to indications (if the perineum does not stretch well); subpudendal anesthesia (C).

Planned caesarean section is performed according to the following indications:

• expected fetal weight is 3700 g or more;
• foot presentation of the fetus;
• extension of the head grade III according to ultrasound data;
• fetal neck tumors and hydrocephalus.

The technique of cesarean section and methods of anesthesia for breech presentations of the fetus are no different from those for cephalic presentations. The fetus is taken out by the inguinal fold (pure breech presentations) or by the leg, which lies in front. The head is brought out using manipulations reminiscent of the Morisot-Levre-LaChapelle techniques.