Williams Manual of Pregnancy Complications, 23 ed.

CHAPTER 92. Injuries to the Fetus and Newborn

INTRACRANIAL HEMORRHAGE

Hemorrhage within the head of the fetus–infant may be located at any of several sites: subdural, subarachnoid, cortical, white matter, cerebellar, intraventricular, and periventricular. Intraventricular hemorrhage into the germinal matrix is the most common type of intracranial hemorrhage encountered and is usually a result of immaturity (see Chapter 90). Isolated intraventricular hemorrhage in the absence of subarachnoid or subdural bleeding is not a traumatic injury. Indeed, nearly 6 percent of otherwise normal newborns at term have sonographic evidence for subependymal germinal matrix hemorrhages unrelated to obstetrical factors.

Birth trauma is no longer considered a common cause of intracranial hemorrhage. The head of the fetus has considerable plasticity and may undergo appreciable molding during passage through the birth canal. The skull bones, the dura mater, and the brain itself permit considerable alteration in the shape of the fetal head without untoward results. However, with severe molding and marked overlap of the parietal bones, bridging veins from the cerebral cortex to the sagittal sinus may tear. Less common is rupture of the internal cerebral veins, the vein of Galen at its junctions with the straight sinus, or the tentorium itself.

Clinical Findings

There are little clinical neurological data available concerning infants suffering intracranial hemorrhage from mechanical injury. With subdural hemorrhage from tentorial tears and massive infratentorial hemorrhage, there is neurological disturbance from the time of birth. Severely affected infants have stupor or coma, nuchal rigidity, and opisthotonus.

Subarachnoid hemorrhage most commonly is minor with no symptoms, but there may be seizures with a normal interictal period in some and catastrophic deterioration in others. Head scanning using sonography, computed tomography, or magnetic resonance imaging not only has proven diagnostic value but has also contributed appreciably to an understanding of the etiology and frequency of intracranial hemorrhage. For example, periventricular and intraventricular hemorrhages occur often in infants born quite preterm (see Chapter 90), and these hemorrhages usually develop without birth trauma.

CEPHALOHEMATOMA

A cephalhematoma is usually caused by injury to the periosteum of the skull during labor and delivery, although it may also develop in the absence of birth trauma. The incidence is 1.6 percent. Hemorrhages may develop over one or both parietal bones. The periosteal edges differentiate the cephalohematoma from caput succedaneum (Figure 92-1). The caput consists of a focal swelling of the scalp from edema that overlies the periosteum. Furthermore, a cephal-hematoma may not appear for hours after delivery, often growing larger and disappearing only after weeks or even months. In contrast, caput succedaneum is maximal at birth, grows smaller, and usually disappears within a few hours if small, and within a few days if very large. Increasing size of the hematoma and other evidence of extensive hemorrhage are indications for additional investigation, including radiographic studies and assessment of coagulation factors.

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FIGURE 92-1 Difference between a large caput succedaneum (left) and cephalohematoma (right). In a caput succedaneum, the effusion overlies the periosteum and consists of edema fluid. In a cephalohematoma, it lies under the periosteum and consists of blood. (Reproduced, with permission, from Cunningham FG, Leveno KJ, Bloom SL, et al (eds). Williams Obstetrics. 23rd ed. New York, NY: McGraw-Hill; 2010.)

SPINAL INJURY

Overstretching the spinal cord and associated hemorrhage may follow excessive traction during a breech delivery, and there may be actual fracture or dislocation of the vertebrae. Rotational forceps have also been associated with high cervical spinal injury.

BRACHIAL PLEXUS INJURY

These injuries are relatively common and are encountered in between 1 in 500 and 1 in 1000 term births. Increasing birthweight and breech deliveries are significant risk factors and are discussed in detail in Chapters 17 and 39.

Duchenne or Erb paralysis is incorrectly thought to occur only with large infants and shoulder dystocia. In reality, only 30 percent of brachial plexus injuries occur in macrosomic infants if defined as birthweight 4000 g or greater. These neurological lesions involve paralysis of the deltoid and infraspinatus muscles, as well as the flexor muscles of the forearm, causing the entire arm to fall limply close to the side of the body with the forearm extended and internally rotated. The function of the fingers usually is retained. The lesion likely results from stretching or tearing of the upper roots of the brachial plexus. Because lateral head traction is frequently employed to effect delivery of the shoulders in normal cephalic presentations, Erb paralysis can result without the delivery appearing to be difficult. Less frequently, trauma is limited to the lower nerves of the brachial plexus, which leads to paralysis of the hand, or Klumpke paralysis.

FACIAL PARALYSIS

Facial paralysis maybe apparent at delivery or it may develop shortly after birth. The injury can be caused by pressure exerted by the posterior blade of forceps on the stylomastoid foramen, through which the facial nerve emerges. Facial marks from the forceps may be obvious. The condition is also encountered after spontaneous delivery. Spontaneous recovery within a few days is the rule.

FRACTURES

Clavicular fractures are common, unpredictable and unavoidable consequences of normal birth. They have been identified in up to 18 per 1000 live births.

Humeral fractures are not common. Difficulty encountered in the delivery of the shoulders in cephalic deliveries and extended arms in breech deliveries often produce such fractures. Up to 70 percent of cases, however, follow uneventful delivery. Upper extremity fractures associated with delivery are often of the greenstick type, although complete fracture with overriding of the bones may occur. Palpation of the clavicles and long bones should be performed on all newborns when a fracture is suspected, and any crepitation or unusual irregularity should prompt radiographic examination.

Femoral fractures are relatively uncommon and usually associated with breech delivery.

Skull fracture may follow forcible attempts at delivery, especially with forceps; spontaneous delivery; or even cesarean section.

MUSCULAR INJURIES

Injury to the sternocleidomastoid muscle may occur, particularly during a breech delivery. There may be a tear of the muscle or possibly of the fascial sheath, leading to a hematoma and gradual cicatricial contraction. As the neck lengthens in the process of normal growth, the head is gradually turned toward the side of the injury, because the damaged muscle is less elastic and does not elongate at the same rate as its normal contralateral counterpart, thus producing torticollis.

AMNIONIC BAND SYNDROME

Focal ring constrictions of the extremities and actual loss of a digit or a limb are rare complications. Their genesis is debated. Some researchers maintain that localized failure of germ plasm is usually responsible for the abnormalities. Others contend that the lesions are the consequence of early rupture of the amnion, which then forms adherent tough bands that constrict and at times actually amputate an extremity of the fetus.

CONGENITAL POSTURAL DEFORMITIES

Mechanical factors arising from chronically low volumes of amnionic fluid and restrictions imposed by the small size and inappropriate shape of the uterine cavity may mold the growing fetus into distinct patterns of deformity, including talipes or clubfoot, scoliosis, and hip dislocation (see Chapter 10). Hypoplastic lungs also can result from oligohydramnios.


For further reading in Williams Obstetrics, 23rd ed.,

see Chapter 29, “Diseases and Injuries of the Fetus and Newborn.”