1 Introduction

Duplication of the gastrointestinal tract could occur anywhere along the entire gut [1]. The condition is uncommon with the incidence of 1:10,000 to 1:4500 births [1, 2]. Most patients were symptomatic during infantile or childhood, which 70% occurred before 2 years old [1]. Presentation could be abdominal pain, vomiting, hematochezia or palpable abdominal mass [3]. Rectal duplication was found in 5.5% of gastrointestinal duplication in children [4]. This condition is rarely presented in adult. We described an adult patient who had a duplicated rectum and review the related literature. The objective of this study was to emphasize the possibility of late presentation of congenital gastrointestinal defect, describe the diagnostic process and the operation.

2 Material and methods

2.1 Case presentation

A 42-year-female presented in 2015 with a 3-year-history of constipation. She explained that she had always felt bloated with frequent desires to defecate. However, the stool could not freely flow out. Occasionally, she got diarrhea of liquid stool. Sometimes only mucous and gas were produced. Her abdomen slowly enlarged. She reported that these symptoms started after the operation to remove her uterus a year before. At that time, an 8-cm myoma uteri was removed by total abdominal hysterectomy via low transverse incision. After the operation, she felt that the bowel had “no function”. Her constipation had been treated since 2012 with multiple laxatives including senna, bisacodyl, mebeverin, milk of magnesia, and prucalopride. Without improvement and increased abdominal bloating, she had limited her eating. Colonoscopy was considered, by a doctor in her primary hospital, in 2014 and could be performed up to transverse colon. This revealed normal colon with suspected colonic pouch near the rectum with impacted feces, and erythematous mucosa. Biopsy of the erythematous area revealed focal active colitis without specific organism, granuloma, dysplasia, or malignancy. She was diagnosed with impact feces and had been treated with rectal enema and combination of various laxatives. In 2018, her symptoms persisted that she visited our hospital which is a tertiary care center. Her timeline is shown in Fig. 1. Physical examination revealed a thin female with palpable large lobulated mass in lower abdomen. This mass was soft, bowel-loop-like and contained moldable fecal-like material.

Fig. 1
figure 1

Timeline of the treatment

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The initial plain abdomen was obtained revealing a huge area of soft tissue containing fecal shadow in the mid abdomen and pelvic cavity (Fig. 2). Further barium enema reveals a huge lobulated outpouching of left anterolateral wall of rectum, occupying almost entire abdominal cavity (Fig. 3). A diagnosis of duplicate rectum was made. Abdominal CT scan was performed to assess the surrounding structure as shown in Fig. 4. The chronic progressively enlarged duplication part causing the perineal bulging and posterior displacement of the anus (Fig. 5) could be demonstrated by physical examination. Anorectal manometry revealed normal resting and squeeze pressure, dyssynergic defecation type I (paradoxical contraction of anal sphincter during attempted defecation), rectal hyposensitivity, and delayed rectoanal inhibitory reflex. Balloon expulsion time was more than 5 min (Table 1). Her laboratory test including thyroid function test were normal (Table 2). After sequential fecal disimpaction under sedation and a few attempts of bowel preparation, colonoscopy was successfully performed up to terminal ileum. This revealed a normal colon with a second rectal pouch of 30-cm long which connected to the so-called native rectum. Mucosa was mildly inflamed without area of suspicion of malignancy (Fig. 6). The operation was performed via low midline incision which exposed an enlarged rectal duplication (Fig. 7a, b). After dissection and mobilization of the duplication part from the native rectum and surrounding tissue, controlled enterotomy to remove the fecaloma (Fig. 7c) was carried out. Division and closure of the neck of the duplication using linear cutter was performed (Fig. 7d). Leakage was checked. After pelvic irrigation, Jackson-Pratt drain was placed, and protective loop sigmoid colostomy was created. The patient recovered uneventfully. The pathology of the removed pouch revealed a 20 × 14x9 cm unilocular cystic lesion lined with colonic mucosa with mucosal ulceration, acute and chronic inflammation, inflammatory polyps, and crypts distortion. Complete colonic muscular layers and serosa were demonstrated. There was no granuloma, organism, dysplasia or malignancy. Ganglion cells were presented.

Fig. 2
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Plain abdomen. There was a huge area of soft tissue density containing feces in the mid abdomen and pelvic cavity, displacing small bowel and colon upwards and to the left

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Fig. 3
figure 3

Barium enema of the rectal duplication. A large lobulated rectal duplication containing fecal material with an opening at left anterolateral aspect of rectum about 5.6 cm from anal verge. The neck of opening was 1.5 cm. a lateral view, b anterior view, c entire view, d post-evacuation, N: native rectum

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Fig. 4
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Computerized tomography of abdomen. Large rectal duplication was anterior to the native rectosigmoid area. Note the white star, the extension of the duplication part into the vagina and perineum

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Fig. 5
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Perineal examination. V: vagina with cystic bulging part, P: bulging perineum, C: posteriorly displaced anus

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Table 1 Anorectal manometry findings
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Table 2 Laboratory test
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Fig. 6
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Colonoscopic findings

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Fig. 7
figure 7

Operation. Low midline incision was used to access the rectal duplication and disconnected it from the native rectum. a rectal duplication exposed through lower midline incision, b the mass extended up to transverse colon, c fecaloma inside the rectal duplication, d diagram of rectal duplication before (star) and after removal, Rd: Rectal duplication

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To correct the dyssynergic defecation, a course of biofeedback was successfully administered in a period of 1 month. Three months later, loopography was obtained (Fig. 8). Complete evacuation of barium was confirmed. Thus, the sigmoid colostomy was reversed. The patient has been doing well with occasional use of osmotic laxative. Currently, it is the 8th year after surgery.

Fig. 8
figure 8

Loopgraphy. Reveal no leakage, normal colorectal lumen without obstruction. Post evacuation shows complete evacuation with minimal residual amount of contrast material

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3 Results and discussions

Rectal duplication is a congenital abnormality and is likely symptomatic during childhood. The accepted etiology was proposed by Lewis and Thynge that the diverticular usually presented in fetal gastrointestinal tract and some of them might not regress [5]. The second possibility is a failure to completely vacuolize the gastrointestinal lumen during the solid phase [3, 6].Other explanations could be the detachment of epithelial lining of the elementary tract during development, split notochord syndrome, or intrauterine events resulting in a cyst or diverticulum [1, 5]. According to development, the duplication could be a part of caudal duplication syndrome with hindgut twinning [6, 7] which associated abnormalities of urogenital organs and spinal cords could be seen. With these explanations, two types of duplication could be found; tubular type and cystic type [3]. The tubular type usually communicates with the gastrointestinal lumen while the cystic type usually completely separate from the lumen [3]. There are 3 characteristics of gastrointestinal duplication which Ladd had described; (1) there is continuity or close adherence to some part of native gastrointestinal tract (2) the duplicated part has a smooth muscle coat, usually of two layers, and (3) the internal lining is the gastrointestinal mucosa [8].

In adult, rectal duplication could be asymptomatic and found incidentally during screening colonoscopy [9] or imaging for unrelated problem [10]. Presentation as asymptomatic buttock mass or perineal hernia had been reported [11, 12]. It could cause chronic abdominal pain [13] pelvic pain [14,15,16], and/or perianal pain [14, 17]. Some patients presented with rectal bleeding [16, 18, 19]. Many presented with recurrent anorectal infection [17, 19, 20] which was intractable to multiple surgical drainage. Some patients complained of abnormal anorectal function, including intractable diarrhea [6], symptoms of constipation, i.e. obstructed defecation [21], feeling of incomplete evacuation [22, 23], and colonic obstruction [24]. Some patient presented with nonspecific intrarectal discomfort [18]. Age at presentation ranged from 26 years old to 79 years old. Most patients did not have associated anomalies but a few had concomitant imperforated anus [25], renal agenesis and congenital hip dislocation [17], and sacral agenesis [20]. Most of the rectal duplication had no communication with the so-called native rectum. However, 20% of the cases, the communication presented [26]. In these cases, symptoms of obstructed defecation [21] and fecal impaction [23] could occur. In our case, the connecting channel was as wide and thus the fecal material had entered the pouch. This might lead to feeling of incomplete evacuation and later on the enlarged pouch containing “large fecaloma” had cause external compression to the rectum itself. Prior to hysterectomy, the enlarged myoma might occupy the pelvic cavity and squeeze the duplicated rectal pouch narrowing its space. This could explain the worsening of constipation after total hysterectomy.

Diagnosis of rectal duplication is usually confirmed by radiological imaging. Plain abdomen may demonstrate abnormal bowel gas pattern. Contrast enema is useful for demonstration of connection to the main rectum and determine the anatomy of the so-called native rectum and colon. In cases with palpable mass, CT scan or MRI is likely obtained. This would show the smooth, fluid-filled round or tubular structure and relation with the surrounding structures and possible presence of multiple duplication [1]. MRI is particularly useful if the rectal duplication is in the retrorectal space and needs to be differentiated from other retrorectal tumor [27, 28]. Transabdominal or transanal or endoscopic ultrasound could demonstrate the uniloculate/multiloculate cyst with presence of inner hyperechoic and outer hypoechoicmuscular wall [9, 26]. There were reports of adenocarcinoma occurring in the rectal duplication [29,30,31,32,33]. Colonoscopy was used to evaluate the gastrointestinal symptoms and to rule out associated malignancy.

Surgical removal of the duplication is recommended to get rid of the symptoms, prevent complications, and avoid the risk of malignancy. Surgical treatment is needed to relieve the patient’s symptoms, reduce the risk of malignant degeneration [34] and prevent additional complications [1]. Complete excision of the cyst could be performed transanally [16, 18], transperineally [13, 17, 20], laparotomy [6, 14], posterior sacral approach [12, 22], combination of anterior laparotomy and posterior approaches [11], or combination of anterior laparotomy and transperineal approach [24]. Laparoscopy could be used to confirm the diagnosis and subsequently removal of the cystic mass [25, 35]. During the cyst removal, care should be taken to preserve the blood supply to native rectum [1]. Due to the proximity of the wall of the duplication part to the wall of native rectum, removal of both may be warranted [19, 21]. Robotic surgery could be applied in these cases [10]. Partial removal of the cyst could lead to recurrence [14]. In our patient, removal of only the duplicate pouch was considered in order to preserve the function of the native rectum and there was no evidence of malignancy. However, the connection channel was large and there was concerned of leakage so that the protective sigmoid colostomy was performed. Associated dyssynergic defecation could be corrected before the closure of ostomy. After re-continuation of the colorectal tract, the patient could return to normal bowel habit again.

4 Conclusion

Duplication of rectum in adulthood is uncommon. A large duplication with connection to native rectum could lead to complaint of constipation and fecal impaction. Multi-disciplinary approach to assess both anatomical and physiological functions would bring the patient to appropriate outcomes.