Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Emergency symptoms such as severe bleeding, fainting, major breathing difficulty, coughing up significant blood, seizure, or sudden neurologic changes require immediate care.
Contact the oncology or trophoblastic disease team promptly for new vaginal bleeding, persistent cough, unusual headaches, abdominal pain, or a positive pregnancy test during surveillance.
Follow-up is an essential part of treatment.
Quantitative hCG tests are repeated until the level becomes normal and then monitored regularly for a defined period.
The schedule and length of monitoring depend on the diagnosis, risk category, treatment, and local protocol.
Routine follow-up visits may include a review of symptoms, physical examination, blood tests, and imaging when indicated.
Keep scheduled appointments even when feeling well, because an hCG increase may be the first sign that further evaluation is needed.
After the recommended follow-up period, future pregnancy is often possible.
A clinician may recommend early ultrasound and hCG testing in a later pregnancy.
Placental or pregnancy tissue may also be examined when clinically appropriate.
The article also says
Pregnancy raises hCG and can make it difficult to tell whether disease has returned.
Clinicians therefore usually recommend reliable contraception during the monitoring period.
The care team can discuss which method fits the person's health and preferences.
Every sign above is quoted from the sofidex article on Choriocarcinoma. If you are not sure, err upward — it is always reasonable to be checked.