*NICE guidelines on Medical management
1.5.9 Do not offer mifepristone as a treatment for missed or incomplete miscarriage.
1.5.10 Offer vaginal misoprostol for the medical treatment of missed or incomplete miscarriage. Oral administration is an acceptable alternative if this is the woman's preference[5].
1.5.11 For women with a missed miscarriage, use a single dose of 800 micrograms of misoprostol[5].
1.5.12 Advise the woman that if bleeding has not started 24 hours after treatment, she should contact her healthcare professional to determine ongoing individualised care.
1.5.13 For women with an incomplete miscarriage, use a single dose of 600 micrograms of misoprostol. (800 micrograms can be used as an alternative to allow alignment of treatment protocols for both missed and incomplete miscarriage[5].)
1.5.14 Offer all women receiving medical management of miscarriage pain relief and anti-emetics as needed.
1.5.15 Inform women undergoing medical management of miscarriage about what to expect throughout the process, including the length and extent of bleeding and the potential side effects of treatment including pain, diarrhoea and vomiting.
1.5.16 Advise women to take a urine pregnancy test 3 weeks after medical management of miscarriage unless they experience worsening symptoms, in which case advise them to return to the healthcare professional responsible for providing their medical management.
1.5.17 Advise women with a positive urine pregnancy test after 3 weeks to return for a review by a healthcare professional to ensure that there is no molar or ectopic pregnancy.*
So they probably are acting within the guidelines, but if you think the miscarriage may be incomplete I wouldn't wait 4 weeks to be rescanned. Maybe you need some worsening symptoms ??