A subgaleal hemorrhage (SGH) is a rare but potentially life-threatening birth injury involving bleeding in a specific layer of the newborn’s scalp. This condition is an accumulation of blood that occurs outside of the skull bone itself, but beneath the superficial layers of the scalp. Because infants have a relatively small total blood volume, even a moderate amount of blood loss into this space can quickly lead to severe complications. Immediate recognition and aggressive medical management are paramount to ensure the best possible outcome for the newborn.
Anatomy and Definition
Subgaleal hemorrhage is defined as a collection of blood within the potential space situated between the periosteum, which is the membrane covering the skull, and the galea aponeurotica, a dense, fibrous sheet of connective tissue in the scalp. This specific area is referred to as the subgaleal space.
The danger of an SGH stems directly from the unique anatomy of the subgaleal space. Unlike other scalp swellings, this space is continuous and is not constrained by the skull’s suture lines, allowing the hemorrhage to spread across the entire cranial vault. This lack of restriction means the area can hold a massive volume of blood, potentially sequestering up to 260 milliliters in a term infant. Since a newborn’s total circulating blood volume is approximately 80 to 90 milliliters per kilogram of body weight, a large hemorrhage can result in the infant losing a significant portion of their blood volume into their own scalp.
SGH is distinct from other common birth-related head swellings like caput succedaneum and cephalohematoma. Caput succedaneum is simply benign edema located in the outermost layer of the scalp, which resolves quickly and presents no risk of internal blood loss. A cephalohematoma is a collection of blood confined by the periosteum to a single skull bone, meaning its size is limited by the suture lines and it does not pose a risk of major blood loss.
Identifying Causes and Symptoms
The most frequent cause of subgaleal hemorrhage involves mechanical trauma to the newborn’s head during delivery. The immense shear forces applied to the scalp during a difficult or prolonged labor can rupture the emissary veins, which are small vessels that connect the veins of the scalp to the larger venous sinuses inside the skull. This rupture allows blood to pour into the large, unconstrained subgaleal space.
The single most common precipitating factor is the use of a vacuum extractor, or ventouse, during an assisted vaginal delivery. The suction cup creates a negative pressure that can cause the scalp to detach from the underlying periosteum, leading to the rupture of the emissary veins. While SGH can occur spontaneously, the risk is significantly higher with vacuum-assisted delivery, increasing the incidence rate up to 60 times.
The clinical presentation of SGH often begins with a soft, diffuse, and rapidly expanding swelling of the scalp that characteristically crosses the suture lines of the skull. This swelling may feel boggy or fluctuant, indicating the presence of fluid blood beneath the tissue. The most serious immediate symptoms are related to acute blood loss.
Signs of hypovolemic shock develop quickly as the infant’s circulating blood volume drops, presenting as pallor (a noticeably pale skin tone) and lethargy. The baby’s body attempts to compensate for the blood loss by increasing the heart rate, resulting in tachycardia, and a measurable decrease in blood pressure. These symptoms, combined with poor peripheral perfusion and a reduced level of consciousness, necessitate immediate emergency intervention.
Clinical Treatment and Stabilization
Due to the high risk of rapid blood loss and subsequent shock, the management of subgaleal hemorrhage requires immediate and aggressive intervention, typically within a Neonatal Intensive Care Unit (NICU). The primary goal of treatment is to restore the lost blood volume and stabilize the infant’s circulatory system. This process begins with rigorous monitoring, including continuous assessment of heart rate, respiratory rate, and blood pressure, often recorded hourly.
Fluid resuscitation is initiated promptly with intravenous (IV) fluids, such as normal saline, to rapidly expand the circulating volume and support blood pressure. If the baby shows signs of severe hemorrhagic shock, which is common in SGH, an immediate transfusion of blood products is often required. This aggressive replacement may involve packed red blood cells (RBCs) to address anemia and fresh frozen plasma (FFP) to aid in clotting.
Strict monitoring of the infant’s blood chemistry is also maintained, with frequent checks of hemoglobin and hematocrit levels to quantify the ongoing blood loss. Furthermore, a significant hemorrhage can consume the body’s clotting factors, leading to a condition called coagulopathy. If blood tests reveal clotting abnormalities, the medical team will treat this specifically with targeted blood products like FFP or cryoprecipitate to prevent further internal bleeding.
The size of the scalp swelling and the baby’s head circumference must be measured hourly for the first several hours to track the rate of bleeding. While most SGH cases are managed solely with supportive care and blood product replacement, the severity of the condition requires constant vigilance. The effective management of shock, acidosis, and any developing coagulopathy is absolutely necessary to prevent a catastrophic outcome.
Prognosis and Recovery
The prognosis for an infant with subgaleal hemorrhage is directly dependent on the speed and efficacy of the initial stabilization and treatment. For newborns who are diagnosed early and aggressively resuscitated to correct hypovolemic shock, the long-term outlook is generally favorable, with most infants recovering without permanent neurological consequences. The swelling itself typically begins to subside over a period of several weeks to a few months as the collected blood is reabsorbed by the body.
A significant potential complication that requires close follow-up is severe hyperbilirubinemia, or jaundice. As the large volume of blood collected in the subgaleal space breaks down, it produces a substantial amount of bilirubin that the newborn’s immature liver must process. If the bilirubin levels become excessively high, there is a risk of a rare but serious condition called kernicterus, which can lead to permanent brain damage.
Other serious complications are primarily related to the initial severity of the trauma, such as accompanying intracranial lesions or metabolic acidosis. Infants who experience severe, prolonged hypovolemic shock or who develop significant metabolic derangements are at a higher risk for neurological deficits. However, the majority of survivors who are stabilized quickly demonstrate normal development upon follow-up.