Internal Rectal Prolapse

Internal rectal prolapse (occult prolapse) is intussusception of the rectal wall that does not protrude through the anus. The rectal wall folds downward within the rectal lumen or anal canal, so this article addresses diagnosis and treatment.

The clinical aim is to establish whether the finding explains the patient's symptoms. Defecography findings are common in people with no complaint, and a high-grade lesion and a difficulty evacuating are the features that link the two. The condition forms part of pelvic floor disorders, and often coexists with a rectocele, an enterocele, perineal descent or rectal hyposensitivity.

• Obstructed defecation: prolonged straining, a feeling of blockage, need to splint the perineum or vagina, and incomplete evacuation
• Frequent unsuccessful toilet visits, rectal pain, mucus and tenesmus
• Rectal bleeding and soiling from the lesion at the leading edge
• Examination: a normal anus at rest, with a fold felt on digital examination when the patient strains
• Red flags: bleeding and a change in bowel habit in patients over 50, weight loss, and a palpable mass

1. Dynamic MRI defecography or evacuation proctography: infolding of the rectal wall during straining or evacuation, with a measure of its depth and level (whether it enters the anal canal), the thickness of the wall, retention of contrast, and pelvic organ descent.
2. Examination under anesthesia or proctoscopy with straining to show the fold.
3. Colonoscopy for a neoplasm, and flexible sigmoidoscopy with biopsy of a solitary ulcer (fibromuscular obliteration of the lamina propria on histology).
4. Anorectal physiology: manometry (resting pressure under 40 mmHg and squeeze increment under 50 mmHg suggest sphincter weakness), balloon expulsion test, and endoanal ultrasound.
5. Colonic transit study for slow transit.

1. Conservative treatment for at least 3 months is the first step:
   • Psyllium 3.4 g orally twice daily and macrogol 3350 17 g orally once daily.
   • Biofeedback therapy (6 to 12 sessions), pelvic floor retraining and toilet posture modification.
   • Glycerin suppository 4 g PR once daily as a stimulant when needed.
   • Treatment of solitary ulcer with a topical agent: mesalazine suppository 1 g PR once daily for 4 to 8 weeks, or sucralfate enema 2 g in 20 mL PR twice daily for 4 to 8 weeks.
2. Surgical selection: offered for a high-grade intussusception (full-thickness, entering the anal canal) with symptoms after failed conservative therapy:
   • Laparoscopic ventral mesh rectopexy (the standard operation), with a mesh anchored to the sacral promontory and fixed to the anterior rectal wall and the pouch of Douglas closed.
   • Resection rectopexy when slow transit constipation coexists.
   • Perineal operations (Delorme mucosectomy with plication, or stapled transanal resection) for frail patients.
   • Treat a concomitant enterocele or rectocele at the same operation when relevant.
3. Prophylaxis: cefazolin 2 g IV as a single dose before incision (3 g if over 120 kg), with metronidazole 500 mg IV as a single dose. Enoxaparin 40 mg SC once daily for 7 days.
4. Postoperative care: macrogol 3350 17 g orally once daily for 6 weeks, no heavy lifting for 6 weeks, and paracetamol 1 g orally every 6 hours.
5. Outcomes: about 70 to 90% report symptom improvement. Complications are mesh erosion (1 to 2%), persistent constipation, bleeding, sexual dysfunction and recurrence of up to about 10%.
6. Sacral neuromodulation or pelvic floor therapy is used for incontinence that remains after correcting the prolapse.

Follow-up at 6 weeks, 6 months and 12 months. Counsel on bowel habit, avoiding straining and long toilet times.