A 32-year-old multiparous woman undergoes vacuum-assisted delivery for arrest of descent at +1 station. After two pulls, the cup detaches from the fetal head. The obstetrician attempts reinsertion and achieves delivery after three more pulls. The neonate is born with a cephalohematoma and poor Apgar score (3 at 1 minute). Which investigation is most appropriate to evaluate for potential intracranial injury?

Explanation

## Investigation of Choice for Suspected Intracranial Injury After Traumatic Vacuum Delivery ### Clinical Context A failed vacuum cup detachment ("pop-off") followed by successful delivery after multiple pulls, combined with cephalohematoma and low Apgar score, raises concern for intracranial hemorrhage or traumatic brain injury in the neonate. ### Why Cranial Ultrasound is the Answer **Key Point:** Cranial ultrasound via the anterior fontanelle is the **first-line imaging investigation** for suspected intracranial hemorrhage in neonates. It is: - Non-invasive - Rapid (can be done at bedside) - No radiation exposure - Excellent sensitivity for intraventricular hemorrhage (IVH), subdural hemorrhage, and parenchymal injury - Can be repeated serially to monitor progression **Clinical Pearl:** In a neonate with poor Apgar score and cephalohematoma after traumatic delivery, cranial ultrasound should be performed urgently to rule out IVH or subdural hemorrhage, which may require intervention (e.g., neurosurgical consultation, management of hydrocephalus). **High-Yield:** The anterior fontanelle remains open in neonates (closes ~18 months), providing an acoustic window for ultrasound imaging. This makes cranial ultrasound the gold standard first-line imaging modality in the immediate postnatal period. ### Comparison of Neuroimaging Modalities in Neonates | Modality | Timing | Sensitivity | Radiation | Practicality | Indication | |---|---|---|---|---|---| | **Cranial ultrasound** | Immediate, bedside | High for IVH, subdural | None | Excellent | First-line for suspected intracranial hemorrhage | | Transcranial Doppler | Continuous monitoring | Assesses blood flow | None | Adjunct only | Not diagnostic; used for vasospasm assessment | | MRI brain | Delayed (hours to days) | Highest for parenchymal injury | None | Requires sedation/transfer | Reserved for detailed evaluation after acute phase | | CT head | Immediate | High for hemorrhage | Yes (radiation) | Requires transport | Avoided in neonates unless ultrasound non-diagnostic | **Mnemonic:** **CUSS** — **C**ranial ultrasound is the **U**rgent, **S**edation-free, **S**tandard first-line test in neonates. **Warning:** CT and MRI expose the neonate to radiation (CT) or require sedation (MRI), delaying urgent assessment. Avoid these as first-line tests in the immediate postnatal period.