Rectal duplication cyst in an adult with a history of imperforate anus: a diagnostic challenge

Abstract

Rectal duplications are rare congenital anomalies that represent 1%–6% of alimentary tract duplications. We report a case of a woman in her 50s who presented to our hospital with perianal pain and urinary retention. She had a history of imperforate anus repaired after birth and dynamic graciloplasty performed during her adulthood for faecal incontinence. Abdominal CT scan showed a fluid collection extending from the electrostimulator, placed in a subcutaneous pocket in the abdomen, to the rectouterine pouch. Infection related to the electrostimulator was assumed and, after a course of antibiotics without patient improvement, the electrostimulator was removed. The symptoms and the pelvic fluid collection persisted, and diagnostic laparoscopy was performed. Diagnosis of rectal duplication cyst was made intraoperatively, and the cyst was completely resected. Patient fully recovered after surgery. This is a rare case of a rectal duplication cyst presenting during adulthood and associated with imperforate anus.

Background

Duplications of the alimentary tract are rare congenital anomalies that can involve any segment of the gastrointestinal tract, from the mouth trough the anus. The paucity of reported cases makes it difficult to determine their incidence, but it is estimated that duplications of the alimentary tract are present in 1 in 4500 live births.¹ Although they can occur at any age, they are usually diagnosed during childhood.²

Rectal duplications represent 1%–6%^2–4 of the duplications of the alimentary tract and are frequently asymptomatic. When symptoms are present, they are often non-specific. The constellation of symptoms can be quite variable and may include pelvic and abdominal pain, constipation, large bowel obstruction, lower urinary tract symptoms and perianal abscess formation.² Advances in ultrasound and cross-sectional imaging made the diagnosis of these conditions easier, but there are still cases diagnosed intraoperatively.2 3 5 6 Once the diagnosis is made, surgical resection is usually recommended.^7–9

Because of the rarity and heterogeneous clinical presentation of rectal duplications, the diagnosis and selection of an adequate treatment might be difficult, hence the special interest of these entities. In this paper, we describe a case of a woman born with an imperforate anus and who was diagnosed with a duplication cyst of the rectum in her adult life.

Case presentation

A woman in her 50s attended the emergency department (ED) of our hospital for urinary retention and perianal pain. She had a history of imperforate anus repaired during the neonatal period. The patient suffered from faecal incontinence since her childhood, and, in her 40s, after failure of multiple conservative treatments for her incontinence, she went through a dynamic graciloplasty. Owing to anal pain, she stopped using the electrostimulatory system 3 years after the surgery. Both imperforate anus repair and dynamic graciloplasty took place in another institution. In the ED, perineal inspection revealed induration of the perianal skin at 07:00 hours in lithotomy position. Digital rectal examination showed anal stenosis. Neither tenderness nor bulging were felt during rectal examination. Pelvic examination showed posterior vaginal wall tenderness and a small opening through which a purulent exudate was draining. An abdominal CT scan revealed a fluid collection extending from the electrostimulator, placed in a subcutaneous pocket in the left inferior abdominal quadrant, to the left side of the rectouterine pouch. The patient was admitted to our department, where she completed a 7-day course of antibiotics with good clinical response. She was then referred to the hospital where the dynamic graciloplasty was performed, in order to remove the neurostimulator that at that time appeared to be the cause of an infection extending from the abdominal wall into the pelvic cavity. The neurostimulator was removed a week after the patient was discharged from our hospital, and there were no surgical complications to report.

Three months after the neurostimulator has been removed, the patient attended the ED due to intense perineal pain in the last 24 hours. Physical examination revealed a perianal orifice at 07:00 hours in the lithotomy position, compatible with the external opening of a fistula-in-ano. A CT scan showed a pelvic fluid collection posterior to the vagina and the uterus with 13×9 cm. The pelvic collection was drained in the operating room through cannulation of the external orifice described above. About 600 mL of a serous fluids were drained. There were no surgical complications, and the patient was discharged 4 days after surgery. Microbiological culture of the fluid showed no bacterial growth. Cytologic analysis was negative for malignancy.

Two weeks later, the patient attended to the ED due to abdominal pain in the last 2 days. No associated symptoms were present, including fever, nausea, vomiting or change in bowel habits. She showed hypogastric tenderness on physical examination. Complete blood count and blood chemistry tests were normal. A CT scan showed recurrence of the fluid collection posterior to the vagina and the uterus now with 11.5×8×7 cm (figures 1 and 2). We recommended that the patient be admitted to our service for pain management and further study of the pelvic collection. However, once the pain was relived after a few hours in the ED, patient preferred to be discharged home.

Figure 1.

CT scan of a patient with a duplication cyst of the rectum. Yellow arrow points to the rectum and orange arrow points to the cyst. The patient presented with perianal pain and urinary retention. Because she had a history of dynamic graciloplasty for faecal incontinence, this pelvic lesion was thought to be a fluid collection related to an infection of the electrostimulator located in the subcutaneous tissue of the abdominal wall. This CT scan was performed after removal of the electrostimulator.

Figure 2.

CT scan of a patient with a duplication cyst of the rectum. Yellow arrow points to the rectum and orange arrow points to the cyst. The patient presented with perianal pain and urinary retention. Because she had a history of dynamic graciloplasty for faecal incontinence, this pelvic lesion was thought to be a fluid collection related to an infection of the electrostimulator located in the subcutaneous tissue of the abdominal wall. This CT scan was performed after removal of the electrostimulator.

Three days after the discharge, patient went to the ED complaining of abdominal pain and urinary retention. Apart from hypogastric tenderness, physical examination was unremarkable. Complete blood count and blood chemistry tests were normal. A diagnostic laparoscopy was proposed to the patient. A cystic lesion was identified in the pelvis intraoperatively. Due to the seemingly benign nature of the lesion and its sterile and continuous recurrence, a decision was made to fenestrate the cyst. After opening the cyst, it could be seen that it was filled with a serous fluid and that its internal surface was lined with what appeared to be colonic mucosa (figure 3). The diagnosis of rectal duplication cyst was made, and the cyst was completely resected. The patient was discharged 6 days after surgery. There were no post-operative complications.

Figure 3.

Picture taken during the diagnostic laparoscopy of a patient presenting with a pelvic lesion anterior to the rectum. This image shows a duplication cyst of the rectum (yellow arrow) posterior to the uterus (black arrow). The cyst was fenestrated during surgery given its apparent benign nature. Complete resection of the cyst was performed laparoscopically.

The histopathological analysis of the surgical specimen confirmed the diagnosis.

Outcome and follow-up

After the surgery, patient’s symptoms disappeared. She no longer complained of abdominal or perianal pain, and there were no more episodes of urinary retention. After 6 months of follow-up, she remains asymptomatic.

Discussion

Alimentary tract duplications are defined based on pathological criteria. More than 80% are spherical cysts, with the remaining being tubular structures. They are located in or immediately adjacent to part of the gastrointestinal tract. They are usually found on the mesentery border of the alimentary tract, sharing a common muscular wall and vascular supply with it but having a separate mucosal lining. They may or may not have one or more communications with the lumen of the adjacent part of the gastrointestinal tract. Rectal duplications are very rare entities that represent only 1%–6% of all alimentary tract duplications.^2–4

Several theories have been proposed to explain the embryological basis of duplications of the alimentary tract: caudal twining,¹⁰ recanalisation defects,¹¹ split notochord,¹² persistent embryologic diverticula¹³ and environmental factors (trauma or hypoxia).¹⁴ However, no single hypothesis satisfactorily explains all duplications in all locations and all their associated anomalies.

The clinical presentation and the onset of symptoms of duplications of the alimentary tract are quite variable, with 67% of cases developing symptoms and being diagnosed before the age of 2.⁴ Improvements in prenatal screening ultrasound made the prenatal diagnosis more frequent.⁴ The signs and symptoms depend on the type and location of the duplication, and some cases may go unnoticed until adulthood. Rectal duplications can remain asymptomatic until later in life, and some cases are detected accidentally during imaging tests performed for another reason.² When present, symptoms may be related to local compression of the rectum, which can lead to constipation, rectal fullness or lower abdominal pain.2 3 15 16 Pain is typically vague and of long duration. Besides abdominal pain, back and perineal pain can also be present.^{2 16} Local mass effect may also result in lower urinary tract symptoms, such as dysuria, urinary frequency and urinary retention.^{3 16} Duplication cyst infection may manifest as perianal discharge, which is often erroneously attributed to perianal fistula or pilonidal disease.¹⁷ Depending on the size and location of the rectal duplication, some lesions can be felt during abdominal palpation or during rectal examination.^{3 16} Nevertheless, physical examination can be quite unremarkable.²

In the present case, patient complained of perianal and abdominal pain, and there was a history of recurrent episodes of urinary retention. On the first visit to the ED, physical examination showed an orifice on the posterior wall of the vagina with purulent discharge and induration of the perianal skin at 07:00 hours in lithotomy position. The patient had an history of a dynamic graciloplasty performed 10 years ago due to faecal incontinence after repair of imperforate anus. Neurostimulator was located in the subcutaneous tissue in the anterior abdominal wall, and the CT performed at the first ED visit showed a collection extending from the neurostimulator to the pelvic cavity. At that point, the diagnosis of an infection starting at the neurostimulator site and extending to the posterior aspect of the uterus and the vagina seemed obvious. Fistulisation of the pelvic collection into the vagina and the perianal region was thought to be the cause of the physical examination findings described above. The patient was put on antibiotics and the neurostimulator was removed. Three months after removal of the neurostimulator, patient sought for medical assistance due to perianal pain. Physical examination revealed a perianal opening at 07:00 hours in the lithotomy position, and a CT scan showed a pelvic collection posterior to the uterus and the vagina. It was assumed that the pelvic collection represented a remaining/recurrent fistulised abscess resulting from the neurostimulator infection. The collection was drained through the perianal opening. The fluid retrieved was not purulent but rather serous in nature. Microbiological culture was negative, and cytologic analysis did not show malignant cells. Recurrence of the pelvic collection along with the reappearance of symptoms about 2 weeks after the drainage procedure led us to perform a diagnostic laparoscopy. Diagnosis of a rectal duplication cyst was made intraoperatively, and the cyst was completely resected. Perhaps, in retrospect, either a fistulography or fistuloscopy after the drainage procedure could have helped in establishing the diagnosis.

This case shows that, despite cross-sectional imaging modalities now available, the diagnosis of rectal duplications can be difficult and often made intraoperatively.² The patient surgical history made the diagnosis even more challenging.

It is not uncommon that rectal duplication cysts are associated with other congenital anomalies, especially vertebral and genitourinary defects.³ In this case, patient was born with an imperforate anus. To the best of our knowledge, there is only another case of rectal duplication cyst associated with imperforate anus described in the literature.¹⁸

Complete surgical resection is the cornerstone in the management of rectal duplication for two reasons. First, most patients require surgical intervention for symptoms relief. Second, surgical resection of the rectal duplication eliminates the otherwise persistent risk of complications, such as bleeding, perforation and malignant degeneration.^7–9 Several surgical techniques have been previously described in the literature for the treatment of rectal duplications, including parasacral, transanal, perianal and abdominal approaches.^18–28 The size and location of the lesion, along with surgeon’s experience should be considered when choosing the operative technique, for there is no consensus about the best surgical approach.^{9 29–31} The parasacral approach may be appropriate for small lesions located posteriorly to the rectum; its major disadvantages are the risk of intraoperative pelvic haemorrhage and injury to the lateral pelvic nerves.^{19 29} Transanal excision may be convenient for small low-lying rectal duplications but can be technically challenging.^20–22 The anterior abdominal approach (open or laparoscopic) allows complete resection of large lesions located either posteriorly or anteriorly to the rectum with little morbidity,^23–29 and, if an anterior rectal resection is necessary, it can be performed from that same approach.²⁶ Given the anterior location of the lesion, its large size and surgeon’s expertise, the laparoscopic approach was considered adequate to completely remove the lesion. As aforementioned, there were no post-operative complications.

Patient’s perspective.

I was very anxious and sad during this period of my life. I was in pain, desperately seeking for medical help, and the doctors simply couldn’t tell what was wrong with me. I am happy that surgery established a diagnosis and fixed my symptoms. I hope that all doctors can learn something with my case and help other people with the same problem.

Learning points.

• Although rare, rectal duplication cysts can be a cause of pelvic and abdominal pain, constipation, large bowel obstruction, lower urinary tract symptoms and perianal abscess formation in the adult.

• Due to the paucity of cases and their heterogeneous clinical presentation, the diagnosis may be challenging and often made intraoperatively. Cross-sectional imaging studies and endoscopic ultrasound may be helpful in establishing a diagnosis.

• Surgery is the treatment of choice to avoid complications, especially malignant degeneration.

Ethics statements

Patient consent for publication

Consent obtained directly from patient(s).