Cephalopelvic disproportion

Cephalopelvic Disproportion (CPD) occurs when a baby's head or body is too large to fit through the mother's pelvis. It is considered a potential obstacle to vaginal delivery, which may necessitate a Cesarean delivery. Understanding CPD involves knowledge of the maternal pelvis anatomy, fetal size, and the labor process.

Causes

CPD can result from several factors, either alone or in combination:

• Maternal Factors: These include a small or abnormally shaped pelvis, which can be due to genetics, injuries, or conditions like osteomalacia.
• Fetal Factors: A baby may be too large (a condition known as macrosomia) due to gestational diabetes, post-term pregnancy, or genetic factors. Abnormal fetal positions, such as breech presentation, can also contribute to CPD.
• Labor Factors: Ineffective uterine contractions can fail to move the baby into an optimal position for birth, contributing to CPD.

Diagnosis

Diagnosis of CPD is challenging and often made during labor when a failure to progress is noted. Methods to predict CPD include:

• Pelvimetry: Measurement of the pelvic dimensions through imaging or physical examination.
• Ultrasound: Estimation of fetal size and assessment of fetal position.
• Trial of Labor: Observing the labor process to determine if vaginal delivery is possible.

Management

Management strategies for CPD aim to ensure the safety of both mother and baby:

• Cesarean Delivery: Often the safest option when CPD is diagnosed.
• Labor Induction: May be attempted in some cases, but close monitoring is necessary to proceed to a Cesarean delivery if needed.
• Pelvic Exercises: Some evidence suggests that exercises to widen the pelvis may be beneficial, though their effectiveness is debated.

Complications

If not properly managed, CPD can lead to complications such as:

• Birth Injuries: To the baby, due to prolonged labor or difficult delivery.
• Maternal Injuries: Including tears or need for significant surgical intervention.
• Psychological Impact: The stress and disappointment of an unexpected Cesarean delivery can affect maternal mental health.

Prevention

Preventing CPD is challenging, as many factors are beyond control. However, maintaining a healthy pregnancy weight and managing conditions like gestational diabetes can reduce the risk of macrosomia. Regular prenatal care allows for monitoring of the baby's size and the mother's pelvis, facilitating early decision-making about delivery methods.

See Also

• Pelvimetry
• Macrosomia
• Cesarean section
• Gestational diabetes
• Breech presentation