Abstract: An injection spool for use in the injection of a fluid, for example a slurry of drilling cuttings, into a subsea wellhead assembly has an outer housing having a central bore therethrough. The housing has a first end for connection to a wellhead assembly such that the central bore of the housing is aligned with the central bore of the wellhead assembly. An inner housing, for example an isolation sleeve, having a central bore therethrough is disposed within the central bore in the outer housing, whereby a cavity is formed between the inner housing and the outer housing. A port in the outer housing has an opening into the cavity between the inner housing and the outer housing, through which a fluid may be injected. The inner housing has a portion extending from within the outer housing beyond the first end of the outer housing for forming a cavity within a wellhead assembly to which the injection spool is connected.