A small pelvis is a major contributing factor in CPD. The small size of the pelvis may be the result of rickets in the early life of the mother, a genetic predisposition, or a pelvis that isn’t fully matured in a young adolescent.

When engagement doesn’t occur in a primigravida, a problem exists. This problem may be a fetal abnormality, such as a largerthan-usual head, or a pelvic abnormality, as in a smaller-thanusual pelvis. It’s important to note that engagement doesn’t usually occur in multigravidas until labor begins. In this situation, a previous delivery of a full-term neonate vaginally without problems is substantial proof that the birth canal is considered adequate.

If the pelvic measurements are borderline or just adequate, especially the inlet measurement, and the fetal lie and position are good, the woman’s practitioner or nurse-midwife may allow a trial labor to determine whether labor can progress normally. A trial labor may be allowed to continue if descent of the presenting part and dilation of the cervix are occurring. In other words, normal labor and delivery are occurring and no complications have been detected.

Because cesarean birth requires a surgical procedure, it can result in systemic effects, including thrombophlebitis from interference in the body’s natural stress response as well as alterations in body defenses, circulatory function, organ function, self-image, and self-esteem.

The skin is the first line of defense against bacterial invasion. When the skin is incised for a surgical procedure, as in cesarean birth, this important line of defense is automatically lost. In addition, if cesarean birth is performed after membranes have been ruptured for hours,
the woman’s risk of infection doubles. Of course, precautions should be taken to minimize the risk to the patient through strict adherence to sterile technique during surgery and the days following the procedure.

During cesarean birth, blood vessels are incised, a consequence of even the simplest surgical procedure. A surgical wound results in blood loss that, if extensive, can lead to hypovolemia and decreased blood pressure. When blood pressure decreases, inadequate perfusion of body tissues results, especially if the problem isn’t recognized and corrected quickly. The amount of blood lost in cesarean birth is relatively high compared with vaginal birth. Pelvic vessels are usually congested with blood needed to supply the placenta. When pressure is placed on these vessels, blood loss occurs freely. During a vaginal birth, a woman may loose up to 500 ml of blood. This loss increases dramatically to 1,000 ml with a cesarean birth.

Like any body organ, the uterus may respond to being manipulated, cut, or repaired with a temporary disruption in function. Pressure from edema or inflammation can occur as fluid moves into the injured area. This normal response can further impair function of the uterus. In addition, handling of the uterus may result in a decrease in its ability to contract, which can lead to postpartum hemorrhage. Because complications may not be evident during the procedure, close assessment of the uterus is required in the postoperative period as well as an assessment of total body function to determine the degree of disruption.

Surgical procedures almost always leave incisional scars that are noticeable to some extent afterward. In some situations, the resulting scar from a cesarean birth may be quite noticeable,
such as when a horizontal incision is performed across the lower abdomen. The appearance of this scar may cause the woman to feel self-conscious later. She may also experience decreased selfesteem. This decrease in self-esteem may stem from a belief that she’s marked as someone who can’t give birth vaginally.

Depending on the type of cesarean incision, a patient may be able to deliver vaginally after previously delivering by cesarean birth (VBAC), now known as trial of labor after cesarean (TOLAC). In 2010, American Congress of Obstetricians and Gynecologists (ACOG) updated its guidelines regarding TOLAC to determine which women can safely have a VBAC. Although there is an increased incidence with uterine rupture with TOLAC, the overall incidence of maternal mortality is higher in women undergoing cesarean section. However, VBAC remains an increasingly successful alternative to elective cesarean birth. The type of incision chosen depends on the presentation of the fetus and the speed with which the procedure can be performed. In general, there are two types of skin incisions: vertical or transverse (Pfannenstiel). Neither is indicative of the type of incision made into the uterus.

Cesarean birth is indicated when labor or vaginal birth carries an unacceptable risk for the mother or fetus, such as in CPD and transverse lie or other malpresentations. It may also be necessary if induction is contraindicated or difficult or if advanced labor increases the risk of morbidity and mortality.

The most common reasons for cesarean birth are:

Special tests and monitoring procedures provide early indications of the need for cesarean birth:

Caregivers must use their most effective communication skills to educate the patient and family. Allow the patient to ask questions, and educate the patient before each procedure is done and the rationale for any intervention. It is important to tell the patient what is being done, why it is being done, and what she may experience. Support of the significant other in the cesarean birth experience is also important. In preparation for cesarean birth, an anesthetic is administered. Patients may have general or regional anesthetic, depending on the extent of maternal or fetal distress. The woman is then positioned on the operating table. A towel may be placed under her left hip to help relocate abdominal contents so that they’re up and away from the surgical field. This can also assist in lifting the uterus off the vena cava, promoting better circulation to the fetus as well as maternal blood return.

In about one-tenth of labors, the fetal position may be posterior rather than the traditional anterior position. When this occurs, the occiput, assuming the presentation is vertex, is directed diagonally and posteriorly, right occipitoposterior or left occipitoposterior. In these positions, during internal rotation, the fetal head must rotate through an arc of approximately 135 degrees rather than the normal 90-degree arc.

This rotation through the 135-degree arc may not be possible if the fetus is above average in size or isn’t in good flexion or if contractions are ineffective. Ineffective contractions may occur in:

Most fetuses are in a breech presentation early in pregnancy. However, in approximately 97% of pregnancies, the fetus turns to a cephalic presentation by week 38. Although the fetal head is the widest single diameter, the fetus’s buttocks (breech), plus the lower extremities, takes up more space. The fundus, being the largest part of the uterus, promotes fetal turning so that the buttocks and lower extremities are within it. Additionally, some evidence suggests that a breech presentation is less likely to occur if a woman assumes a knee-chest position for approximately 15 minutes three times per day during pregnancy.

In a face presentation, the chin, or mentum, is the presenting part. Although this presentation is rare, when it does occur, birth usually can’t proceed because the diameter of the
presenting part is too large for the maternal pelvis. Face presentation is considered a warning sign because its cause is always some abnormality in the fetus or mother.

Transverse lie occurs when the fetus lays horizontal to the uterus. Because there’s no firm presenting part, a vaginal delivery isn’t possible.

Posterior positions tend to occur in women with these pelvic structures:

Breech presentation may occur for various reasons, including:

A fetus in a posterior position, instead of flexing the head as labor proceeds, may extend the head, resulting in a face presentation. The situations in which this occurs include:

Transverse lie occurs in these conditions: