According to your husbands report ,only 15% of his sperms are motile,that is,only they have the capability to move forward and cause conception.there are a many other factors into consideration which you have not mentioned from the report.
Scrotal doppler is done to see if there is presence of varicocele
.if necessary the doctor can take fnac(biopsy
A man's semen count can vary feom time to time.as for now , i advice your husband should consult a general surgeon
who will conduct a local examination on his testicles.if required he will advice you for a semen culture.your husband should involve in brisk walk for 30- 45 minutes each day and should wear loose underwears.this will help in improving the sperm count
Important- a semen analysis
should be conducted after atleast 3 days of abstinance and the sample should be processedwithin half an hour.if the sample was collected at home and later taken for test,chances are that the sample gets destroyed and gives false test report.in such a case ,a repeat examination should be done.