I have used
http://www.canine-pd-scan.co.uk/ four times-
1st time scanned as having 9 and 9 were born
2nd time scanned as 8 and 8 born
3rd time to crowded to count but guessed at 10 plus, - 10 born
4th time scanned with 5 and 7 born
so bang on 3 out of 4 times and the 4th bitch is a broad ribbed bitch and carries puppies right under the ribs.
I have also used her to scan bitches after whelping to check there empty.
Luckily she lives only 4 miles from so i go to the kennels.
I would recommend her 100%