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Labor and delivery is the physiological process by which a fetus, placenta, and membranes are expelled from the uterus, typically occurring between 37-42 weeks of gestation. This process involves three distinct stages: cervical dilation and effacement, fetal descent and delivery, and placental expulsion.
Labor is initiated through a complex interplay of hormonal signals including increased estrogen, prostaglandins, and oxytocin, along with mechanical factors such as uterine distension and fetal positioning. Uterine contractions become progressively stronger and more coordinated, causing cervical changes and facilitating fetal descent through the birth canal via cardinal movements including engagement, descent, flexion, internal rotation, extension, and external rotation.
Assessment of labor progress involves monitoring cervical dilation, effacement, and fetal station using the Bishop score and partogram to identify normal versus abnormal labor patterns. Key clinical considerations include fetal heart rate monitoring, maternal vital signs, pain management options, and recognition of complications such as dystocia, fetal distress, or postpartum hemorrhage that may require intervention.
Key imaging focus: Nodular liver surface, caudate hypertrophy, ascites, portal hypertension signs, varices