The physical assessment of a newborn is a comprehensive process designed to identify any congenital or transitional issues. A systematic check of the circulatory system forms a major part of this examination, ensuring that the heart and blood vessels are functioning correctly. Checking the femoral pulse is one of the most direct ways to assess the integrity of a newborn’s systemic blood flow. The femoral pulse is felt in the groin, where the large femoral artery passes down into the leg, reflecting the circulation to the lower half of the body.
The Femoral Pulse Check in Routine Newborn Screening
The palpation of the femoral pulse is incorporated into the standard Newborn and Infant Physical Examination (NIPE), which is typically performed within the first 72 hours of birth. This simple, non-invasive screening tool is a routine component of the overall assessment of circulatory function. The check provides unique information about the systemic blood pressure and blood flow distribution.
The goal of this specific check is to compare the strength and timing of the pulse in the lower body with the pulse felt in the upper body, typically at the brachial or radial artery. A synchronous and equally strong pulse in both the arms and legs suggests an unobstructed flow of blood from the heart through the major arteries. This comparison is a powerful diagnostic indicator that can detect a physical barrier to blood flow.
The Primary Condition Screened: Coarctation of the Aorta
The most significant condition the femoral pulse check screens for is Coarctation of the Aorta (CoA). Coarctation is a congenital heart defect characterized by a localized narrowing of the aorta, the body’s main artery. This narrowing most commonly occurs in the aortic arch, often near the point where the ductus arteriosus connects.
The constricted segment acts as a physical bottleneck, impeding the flow of blood from the heart to the lower half of the body. Blood pressure builds up proximal to the narrowed area, which is why the blood pressure in the arteries supplying the head and arms remains high. Conversely, the blood flow supplying the trunk and legs is significantly reduced.
This difference in blood flow is directly reflected in the pulses, resulting in a femoral pulse that is noticeably weaker, diminished, or delayed when compared to the pulse felt in the arm. The clinical presentation of CoA is often delayed until the ductus arteriosus begins to close naturally in the first few days of life. While patent, the ductus can bypass the coarctation and supply blood to the lower body, masking the condition. Once the ductus closes, the full obstruction is realized, and the newborn can experience a rapid decline into shock and severe heart failure.
Assessing and Interpreting Pulse Quality
The assessment of the femoral pulse involves a simultaneous comparison with the brachial pulse in the arm to evaluate both the pulse quality and the timing of the wave. A normal finding is one where the femoral pulse is easily palpable, strong, and occurs at the same moment as the brachial pulse. The absence of a discernible pulse, or a pulse that is notably weak or thready, raises suspicion of a severe obstruction, such as CoA.
The presence of a delayed pulse, known as radio-femoral delay, is also a strong sign of coarctation. In contrast to a diminished pulse, a bounding femoral pulse can also be an important abnormal finding. A bounding peripheral pulse, which feels strong and forceful, may indicate conditions such as a large Patent Ductus Arteriosus (PDA). This finding is caused by a large volume of blood leaving the aorta during systole and a rapid drop in diastolic pressure.
Immediate Actions Following an Abnormal Finding
The detection of an abnormal femoral pulse, whether diminished, absent, delayed, or bounding, necessitates an immediate and systematic medical response. The initial step for confirmation is to obtain blood pressure readings in all four extremities—the right arm, left arm, and both legs. A significant difference in blood pressure, specifically a reading in the arms that is higher than in the legs, strongly supports the diagnosis of coarctation.
The definitive diagnostic tool is an echocardiogram, which uses ultrasound to visualize the heart structure and blood flow dynamics. Because a critical coarctation can lead to rapid cardiovascular collapse as the ductus arteriosus closes, immediate stabilization measures are often necessary. For infants whose systemic circulation is dependent on the ductus remaining open, an intravenous infusion of Prostaglandin E1 is started. This medication acts to maintain its patency and ensure adequate blood flow to the lower half of the body before surgical intervention can be performed.