In Froh v. Milwaukee Medical Clinic, S.C. (Ct.App. 1978) 85 Wis.2d 308 [270 N.W.2d 83], the trial court granted a physician's motion to dismiss at the conclusion of the defendant's evidence on the ground that the plaintiff's evidence did not sustain a cause of action for malpractice. The court of appeals reversed, holding that the motion should not have been granted and that the jury should have been instructed on the doctrine of res ipsa loquitur. The court stated: "The trial judge attempted to distinguish the application of res ipsa loquitur to the cases involving the failure to remove surgical tools and sponges from the insertion of a drain that is to remain in the incision after surgery is completed for therapeutic reasons. That distinction is invalid because it overlooks the medical testimony from Dr. Schmidt that presence of the drain for more than 7 days will result in infection. The attempted distinction also overlooks the testimony that the surgeon was unable to locate the drain or to account for its disappearance although it should have been removed within a short period of time after its insertion. ... We are clearly of the opinion that a layman is able to conclude as a matter of common knowledge that a Penrose drain of this type left inside the body of an individual beyond the time that it serves the purpose for which it was inserted will cause infection as occurred in this case as a result of the professional treatment herein. We are further of the opinion that a layman can have an opinion that the consequences of this professional treatment are not those which ordinarily result if due care is exercised in that the doctor testified that when drains are left within the body there is evidence that infection will result if they are in that body for a period of more than 7 days. This does not require medical expert testimony." (Froh v. Milwaukee Medical Clinic, S.C., supra, 270 N.W.2d at p. 86.)