Background An unexplained scalp swelling in under 1 year children are rare and particularly in nonmobile infants raises suspicion of non-accidental injury. We describe a case which presented with an unexplained scalp swelling in an 18 weeks baby.

Case report A 4 month old boy presented to ED with a swelling on the back of head. An 8 × 11 cm swelling on the vertex crossing the suture lines was noted. A CT scan of head showed a subaponeurotic fluid collection(SAFC). As no possible explanation of mechanism of injury was given in a non-mobile infant, it was felt that a non-accidental cause needed to be investigated, so Children social services were involved and the child was removed from the family and kept in a place of safety. On further enquiry from the neighbouring hospital, it was found that fetal scalp electrodes and kielland’s forceps were used before progressing to caesarian section. After reviewing literature it was felt, sub-aponeurotic fluid collection can have a delayed presentation following a birth trauma and the child protection order was retrieved.

Discussion Subgaleal or sub-aponeurotic haemorrhage can occur in immediate post-delivery period due to instrumental delivery or difficult delivery. SAFC is a very rare cause of scalp swelling which can have delayed presentation. Aisling¹ have reported 11 cases (7–11 weeks) and Wang² reported 9 cases of spontaneous SAFC (5 weeks to 9 months) who all had either successful vacuum assisted delivery or attempted vacuum deliver. In a series of 4 cases reported by schoberer³ the aspirated fluid from 3 cases was serosanguinous and interestingly re-accumulated in all 3 cases. SAFC resolves spontaneously without any treatment^1,2.

Learning points

• Sub-aponeurotic fluid collection is a rare cause of scalp swelling in infants which is fluctuant, ill-defined and not limited by sutures. It can have delayed presentation and resolves spontaneously.

• SAFC usually associated with vacuum or instrumental delivery or use of electrodes

• SAFC should be considered as differential diagnosis in safeguarding and information should be added to COREINFO