Complications after Surgical Correction of Anorectal Malformations

Hong Kong J Radiol 2020 Sep;23(3):176-84

 

 

¹ Department of Radiology, Saitama Children’s Medical Center, Saitama, Japan

² Department of Radiology, Keio University School of Medicine, Tokyo, Japan

³ Department of Pediatric Surgery, Nagoya University Graduate School of Medicine, Saitama, Japan

⁴ Department of Surgery, Saitama Children’s Medical Center, Saitama, Japan

 

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Congenital anorectal malformations (ARMs), also known as imperforate anus, affect approximately 1 in 5000 newborns.[1] These ARMs are classified as low, intermediate, or high types,1 with treatment based on this classification.[2] Although a variety of treatments are available for imperforate anus, almost all cases of low-type imperforate anus are managed with a one-step anoplasty immediately after birth.[2] [3] In contrast, although primary anorectal repair without a diverting enterostomy is performed in some patients with intermediate- or high-type imperforate anus,[3] [4] [5] almost all patients with these types are treated first with a diverting colostomy, then anorectoplasty.[3] [4] [5] Patients with ARMs are treated with anorectoplasty for complete repair of the ARMs, regardless of type. There are several other approaches similar to anorectoplasty for complete surgical repair of ARM.[4] [6] [7] [8] Currently, many surgical procedures, such as perineal anorectoplasty, sacroperineal anorectoplasty, abdominosacroperineal anorectoplasty, posterior sagittal anorectoplasty (PSARP),[6] anterior sagittal anorectoplasty (ASARP),[8] and laparoscopically assisted anorectoplasty (LAARP)[4] are performed for complete surgical repair of ARM. Despite advances in surgical procedures, there are possibilities of postoperative complications.

 

Reports on postoperative complications of surgical repair of ARMs have documented the involvement of pelvic organs (such as anus, rectum, urethra, and vagina) as well as cutaneous structures.[9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] Various imaging techniques, such as plain radiography, colonography, voiding cystourethrography, ultrasonography, computed tomography, and magnetic resonance imaging (MRI) can be used for diagnosis.[9] [11] [16] [18] [19] [21] [29] [30] Unlike surgeons, radiologists are often unfamiliar with ARMs and have little knowledge about the surgical procedures for their repair; to date, only one review article related to radiography has been published.[30]

 

The aim of this article was to familiarise radiologists with common complications of specific surgical approaches and ARM types, which would be useful in diagnosis and in assisting surgeons with the management of these complications. In this article, we provide a comprehensible description of the surgical procedures for radiologists, review previous literature, and summarise the incidence of complications. Moreover, we describe and discuss eight major postoperative complications specific to ARM, including anorectal prolapse, anal stenosis, urethral injury, posterior urethral diverticulum, adhesion of reconstructed vagina, leakage from suture lines, neurogenic bladder, and trocar site hernia.

 

Several surgical procedures are performed to repair ARMs. Innovative approaches such as PSARP by Peña and Devries[6] and LAARP by Georgeson et al[4] have been reported. The anterior or posterior perineal approach is selected according to fistula location and ARM type. The anterior perineal approach is usually selected in low-type or anovestibular ARM, and the posterior perineal approach is usually selected for intermediate-type ARM (Figure 1).

 

Figure 1. Schematic presentation of the surgical approaches for repair of anorectal malformation. (a) The pull-through can be performed via the abdominal, anterior perineal (anterior sagittal), or sacroperineal (posterior sagittal) approach. Posterior sagittal anorectoplasty or the sacroperineal approach comprises incising the posterior area of the anal site (dotted yellow line) and performing pull-through (yellow curved arrow). Anterior sagittal anorectoplasty involves incising the anterior area of the anal site (dotted blue line) and performing pull-through (blue curved arrow). The abdominal approach involves performing pull-through after abdominal incision (red arrow). Laparoscopy may be used instead of abdominal incision. (b) Low-type anorectal malformation with anovestibular fistula. In female patients with low-type anovestibular fistula, anterior sagittal anorectoplasty is usually selected as the surgical approach. Anterior sagittal anorectoplasty involves incising the anterior area of the anal site (dotted blue line), performing pull-through (blue curved arrow), and separating the anovestibular fistula (green arrow) from the vestibule. During anterior sagittal anorectoplasty, the fistula is identified without rectal incision under direct vision. (c) Intermediate-type anorectal malformation with rectourethral fistula. In male patients with intermediate-type anorectal malformation with rectourethral fistula, the posterior sagittal anorectoplasty or abdominal approach (including laparoscopically assisted anorectoplasty) is usually selected as the surgical approach. Posterior sagittal anorectoplasty or the sacroperineal approach involves incising the posterior area of the anal site (dotted yellow line), performing pull-through (yellow curved arrow), and separating the rectourethral fistula (green arrow) from the rectum. During posterior sagittal anorectoplasty, the rectum is incised from the dorsal side and the fistula is identified in the rectal lumen. The abdominal approach or laparoscopically assisted anorectoplasty involves performing pull-through from the abdominal side (red arrow) and separating the rectovesical fistula from the rectum. During laparoscopically assisted anorectoplasty, the fistula identified without incision of the rectum under direct vision. (d) High-type anorectal malformation with rectovesical fistula. In male patients with high-type anorectal malformation with rectovesical fistula, the abdominal approach (including laparoscopically assisted anorectoplasty) is usually selected as the surgical approach. The abdominal approach or laparoscopically assisted anorectoplasty involves performing pull-through from the abdominal side (red arrow) and separating the rectovesical fistula (green arrow) from the rectum. Surgical repair of anorectal malformation is divided into two steps: anoplasty and the pull-through step. Anoplasty involves creating a new anus at the correct site. This step is performed at the perineum (asterisks). The pull-through step entails moving the distal rectal pouch to the correct new anal site and anastomosing it with the distal anus. During pull-through, the fistula is separated from the anorectal tract.

 

There are several approaches for surgical repair of ARMs, and there are numerous reports on related complications. We reviewed previous reports on complications after surgery for ARM by the abdominal pull-through approach (Table 1 [17] [27]), PSARP (Table 2 [9] [12] [13] [15] [25] [26] [27] [31] [32] [33]), anterior sagittal anorectoplasty (Table 3 [20] [23]), and LAARP (Table 4 [10] [13] [24] [29] [31] [32] [33]). Previous reports that included multiple surgical approaches are excluded. The reports exhibit differences with respect to patient sex and ARM type. Therefore, the prevalence of each complication shows variations. Furthermore, while the incidence of the complications decreases with the improvement in surgical techniques and skills,[10] [15] [25] some complications still occur when the techniques are applied by highly skilled surgeons.

 

Table 1. Data in previous reports on complications after surgery for anorectal malformation by the abdominal pull-through approach.

 

Table 2. Data in previous reports on complications after surgery for anorectal malformations by posterior sagittal anorectoplasty.

 

Table 3. Data in previous reports on complications after surgery for anorectal malformation (not including laparoscopically assisted anorectoplasty).

 

Table 4. Data in previous reports about complications after surgery for anorectal malformation by laparoscopically assisted anorectoplasty.

 

Anorectal prolapse (Figure 2) is defined as anal prolapse >5 mm.[12] There have been no radiographic reports on anorectal prolapse, as this complication is clinically diagnosed. Anal prolapse has a significantly higher incidence in patients with a low quality of the levator ani muscle and in those with vertebral anomalies,[12] [22] and the frequency of this complication is also reported to be associated with surgical approaches as LAARP.[29] [31] [32] [34] High-type ARM is characterised by poor muscle quality, which may render anal prolapse an inevitable complication, with a higher likelihood of recurrence than in low-type ARM.[26] [35] It may be accidentally detected on an MRI requested to evaluate the levator ani muscle.[31] [36]

 

Figure 2. Anorectal prolapse. This male patient presented with a rectovesical fistula with high-type anorectal malformation at age 2 years. Laparoscopically assisted anorectoplasty had been performed as the second surgical repair at age 10 months. After the second surgical repair, anorectal prolapse occurred. Therefore, surgical repair (Gant-Miwa method) was performed at age 2 years. (a) T2-weighted sagittal magnetic resonance imaging showing rectal and anal depression from the pelvic floor to the distal side. Rectal prolapse is located at 7 mm (double headed arrow) from the skin around the anus [dashed line]. (b) Axial T2-weighted magnetic resonance imaging in a male infant aged 6 months with rectovesical fistula. It detects asymmetrical puborectalis muscle only on the left side (arrow), which cannot be clearly visualised.

 

Anal stenosis (Figure 3) may occur with all surgical procedures and ARM types, and it may be caused by ischaemia or inadequate dilation of the anus.[7] Ischaemic necrosis of the pull-through bowel is a technical problem caused by a reduction in vascular supply to the border after colon mobilisation.[17] In abdominal radiography after surgical repair of ARM, constipation rather than poor levator ani muscle function may be observed, but anal stenosis must still be considered.[36] [37]

 

Figure 3. Anal stenosis. This female patient presented with an anovestibular fistula with a low-type anorectal malformation at age 10 months. After surgical repair via perineal anoplasty, mucosal necrosis was observed. Severe constipation persisted and the patient was diagnosed with anal stenosis. Subsequent dilation was required. (a) Abdominal radiograph showing dilated rectum and colon. The rectum is full of faeces. (b) Colonography using barium revealed anal stenosis (arrow).

 

Urethral injury (Figure 4) during surgery has been found to occur more often in male patients with intermediate- or high-type ARM.[15] [38] To repair a rectourethral fistula, separation of the urinary tract from the rectum is required. Therefore, there is a risk of urethral injury while repairing such an ARM, which should be avoided by paediatric surgeons.[16] [19] To prevent injury to the urinary tract, an augmented-pressure distal colostogram before surgical repair is recommended.[15] [38]

 

Figure 4. Urethral injury. This male patient presented with rectourethral fistula with an intermediate-type anorectal malformation at age 1 month. Perineal anoplasty had been performed on the day after birth. During surgical repair, urethral injury occurred, and prolonged indwelling urinary catheterisation was required. (a) Voiding cystourethrography performed after surgical repair. Leakage of iodine contrast medium from injury site (arrows). This finding was not revealed in the preoperative voiding cystourethrography (not shown). (b) An indwelling urinary catheter was required and a voiding cystourethrography was performed after 3 years. Voiding cystourethrogram showing mild urethral stenosis (arrow).

 

Urethral injury (Figure 4) during surgery has been found to occur more often in male patients with intermediateor high-type ARM.[15] [38] To repair a rectourethral fistula, separation of the urinary tract from the rectum is required. Therefore, there is a risk of urethral injury while repairing such an ARM, which should be avoided by paediatric surgeons.[16] [19] To prevent injury to the urinary tract, an augmented-pressure distal colostogram before surgical repair is recommended.[15] [38]

 

Posterior urethral diverticulum (Figure 5) is more likely to occur in LAARP than in the other types of surgery.[10] This is important because it may result in dysuria, formation of urinary stones, infection, and malignancy.[10] [16] [18] [19] Meanwhile, some patients with posterior urethral diverticula may not exhibit any symptoms.[10] [16] [18] [19] Therefore, it may be accidentally detected on an MRI performed to evaluate the levator ani muscle.[31] [36] There have been some radiographic reports about posterior urethral diverticulum, and in some cases, posterior urethral diverticula could not be revealed using voiding cystourethrography, being detectable only using MRI.[10] [11] [16] [18] Histopathology of the excised mucosa of the cyst showed colonic mucosa and confirmed that cyst was indeed an enlarged residual rectourethral fistula.[16] To prevent posterior urethral diverticula, novel surgical approaches and enhanced surgical skills are required.[16] [19] [39]

 

Figure 5. Posterior urethral diverticulum. This male patient presented with an intermediate-type anorectal malformation at age 6 months and underwent laparoscopically assisted anorectoplasty as the second surgical repair. At age 2 years, magnetic resonance imaging was performed for evaluation of a cystic lesion anterior to the rectum, which was asymptomatic and incidentally detected using ultrasonography. Surgical resection was performed. (a) Axial T2-weighted image showing cystic lesion with high signal intensity between the rectum and bladder (arrow). (b) Sagittal fat-suppression T2-weighted image showing the oval lesion posterior to the urethra (arrow).

 

Although neurogenic bladder (Figure 6) is a complication of ARM repair,[15] [21] spinal anomalies commonly accompany ARMs.[35] Laberge et al[17] reported that three patients had prolonged poor bladder emptying and that these patients had severe sacral anomalies. However, determining whether the cause of neurogenic bladder is iatrogenic may be difficult. Follow-up regarding urological complications is important for management of patients with ARM.[40]

 

Figure 6. Neurogenic bladder and adhesion of reconstructed vagina. This female patient presented with a cloacal malformation at age 12 years. She had undergone surgical repair and vaginal reconstruction using the small intestine at age 1 year. After surgical repair, she developed a neurogenic bladder requiring clean intermittent self-catheterisation. Voiding cystourethrogram showing the bladder wall with several diverticula and a large volume.

 

Reconstruction of the vagina may be required in girls with cloacal malformation, which is classified as high-type ARM. Reconstruction of the vagina using the intestine has been previously reported,[41] with some patients requiring dilatation.[41] Partial adhesion (Figure 7) of the reconstructed vagina or uterus must be diagnosed early to reduce decline in quality of life of patients with ARMs.[41] Furthermore, some patients may require additional surgical repair.[42] [43] [44] [45]

 

Figure 7. The same female patient as Figure 6. (a) Vaginography performed at age 12 years showing adhesion within the reconstructed vagina. Vaginal stenosis was observed (arrow). (b) Vaginography after balloon dilatation showing that the proximal side of the vagina was dilated.

 

Leakage from suture lines (Figure 8), failed anastomoses, and perineal abscesses has been reported.[9] [10] [13] [14] Infection after operation is a common complication,[9] [10] [13] [14] [20] and the diagnosis of leakage from the suture line is important in determining the best treatment option. Leaks may be detected with colonography,[9] whereas only one report has included radiographic images.[9] Fistula repair can be achieved via colonostomy, antibiotic therapy, and spontaneous selfclosure. [9] [13] [14]

 

Figure 8. Leakage from suture line. This female patient presented with anovestibular fistula with a low-type anorectal malformation at age 1 year. She was discharged from the hospital after undergoing perineal anoplasty. Then, her buttocks began to swell because of an abscess. Colonography showing the presence of a fistula extending from the suture line to the skin. She underwent colostomy and antibiotic therapy was initiated. (a) Lateral radiograph with colonography using barium showing anorectal cutaneous fistula extending from the suture line (arrow). (b) Sagittal reformatted contrast computed tomography showing a low attenuation area surrounding an enhanced rim posterior to the rectum (arrow). In this lesion, gas was detected, and an abscess was identified.

 

LAARP is associated with trocar site hernia (Figure 9). Previous studies have shown that the incidence of this complication ranges between 1% and 10%.[24] [33] [46] [47] More than 90% of trocar site hernias are within 10 mm,[46] [47] and they have occurred in paediatric patients.[24] [33] Some cases may need surgical repair because of small bowel obstruction with strangulation caused by a port site hernia.[48] If this complication is detected, radiologists should evaluate the possibility of bowel strangulation. To prevent this complication, laparoscopic port closure is usually performed using different techniques.[49] [50] For radiologists, knowledge of trocar site hernia is important for early diagnosis.

 

Figure 9. Trocar site hernia. This male patient presented with a recto-prostatic-urethral fistula with a high-type anorectal malformation at age 8 months. Laparoscopically assisted anorectoplasty was performed as the second surgical repair at age 8 months. Five days after surgery, the patient developed abdominal distension. Ultrasonography and computed tomography scan showed evisceration on a 5-mm trocar site, for which surgical repair was performed. (a) Axial sonogram showing evisceration of small intestine at trocar site (arrow). (b) Contrast axial computed tomography image showing small intestine evisceration at the trocar site (arrow).

 

We have described eight complications after surgery for ARM. These complications involve the pelvic organs. Various imaging techniques are used to diagnose these complications. Although the incidence of these types of complications varies across reports, knowledge of their manifestation and treatment is important for radiologists.