MumNWLondon you are absolutely right. Testing (of any sort really) should only be done where there is a clinical need (IE where it may change the management of the patient) and not 'on request'. Routine early scans are not offered through the NHS. Early scans are performed only under specific circumstances. The main ones are (and this might not be an exhaustive list):
-routinely in IVF pregnancy
-routinely for SOME women who have a history of recurrent early pregnancy loss (but it is NOT done for the majority as it is unlikely to be helpful for most)
-For any women who have bleeding and/or pain in early pregnancy, to exclude ectopic/ other abnormal pregnancy
The problems arise when scans are done TOO early - under 6-7 weeks the scan may well not give a useful result (it CAN, but if, for example, it shows no foetal pole or HB, you are no further forward - you don't know whether you have miscarried or if the foetus is still too early & small to detect). Thus women bleeding before 6-7 weeks are in an awful limbo situation where there is NO totally reliable way of knowing what is happening. Serial blood tests (serum Bhcg) can SOMETIMES help (a one-off test is next to useless), but the decision to take a woman at this stage to theatre to look for an ectopic pregnancy is still largely made on clinical grounds and not based on scan findings.
The final issue is that even if an early scan shows a healthy-looking pregnancy, there is absolutely no guarantee that it will continue like this. The vast majority of miscarriages occur before 12 weeks. Some missed miscarriages happen to women who have had a fine early scan, and no more warning signs after it.
I guess what I'm saying is that early pregnancy is a very uncertain time for everyone. If there is a clinical need (bleeding, pain etc), then a scan is mandatory. But they should not be offered 'for reassurance' in the absence of clinical need. They may make a woman feel more confident about her pregnancy, but they do not guarantee that everything will be just fine.