The aim of the present prospective, double-blind, randomized study is to study whether laparoscopic anterior mesh rectopexy is as good as laparoscopic posterior rectopexy with respect to obstructive defecation afterwards.

Full-thickness rectal prolapse is defined as a "falling down" of the rectum so that it is outside the body. Rectal prolapse can only be treated by surgery.

The choice of procedure depends on the patient's general condition and is based on a clinical judgment. Usually, elderly, high-risk patients are treated by perineal procedures. All other patients are offered an abdominal rectopexy using open or laparoscopic techniques. The general principle for all abdominal procedures is to induce adhesions between the mobilised, elevated rectum and the presacral fascia.

At least 30%-60% develop long-term complications: Obstructive defecation, which may be related to peroperative trauma to rectums innervation. Sparing of the lateral stalks during the rectal mobilisation results in lower frequency of obstructive defecation afterwards, but also higher recurrence rate.

A nerve-sparing laparoscopic technique for rectal prolapse has been developed in Belgium: Laparoscopic anterior mesh rectopexy.

After this procedure, the rate of obstructed defecations afterwards has been reported to less than 10%, that is, much lower than observed after other procedures.

The functional results after this nerve-sparing laparoscopic technique should be compared to those after laparoscopic posterior rectopexy, i.e. the conventional laparoscopic method.

Inclusion Criteria:

• Patients with full-thickness rectal prolapse for whom the department otherwise would offer abdominal rectopexy according to the department's recommendation. That is, patient being fit for an abdominal rectopexy procedure.

Exclusion Criteria:

• Age below 18 years.
• Pregnancy or breast-feeding.
• Patients who do not speak or read Danish.
• Dementia or other psychiatric disease, i.e., inability to give informed consent.
• Recurrence of rectal prolapse.