Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
1
Is any of this happening now?
Call 911
Seek emergency medical help if a child or adult with a cystic hygroma has:
Difficulty breathing or severe noisy breathing
Blue, grey, or unusually pale lips or skin
Rapid neck or tongue swelling that is affecting the airway
Inability to swallow saliva, choking, or marked drowsiness
Other emergency signs, for anyone
Someone who is struggling to breathe, gasping, choking, or cannot get words out
Someone who has chest pain, tightness or pressure lasting more than a few minutes
Someone who has sudden weakness or drooping on one side of the face or body, slurred speech, or sudden confusion
Someone who is unconscious, or cannot be woken
Someone who is bleeding heavily and it will not stop with firm pressure
Someone who has had a seizure that will not stop, or does not wake up afterwards
Someone who has lips or skin that look pale, blue, grey or blotchy
Someone who you believe has taken an overdose or swallowed something poisonous
2
Is any of this happening?
Be seen today
Contact the care team urgently on the same day for rapid enlargement, new trouble swallowing, bleeding, fluid leaking through the skin, or signs of infection such as fever, redness, warmth, and increasing pain.
3
Does any of this apply?
Book an appointment
Arrange routine follow-up if the swelling is slowly changing, symptoms return after treatment, or the malformation begins affecting eating, speech, sleep, movement, or confidence.
Routine appointments also monitor stable malformations and determine whether repeat imaging is needed.
If cystic hygroma is found during pregnancy, keep planned fetal medicine and ultrasound appointments.
Contact the maternity unit about concerns such as reduced fetal movement, following the advice given for the stage of pregnancy.
Every sign above is quoted from the sofidex article on Cystic hygroma. If you are not sure, err upward — it is always reasonable to be checked.