Fetal malposition

Incorrect fetal position is a position in which the fetal axis does not coincide with the uterine axis. In cases where the axes of the fetus and uterus intersect to form an angle of 90°, the position is considered transverse (situs transversus); if this angle is less than 90°, the fetal position is considered oblique (situs obliguus).

In practice, the transverse position of the fetus can be spoken of in the case of its head being located above the iliac crest, and the oblique position - below. Incorrect fetal positions occur in 0.2-0.4% of cases. It should be noted that the position of the fetus interests the obstetrician from the 22nd week of pregnancy, when premature labor may begin.

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Causes of abnormal fetal position

Among the causes of abnormal fetal positions, the most important are decreased uterine muscle tone, changes in the shape of the uterus, excessive or severely limited fetal mobility. Such conditions are created by developmental anomalies and tumors of the uterus, fetal developmental anomalies, placenta previa, polyhydramnios, oligohydramnios, multiple pregnancies, laxity of the anterior abdominal wall, as well as conditions that make it difficult to insert the presenting part of the fetus into the entrance to the small pelvis, such as tumors of the lower segment of the uterus or significant narrowing of the pelvis. An abnormal position, especially an oblique one, can be temporary.

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How to recognize an abnormal fetal position?

Transverse and oblique fetal position are diagnosed without much difficulty in most cases. When examining the abdomen, the shape of the uterus, which is elongated in the transverse direction, attracts attention. The abdominal circumference always exceeds the norm for the corresponding gestational age at which the examination is carried out, and the height of the fundus of the uterus is always less than the norm. When using Leopold's techniques, the following data are obtained:

• there is no large part of the fetus in the bottom of the uterus, which is found in the lateral parts of the uterus: on one side - a round, dense one (the head), on the other side - a soft one (the pelvic end);
• the presenting part of the fetus above the entrance to the small pelvis is not determined;
• the fetal heartbeat is best heard in the navel area;
• the position of the fetus is determined by the head: in the first position, the head is determined on the left side, in the second - on the right;
• The type of fetus is recognized by its back: the back is facing forward - anterior view, the back is facing backward - posterior. If the back of the fetus is turned downwards, then an unfavorable variant takes place: it creates unfavorable conditions for the extraction of the fetus.

A vaginal examination performed during pregnancy or at the beginning of labor with an intact amniotic sac does not provide much information. It only confirms the absence of the presenting part. After the amniotic fluid has been released, with sufficient dilation of the cervix (4-5 cm), the shoulder, scapula, spinous processes of the vertebrae, and inguinal cavity can be identified.

Ultrasound is the most informative diagnostic method, which allows determining not only the abnormal position, but also the expected body weight of the fetus, the position of the head, the location of the placenta, the amount of amniotic fluid, umbilical cord entanglement, the presence of anomalies in the development of the uterus and its tumor, anomalies in the development of the fetus, etc.

The course and tactics of pregnancy management

Pregnancy with an abnormal fetal position occurs without any particular deviations from the norm. The risk of premature rupture of membranes increases, especially in the third trimester.

A preliminary diagnosis of abnormal fetal position is established at 30 weeks of pregnancy, and a final diagnosis at 37-38 weeks. Starting from the 32nd week, the frequency of spontaneous rotation decreases sharply, so it is advisable to correct the fetal position after this period of pregnancy.

In the antenatal clinic at 30 weeks, to activate the fetus's self-rotation onto the pregnant woman's head, it is necessary to recommend corrective gymnastics: position on the side opposite to the fetus's position; knee-elbow position for 15 minutes 2-3 times a day. From the 32nd to the 37th week, a set of corrective gymnastics exercises is prescribed according to one of the existing methods.

Contraindications to performing gymnastic exercises are the threat of premature birth, placenta previa, low placenta attachment, anatomically narrow pelvis of II-III degree. External prophylactic version of the fetus on the head is not performed in the conditions of the antenatal clinic.

External cephalic version of the fetus

Further pregnancy management tactics include attempting external cephalic version of the fetus at term and subsequent induction of labor or expectant pregnancy management and attempting to turn the fetus at the onset of labor if its abnormal position persists. In most cases, with expectant pregnancy management tactics, fetuses that had an abnormal position are positioned longitudinally by the onset of labor. Only less than 20% of fetuses that were positioned transversely up to 37 weeks of pregnancy remain in this position by the onset of labor. At 38 weeks, the need for hospitalization in a level III obstetric hospital is determined based on the following indications: the presence of a complicated obstetric and gynecological anamnesis, complicated course of this pregnancy, extragenital pathology, the possibility of performing external version of the fetus. In the obstetric hospital, in order to clarify the diagnosis, an ultrasound is performed, the condition of the fetus is assessed (BPP, Doppler ultrasound is performed if necessary), the possibility of external cephalic version of the fetus is determined, and the readiness of the woman's body for childbirth is determined.

The plan for managing the birth is developed by a council of doctors with the participation of an anesthesiologist and neonatologist and agreed upon with the pregnant woman. In the case of a full-term pregnancy in a level III hospital, external cephalic version of the fetus may be performed by the onset of labor, subject to the informed consent of the pregnant woman. External cephalic version of the fetus in the case of a full-term pregnancy leads to an increase in the number of physiological births in the cephalic presentation.

External cephalic version during full-term pregnancy allows spontaneous fetal version to occur more frequently. Thus, waiting until the due date reduces the number of unnecessary attempts at external version. During full-term pregnancy, if complications arise during version, emergency abdominal delivery of a mature fetus can be performed. After successful external cephalic version, reverse spontaneous versions are less common. The disadvantages of external fetal version during full-term pregnancy are that it can be hampered by premature rupture of the amniotic sac or labor that began before the planned attempt to perform this procedure. The use of tocolytics during external version reduces the failure rate, facilitates the procedure, and prevents the development of fetal bradycardia. These advantages of tocolytic use should be compared with their possible side effects on the mother's cardiovascular system. It should be noted that the risk of complications during external version is reduced, since the procedure is performed directly in the maternity ward with continuous monitoring of the fetus's condition.

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Conditions for performing an external turn

Estimated fetal weight < 3700 g, normal pelvic dimensions, empty bladder of the pregnant woman, possibility of ultrasound assessment of the position and condition of the fetus before and after the rotation, satisfactory condition of the fetus according to the BPP and the absence of developmental anomalies, sufficient fetal mobility, sufficient amount of amniotic fluid, normal uterine tone, intact fetal bladder, readiness of the operating room to provide emergency care in case of complications, availability of an experienced qualified specialist who knows the rotation technique.

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Contraindications to external rotation

Complicated pregnancy at the time of the decision to perform external version (bleeding, fetal distress, preeclampsia), complicated obstetric and gynecological history (habitual miscarriage, perinatal loss, history of infertility), polyhydramnios or oligohydramnios, multiple pregnancy, anatomically narrow pelvis, presence of cicatricial changes in the vagina or cervix, placenta previa, severe extragenital pathology, uterine scar, adhesive disease, fetal developmental abnormalities, uterine developmental abnormalities, tumors of the uterus and its appendages.

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Technique

The doctor sits on the right side (facing the pregnant woman), places one hand on the fetus's head, the other on its pelvic end. With careful movements, the fetus's head is gradually moved to the entrance to the small pelvis, and the pelvic end to the bottom of the uterus.

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Complications during external rotation

Premature detachment of a normally located placenta, fetal distress, uterine rupture. In case of careful and skilled performance of external cephalic version of the fetus, the complication rate does not exceed 1%.

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The course and tactics of labor management in transverse fetal position

Childbirth in the transverse position is pathological. Spontaneous delivery through the natural birth canal of a viable fetus is impossible. If labor begins at home and the woman in labor is not sufficiently monitored, complications may begin already in the first period. In the transverse position of the fetus, there is no division of the amniotic fluid into anterior and posterior, so untimely rupture of the amniotic fluid is often observed. This complication may be accompanied by prolapse of the umbilical cord loops or the fetal arm. The uterus, deprived of amniotic fluid, tightly fits the fetus, and an advanced transverse position of the fetus is formed. During normal labor, the fetal shoulder descends deeper and deeper into the pelvic cavity. The lower segment is overstretched, the contraction ring (the border between the body of the uterus and the lower segment) rises upward and takes an oblique position. Signs of a threatening rupture of the uterus appear, and in the absence of adequate assistance, it may rupture.

To avoid such complications, 2-3 weeks before the expected birth, the pregnant woman is sent to an obstetric hospital, where she is examined and prepared for the end of pregnancy.

The only method of delivery in the transverse position of the fetus, which ensures the life and health of the mother and child, is a cesarean section at 38-39 weeks.

Classic obstetric version of the fetus on the leg

Previously, the operation of classical external-internal rotation of the fetus on the leg with subsequent extraction of the fetus was often used. But it gives many unsatisfactory results. Today, with a living fetus, it is performed only in the case of the birth of a second fetus in twins. It should be noted that the operation of classical obstetric rotation of the fetus on the leg is very complex and therefore, given the trends of modern obstetrics, is performed very rarely.

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Conditions for the operation of obstetric classical rotation

• full dilation of the cervix;
• sufficient fetal mobility;
• correspondence between the sizes of the fetal head and the mother's pelvis;
• the amniotic sac is intact or the water has just broken;
• live fruit of medium size;
• precise knowledge of the position and location of the fetus;
• absence of structural changes in the uterus and tumors in the vaginal area;
• consent of the woman in labor to the turn.

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Contraindications to performing the operation of obstetric classical rotation

• neglected transverse fetal position;
• threatened, incipient or completed rupture of the uterus;
• congenital defects in fetal development (anencephaly, hydrocephalus, etc.);
• fetal immobility;
• narrow pelvis (II-IV degree of narrowing);
• oligohydramnios;
• large or giant fruit;
• scars or tumors of the vagina, uterus, pelvis;
• tumors that interfere with natural childbirth;
• severe extragenital diseases;
• severe preeclampsia.

Preparation for surgery includes the activities required for vaginal surgeries. The pregnant woman is placed on the operating table in a supine position with her legs bent at the hip and knee joints. The bladder is emptied. The external genitalia, inner thighs and anterior abdominal wall are disinfected, the abdomen is covered with a sterile diaper. The obstetrician's hands are treated as for abdominal surgery. Using external techniques and a vaginal examination, the position, position, appearance of the fetus and the condition of the birth canal are studied in detail. If the amniotic fluid is intact, the amniotic sac is ruptured immediately before the rotation. Combined rotation should be performed under deep anesthesia, which should ensure complete muscle relaxation,

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The technique of the obstetric classical rotation operation includes the following stages:

• inserting hand into vagina:
• insertion of the hand into the uterine cavity;
• finding, selecting and capturing a leg;
• the actual rotation of the fetus and extraction of the leg to the popliteal fossa.

After the rotation is completed, the fetus is extracted by the leg.

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Stage I

Any hand of the obstetrician can be inserted into the uterus, however, it is easier to perform a turn when inserting the hand of the same position of the fetus: in the first position - the left hand, and in the second - the right. The hand is inserted in the form of a cone (fingers are extended, their ends are pressed against each other). The second hand is used to spread the genital slit. The folded inner hand is inserted into the vagina in the direct size of the outlet from the small pelvis, then with light screw-like movements it is transferred from the direct size to the transverse, simultaneously moving towards the internal os. As soon as the hand of the inner hand is completely inserted into the vagina, the outer hand is moved to the bottom of the uterus.

Stage II

The hand's advancement in the uterine cavity may be impeded by the fetus's shoulder (in the transverse position) or the head (in the oblique position of the fetus). In this case, it is necessary to move the fetus's head toward the back with the inner hand or grab the shoulder and carefully move it toward the head.

Stage III

When performing stage III of the operation, it should be remembered that today it is customary to perform a turn onto one leg. Incomplete foot presentation of the fetus is more favorable for the course of labor than complete foot presentation, since the bent leg and buttocks of the fetus represent a more voluminous part, which better prepares the birth canal for the passage of the subsequent head. The choice of the leg to be grasped is determined by the type of fetus. With an anterior view, the lower leg is grasped, with a posterior view - the upper. If this rule is followed, the turn is completed in the anterior view of the fetus. If the leg is chosen incorrectly, then the birth of the fetus will occur in the posterior view, which will require a turn to the anterior view, since posterior labor with breech presentations through the natural birth canal is impossible. There are two ways to find the leg: short and long. In the first, the obstetrician's hand moves directly from the side of the fetus's tummy to the place where the legs of the fetus are approximately located. The long way to find the leg is more accurate. The midwife's inner hand gradually slides along the side of the fetus's body to the sciatic region, then to the thigh and shin. With this method, the midwife's hand does not lose contact with the parts of the fetus, which allows for good orientation in the uterine cavity and the correct search for the desired leg. When searching for the leg, the outer hand lies on the pelvic end of the fetus, trying to bring it closer to the inner hand.

After finding the leg, it is grasped with two fingers of the inner hand (index and middle) in the ankle area or with the entire hand. Grasping the leg with the entire hand is more rational, since the leg is firmly fixed, and the obstetrician's hand does not get tired as quickly as when grasping with two fingers. When grasping the shin with the entire hand, the obstetrician places the extended thumb along the tibia muscles so that it reaches the popliteal fossa, and the other four fingers clasp the shin from the front, and the shin is as if in a splint along its entire length, which prevents its fracture.

Stage IV

The actual rotation is performed by lowering the leg after it has been captured. The head of the fetus is simultaneously moved to the bottom of the uterus with the outer hand. Traction is performed in the direction of the leading axis of the pelvis. The rotation is considered complete when the leg is brought out of the genital slit to the knee joint and the fetus has assumed a longitudinal position. After this, following the rotation, the fetus is extracted by the pelvic end.

The leg is grasped with the whole hand, placing the thumb along the length of the leg (according to Fenomenov), and the remaining fingers grasp the shin from the front.

Then traction is applied downwards, possibly using both hands.

Under the symphysis, the area of the anterior inguinal fold and the wing of the ilium appear, which is fixed so that the posterior buttock can cut through above the perineum. The anterior thigh, grasped with both hands, is lifted up, and the posterior leg falls out on its own; after the birth of the buttocks, the obstetrician's hands are positioned so that the thumbs are placed on the sacrum, and the rest - on the inguinal folds and thighs, then traction is applied to oneself, and the body is born in an oblique size. The fetus is turned with its back to the symphysis. 

Then the fetus is turned 180° and the second arm is removed in the same way. The fetal head is released using the classical method.

When performing an obstetric version, a number of difficulties and complications may arise:

• rigidity of the soft tissues of the birth canal, spasm of the cervical os, which are eliminated by using adequate anesthesia, antispasmodics, and episiotomy;
• handle falling out, handle coming out instead of the leg. In these cases, a loop is put on the handle, with the help of which the handle is moved away during rotation towards the head;
• uterine rupture is the most dangerous complication that can occur during rotation. Taking into account contraindications to the operation,
• examination of the woman in labor (determination of the height of the contraction ring), the use of anesthesia are necessary for the prevention of this formidable complication;
• prolapse of the umbilical cord loop after the end of the rotation requires mandatory rapid extraction of the fetus by the leg;
• acute fetal hypoxia, birth trauma, intranatal fetal death are common complications of internal obstetric version, which generally determine the unfavorable prognosis of this operation for the fetus. In this regard, in modern obstetrics, classical external-internal version is rarely performed;
• Infectious complications that may arise in the postpartum period also worsen the prognosis of internal obstetric version.

In case of advanced transverse position of the dead fetus, labor is terminated by performing a fetal-destroying operation - decapitation. After the classic turn of the fetus on the leg or after the fetal-destroying operation, a manual examination of the uterine walls should be performed.