[1] Normally, no appeal lies from an interlocutory order which does not deprive the appellant of a substantial right which he would lose if the order or ruling is not reviewed before final judgment. Blackwelder v. North Carolina Dep’t of Human Resources, 60 N.C. App. 331, 299 S.E.2d 777 (1983). A court order requiring parties and their minor child to submit to blood grouping testing does not affect a substantial right and is, therefore, interlocutory and not appealable. Heavner v. Heavner, 73 N.C. App. 331, 326 S.E.2d 78, disc. review denied, 313 N.C. 601, 330 S.E.2d 610 (1985). In our discretion, however, we will address the merits of this case in order to expedite the decision in the public interest. See Person County ex rel. Lester v. Holloway, 74 N.C. App. 734, 329 S.E.2d 713 (1985).
[2J The sole issue before this Court is did the trial court err in ordering DNA or gene testing subsequent to an adjudication of paternity. We find that, based on the doctrine of res judicata, the order was entered in error and must be vacated.
It is fundamental that a final judgment, rendered on the merits, by a court of competent jurisdiction, is conclusive of rights, questions and facts in issue, as to the parties and privies, in all other actions involving the same matter. Bryant v. Shields, 220 N.C. 628, 18 S.E. 2d 157. “. . . (W)hen a fact has been agreed upon or decided in a court of record, neither of the parties shall be allowed to call it in question, and have it tried over again at any time thereafter, so long as the judgment or decree stands unreversed.” Humphrey v. Faison, 247 N.C. 127, 100 S.E. 2d 524, citing and quoting Armfield v. Moore, 44 N.C. 157.
Masters v. Dunstan, 256 N.C. 520, 523-24, 124 S.E.2d 574, 576 (1962).
The doctrine has been repeatedly applied in cases where there has been a judicial finding of paternity and the defendant subsequently raises the issue of paternity in an effort to avoid payment of child support. State ex rel. Lewis v. Lewis, 311 N.C. 727, 319 S.E.2d 145 (1984) (defendant estopped from challenging paternity when previous criminal conviction for willful neglect of and refusal to support children necessarily established paternity); see Sampson County Child Support Enforcement Agency ex rel. McNeill v. *773 Stevens, 101 N.C. App. 719, 400 S.E.2d 776 (1991) (original paternity judgment ruled res judicata in later contempt proceedings where a blood test was requested); Holloway, 74 N.C. App. 734, 329 S.E.2d 713 (reversal of trial court granting motion for blood grouping test where issue of paternity was determined at earlier hearing).
In the present case, upon motion of defendant, a blood grouping test was ordered and submitted to by the parties and the minor child. The trial court held the results of that test were sufficient to establish paternity beyond a reasonable doubt. Under existing case law defendant is precluded from raising that issue in subsequent hearings.
We hold that the trial court erred in ordering the parties to submit to DNA or gene testing, and we vacate that order.
Vacated.
Judges GREENE and MARTIN concur.