Risk factors and etiology
The leading cause of injuries is mechanical overload. There are a number of predisposing factors that significantly increase the likelihood of fetal trauma in the perinatal period.
The main risk factors include:
- Size mismatch: occurs in cases of an anatomically narrow maternal pelvis, as well as excessive or, conversely, insufficient fetal weight.
- Gestational age abnormalities: pronounced prematurity.
- Labor anomalies: precipitate or excessively prolonged labor.
- Malpresentation: various abnormalities of fetal presentation and position.
- Obstetric interventions: injuries may result from manual aids or manipulations, such as the application of obstetric forceps, version of the fetus to the foot, and other maneuvers.
Soft tissue and cranial bone injuries
Head injuries are divided into external (soft tissues and bones) and internal.
Damage to external structures:
- Caput succedaneum: represents edema and subcutaneous hemorrhages in the presenting part of the fetus. As a rule, this condition has no serious clinical significance and resolves spontaneously.
- Cephalhematoma: an accumulation of blood under the periosteum of the cranial vault. Its key morphological sign is strict restriction within the boundaries of a single bone (most commonly the parietal bone), since the periosteum is tightly fused with the cranial sutures. In rare cases, cephalhematoma may be complicated by suppuration. It is important to perform differential diagnosis with a skull fracture, which can also be accompanied by subperiosteal hemorrhage.
- Cranial bone trauma: rare in modern practice. Includes fissures, fractures, bone depression, as well as tears and ruptures of sutures (occipital, frontal, parietal).
- Epidural hemorrhages: form against the background of fractures and fissures of the cranial vault bones, less commonly due to a rupture of the middle meningeal artery.
Intracranial birth trauma: The main mechanism is the rupture of dural folds (duplicatures) and large veins.
- Tentorium cerebelli tear: the most formidable injury, accounting for 90–93% of all fatalities from birth trauma. Most commonly accompanied by massive subdural hemorrhage in the posterior and middle cranial fossae.
- Tears of the falx cerebri and superior cerebral veins are diagnosed significantly less often.
Spine and spinal cord trauma
Spine and spinal cord pathology during labor occurs 2–3 times more frequently than intracranial injuries.
Features of spinal trauma: Usually manifests as tears or stretches of intervertebral discs, avulsions of vertebral processes and bodies, as well as fractures. The typical localization of fractures is the VI–VII cervical vertebrae region. Morphologically, such injuries are almost always accompanied by massive hemorrhages into the surrounding soft tissues.
Features of spinal cord trauma: Injuries to the spinal cord itself are observed even more frequently than trauma to the bony framework of the spine.
- Pathogenesis: based not so much on mechanical rupture or crushing of tissues (though these are also possible) as on ischemia (impaired blood circulation) in the vertebral artery basin. This leads to combined damage to the brainstem, cerebellum, and cervical spinal cord.
- Clinical manifestations directly depend on the level of the lesion:
- Upper cervical segments: spinal shock or diaphragmatic paresis develops.
- C5–T1 level: various paralyses and pareses of the upper extremity occur.
- Thoracic region: characterized by pronounced respiratory disorders.
Peripheral nerve and clavicle injuries
In addition to the central nervous system, peripheral nerve trunks and the shoulder girdle are frequently subjected to mechanical impact.
Peripheral nerves:
- Facial nerve palsy is often associated with the application of obstetric forceps.
- Brachial plexus palsy occurs due to excessive finger pressure on the neck area or excessive traction during fetal extraction.
- Phrenic nerve palsy.
Microscopically, these injuries reveal tissue edema, perineural, and endoneural hemorrhages. Complete mechanical ruptures of nerve trunks with the formation of extensive hematomas are rare.
Clavicle fracture: This is one of the most common birth injuries. The nature of the damage is usually subperiosteal. The prognosis is favorable: with proper application of a fixing bandage, the bone completely heals by the end of the second week of the newborn's life.
Briefly: answers to topical questions
What types of intracranial hemorrhages occur in birth trauma?
Epidural and subdural intracranial hemorrhages occur in birth trauma.
- Epidural hemorrhages — form in fissures and fractures of the cranial vault bones, less commonly upon rupture of the middle meningeal artery.
- Subdural hemorrhages — often accompany a tentorium cerebelli tear and are localized in the middle and posterior cranial fossae.
What obstetric aids and manipulations can cause birth trauma?
Various instrumental and manual obstetric interventions can cause birth trauma.
- Application of obstetric forceps — can cause facial nerve palsy and cephalhematomas.
- Use of a vacuum extractor — leads to the formation of cephalhematomas.
- Version of the fetus to the foot — refers to risk factors for trauma.
- Breech extraction of the fetus (including extraction by the leg) — can be accompanied by excessive traction or pressure on the neck area, leading to brachial plexus palsy, as well as fractures of the humerus and leg bones.
Which long tubular bones, besides the clavicle, can fracture during birth trauma?
In addition to the clavicle, the humerus and leg bones can fracture during birth trauma.
- Humerus — fractures occur when delivery of the arm is difficult. The injury is most often localized in the upper and middle third of the diaphysis (can be complete or subperiosteal). Birth epiphyseolysis of the proximal end of the humerus is also distinguished.
- Leg bones — fractures occur during extraction of the fetus by the leg.
Such injuries are rare, but require serious treatment because, due to severe muscle tension in the newborn, they are usually accompanied by pronounced displacement of bone fragments.
How to distinguish a cephalhematoma from a caput succedaneum? Cephalhematoma "respects boundaries": it never extends beyond a single bone, as the periosteum is tightly attached to the sutures.
Class and exam questions
What is caput succedaneum and is it dangerous?
This is edema and subcutaneous hemorrhage in the presenting part of the fetus. As a rule, it is clinically insignificant and resolves quickly without sequelae.
Which intracranial injury most commonly leads to a fatal outcome?
The most common cause of death (90–93% of fatal cases) is a tentorium cerebelli tear, which leads to subdural hemorrhage.
Why is the spinal cord injured during labor if the spine remains intact?
The main mechanism of spinal cord injury is impaired blood circulation (ischemia) in the vertebral artery basin, rather than direct mechanical crushing.
What else to study on this topic
- Pathogenesis of meconium aspiration syndrome
- Formation of hyaline membranes in hypoxia
- Bronchopulmonary dysplasia in premature infants
- Persistent pulmonary hypertension of the newborn
- Differential diagnosis of cephalohematoma and skull fracture
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